B&W DM2A refurb's

[Audio Al]

Hello

Left home this morning to collect the speakers and 6 hours later home

Some photos as purchased
http://img.photobucket.com/albums/v240/bigboobs/IMG_2100.jpg
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2101.jpg
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2102.jpg

This speaker case has black marks in the grain of the veneer , not good cosmetically :(
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2103.jpg
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Both grills are very good and have the B&W badges

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http://img.photobucket.com/albums/v240/bigboobs/IMG_2104.jpg
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With the grill off
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2105.jpg
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Driver unit
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2106.jpg
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Not sure what this unit is ?
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2107.jpg
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Tweeter unit
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2108.jpg
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This wadding does not look original its like a giant scotchbrite / hard plastic sort of material ?
Any ideas
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2109.jpg
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The speaker front mounting plate is held in with cross head screws ?
Are these correct for the year as the tweeter screws are slot heads

Looks like they may have been got at / serviced at some point

I will get them wired up and have a listen and see if everything is working

Then tomorrow will take out the front plates and have a proper look inside

Any comments welcome :)

[Macca]

They look in good condition - those cabs wil come up good without too much hassle. Good job the grils are nice 'cause they are ugly buggers underneath aren't they? I'm guessing that weird 'circualar saw' driver is a supertweeter. You're gonna need some stands.

[Alex_UK]

The "Circular Saw" is the tweeter - Celestion HF1300 - the silver one is a Coles 4001G Super-Tweeter

[spendorman]

Stuffing is original and correct.

[Rare Bird]

I used a pair for a bit but prefered the smaller 'DM4'.

[DSJR]

I found the bass rather ill defined in comparison with the then new and similarly priced KEF 104ab's. having said that, a crossover refurb and a properly matched amp (Mini-T??? :lol:) will definitely work wonders here :)

[walpurgis]

The DM2A has a well damped 1/8th wavelength transmission line cabinet design, tuned to around 40Hz if I recall, so the bass should not be ill defined. Room acoustics and positioning are important with transmission line designs as they can be a bit prone to exciting resonances.

The odd looking "wadding" is acoustically transparent material and is just there to keep the long fibre wool wadding behind it in position.

As mentioned they definitely want stands.

[Audio Al]

http://img.photobucket.com/albums/v240/bigboobs/IMG_2120.jpg

[Jonboy]

crossover rebuilds can transform these speakers, really must dig mine out and have a fiddle :D

[walpurgis]

http://img.photobucket.com/albums/v240/bigboobs/IMG_2120.jpg

Have the kids been kicking footballs up against your ESLs Al?

[Audio Al]

Sadly thats the condition they were in when purchased :(

But the sound more than makes up for the cosmetics :D


May see if I can make some stretchy covers for them in a more acceptable colour to me ;)

[walpurgis]

Take the grilles off and 'dolly' out the kinks. Shouldn't be too hard.

They do sound nice. I had a pair. Had to rebuild the rectifiers in mine.

[Audio Al]

Take the grilles off and 'dolly' out the kinks. Shouldn't be too hard.


I did think of doing that but they have a printed pattern / texture to the grill and you would flatten this as well :(

[Audio Al]

Just found this on the web a review of the 35 year olds

" These speakers were manufactured in the '70s... yep, 35 years ago... Then, why this review? because their technology was very special, and still interesting.
The mid-bass was 7.5", huge magnet, cast frame, bextrene shallow cone.
They were loaded by a quarter-wave Transmission Line, and covered the spectrum up to 3kHz. The T.L., high crossover frequency, very thick baffle and Bextrene cone resulted in a very neutral, non-boxy sound, still excellent today. The efficiency was very low, though, and a powerful amplifier is required (100W per channel).
There were 2 dome tweeters, one 38mm and one 19m (above 14kHz). Dome tweeters were in their infancy, and use of 2 tweeters was logical at the time, but one 25~30mm modern dome tweeter today would provide a less harsh, more detailed sound.
I wonder if somebody ever modded a pair of B&W DM2a. Keeping the enclosure and the mid-bass, augmented by a modern top-quality dome tweeter with an adequate crossover, should be a killer combination.
It is a pity that T.L. are not used more often. The freedom from 'boxiness' and the possibility to produce very low bass from a mid-size woofer are exceptional. "

:D

[walpurgis]

Dunno where you got that info, but they are 1/8th wavelength lines, not 1/4. I spoke to John Bowers about his design when they were released.

[Macca]

You not thought about getting those ESL 57 refurbished, Al?

[Audio Al]

You not thought about getting those ESL 57 refurbished, Al?

Yes many times :)

Then I looked in my bank account and stopped thinking :lol:

[dowser]

Yes many times :)

Then I looked in my bank account and stopped thinking :lol:

Do yours have the wax potted EHT units? If so its a fairly easy DIY job to rebuild them with new caps and diodes. Assuming they are still stock then you are not hearing them anywhere near their best.

I have a spare pair here I always intended to rebuild and then sell on an exchange basis for old ones.

I'd recommend taking grills off, gently push out dings & wash them, check EHT units to see if they are wax potted & and clean all the dust off the panels (nappy wipes are good) - you can then also check panels for arc damage.

Richard

[seoirse2002]

Hello

Left home this morning to collect the speakers and 6 hours later home

Some photos as purchased
http://img.photobucket.com/albums/v240/bigboobs/IMG_2100.jpg
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2101.jpg
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2102.jpg

This speaker case has black marks in the grain of the veneer , not good cosmetically :(
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2103.jpg
.
Both grills are very good and have the B&W badges

.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2104.jpg
.
With the grill off
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2105.jpg
.
Driver unit
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2106.jpg
.
Not sure what this unit is ?
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2107.jpg
.
Tweeter unit
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2108.jpg
.
This wadding does not look original its like a giant scotchbrite / hard plastic sort of material ?
Any ideas
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2109.jpg
.
The speaker front mounting plate is held in with cross head screws ?
Are these correct for the year as the tweeter screws are slot heads

Looks like they may have been got at / serviced at some point

I will get them wired up and have a listen and see if everything is working

Then tomorrow will take out the front plates and have a proper look inside

Any comments welcome :)

Be interesting to see how you are going to get the cabinets back to normal....Ive got a pair that look like that lurking undercover in the garage and would be nice to refurb the wood:cool:

[seoirse2002]

Hello

Left home this morning to collect the speakers and 6 hours later home

Some photos as purchased
http://img.photobucket.com/albums/v240/bigboobs/IMG_2100.jpg
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2101.jpg
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2102.jpg

This speaker case has black marks in the grain of the veneer , not good cosmetically :(
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2103.jpg
.
Both grills are very good and have the B&W badges

.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2104.jpg
.
With the grill off
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2105.jpg
.
Driver unit
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2106.jpg
.
Not sure what this unit is ?
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2107.jpg
.
Tweeter unit
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2108.jpg
.
This wadding does not look original its like a giant scotchbrite / hard plastic sort of material ?
Any ideas
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2109.jpg
.
The speaker front mounting plate is held in with cross head screws ?
Are these correct for the year as the tweeter screws are slot heads

Looks like they may have been got at / serviced at some point

I will get them wired up and have a listen and see if everything is working

Then tomorrow will take out the front plates and have a proper look inside

Any comments welcome :)

just like that actually

[Audio Al]

I have removed the speaker front mounting plate to have a look inside :)

http://img.photobucket.com/albums/v240/bigboobs/IMG_2121.jpg

Looks like they have been mounted in several different ways , Red felt , Blue tack and evidence of spike marks
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2122.jpg
Tweeter rear
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2123.jpg
Super tweeter
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2125.jpg
The drive unit with a cloth cover over it ?:scratch:
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2126.jpg
Masses of wadding 3 different types
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http://img.photobucket.com/albums/v240/bigboobs/IMG_2127.jpg

This shows a date of 4 Jan 1974, fits in with the age of the speakers

Stephenson Blake and Co
Caslon Letter foundry
Sheffield

A bit of history re the company http://www.stephensonandblake.com/ , not sure why this would be stamped on the chipboard ? maybe early recycling of printing press cases ?

http://img.photobucket.com/albums/v240/bigboobs/IMG_2128.jpg

And shows initials GW , maybe the person who built these speakers :)

http://img.photobucket.com/albums/v240/bigboobs/IMG_2129.jpg

The crossover unit , Now I feel stupid :mental: don't know what any of it does :scratch:

Will have a look in the other one , I am assuming it will be the same :)
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[Rare Bird]

http://img.photobucket.com/albums/v240/bigboobs/IMG_2129.jpg

The crossover unit , Now I feel stupid :mental: don't know what any of it does :scratch:

.

You may well be suprised how many Audio companies had their woodworking jobs carried out in Sheffield ;)

The switch in the centre is an HF level switch, variable from -2 to +2.. the two fixing underneith are the speaker inputs.. The green jobbies are power resistors, the brown boxes are caps..The others are obviously Inductors.

Leave the inductors, rebuild the rest.

Might be an idea to check see if the Coles super tweeters are working..

btw: I used to have 'DM2a' Mk.II (Not DM2 Mk.II). I replaced the original X Over with an hardwired version, i retained the inductors but used Mills 'MRA-12' power resistors, Ansar 'Supersound' polyprops, bypassed the HF switch..High quality binding posts & wiring.

[synsei]

Super speakers these, the best I have ever owned. Disregarding financial limitations (which I can't sadly) it would take something really special to push my DM2's off their perch. As for them being inefficient, I disagree wholeheartedly. The Mini-T has no problems driving mine to insane levels whilst still keeping things clean and tight. Incidentally, mine are original DM2's without the HF pot :)

[spendorman]

Super speakers these, the best I have ever owned. Disregarding financial limitations (which I can't sadly) it would take something really special to push my DM2's off their perch. As for them being inefficient, I disagree wholeheartedly. The Mini-T has no problems driving mine to insane levels whilst still keeping things clean and tight. Incidentally, mine are original DM2's without the HF pot :)

The ones without the treble control have some subtle differences in the crossover and I believe that the HF1300 is connected in opposite electrical phase to the version with treble control. It is possible that the midrange of the ones without the treble control is better that the version with it.

I have several of each type of DM2/ DM2A

[synsei]

That's interesting to hear Alex. I've listened to several pairs of DM2a's and although there is very little difference, I do prefer the midrange on my DM2's by a smidgeon. I also find DM2a's to be a a tad brighter sounding, even harsh on some material.

[spendorman]

If anyone is interested I can dig out the crossover circuit diagrams for the DM2/DM2a.

Would not be tonight though. Probably tomorrow.

[walpurgis]

I distinctly recall seeing DM2s with a soft dome used as the super-tweeter, maybe an early version. I think it was an Audax unit, I believe IMF used the same unit in the TLS50, but in that speaker, used with an STC/ITT/Coles super-tweeter.

[synsei]

It would be good if someone could post up a step by step guide on what to replace on the crossovers as I can't read circuit diagrams. :eyebrows:

[Audio Al]

If anyone is interested I can dig out the crossover circuit diagrams for the DM2/DM2a.

Would not be tonight though. Probably tomorrow.


Yes please :)

[spendorman]

I distinctly recall seeing DM2s with a soft dome used as the super-tweeter, maybe an early version. I think it was an Audax unit, I believe IMF used the same unit in the TLS50, but in that speaker, used with an STC/ITT/Coles super-tweeter.

It was a soft dome, but not Audax, was a Heco (or Heyco, can't remember the spelling), very similar to the Peerless DT10HFC.

http://mxlml.home.xs4all.nl/projects.html

[spendorman]

Yes please :)


DM2/ DM2a info.

https://docs.google.com/file/d/0B2oWzw3IqVhlQklaWmlmS2lIOUU/edit

https://docs.google.com/file/d/0B2oWzw3IqVhlQndqdW9rQjBHSEk/edit

https://docs.google.com/file/d/0B2oWzw3IqVhlQ1ZpckEtZEVIeGs/edit

https://docs.google.com/file/d/0B2oWzw3IqVhlREVxdlVUY0RoNGc/edit

[Dingdong]

Those DM2a's don't look too shabby. Not sure what the veneer is (walnut) but I like it more than the normal teak ones you come accross.
If you want the bass to be tighter you will have to stuff a few watts up them. I briefly had a 200w Perreaux amp hooked up to mine and the bass was really bloody good. Sticking them on big chunky stands helps as well.

If you have a meter then check the Coles have not blown. Or just stick your ear up against them when playing music. They don't produce a lot of sound. New ones are still available from Falcon if they are dead.

I hope you enjoy them. I quite like mine. I've got one pair with the veneered front that look slightly prettier, a teaktastic pair that are currently in use, and a walnut pair in need of a little restoration.

[Audio Al]

DM2/ DM2a info.

https://docs.google.com/file/d/0B2oWzw3IqVhlQklaWmlmS2lIOUU/edit

https://docs.google.com/file/d/0B2oWzw3IqVhlQndqdW9rQjBHSEk/edit

https://docs.google.com/file/d/0B2oWzw3IqVhlQ1ZpckEtZEVIeGs/edit

https://docs.google.com/file/d/0B2oWzw3IqVhlREVxdlVUY0RoNGc/edit


Hello

I cant open the links ?

Get this message

You are signed in as XXXXX.XXXXX@ntlworld.com, but you don't have permission to access this item. You can request access from the owner or choose a different account.

[spendorman]

Hello

I cant open the links ?

Get this message

You are signed in as XXXXX.XXXXX@ntlworld.com, but you don't have permission to access this item. You can request access from the owner or choose a different account.



I will look in to that, if all else fails I can email them to you

[spendorman]

I have changed permissions, hopefully, should work now.

[Audio Al]

I have changed permissions, hopefully, should work now.


Working now

Thank you :)

[Audio Al]

You may well be suprised how many Audio companies had their woodworking jobs carried out in Sheffield ;)

The switch in the centre is an HF level switch, variable from -2 to +2.. the two fixing underneith are the speaker inputs.. The green jobbies are power resistors, the brown boxes are caps..The others are obviously Inductors.

Leave the inductors, rebuild the rest.

Might be an idea to check see if the Coles super tweeters are working..

btw: I used to have 'DM2a' Mk.II (Not DM2 Mk.II). I replaced the original X Over with an hardwired version, i retained the inductors but used Mills 'MRA-12' power resistors, Ansar 'Supersound' polyprops, bypassed the HF switch..High quality binding posts & wiring.


Might be an idea to check see if the Coles super tweeters are working..

Hi can you advise how to do this please ? :scratch:

[Rare Bird]

Hard wire on a board using the original as a guide..I use turret tags as below.. You'll have to decide what you want to do about the switch yourself..

http://www.hificollective.co.uk/catalog/turret-teflon-support-p-8317.html

btw: You crossover seems to have a slightly different layout to the one Alex provided! however you sould find all the value on each of the components on your boards.

[walpurgis]

Hi can you advise how to do this please ? :scratch:

To check the super-tweeter, just use a cheap meter to check continuity of the voicecoil. Ussuming it's an 8ohm impedance driver it'll measure around 6ohms DC. If the coil measures OK, the tweeter is probably fine.

If you want to get fancy, connect it to an amplifier via a 2mFd capacitor in series and play some white noise through it (interstation hiss from a tuner will do), not too loud though. You'll hear the hiss from the driver.

[Audio Al]

To check the super-tweeter, just use a cheap meter to check continuity of the voicecoil. Ussuming it's an 8ohm impedance driver it'll measure around 6ohms DC. If the coil measures OK, the tweeter is probably fine.

If you want to get fancy, connect it to an amplifier via a 2mFd capacitor in series and play some white noise through it (interstation hiss from a tuner will do), not too loud though. You'll hear the hiss from the driver.

Can I do this with the original wiring attached or unsolder and test not wired up ?

[spendorman]

To check the super-tweeter, just use a cheap meter to check continuity of the voicecoil. Ussuming it's an 8ohm impedance driver it'll measure around 6ohms DC. If the coil measures OK, the tweeter is probably fine.

If you want to get fancy, connect it to an amplifier via a 2mFd capacitor in series and play some white noise through it (interstation hiss from a tuner will do), not too loud though. You'll hear the hiss from the driver.

The DC resistance of the Coles 4001G should be around 23 Ohms.

I would not advise connecting a 2 uF capacitor in series with it and feeding the tweeter with audio. The tweeter is very delicate. A 0.5 uF would be safer.

[walpurgis]

The DC resistance of the Coles 4001G should be around 23 Ohms.

I would not advise connecting a 2 uF capacitor in series with it and feeding the tweeter with audio. The tweeter is very delicate. A 0.5 uF would be safer.

I was not aware that the version used in the DM2A is 23ohms, if so then a reading of around 17ohms would be what you require.

I've owned quite a few of the Coles/STC/ITT tweeters in various forms and not had any problems testing with 2mFd. However use a smaller value by all means, it does make it a bit harder to hear any output though. 2mFd was a value actually quoted for use in some project applications.

I'd suggest disconnecting the unit to test it.

[spendorman]

I was not aware that the version used in the DM2A is 23ohms, if so then a reading of around 17ohms would be what you require.

I've owned quite a few of the Coles/STC/ITT tweeters in various forms and not had any problems testing with 2mFd. However use a smaller value by all means, it does make it a bit harder to hear any output though. 2mFd was a value actually quoted for use in some project applications.

I'd suggest disconnecting the unit to test it.

Stated DCR is 23 Ohms. It is the so called 16 Ohm impedance unit. Same as in BC1, BC2, DM1, DM2, DM2a, DM3, DM4 etc.

http://www.falconacoustics.co.uk/coles-4001g-16-ohm-super-tweeter.html

http://www.coleselectroacoustics.com/drivece4100.shtml

[walpurgis]

Are you sure Alex?

I'm open to educating, but my understanding is that the DC resistance of moving coil drivers tends to be between 2/3 and 3/4 of the rated impedance.


Geoff.

[walpurgis]

Just found this, it may be of interest in this context.

http://www.transparentsound.com/measurements/Tomi_Engdahl.pdf

[spendorman]

Are you sure Alex?

I'm open to educating, but my understanding is that the DC resistance of moving coil drivers tends to be between 2/3 and 3/4 of the rated impedance.


Geoff.

Absolutely sure that the DC resistance of the STC/ Coles 4001G is 23 Ohms. I have measured many of them, including unused ones. 23 Ohms is stated by Coles and suppliers. A faulty 4001G can measure less than this due to shorted turns on the voice coil (quite common).

I referred to the 4001G as "so called 16 Ohm" as it's actual impedance is likely to be a fair more than 16 Ohms or 23 Ohms. I could measure this to find out a typical value.

I presume that STC called it 16 Ohms as it may have originally been intended for use in systems of overall impedance of 16 Ohms.

[Dingdong]

Absolutely sure that the DC resistance of the STC/ Coles 4001G is 23 Ohms. I have measured many of them, including unused ones. 23 Ohms is stated by Coles and suppliers. A faulty 4001G can measure less than this due to shorted turns on the voice coil (quite common).

I referred to the 4001G as "so called 16 Ohm" as it's actual impedance is likely to be a fair more than 16 Ohms or 23 Ohms. I could measure this to find out a typical value.

I presume that STC called it 16 Ohms as it may have originally been intended for use in systems of overall impedance of 16 Ohms.

This is correct. The 16ohm Coles do measure 22ohms. I've got a few dead ones. Only one of them died at my hands. They can be a bit delicate and don't like loud crackly noises up 'em.
The Celestion tweeters seem fairly robust though. As do the woofers.

I haven't bothered replacing any components on the crossovers. I reckon it could probably improve the sound, but at the expense of pair matching. Unless you can get matching components.

[Audio Al]

OK , This morning I disassembled the speakers :) ( that's the easy bit )

The rear of the switch has some crusty looking item fitted :scratch: not a clue what they are :scratch: cant read what is printed on them , may just make out 5 ohms ?

http://img.photobucket.com/albums/v240/bigboobs/IMG_0111.jpg
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http://img.photobucket.com/albums/v240/bigboobs/IMG_0112-1.jpg
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http://img.photobucket.com/albums/v240/bigboobs/IMG_0113.jpg
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http://img.photobucket.com/albums/v240/bigboobs/IMG_0115-1.jpg
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The speaker connecter plugs look to be good quality with heavy pins so I will retain these

http://img.photobucket.com/albums/v240/bigboobs/IMG_0116-1.jpg
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http://img.photobucket.com/albums/v240/bigboobs/IMG_0119-1.jpg
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http://img.photobucket.com/albums/v240/bigboobs/IMG_0120-1.jpg

The rear of the circuit boards

I am cacking myself re doing these :scratch: Just hope I dont ruin them :mental:

Time will tell :)

[walpurgis]

Those look like they are the tweeter level control resistors.

I think I can see 4R on one, probably 4ohm and the other marking looks like the tolerance percentage. Just give them a clean in situ with a softish brush, they get "crusty" looking sometimes but are normally OK. If you have a meter just check that the resistance measures approximately the same for the equivalent resistors on each crossover (they won't be exactly identical values).

You can get a cheap meter for about a fiver. Squirt some switch cleaner into the contact area of the rotary switch and work the control back and forth, but test the cleaner on a small area of any plastic it may contact first as some plastics dissolve.

The crossovers look basically sound and if you're not too happy about tinkering, don't! Just give them a quick clean and bung 'em back. If the speakers are working fine I'd not get too involved myself.

You'll probably find a cheap meter and an aerosol of switch cleaner at Maplins or on eBay. If you don't mind paying a few quid more get a meter that measures capacitance too, as that can be handy.

[spendorman]

The resistor values are stated here:

https://docs.google.com/file/d/0B2oWzw3IqVhlREVxdlVUY0RoNGc/edit

[Audio Al]

Off to Maplins later to see if I can get the components

Will I need a solder sucker ? suppose I will

Any thing else while I am there ?:)

[spendorman]

Off to Maplins later to see if I can get the components

Will I need a solder sucker ? suppose I will

Any thing else while I am there ?:)

Solder sucker, not a bad thing to have.

You need to know roughly the wattage of the resistors. At a guess, probably 6 Watt wire wound would be OK. Higher, fine, but no need for massive ones.

Perhaps some Servisol Super 10 switch cleaner/ lubricant.

Tin/ Lead solder possibly.

[Audio Al]

I just wasted 1 hour 40 mins of my life going to Maplin's :doh:

The did not have one item I needed capacitors or resisters in stock or listed in there electronics catalog

back to square one :scratch:

[spendorman]

I just wasted 1 hour 40 mins of my life going to Maplin's :doh:

The did not have one item I needed capacitors or resisters in stock or listed in there electronics catalog

back to square one :scratch:


Have you got a multimeter?

I would expect that the capacitors are still OK, probably the resistors too, even though they have that corrosion effect on them. Would be good to measure them though.

Strange, my friend bought quite a few different value wire wound resistors recently in Maplin Sheffield.

[Audio Al]

Have you got a multimeter?

Yes I have a Bosch digital unit

[spendorman]

Yes I have a Bosch digital unit

No problem checking resistors then, in some cases you will have to disconnect one side of the resistor first.

[Dingdong]

I just wasted 1 hour 40 mins of my life going to Maplin's :doh:

The did not have one item I needed capacitors or resisters in stock or listed in there electronics catalog

back to square one :scratch:

Have a look at RS. You can set your own account up and they normally deliver pretty quickly.
Also the green RS solder suckers, if they still sell them, are the best I've used.

[Audio Al]

Have a look at RS. You can set your own account up and they normally deliver pretty quickly.
Also the green RS solder suckers, if they still sell them, are the best I've used.


I am going to the shop tomorrow recommended

for electrical parts by maplins :mental:

http://directelectronicsuk.com/index.html

fingers crossed :)

[Dingdong]

Good luck with it. If you have a meter hat measures capacitance then I'd try to match up the cap values as close as possible. Tolerances can be around 10% on caps.

[walpurgis]

I'd test the component values before changing any.

B&W crossovers were designed with the sound quality in mind even back then and older capacitors and resistors etc. aren't necessarily inferior.

If you decide to change anything, but intend to retain the original circuit board (PCB), make sure the replacement can actually be fitted, as sizes and proportions vary. Use a bit of sleeving if there are going to be long sections of wire.

Be as gentle as possible with the PCB, as being a bit too energetic can lift the printed circuit track right off the board, as can using too much heat, too often.

I'd certainly recommend a bit of practise soldering if you're not used to doing it, as it can be tricky until you get familiar with it. I still cock it up now and then and I've been doing it all my life.

Your soldering iron needs to be a good'n. I use a Skytronic 703 260 dual heat range model, nominally 20 watts, but has a short term 130 watt capability at the press of a button, perfect for speaker soldering and use with silver solder.

[Audio Al]

Left home at 12 noon

Sat in a 4 mile traffic jam on the A13 , was going to Direct Electronics

Gave up and at the first opportunity to get off the A13 returned home

So that's 1 1/2 hours of my life wasted :rolleyes:

Its like madness on the roads ( Bloody Christmas ) :steam:

[dowser]

Register with farnell and order there, or get relevant bits off ebay?

Richard

[Audio Al]

Binding posts now on order

http://www.ebay.co.uk/itm/320688447341?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

:)

[spendorman]

Sorry, can't see the logic, that's nearly half the cost of the B&W's. Money better spent elsewhere, perhaps on new Coles 4001G's. Stiil, my opinion only.

[nat8808]

Left home at 12 noon

Sat in a 4 mile traffic jam on the A13 , was going to Direct Electronics

Gave up and at the first opportunity to get off the A13 returned home

So that's 1 1/2 hours of my life wasted :rolleyes:

Its like madness on the roads ( Bloody Christmas ) :steam:

If you're in that neck of the woods, continue to near where it crosses the A12, a turning off the A12 "Old Ford" or something - there's an RS components pick-up shop where you can order online and pick up the next day (if of course you order soon enough) sometimes you have to spend a certain amount before you can get free postage so it can be helpful to be near that place (you have to register with RS first).

[nat8808]

Might be an idea to check see if the Coles super tweeters are working..
Hi can you advise how to do this please ? :scratch:

Did you listen to them when you got them? Just put your ear to it and block off the other tweeter with your hand - should be able to hear it doing something.

[Audio Al]

Did you listen to them when you got them? Just put your ear to it and block off the other tweeter with your hand - should be able to hear it doing something.

Yes I did try that and could hear nothing

Drivers and tweeters both had audio ,

Thats why I asked in a previous post how to test them ? :)

[Audio Al]

Sorry, can't see the logic, that's nearly half the cost of the B&W's. Money better spent elsewhere, perhaps on new Coles 4001G's. Stiil, my opinion only.


These arrived in the post today ( NO import tax or additional costs :cool:)


http://img.photobucket.com/albums/v240/bigboobs/IMG_2161.jpg

I think you will see why I upgraded them :)
.
.
.
.

[Tarzan]

These arrived in the post today ( NO import tax or additional costs :cool:)


http://img.photobucket.com/albums/v240/bigboobs/IMG_2161.jpg

I think you will see why I upgraded them :)
.
.
.
.



Mmmm, would be interested to see how these perform over the old ones Al.

[Audio Al]

Later this evening I will be de waxing the cases and 0000 wire wool with white spirit and sugar soap

If I get time will paint them tomorrow :)

Certainly impressed with the quality of the new binding posts ;)

[seoirse2002]

you're going to use paint rather than varnish,danish oil etc?

[Audio Al]

you're going to use paint rather than varnish,danish oil etc?

Yes paint it is , I am not keen on the old 70's wood finish , also it does not fit in the my home decor :)

[walpurgis]

Shame to see a pair of what are 'classic' speakers lose their originality. You wouldn't paint a pair of Tannoy GRFs, now would you? (or would you?)

[Dingdong]

How are you going to fit the new binding posts? They look a bit wider than he original ones.

[seoirse2002]

How are you going to fit the new binding posts? They look a bit wider than he original ones.

+ 1 and can you let us know where you got them?:)

[Audio Al]

Shame to see a pair of what are 'classic' speakers lose their originality. You wouldn't paint a pair of Tannoy GRFs, now would you? (or would you?)


Surprised to be questioned on this

I can do what I want with them I own them , Classic or not they do not fit in with my decor , changing the colour does not affect the sound quality , Changing the binding posts hopefully will improve the sound quality that's why I am changing them

The binding posts came of ebay Chinese seller

http://www.ebay.co.uk/itm/2-pairs-CMC-Speaker-Binding-Post-878L-SE-Lock-Function-/320688447341?pt=US_Amplifier_Parts_Components&hash=item4aaa855f6d

[synsei]

Surprised to be questioned on this

I can do what I want with them I own them , Classic or not they do not fit in with my decor , changing the colour does not affect the sound quality , Changing the binding posts hopefully will improve the sound quality that's why I am changing them

The binding posts came of ebay Chinese seller

http://www.ebay.co.uk/itm/2-pairs-CMC-Speaker-Binding-Post-878L-SE-Lock-Function-/320688447341?pt=US_Amplifier_Parts_Components&hash=item4aaa855f6d

Each to their own Al, it's your call and you have to live with them. As long as you are aware that painting the cabs is likely to affect their resale value should you ever want to sell them. Personally I prefer the original finish on mine, the Teak veneer is of excellent quality and comes up lovely when treated with Teak oil ;)

[Audio Al]

Each to their own Al, it's your call and you have to live with them. As long as you are aware that painting the cabs is likely to affect their resale value should you ever want to sell them. Personally I prefer the original finish on mine, the Teak veneer is of excellent quality and comes up lovely when treated with Teak oil ;)

Dave, that's a chance I am willing to take if they look good ( to me ) and sound good they will be keepers ;)

[synsei]

I think you are going to love 'em Al, they are the least 'boxy' sounding speaker I have ever heard, they just breath so freely :)

[Audio Al]

I think you are going to love 'em Al, they are the least 'boxy' sounding speaker I have ever heard, they just breath so freely :)


Dave , I have had them up and running for a week before taking them apart , They sounded lovely hence spending money on them to improve cosmetically and sound wise
I had the heating on in my workshop for 24 hours and the temp got to 8degrees the paint finish I am using requires 15 and above so may be some delay in getting them painted , I can make the new binding post mounting plates and fit the new resistors on the frequency switch , and test the super tweeters
So still work to do

Already prepped the cases

First a light going over with a cabinet scraper

http://img.photobucket.com/albums/v240/bigboobs/IMG_2162.jpg

Then a wash with white spirit and 0000 wire wool

Loads of old brown polish came off

http://img.photobucket.com/albums/v240/bigboobs/IMG_2166.jpg

Then after drying a wash with sugar soap

http://img.photobucket.com/albums/v240/bigboobs/IMG_2163.jpg
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2164.jpg
.
.
http://img.photobucket.com/albums/v240/bigboobs/IMG_2165.jpg
.
.
Lastly a light sand with 240


Just need a day when it will warm up a bit :)
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.

[synsei]

It might be worth painting the front baffles too as they aren't the prettiest things with their grills off in standard dress... ;)

[Dingdong]

Iirc DM2's were originally available in white. As well as walnut and teak.

What color grille cloth are you going to use?

[Rare Bird]

Iirc DM2's were originally available in white.

Don't remember those only the B&W made Sony 'SS7000' ('DM70)

[Dingdong]

According to the B&W website they were available in rosewood, teak, walnut and white. I've got pairs in walnut and teak, but have never seen the others.

http://www.bwgroupsupport.com/archives/bw

[spendorman]

Iirc DM2's were originally available in white. As well as walnut and teak.

What color grille cloth are you going to use?


I have some white DM1 cabinets. Picked them up from Stephenson Blake Sheffield in the early 70's. They used to make cabinets for B&W, Mordaunt Short, etc. etc.

[walpurgis]

Surprised to be questioned on this

I can do what I want with them I own them , Classic or not they do not fit in with my decor , changing the colour does not affect the sound quality , Changing the binding posts hopefully will improve the sound quality that's why I am changing them

The binding posts came of ebay Chinese seller

http://www.ebay.co.uk/itm/2-pairs-CMC-Speaker-Binding-Post-878L-SE-Lock-Function-/320688447341?pt=US_Amplifier_Parts_Components&hash=item4aaa855f6d

Not to worry, I wasn't criticising. As you say, they are yours!

[surv1v0r]

Fascinating thread; how did it all work out in the end? I ask because I have a similar, lovely sounding pair of DM2s. I would very much like to refurb the cabinets but probably not with paint (personal preference I accept).

Incidentally, I contacted Falcon Acoustics (who are incredibly helpful and absolutely first class in my opinion), they didn't recommend replacing the capacitors and I haven't altered the crossovers in any way - still a lovely sound, even better when mounted on stands, away from any wall :)

[spendorman]

Fascinating thread; how did it all work out in the end? I ask because I have a similar, lovely sounding pair of DM2s. I would very much like to refurb the cabinets but probably not with paint (personal preference I accept).

Incidentally, I contacted Falcon Acoustics (who are incredibly helpful and absolutely first class in my opinion), they didn't recommend replacing the capacitors and I haven't altered the crossovers in any way - still a lovely sound, even better when mounted on stands, away from any wall :)

Yes, caps in DM2 / DM2a should still be OK, I've used Falcon since they started decades ago. If your DM2 / DM2a's have the treble adjustment on the back panel, it can sometimes be worth putting a very small amount of switch cleaner / lubricant on them.

[Mike - H]

Yes it would be good to see the finished article Al, did you fettle the crossovers?

[Audio Al]

Yes it would be good to see the finished article Al, did you fettle the crossovers?


Sadly the project went wrong , I know its anti to some people , I tried spraying them after rubbing them down , it went ti-s up as the paint reacted badly , looks like someone may have used silicone polish

The cabs are currently in the garage gathering dust :(

However its payday so your reminder may kick start me into getting them professionally sealed and painted

if I can find someone who wants the job

Time will tell

[surv1v0r]

Any further development on this?

[Audio Al]

No further progress , They are still in the garage :(

[surv1v0r]

I don't know about your garage but mine is an absolutely awful listening environment ;)

Part of the reason that I am interested in your project is that the cabinets of my DM2s are less than perfect and I would like to tidy them up. I have talked to someone about renewing the veneer but it appears that it isn't quite as straightforward as I had hoped . . . depth of the speakers and availability of veneer with sufficient width and adhesion to the existing surface.

[The Barbarian]

Because book matching veneers needs skill ;)

[Reffc]

Because book matching veneers needs skill ;)

Indeed it does. As does the preparation of the existing surfaces which have to be near perfect. My advice FWIW is if doing this yourself, sand off the existing veneers, select the new veneer sheets (only use fresh premium grade veneers), buying consecutive sheets. You then use these to book-match the veneer with the join line in the centre. If properly done, you should struggle to see the joint at all and the grain pattern should be mirrored. If you so much as nick one of the edges whilst cutting, you'll need to cut the damaged width off the veneer edge, do the same with the opposing veneer and start again. Use only high grade PVA glue allowing around 20 minutes positioning and use a pressing/smoothing tool (make one up from a softwood scrap) to press firmly into place and eliminate any air bubbles before clamping the veneer in a clamping press of some description for at least 3 hours. You then need to finish the veneered surface using very fine grade sand paper and finish using either water based lacquer or a very thin coats of Danish oil lightly sanded between coats.

It's not an easy job and not cheap if selecting decent veneer.

[surv1v0r]

Indeed [book matching veneers does need skill]it does. As does the preparation of the existing surfaces which have to be near perfect. My advice FWIW is if doing this yourself, sand off the existing veneers, select the new veneer sheets (only use fresh premium grade veneers), buying consecutive sheets. You then use these to book-match the veneer with the join line in the centre. If properly done, you should struggle to see the joint at all and the grain pattern should be mirrored. If you so much as nick one of the edges whilst cutting, you'll need to cut the damaged width off the veneer edge, do the same with the opposing veneer and start again. Use only high grade PVA glue allowing around 20 minutes positioning and use a pressing/smoothing tool (make one up from a softwood scrap) to press firmly into place and eliminate any air bubbles before clamping the veneer in a clamping press of some description for at least 3 hours. You then need to finish the veneered surface using very fine grade sand paper and finish using either water based lacquer or a very thin coats of Danish oil lightly sanded between coats.

It's not an easy job and not cheap if selecting decent veneer.Hi would you mind giving me a bit more advice on some of the points you make please?

What would you use to sand off the existing veneer?
What "high grade PVA" would you advise using?
Can you describe what you mean by "a pressing/smoothing tool"? Are we talking something like a wooden rolling pin?
Can you describe what you mean by "clamping press of some description" would "G Clamps" and some thick MDF suffice?

Sorry if these seem novice questions - I am a complete novice!

[Emmett123]

Hi, was wondering if I could revive this thread?

I recently got a set of DM2s off marketplace for a nice price. I would appreciate if members could offer advice or opinions on the nature of the DM2s.

The Issue:
The tweeters and woofers are all working, sound coming from all cones. There is a very pleasing heft, presence authority from the low end. The bottom end on the track Angel by Massive Attack is the best I have ever heard. However they seem to be cloudy/dark when come to instruments like cymbals, tambourines and vocals seem to lack in clarity or transparency.
I am comparing the DM2s to the Wharfedale Dovedale 3s.. the only other speakers I have.. which has that jangle/sparkle or detial. The Dovedales do not have the same oomph in the bottom end.

I would love to know what I could do to open up the details in the DM2s.

Possibility 1.
Change the amp. I am running the speakers off a valve amp (20Wx2 (SELF BIAS)
40Wx2(FIXED BIAS). The amp has no problem driving the speakers to volume, more than I could listen to regularly. But when the volume is cranked, the lack of clarity remains. I have read that these speakers like increased amp power. Would getting more powerful amp make a difference? A solid state with 100watts type thing? I am not after volume so much as increased clarity.

Possibility 2.

A recap of the cross-overs. I read earlier on this thread and in other threads that the components in the DM2 are generally of a good quality and don't necessarily benefit so much from a recap. Is this true? or could the speaker sound benefit from a recap.

Any pointers would be greatly appreciated.

[walpurgis]

The DM2 should not sound lacking in clarity and should be at least as clear as the Wharfedales. Are you certain the HF1300 lower tweeters are functional? They are the ones with the slotted fronts.

Anyway, I'd start with a re-cap and see if that helps, it's cheap to do and reversible if need be. The crossovers probably have old Elcap capacitors, which are no longer made. I usually substitute modern Alcaps, which work just fine and don't cost the earth.

If your amp sounds OK with other speakers, the problem is unlikely to be there.

[Emmett123]

The DM2 should not sound lacking in clarity and should be at least as clear as the Wharfedales. Are you certain the HF1300 lower tweeters are functional? They are the ones with the slotted fronts.

Anyway, I'd start with a re-cap and see if that helps, it's cheap to do and reversible if need be. The crossovers probably have old Elcap capacitors, which are no longer made. I usually substitute modern Alcaps, which work just fine and don't cost the earth.

If your amp sounds OK with other speakers, the problem is unlikely to be there.

After double checking. With toilet paper tube. Definitely sound coming from the two black vented tweeters. However I can hear nothing from the two metal super-tweeters on the bottom.

[Emmett123]

https://scontent.flhr3-2.fna.fbcdn.net/v/t1.0-9/s960x960/96149979_608465026683918_2247037167400386560_o.jpg ?_nc_cat=106&_nc_sid=110474&_nc_ohc=qhWYfHnNhmQAX9aOVAH&_nc_ht=scontent.flhr3-2.fna&_nc_tp=7&oh=de8e42a5eee8075b18edc38b7eb65f5f&oe=5ED732D0

[walpurgis]

However I can hear nothing from the two metal super-tweeters on the bottom.

They may well be OK. They come in very high up the frequency range and emit little that most of us would hear. They handle only a small amount of the overall signal power and generally don't fail.

[Emmett123]

They may well be OK. They come in very high up the frequency range and emit little that most of us would hear. They handle only a small amount of the overall signal power and generally don't fail.

Thanks for the heads up on the super-tweeter, it was looking like it might be a bigger problem than I thought. I took this photo of the crossover from earlier in the thread. Am I correct in thinking the caps are under those little brown box/lids? Do they just pop off?

http://img.photobucket.com/albums/v240/bigboobs/IMG_2129.jpg

[M6NTL]

Those little brown boxes ARE capacitors, they are not covers over them...

Sent from my G8441 using Tapatalk

[spendorman]

Those little brown boxes ARE capacitors, they are not covers over them...

Sent from my G8441 using Tapatalk

Absolutely, and they are not reversible electrolytics, therefore unlikely to be in poor condition. In fact those particular capacitors I have never had a problem with, all I have measured were within spec despite their age.

[walpurgis]

Yes, it's all likely to be OK from the look of it, apart from maybe the rotary switch which I'm sure I've not seen on DM2 crossovers before. Maybe I'm thinking of the DM2a? Anyway, the switch may have dirty contacts, which could reduce treble output. There's certainly no harm in giving it a squirt of contact cleaner and working it back and forth a few times.

[spendorman]

It's strange, some speakers marked DM2 had the treble level rotary switches, some did not.

[Batty]

I had a pair of DM2a in the late 80s/ early 90s, I paid 80 quid for them, drove them with a Cyrus 2 and PSX. Fantastic speakers.
Mine had the treble control.
Unfortunately the ferro fluid dried out and my insurance paid up :) That would have been 1995, then I bought a pair of Castle Howard s1. I still have them as my main speakers.

[spendorman]

As far as I know, DM2 and DM2a did not have ferrofluid in the tweeters, DM2 Mk2, possibly.

[walpurgis]

I'm pretty sure there's no ferrofluid in these. The bass driver and HF1300 use none and I'm pretty sure the Coles supertweeter doesn't either. The DM2's with the Audax soft dome may though.

[spendorman]

I'm pretty sure there's no ferrofluid in these. The bass driver and HF1300 use none and I'm pretty sure the Coles supertweeter doesn't either. The DM2's with the Audax soft dome may though.
I believe the soft dome was a Heyco/ Peerless, no ferrofluid in those either.

[walpurgis]

I believe the soft dome was a Heyco/ Peerless, no ferrofluid in those either.

Could be. It's a hell of a long time since I saw any :).

[spendorman]

Heyco/ Peerless tweeter used as supertweeter in early DM2

https://live.staticflickr.com/65535/49863042052_23d6712f49_z.jpg (https://flic.kr/p/2iYe8cA)dm2 (https://flic.kr/p/2iYe8cA) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

[Barry]

The capacitors look to be made by TCC and are generally quite reliable.

I have a pair of DM2As, with the Coles and Celestion tweeters, and the HF level switch on the back. I picked them up a few years ago for £50, and are used in my second system (largely used with my TV).

They have been variously powered with a Quad 303, Quad 520 and a Mini-T digital amplifier; the latter of which works very well with the speakers.

[Emmett123]

They may well be OK. They come in very high up the frequency range and emit little that most of us would hear. They handle only a small amount of the overall signal power and generally don't fail.

Given that it might not be possible to hear the super-tweeter even if they were working, would them not working make a difference to the overall operation of the speakers?

[Pharos]

Unlikely.

[Batty]

I was just going on what the insurance guy said.

[sailor]

Hi Emmett,

The tweeter for the extreme highs will definitely make a difference. Perhaps remove them and connect them to your amplifier with a cap in series with either leg. If they work when you do this but not in box then the XO is faulty or the voice coil is open circuit. Post 31 has a link to the crossover which shows C10 is 1.5uf. Snip it out and use it for the job. Turn volume up very slowly. Best if you download a clip of white noise for testing both tweets.

Your speakers are from the mid 70's which means they are about 45 years old!

Just rebuild the crossovers. The caps might still measure to spec but discard the lot. Not everything in audio has advanced that much but modern caps most definitely have. Replace with film caps and certainly no electrolytics. I notice the inductors are all jammed close up to each other and incorrectly orientated. This means they are all talking to each other and smearing fine detail.

Were it mine I would salvage the inductors and configure them correctly on a much bigger board, at the same time spacing them as far apart from each other as possible, similar to the requirements for Covid 19 :eyebrows:

Try and assemble the XO boards using the leads of all components to connect point to point avoiding adding little scraps of wire or PCB traces.

The story below I copied and pasted from another reply which I feel is pertinent to your predicament.

"Hi Keith, rebuilding the XO with good parts will minimize the damage components do to the signal. My previous recommendations stand. This will provide a cleaner and more detailed signal which will give you the clarity in the top end and also improve bass and midrange. This may seem a little hard to comprehend when the main target of this rebuild is to improve the tweeter's response.

What is at play here is that the upper harmonics of voices and instruments, from the drummers bass drum, side tom, snare drum and other instruments going upwards, is reproduced by the tweeter. The transient performance is crucial for life-like sound, this stems from our senses being tuned for survival in the wild. The sharp snap of dry twig alerts you to danger and gives its location.

The transient or leading edge of the waveform is handled by the tweeter so when you provide it with a cleaner signal your ability to recognise and locate their position is enhanced, hence better imaging and staging.

I mentioned using Mills resistors. Use the 12W and not the 5W. Remember you are looking to maximise the transient snap and the bigger resistor will cause less thermal compression, and that's good. This is an excellent choice, noticeably better than that grainy thing used in your XO and used by many so-called high end designs. For a more precise response, and is what I like using, and feel may suit your speaker better is the Powertron, a Vishay foil. rated 3W or 30W when mounted on a heat sink"

This link takes you to a very informative in depth look at caps from cheap to stratospheric. http://www.humblehomemadehifi.com/Cap.html

I am situated on the same damp rock in the North Atlantic as you, just a little further south in Abbeyfeale. If you need a little help you can load up your beauties and drive down when this silliness is over. My room has acoustic treatment and am able to measure the response.

I include pics of one of my builds for OB speakers
1st: original XO supplied with speaker
2nd: the planning stage
3rd: close of of my new favourite resistor
4th: XO hooked up

https://i.imgur.com/gzlbE1e.jpg?1

https://i.imgur.com/CSF6cqS.jpg?1

https://i.imgur.com/HtZL5Hg.jpg

https://i.imgur.com/NGKKjsD.jpg?1

[Emmett123]

Hi Emmett,

The tweeter for the extreme highs will definitely make a difference. Perhaps remove them and connect them to your amplifier with a cap in series with either leg. If they work when you do this but not in box then the XO is faulty or the voice coil is open circuit. Post 31 has a link to the crossover which shows C10 is 1.5uf. Snip it out and use it for the job. Turn volume up very slowly. Best if you download a clip of white noise for testing both tweets.

Your speakers are from the mid 70's which means they are about 45 years old!

Just rebuild the crossovers. The caps might still measure to spec but discard the lot. Not everything in audio has advanced that much but modern caps most definitely have. Replace with film caps and certainly no electrolytics. I notice the inductors are all jammed close up to each other and incorrectly orientated. This means they are all talking to each other and smearing fine detail.

Were it mine I would salvage the inductors and configure them correctly on a much bigger board, at the same time spacing them as far apart from each other as possible, similar to the requirements for Covid 19 :eyebrows:

Try and assemble the XO boards using the leads of all components to connect point to point avoiding adding little scraps of wire or PCB traces.

The story below I copied and pasted from another reply which I feel is pertinent to your predicament.

"Hi Keith, rebuilding the XO with good parts will minimize the damage components do to the signal. My previous recommendations stand. This will provide a cleaner and more detailed signal which will give you the clarity in the top end and also improve bass and midrange. This may seem a little hard to comprehend when the main target of this rebuild is to improve the tweeter's response.

What is at play here is that the upper harmonics of voices and instruments, from the drummers bass drum, side tom, snare drum and other instruments going upwards, is reproduced by the tweeter. The transient performance is crucial for life-like sound, this stems from our senses being tuned for survival in the wild. The sharp snap of dry twig alerts you to danger and gives its location.

The transient or leading edge of the waveform is handled by the tweeter so when you provide it with a cleaner signal your ability to recognise and locate their position is enhanced, hence better imaging and staging.

I mentioned using Mills resistors. Use the 12W and not the 5W. Remember you are looking to maximise the transient snap and the bigger resistor will cause less thermal compression, and that's good. This is an excellent choice, noticeably better than that grainy thing used in your XO and used by many so-called high end designs. For a more precise response, and is what I like using, and feel may suit your speaker better is the Powertron, a Vishay foil. rated 3W or 30W when mounted on a heat sink"

This link takes you to a very informative in depth look at caps from cheap to stratospheric. http://www.humblehomemadehifi.com/Cap.html

I am situated on the same damp rock in the North Atlantic as you, just a little further south in Abbeyfeale. If you need a little help you can load up your beauties and drive down when this silliness is over. My room has acoustic treatment and am able to measure the response.

I include pics of one of my builds for OB speakers
1st: original XO supplied with speaker
2nd: the planning stage
3rd: close of of my new favourite resistor
4th: XO hooked up

https://i.imgur.com/gzlbE1e.jpg?1

https://i.imgur.com/CSF6cqS.jpg?1

https://i.imgur.com/HtZL5Hg.jpg

https://i.imgur.com/NGKKjsD.jpg?1

Hi Charles,

Thanks for this. Certainly a lot to get my head around. I have never dabbled in electronics beyond soldering in some new caps on a set of Dovedale 3. But constructing a new crossover would be a nice wee project to attempt in the coming weeks of CoVid restrictions. I think the biggest challenge to me would be getting the order/pattern/ circuit right.But if I'm slow and careful hopefully I can get it right.

[Emmett123]

https://scontent.flhr3-2.fna.fbcdn.net/v/t1.0-9/96266840_609521723244915_3756634548931133440_n.jpg ?_nc_cat=109&_nc_sid=110474&_nc_ohc=erimE3waeMsAX9JGng1&_nc_ht=scontent.flhr3-2.fna&oh=aa086993c67c75f305ebacd8d71ce422&oe=5ED8E109

I opened the speakers today, just to have a look and check on all the connections were in place, no broken solders. Appears to be sound in this regard.

[walpurgis]

Bear in mind that in revamping the crossovers, you may spend as much or more on components as the speakers are worth. And that there is no guarantee that you will like the end result.

I still think a good first move would be to use some contact cleaner on the rotary switch, the results may surprise you.

[spendorman]

Bear in mind that in revamping the crossovers, you may spend as much or more on components as the speakers are worth. And that there is no guarantee that you will like the end result.

I still think a good first move would be to use some contact cleaner on the rotary switch, the results may surprise you.

Above agreed, There is nothing really terribly wrong with the standard original crossover. B&W pretty well knew what they were doing. Just in case you did not realise, the rotary switch controls the level of only the Celestion HF1300 tweeter.

It's a bit personal, but your age matters, I'm 69 and my top end hearing is going a bit, I'm good for my age, my Dad at a similar age could not hear much above 8KHz, as other have said, what comes out of the supertweeter is pretty high, the crossover point is probably about 13KHz.

A good, but not infallible test of the supertweeter is to measure it's resistance with a multimeter. It does not have to be disconnected to do this. A good Coles 4001G should measure around 23 Ohms.

[Emmett123]

Bear in mind that in revamping the crossovers, you may spend as much or more on components as the speakers are worth. And that there is no guarantee that you will like the end result.

I still think a good first move would be to use some contact cleaner on the rotary switch, the results may surprise you.

It does require a good deal of force to move them at the moment. I dabbed a bit of WD40 on them today and left them to sit. i have not tried them on an amp since. I was reading too on a thread concerning B&W DM6 a problem with corrosion on the binding posts as they connected the back of the crossover board. A closer look at the binding posts external of mine shows that one is slightly bent out of line. But because the speakers worked at all I had dismissed that as a problem.

[walpurgis]

It does require a good deal of force to move them at the moment. I dabbed a bit of WD40 on them today and left them to sit..

The switches are supposed to have a reasonably stiff action. WD40 is not a good thing to use, as it leaves a residue. Something like Servisol would be better, preferably non-lubricating..

[spendorman]

The switches are supposed to have a reasonably stiff action. WD40 is not a good thing to use, as it leaves a residue. Something like Servisol would be better, preferably non-lubricating..

Agreed that WD40 is not the best thing to use, Servisol is ideal, Servisol Super 10 switch cleaner, does provide a lubricant as well, all to the good in my opinion, minimises wear on the cleaned contacts.

https://www.amazon.co.uk/Servisol-701-100UK-Super-10/dp/B000KEB6WW

https://www.amazon.co.uk/Servisol-Switch-Cleaner-Lubricant-Contact/dp/B06ZZX2RL3/ref=pd_sbs_229_3/261-9327490-7754146?_encoding=UTF8&pd_rd_i=B06ZZX2RL3&pd_rd_r=de6b567f-a56b-4093-94f8-9007b9c15b15&pd_rd_w=en9qT&pd_rd_wg=u0ZU1&pf_rd_p=2773aa8e-42c5-4dbe-bda8-5cdf226aa078&pf_rd_r=E47G59WG4XX34MSSM7KR&psc=1&refRID=E47G59WG4XX34MSSM7KR

[Pharos]

"Switch lubricant has become an embedded sloppy term often touted by Hi-Fi journalists.

There are two separate things to consider with a switch; mechanical functioning which should be treated with appropriated lubricants, and cleanliness and freedom from oxidation on contacts, needing a deoxidant, and possible preventer of further oxidation.

WD40 is not suitable for either purpose, it is a poor lubricant, which is partly why it is recommended for locks, to reduce the chances of easy opening, and the other reason being to displace water to prevent freezing and corrosion, as the name WD suggests, (Water Displacer).

[sailor]

Bear in mind that in revamping the crossovers, you may spend as much or more on components as the speakers are worth. And that there is no guarantee that you will like the end result.

Bear in mind that Emmett was considering buying a new amp to try and sort out his problem so I think it safe to assume he values the speakers and is prepared to spend some money to achieve this. Regarding the guarantee about him liking the sound, from my experience if done correctly I should think he will love the sound :wow:

The XO shown in the pics I posted were a substantial improvement over the original. The basic character remained but with cleaner highs, more detail and simply just more fun. I have rebuilt many XO's for many years and in every case the owners have been delighted. Some rebuilds have resulted in dramatic improvements.


Above agreed, There is nothing really terribly wrong with the standard original crossover. B&W pretty well knew what they were doing. Just in case you did not realise, the rotary switch controls the level of only the Celestion HF1300 tweeter.

It's a bit personal, but your age matters, I'm 69 and my top end hearing is going a bit, I'm good for my age, my Dad at a similar age could not hear much above 8KHz, as other have said, what comes out of the supertweeter is pretty high, the crossover point is probably about 13KHz.

A good, but not infallible test of the supertweeter is to measure it's resistance with a multimeter. It does not have to be disconnected to do this. A good Coles 4001G should measure around 23 Ohms.

We are 180 degrees out of phase here Spendorman :) B&W may know what they are doing now but back then I would have to disagree, looking at the XO they built. They did not take cognisance of proper orientation of inductors, whether by choice or because this phenomenon was at that time not widely known, if at all. The pics I posted illustrate the correct orientation. I was made aware of this important fact from articles published in Sound Practices. Simple to try for yourself. Hook up a coil to a signal genny and drive it at 1Khz. Hook up a second coil to an oscilloscope and watch the display as you move it towards the driven coil. A dual O'scope would be better and show almost full coupling if you placed one coil on top of the other. That's how transformers work. As you move the coils apart it will show the amplitude of waveform diminish. It will be seen that if they remain orientated as per B&W they need to be well apart. It will also be seen that orientated as per my pics there is very little coupling even when close to each other and zero coupling at the distance I have them. This is not whim or guesswork it is provable sobering fact. The B&W XO has a bunch of coils all closely coupled. So it should be apparent that coils for the bass driver are influencing the tweeter coils and the tweeter coil are effecting neighboring coils etc. They are all in a little huddle arguing, just like us :) I have upgraded XO's on modern B&W speakers that are properly done. I am not having a dig at B&W here.

The age of the listener is not important. As I mentioned previously, the tweeter response is responsible for providing the higher order harmonics, which regardless of whether or not they can be heard individually, when overlaid on the fundamental, give you the timbre of voice or instument and provide directional clues. If you take a saxophone, piano and guitar and they all play middle C, but robbed totally of all harmonics then you would not be able to tell them apart. All you would hear is a 261.6Hz sine wave. It is the harmonic structure overlaid on the fundamental that provides the clue to the instrument playing. This is the tweeters job. Provide it with a clean pure signal, which is the XO's job. Provide these conditions then for example a piano will sound more like a piano Read up on Max Townshend's super-tweeter for the psychoacoustics or Leo Beranek (a true acoustician)

You are correct that measuring a tweeter in place is fallible, in fact pointless. Tweeter attenuation is usually done after the last series cap so any shunt resistance would give a reading. In this case, 45 years grand old age, the adhesives will be suspect, the voice coil could have separated from the former yet still give a reading. Establishing continuity is a wasted exercise, that's why I didn't mention it. Ears are best.

Emmett: build a new XO along the lines I have suggested, avoid the level-control switch which is unnecessary and you will hear a vastly improved, top to bottom performance. The missing sparkle will be back along with previously unheard detail and imaging. This need not be that expensive. All the coils can be reused and probably the resistors unless out of spec. although replacing them is advisable. Mill are a safe bet at about 5 pounds a pop. The series caps to the 2 high frequency drivers is where the bulk of you budget should go. Feel free to PM me for specifics.

[walpurgis]

That seems pretty dismissive of the foregoing posts by others.

[spendorman]

That seems pretty dismissive of the foregoing posts by others.

I hope it does not put Emmett on a long unnecessary road of actions.

Just for example in the DM2a one can accurately measure the resistance on the Coles whilst still in circuit. It is a good start to checking the unit, however there is a chance (smallish) that the coil measures around 23 Ohms and the unit does not work. For example if the coil has separated from the diaphragm former.

In an ideal world we would space the inductors differently. I am aware of these things having worked the major part of my working life as an electronic engineer. Admittedly, I don't know everything.

[sailor]

Well I'm surprised Geoff and Alex.

Please excuse me for intruding into your exalted domain. I was not dissing anybody but saw little of value being offered. None of the responses to his cry for help were actually steering him in the right direction. Basically he was told, B&W knew what they were doing, all looks fine, clean the switch and you're good to go.

Post 97, when Emmett joined this thread he declared that his speaker sounded cloudy/dark with a lack of detail and transparency and would love to know what could be done. He so wanted to get his speakers to perform that he was prepared to by a more powerful amp.

So, in the spirit, ethos and intent of this forum, I tried to assist the poor fellow by offering a proven solution. My post was not only to provide the necessary information but also why it was necessary, and why the correct functioning of the tweeter is vitally important.

And You're criticising me for trying to be helpfull. Really?


I hope it does not put Emmett on a long unnecessary road of actions.

In an ideal world we would space the inductors differently. I am aware of these things having worked the major part of my working life as an electronic engineer. Admittedly, I don't know everything.

In what way do you find anything I recommended unnecessary, if as you say "In an ideal world we would space the inductors differently? It was precisely this point I was addressing by providing the means for anyone to test this for themselves. Would it not be sensible to optimise the correct mounting of the inductors if he were to opt for a full rebuild? Correct orientation is something you claim you were aware of yet did did not suggest this vital aspect of optimising XO component layout, which is the 'heart' of any speaker.

I, too, admit I don't know everything but I have spent a lifetime specifically targeting speaker design and measurement with hands-on application in this field. It is my accumulated, tried, tested and proven with measurement experience that I tried to impart to Emmett.

We are all big boys here and surely the man can decide for himself the road he wants to take!

[walpurgis]

Try addressing the subject, without having a dig at other members.








.

[Barry]

The inductors shown attached to the wooden (!) board are air-cored, so there is poor confinement of the magnetic flux around them, thus the need for an orthogonal disposition between the two.

The inductors of the B&W crossover use ferrite cores, so there is much tighter flux confinement. You could rearrange them to be mutually orthogonal to one another, but I doubt it would make much difference to the SQ.


I have a pair of the DM2a speakers as shown. No modifications have been made and they do not display the 'dark' 'cloudy' symptoms complained of.

[walpurgis]

I did wonder about the influence of the ferrite cored items.

[Emmett123]

Thanks for all the advice so far. Its been amazing, if disputed. The prospect of building a cross-over is daunting for some-one who as only started to dip a toe in this world. However I'd be willing to give it go.
I think the advice of Spendorman to measure the functionality of the Coles is a good place to begin. I have bought a multi-meter online (reflecting just what a noobie I am). Testing those should narrow down where the problem might lie.

I wonder too if tweeter/woofers can be function but not be working at their best? Could there be a deterioration of their quality if previously driven too hard? I checked the rubber surrounds on the woofers and they seem to be fine.

[spendorman]

The inductors shown attached to the wooden (!) board are air-cored, so there is poor confinement of the magnetic flux around them, thus the need for an orthogonal disposition between the two.

The inductors of the B&W crossover use ferrite cores, so there is much tighter flux confinement. You could rearrange them to be mutually orthogonal to one another, but I doubt it would make much difference to the SQ.


I have a pair of the DM2a speakers as shown. No modifications have been made and they do not display the 'dark' 'cloudy' symptoms complained of.

Good point Barry, I have three pairs of DM2/ DM2a, and none of them sound 'dark' 'cloudy', well, I'm exaggerating slightly, only three pairs as one pair is on permanent loan to a friend.

[sailor]

Barry, the inductors shown in my pics are not orthogonally disposed. You are looking at the coil windings, instead look at the axes. I could probably find the article I referred to in Sound Practices but I'm not going to bother. I made exhaustive tests with cored coils and air-cored coils and they both benefit from being orientated the way I demonstrated.

Have you ever tried the test I described. Do it then report back.

I am bowing out of this thread as I see no constructive advice being offered. What I see is, for some reason I do not understand, the desire to downplay my advice and experience. :mental:

Good luck Emmett. :)

[walpurgis]

I am bowing out of this thread as I see no constructive advice being offered.

Yet again. Dismissing the opinions of other members! Others are not precluded from expressing a view, just because you apparently think you know best!

[Lawrence001]

I've owned about 5 pairs of these over the years and I have noticed some differences in sound between them and one or two pairs tended towards the possible description of muddy. I'll admit though after reading up about the crossovers and that the caps didn't age that badly compared to Elcaps for example, I didn't try replacing the components. However is I was particularly attached to them I would probably have tried.

Can I make a first suggestion which is that you put some choral music on quietly with boy trebles or sopranos (Tallis works quite well :) ) play one channel at a time if you have a balance control on your amp (or disconnect the other speaker). Cover the lower tweeter with your hand and put your ear near the supertweeter. You should hear some sound from them, it might be either hissing or sibilance, but if you hear it it's working.

There's the chance as mentioned your hearing is no longer sensitive to the frequencies generated by the supertweeters. Therefore maybe don't assume they're broken if you can't hear. Maybe progress to the resistance check if so. Also this may not mean you don't need them as they apparently can contribute to dispersion of the lower frequencies and improve the audible frequencies. This idea is a little controversial I think (in the realm of genuine supertweeters >20khz) and I'm not qualified to have an opinion.

The other potential issue is that the Coles may have been replaced at some point in the past with the incorrect type, they had at least 2 models with different resistance I'll say 8 and 16 ohms but that's a guess. If someone just dropped the wrong type in without checking (esp. if they replaced the lower resistance with the higher) then it might have the effect you noticed, even if they are working.

[walpurgis]

The HF1300 is a strange device, it can sound a bit hard, despite having a very flat response up to the slight 'ring' just before the upper end cut off. I think the hardness must be a colouration, possibly a reflection through the diaphragm. Nonetheless, it's a very fine tweeter with great transparency and transient response. I have several pairs of varying impedances, including the rare T718 variant with recessed front plate.

[spendorman]

The HF1300 is a strange device, it can sound a bit hard, despite having a very flat response up to the slight 'ring' just before the upper end cut off. I think the hardness must be a colouration, possibly a reflection through the diaphragm. Nonetheless, it's a very fine tweeter with great transparency and transient response. I have several pairs of varying impedances, including the rare T718 variant with recessed front plate.

I believe that Spendor ran the HF1300 out of phase with the Coles 4001G so as to partly nullify the "slight ring". Nerveless, the HF1300 is a fine unit. My almost fav speakers, LS3/6 use it with a HF2000 supertweeter.

The Celestion HF1400, is interesting, basically a 1300 with a larger magnet, used in another BBC speaker and the B&W DM3, probably making it more efficient. I have a couple of pairs of these, one pair in DM3's

[walpurgis]

HF2000 supertweeter

I have a late (UL10) set of those too. :)

[spendorman]

I have a late (UL10) set of those too. :)

Strangely, I have not come across these, I remember the UL6. The UL10 seem very interesting, look like that have a good selection of units, should sound very good.

[walpurgis]

Strangely, I have not come across these

You won't. The thermally shaped poly bass cones would start flattening out and the cone surround adhesive failed.

[Emmett123]

I hope it does not put Emmett on a long unnecessary road of actions.

Just for example in the DM2a one can accurately measure the resistance on the Coles whilst still in circuit. It is a good start to checking the unit, however there is a chance (smallish) that the coil measures around 23 Ohms and the unit does not work. For example if the coil has separated from the diaphragm former.

In an ideal world we would space the inductors differently. I am aware of these things having worked the major part of my working life as an electronic engineer. Admittedly, I don't know everything.

Hi,

Multimeter arrived and I tested the Coles (out of circuit). It read at 3.2 ohm for one and 2.9ohm for the other. Is this significant when the tweeters are rated at either 8ohm or 16ohm?

Tried it again with the cords connected back in to the crossover and it measure the same.

[spendorman]

Hi,

Multimeter arrived and I tested the Coles (out of circuit). It read at 3.2 ohm for one and 2.9ohm for the other. Is this significant when the tweeters are rated at either 8ohm or 16ohm?

Tried it again with the cords connected back in to the crossover and it measure the same.

If that is a correct reading(s), your Coles are fried, not the end of the world, but unfortunate.

Try measuring something else to check the meter, like the Celestion HF1300, they should measure something around 11-13 Ohms.

[VanDerGraaf]

I'm rather late on this great thread :)but yes it does sound like the Coles are goners. At least new replacements don't break the bank from Falcon.

I am fairly sure that the ones in my DM2a are dead too. Despite what people say I think if you are young enough you really do notice their absence- I don't have the data in front of me but the crossover point isn't astronomically high- 13kHz?

We hear this as a lack of air and what I always refer to as a lack of "crystalline" sound. I certainly have noticed something different, and I can't hear them anymore when I put my ear next to them- which I can on my similarly-Coles-equipped Mordaunt Short MS400.

[Macca]

I'm rather late on this great thread :)but yes it does sound like the Coles are goners. At least new replacements don't break the bank from Falcon.

I am fairly sure that the ones in my DM2a are dead too. Despite what people say I think if you are young enough you really do notice their absence- I don't have the data in front of me but the crossover point isn't astronomically high- 13kHz?

We hear this as a lack of air and what I always refer to as a lack of "crystalline" sound. I certainly have noticed something different, and I can't hear them anymore when I put my ear next to them- which I can on my similarly-Coles-equipped Mordaunt Short MS400.

The supertweeter comes in at 14Khz according to the internet. Sounds about right. Most of us should still just about be able to hear it make a contribution.

[Emmett123]

If that is a correct reading(s), your Coles are fried, not the end of the world, but unfortunate.

Try measuring something else to check the meter, like the Celestion HF1300, they should measure something around 11-13 Ohms.

Thanks for the tip. Just tried them too. Reading at 11.9 and 12.4. So they seem good. To replace the Coles, I take it that the 16 ohm Coles 4001 G are the ones to go for, as opposed to the 8 ohm "K" variety?

[walpurgis]

You can't just change a tweeter to a different spec or model without altering the crossover to suit. Better to stick with original types unless you're feeling adventurous :).

[spendorman]

Thanks for the tip. Just tried them too. Reading at 11.9 and 12.4. So they seem good. To replace the Coles, I take it that the 16 ohm Coles 4001 G are the ones to go for, as opposed to the 8 ohm "K" variety?

You are correct. If the new Coles 4001G tweeters are too expensive, I have a reasonably good bodge.

[Barry]

Re the Coles 4001G units, I don't understand how the resistance (~ 23 Ohm) can be greater than the impedance (~ 15 Ohm).

But having sold some 4001Ks a few years ago, I did measure the DC resistance and it was around 23 Ohm, with accceptable and expected unit-to-unit variation.

[spendorman]

Re the Coles 4001G units, I don't understand how the resistance (~ 23 Ohm) can be greater than the impedance (~ 15 Ohm).

But having sold some 4001Ks a few years ago, I did measure the DC resistance and it was around 23 Ohm, with accceptable and expected unit-to-unit variation.

The resistance of 23 Ohms is correct for the 4001G, even says so on the Coles site. I reckon that the actual impedance of the 4001G is in excess of 23 Ohms.

The 16 Ohm impedance rating is probably because the Coles (originally STC) may have been used on early Hi Fi speaker systems of 16 Ohm nominal impedance.

http://www.coleselectroacoustics.com/drive-units/super-tweeter

[spendorman]

Just measured the resistance of a Coles 4001G, get 23 Ohms, also measured it's inductance, result 0.2mH.

Inductive reactance in Ohms is XL = 2PiƒL. Using L= 0.2mH and frequency = 13Khz, we get a calculation of XL = 16 Ohms, if I am correct. Someone please check!

[Pharos]

Yes.

[spendorman]

Yes.


Thank you. Seaford, nice place, not been there for about 30 years!

[Barry]

So Coles quote the inductive reactance as an impedance? Impedance should include the resistance.

As far as I am concerned the modulus of the impedance |Z| = sqrt(R2 + X2). Thus sqrt(232 + 162) = 28 Ohm.

But I digress, as it not helping VanDeGraff

[spendorman]

So Coles quote the inductive reactance as an impedance? Impedance should include the resistance.

As far as I am concerned the modulus of the impedance |Z| = sqrt(R2 + X2). Thus sqrt(232 + 162) = 28 Ohm.

But I digress, as it not helping VanDeGraff

Spot on, I did not do the impedance calculation for fear of confusing, self included!

Still, I think we have got there explaining the so called 16 Ohm rating.

Next, is Emmett going to buy some nice new Coles 4001G?

[Barry]

Spot on, I did not do the impedance calculation for fear of confusing, self included!

Still, I think we have got there explaining the so called 16 Ohm rating.

Next, is Emmett going to buy some nice new Coles 4001G?

No problem - it was just me being a bit pedantic (caused by working 30 years in electronics research). :)

[spendorman]

As discussed previously, we basically worked for the same company, I was only there for a bit less than 20 years, before that still in electronics / engineering.

In fact my BAE Systems (Marconi) Pension Newsletter just came through my letterbox!

[Emmett123]

Spot on, I did not do the impedance calculation for fear of confusing, self included!

Still, I think we have got there explaining the so called 16 Ohm rating.

Next, is Emmett going to buy some nice new Coles 4001G?

Yip, got some from Falcon yesterday. Popped out the old ones to have a look, a simple enough procedure to solder them in. Though I noticed that old ones do not have a + or - terminal rather the wires are soldered to a flat panel on the back?

Started too to rub down the cabinets. White spirit, wire wool and a light sanding. A bit bashed on a few corners but not enough to be annoying. Debating whether to introduce some teak wood stain . Otherwise some Danish oil, or a varnish.

[spendorman]

Not quite sure what you mean in your first paragraph. Unless you mean the terminal strip.

The bashed corners can be carefully repaired using Brummer Stopping Wood Filler in the correct colour, I'm assuming that your cabinets are teak veneered, most are. I would not stain, just oil or a satin varnish.

[Emmett123]

https://scontent.flhr3-1.fna.fbcdn.net/v/t1.0-9/s960x960/97373800_614839296046491_8295066210748334080_o.jpg ?_nc_cat=103&_nc_sid=110474&_nc_ohc=1V0TIcbikYgAX_pQoxl&_nc_ht=scontent.flhr3-1.fna&_nc_tp=7&oh=e3e45059095cef26bf761430c9440c16&oe=5EE5A757

Ah there is a little red mark on them. To denote the positive or in side?

[spendorman]

Correct, just connect the new ones as the old ones.

Be careful not to have the soldering iron on the terminals too long.

[ramsden]

I am another one in the row who got these speakers recently, running them about 3 days now and opposite experience so far, they seem to sound a bit bright for my taste, and thin unless pushed into higher volumes.
Also I can not hear super tweeters.. will check them soon.

[ramsden]

@emmett123
How the speakers sound now after fitting new super tweeters?
Is dullness gone?

I just wonder why they showed both your old ones about 3ohm each, as I would suspect no continuity at all when faulty. Am I missing something? Maybe someone could clarify it. Thank you

[spendorman]

@emmett123
How the speakers sound now after fitting new super tweeters?
Is dullness gone?

I just wonder why they showed both your old ones about 3ohm each, as I would suspect no continuity at all when faulty. Am I missing something? Maybe someone could clarify it. Thank you

Shorted turns on the voice coil windings. Not unusual.

[spendorman]

I am another one in the row who got these speakers recently, running them about 3 days now and opposite experience so far, they seem to sound a bit bright for my taste, and thin unless pushed into higher volumes.
Also I can not hear super tweeters.. will check them soon.

A bit bright, possibly just revealing what's there in the signal. As a first check on the supertweeters, measure resistance with a meter, should get around 23 Ohms.

[Emmett123]

@emmett123
How the speakers sound now after fitting new super tweeters?
Is dullness gone?

I just wonder why they showed both your old ones about 3ohm each, as I would suspect no continuity at all when faulty. Am I missing something? Maybe someone could clarify it. Thank you

I'm waiting for them to arrive. In the meantime the cabinets are getting rubbed down. First coat of Danish oil applied about half hour ag.

[spendorman]

I'm waiting for them to arrive. In the meantime the cabinets are getting rubbed down. First coat of Danish oil applied about half hour ag.

Pics!

[Emmett123]

https://scontent.flhr3-2.fna.fbcdn.net/v/t1.0-9/98306567_616923089171445_2882028462703378432_n.jpg ?_nc_cat=104&_nc_sid=110474&_nc_ohc=qQKFKDaUHRIAX-qvUwl&_nc_ht=scontent.flhr3-2.fna&oh=fe5cf93a7026a896dcfb6cfa6df47e5e&oe=5EE82E13

https://scontent.flhr3-2.fna.fbcdn.net/v/t1.0-9/97966249_616923129171441_4355071669635645440_n.jpg ?_nc_cat=102&_nc_sid=110474&_nc_ohc=-9_W-2ZKn_YAX_GJMUc&_nc_ht=scontent.flhr3-2.fna&oh=ca024e69c029777c164fadb4afa522bf&oe=5EEA6112

https://scontent.flhr3-2.fna.fbcdn.net/v/t1.0-9/98183925_616923172504770_5150014032442294272_n.jpg ?_nc_cat=107&_nc_sid=110474&_nc_ohc=UpNXY4DMgVYAX_2WgGn&_nc_ht=scontent.flhr3-2.fna&oh=3f2e1c628d18218c6883cea66c7b23b8&oe=5EE6B5BF

https://scontent.flhr3-1.fna.fbcdn.net/v/t1.0-9/97878358_616923215838099_1083324179505217536_n.jpg ?_nc_cat=110&_nc_sid=110474&_nc_ohc=twmgqMohO0wAX-Dvk9U&_nc_ht=scontent.flhr3-1.fna&oh=1a01a23d57ebbb47b923e61f0ba419b9&oe=5EE97AED

patchy as it dries in, will rub them down with wire wool in the morning and apply another coat.

[spendorman]

Thanks for the pics. Cabinets don't look too bad. I didn't get the patchy effect when I did my DM2's with teak oil.

[ramsden]

I was able to check the supertweeters, they don’t show anything.
Did some testing of random resistors just after that to be sure my multimeter works, the values shown were ok.
But battery is low I need to buy new battery.
What to do in case I would like to use them without supertweeters?
With my limited understanding and little time available I was able to put temporarily 22ohm resistors in place of supertweeters, they are now disconnected.

[spendorman]

I was able to check the supertweeters, they don’t show anything.
Did some testing of random resistors just after that to be sure my multimeter works, the values shown were ok.
But battery is low I need to buy new battery.
What to do in case I would like to use them without supertweeters?
With my limited understanding and little time available I was able to put temporarily 22ohm resistors in place of supertweeters, they are now disconnected.

No problem just disconnecting the supertweeters, no problem with what you have done connecting 22 Ohm resistors in place of the Coles 4001G.

Are you going to buy new Coles 4001G supertweeters?

[ramsden]

Thank you spendorman 🙂
I think I am going to go through matching phase first.
Like with subwoofer is just for fine bass extension analogy.
First they have to sound to my liking 🤪
So far I have tried a few amplifiers with them.
And they seem to be dependant on that, will be back after my work to tell more..

[spendorman]

Sheffield, I was there in the early 70's doing Electronic Engineering at the University. I still have a friend in Sheffield, he picked up the speaker bug from me, he's got it worse than me.

[ramsden]

Lol, would be nice to meet him 🙂
It is already about 5 years now I bought almost everything for 3way speaker project called Black Box, creation of Tony Gee (humblehomemadehifi web site I think). So hard to get myself to finish it 😂
But now DM2 came along the way.. So Black Box will have to wait a bit longer 😎

[ramsden]

Would you guys share what amplification you use with these speakers, whether you did some comparison with various amps, sources, cabling etc and how you think they sound in general, strengths, weaknesses, odds etc?
As said before, my DM2s operates without supertweeters, 22ohm resistors there now, so it may influence the sound output..

[ramsden]

So I did some search in order to find good match for these speakers from the amps I have at home available.
They are Hegel H90, SoulNote SA3.0, Proart PP-7160, Sansui 5000, Teac AS-100, Akai AV-U8, Akai AM-U55.
As source were used Denon DCD-3300 (PCM56), Sony CDP-337ESD (TDA1541), Marantz CD74 (TDA1540), Marantz CD6002 (CS4398), Subbu DAC (ESS9023).
Interconnects Oehlbach, Silver, Wireworld.
Speaker cables QED XTC, Sharkwire 2.5mm2. So nothing exotic there.
As music, various genres with a bit emphasis on Keiko Matsui - Moyo, Opeth - Heritage, Katie Melua, Biffy Clyro, Steven Wilson, Suzanne Vega, Diana Krall, some metal music like Lamb of God, some audiophile recordings selection I made, and more..
Everything started with PP-7160, although I like that amp, it is not suited for DM2.
Then I continued with Hegel, that amp is able to push wide range of speakers, however the sound here was strong controlled bass, too bright for my ears with emphasis on upper midrange here, so it sounded kind of nasal, although fast and detailed, no match.
Here I would stop for a little. Interaction between the amp and speakers is very obvious here, as both of the amps above I like a lot with different speakers.
Next SoulNote, otherwise musical, smooth sounding amp, with DM2 again too much trebles, recessed midrange a bit, wooly bass, bigger then Hegel though, but all together not good match again.
These amps are more recent designs, coincidence?
I would need good at least treble correction to get Hegel sound great there, it might if I would have it 😎
And in general, good bass correction would help too, for lower level listening or music source compensation, fortunately all other amps are old and they have both.
So I have tried Sansui, midrange focused amp, again, no luck, something was not right there, too colored sound, not close to real at all, not match.
Teac connected.. wow! That’s it, the match found! At least to my ears. Still needs some tone corrections here and there, but the basic sound is very good indeed. The drivers ability control not fully there like with Hegel, not going as deep too, it just sounds right through whole spectrum. Sound is bigger, balanced, non nasal with quite right timbre, speed, clarity, ambience.

[ramsden]

After Teac I tried also smaller Akai U8, it didn’t disappoint too, sound was good.
Finally bigger U55, and again very nice match with DM2.
Experimenting with sources Denon was the best of the batch, it is my main CD player.
However I was quite surprised with Marantz CD6002, this one is usually put aside.
It has quite rich sound, nice for lower level listening.
So at the end, one can get extremely pleasing listening experience for not much money.
Marantz CD6002, Akai AM-U55 with B&W DM2 are all affordable components these days.

[VinylChef]

Hi All,
My first (real) post!
I've read every post in this insanely long thread!
I have a pair of DM2A's with the same crossover as the original one the OP posted.
I've viewed the schematic diagrams on the B&W website, but they are different to mine. I believe Spendorman was stated as the authority on this. Spendorman, do you have a schematic diagram of the DM2A's the OP put picture up of?
Thanks,
David

PS I wanted to upload a picture of my crossover but it constantly says it fails. Any advice?

[walpurgis]

PS I wanted to upload a picture of my crossover but it constantly says it fails. Any advice?

I don't know what device or O/S you're using, but you could try a fee image hosting site like ImgBB: https://imgbb.com/

[spendorman]

Send me a PM with your email address and I'll email them to you.

[VinylChef]

I don't know what device or O/S you're using, but you could try a fee image hosting site like ImgBB: https://imgbb.com/

I've just done as you suggested. Now do I just post the embed codes?

https://ibb.co/0KCPBfS
https://ibb.co/F7Vg5mx

[VinylChef]

Send me a PM with your email address and I'll email them to you.

Hi Spendorman,
Thanks very much.
Is it just me or is this website quite hard to navigate? I tried to send you a private message but all I could find was a way to add you as a friend or send you a publicly visible 'visitor message'. Can you clarify?
Regards,
David

[walpurgis]

PM's activate once five posts have been made..........which you now have.