B&W DM7 Kenneth Grange classic

[Guitarrero]

Thinking about getting B&W DM7 speakers and wondered if any here have experiences or advice.... good or bad!
I like the B&W sound but could not afford them in the late 70s so had to settle for DM10's and later DM110's, both of which I still have.
I have heard that they like a reasonably powerful (100w plus) amp to drive them properly, although the factory advises that they are " Entirely suitable for all high quality amplifiers up to 200 watts rating" ..... not sure if my Quad 33/303 will cope?

Thanks in advance,
Steve

[57charles]

Thinking about getting B&W DM7 speakers and wondered if any here have experiences or advice.... good or bad!
I like the B&W sound but could not afford them in the late 70s so had to settle for DM10's and later DM110's, both of which I still have.
I have heard that they like a reasonably powerful (100w plus) amp to drive them properly, although the factory advises that they are " Entirely suitable for all high quality amplifiers up to 200 watts rating" ..... not sure if my Quad 33/303 will cope?

Thanks in advance,
Steve

The problem is that you and 100's if not 1000's would go for these speakers if they performed today as they should i.e. when they were new - the engineering and build quality dictates that if these speakers were produced today they would cost 1000's of pounds.
The 2 problems are that the kevlar bass/ mid units tend to deform over time but the most important thing is that the ferrofluid in those tweeters willl have dried out reducing HF output significantly. B & W do not service spares and you will be left high and dry - replacements are not available. Stop dreaming about getting something on the cheap and bite the bullet by either paying a lot of money for the modern B & W equivalent to DM7 or buy something new within your price range. Won't sound as good as DM7 but at least spares would be available if you need them. Strilkes me that you are the kind of person who thinks you can get something for nothing. In the case of model DM7 you'll end up with a load of potential problems. Oh and I forgot to mention you'll never get those grilles to stay on because the lugs will ALWAYS be broken.

[struth]

The problem is that you and 100's if not 1000's would go for these speakers if they performed today as they should i.e. when they were new - the engineering and build quality dictates that if these speakers were produced today they would cost 1000's of pounds.
The 2 problems are that the kevlar bass/ mid units tend to deform over time but the most important thing is that the ferrofluid in those tweeters willl have dried out reducing HF output significantly. B & W do not service spares and you will be left high and dry - replacements are not available. Stop dreaming about getting something on the cheap and bite the bullet by either paying a lot of money for the modern B & W equivalent to DM7 or buy something new within your price range. Won't sound as good as DM7 but at least spares would be available if you need them. Strilkes me that you are the kind of person who thinks you can get something for nothing. In the case of model DM7 you'll end up with a load of potential problems. Oh and I forgot to mention you'll never get those grilles to stay on because the lugs will ALWAYS be broken.

you speak to member that way again and you are out

[Marco]

Yup... Charles, we don't address people here like that, so please don't do it again and instead engage with others in a more polite, less confrontational way, or I will have no option but to take appropriate action.

Marco.

[Virkon]

I am listening to my DM7 tonight. I don't know if the kevlar unit is deformed it certainly dosen't look it and it sounds sumptuous neither do I know if the tweeter has dried out and that sounds the business too. I got these late seventies and you'll probably guess I won't be parting with them. There's a couple of pairs on ebay at the moment.

[Guitarrero]

I am listening to my DM7 tonight. I don't know if the kevlar unit is deformed it certainly dosen't look it and it sounds sumptuous neither do I know if the tweeter has dried out and that sounds the business too. I got these late seventies and you'll probably guess I won't be parting with them. There's a couple of pairs on ebay at the moment.

Thanks John,
Glad to hear you are enjoying your DM7s regardless of the ravages of time!
I think we have all distorted and dried out a bit since the late 70s, I know I certainly have, but I'm still hoping there's plenty of life left in this old vintage number :lol:

[VanDerGraaf]

DM7.....very nice presentation indeed, yes, the kevlar cones do seem to age oddly (discolouration and rippling seems a common problem). I believe the caps are all polyester so "good for life".

I had read on some other forum that a coating was used on the tweeter that degrades with age and that a coating of shellac applied with an artist's brush does much to restore lost high frequency performance. Do not slay me- the opinions of others are merely being retold! :D

The design is quite beautiful and they are bloody heavy with the integrated stands.

I can't give much further comment about the sound as I haven't heard mine for quite a long time; they have been in the custody of my cupboard since last year.

[sumday]

IIRC there is a component or two built in to the crossover to give automatic overload protection for the tweeters.
These can fail over the years and give the impression of tweeter failure.

This happened to a pair owned by a friend of mine years ago, B&Ws advice was to simply bypass the suspect parts....and watch the volume.

[Virkon]

IIRC there is a component or two built in to the crossover to give automatic overload protection for the tweeters.
These can fail over the years and give the impression of tweeter failure.

This happened to a pair owned by a friend of mine years ago, B&Ws advice was to simply bypass the suspect parts....and watch the volume.

Yes I had the fuses bypassed years ago while changing the speaker terminals to Michell 'big mother' terminals. Still go loud :)

[Guitarrero]

DM7.....very nice presentation indeed, yes, the kevlar cones do seem to age oddly (discolouration and rippling seems a common problem). I believe the caps are all polyester so "good for life".

I had read on some other forum that a coating was used on the tweeter that degrades with age and that a coating of shellac applied with an artist's brush does much to restore lost high frequency performance. Do not slay me- the opinions of others are merely being retold! :D

The design is quite beautiful and they are bloody heavy with the integrated stands.

I can't give much further comment about the sound as I haven't heard mine for quite a long time; they have been in the custody of my cupboard since last year.

Thanks Rohan,
I fully expect and embrace some deterioration on almost 40 year old equipment, and it seems that people will continue to enjoy the DM7 warts and all. Thanks for the shellac tip; don't worry, I won't shoot the messenger!
I agree, great design by Kenneth Grange .... maybe you should muster the strength to haul them out of the cupboard and fire them up again ... bound to put a smile on your face :)

[Guitarrero]

IIRC there is a component or two built in to the crossover to give automatic overload protection for the tweeters.
These can fail over the years and give the impression of tweeter failure.

This happened to a pair owned by a friend of mine years ago, B&Ws advice was to simply bypass the suspect parts....and watch the volume.
Am I right in thinking that the Mk II versions had more sophisticated overload circuitry, which would shut down the overloaded unit and display a warning light in the tweeter housing until reset?
Is the Mk 1 version just fuse protected?

[VanDerGraaf]

I'm pretty sure that is correct.

[57charles]

Yes, the mk1's were fuse protected and the mk2's had the proprietary B &W overload protection. Visually, the MK 1's were stunning with brushed steel top plates to the top of the speakers and matching speaker stand bases in brushed steel. Very expensive looking and beautifully built speakers - they looked stunning with the top mounted tweeter - a stand out design at the time. Very heavy and beautifully finished. The MK2 was slightly 'dumbed down' deleting the stainless steel top and stand base but nevertheless still superb build quality. Unfortunately, in spite of all the high tech involved in this speaker (and the enschewing relative high cost), they were outperformed by speakers costing 25% - 33% at the time - basically speakers from 'box stuffers' - small companies using bought in drivers and crossovers designed in house but contracted out. These companies made nothing themselves but produced some great speakers using bouhht in components. The DM7 was one of B & W 's worst speakers and should be avoided at all costs. Check out the historic HiFi Choice review which slammed it. I remember trying to sell them in the late 70's - early 80's and they performed badly sonically in comparison to similar sized but cheaper competitors from the myriad of smaller 'box stuffer' speaker producers at that juncture in time. If the reader can locate the requisite issue of HiFi choice speaker issue , they will see how many similar sized speakers from small box stuffer operations at that time, completely outperformed the DM7 in MK1 or MK2 form. The only reason for persevering with this under performing speaker is merely for looks - especially the original MK1. Unfortunately, they sounded crap in their day and they sound crap today ( that is if they're still performing to spec which I doubt ANY examples will be due to ferrofluid issues in the tweeters and physical distortion of the kevlar bass/mid drivers which is a well known problem with old B &W kevlar units). Dreamers dream on.

[Guitarrero]

57charles,
After offensive comments contained within your earlier post in this thread I have no desire to interact with you.
You should re-read your posts before hitting the send button to ensure you are not going to offend anyone.

Please do not post on any of my topics/threads in the future.
I have added you to my ignore/block list.

[Virkon]

Here here or should that be hear hear!

[Guitarrero]

:
Here here or should that be hear hear!

:) Thanks John !

[struth]

they are pretty good speakers if driven well. need a powerful amp with grip tho. plenty good reviews out there if you look. looking at 2/3k value speaker if made today

[Marco]

Yes, the mk1's were fuse protected and the mk2's had the proprietary B &W overload protection. Visually, the MK 1's were stunning with brushed steel top plates to the top of the speakers and matching speaker stand bases in brushed steel. Very expensive looking and beautifully built speakers - they looked stunning with the top mounted tweeter - a stand out design at the time. Very heavy and beautifully finished. The MK2 was slightly 'dumbed down' deleting the stainless steel top and stand base but nevertheless still superb build quality. Unfortunately, in spite of all the high tech involved in this speaker (and the enschewing relative high cost), they were outperformed by speakers costing 25% - 33% at the time - basically speakers from 'box stuffers' - small companies using bought in drivers and crossovers designed in house but contracted out. These companies made nothing themselves but produced some great speakers using bouhht in components. The DM7 was one of B & W 's worst speakers and should be avoided at all costs. Check out the historic HiFi Choice review which slammed it. I remember trying to sell them in the late 70's - early 80's and they performed badly sonically in comparison to similar sized but cheaper competitors from the myriad of smaller 'box stuffer' speaker producers at that juncture in time. If the reader can locate the requisite issue of HiFi choice speaker issue , they will see how many similar sized speakers from small box stuffer operations at that time, completely outperformed the DM7 in MK1 or MK2 form. The only reason for persevering with this under performing speaker is merely for looks - especially the original MK1. Unfortunately, they sounded crap in their day and they sound crap today ( that is if they're still performing to spec which I doubt ANY examples will be due to ferrofluid issues in the tweeters and physical distortion of the kevlar bass/mid drivers which is a well known problem with old B &W kevlar units). Dreamers dream on.

Hi Charles,

"Dreamers dream on".

Whilst the rest of the above post is simply your opinion (based on experience), which you're entitled to, the bit in bold is unacceptable, because it's simply an assumption on your part, and also rather insulting to those that comment was aimed at.

It's really none of your business whether someone is a "dreamer" or not, and so that comment was completely unnecessary, in order for you to have made your point, and only serves to irk anyone whose opinion on the speakers in question is different from yours; one which they're equally entitled to hold.

You're also just back from a week's ban for behaving in an aggressive and confrontational manner, and here you are again doing precisely the same! :doh:

Therefore, this is your final warning, before the next ban you receive is permanent. In future, please refrain from making provocative remarks towards others, such as those highlighted above, when simply expressing your opinion, as it's unnecessary and doesn't add value to the point you're making (quite the opposite in fact).

This is a friendly forum, where we treat each other automatically with courtesy, whether we agree with each other or not, and that's how *I insist* people behave here, so please remember that in future. Also note that this warning is not up for debate, discussion or any form of challenging (and so any responses from others or you, in that respect, will be deleted).

Therefore simply read the warning you've been given, and comply accordingly. Cheers! :cool:

Marco.

[Guitarrero]

Hi Charles, This is a friendly forum, where we treat each other automatically with courtesy, whether we agree with each other or not, and that's how *I insist* people behave here, so please remember that in future.


Thanks Marco .... all this malarkey is causing my tinnitus to play up something rotten :lol:

[Andy1]

Hi Steve. I have taken the plunge myself and bought a pair of DM7 Mk1's. I'm now facing the same challenge of finding something to drive them..
I ve looked at loads of stuff but just feel I need more power.. much more power. Maybe a musical fidelity a5..? I am tempted to find something vintage to join them. I am on a budget though. I'd be interested to know where your amp search has taken you so far!
Always loved these speakers! 😀

[struth]

try a nad c350 amp

[Guitarrero]

Hi Steve. I have taken the plunge myself and bought a pair of DM7 Mk1's. I'm now facing the same challenge of finding something to drive them..
I ve looked at loads of stuff but just feel I need more power.. much more power. Maybe a musical fidelity a5..? I am tempted to find something vintage to join them. I am on a budget though. I'd be interested to know where your amp search has taken you so far!
Always loved these speakers! 😀
Hi Andy,
I must admit I haven't looked into suitable amps too much ... was going cross that hurdle if/when I bought the DM7s. I do like classic British kit and was wondering if a Quad 405 might just about be up to the task? ... others with more knowledge than I please chime in:)

Btw, did you buy the pair of DM7s in Peterborough? ... photos looked ok but too far from me to go looksee :(

[Guitarrero]

they are pretty good speakers if driven well. need a powerful amp with grip tho. plenty good reviews out there if you look. looking at 2/3k value speaker if made today

Yes, I've read some of the better reviews and heard more positive comments from happy owners of the DM7; thanks Grant

[57charles]

I'm very sorry and apologise if my comments have caused distress. I genuinely do not want to upset anyone. However, I thought it woyld be useful to let members know what I know. I definately recall Hifi choice panning these speakers in around '79 -81 in one of their little tests books of the time. Perhaps someone has the review - it went something along the lines of 'for all the high tech input into this design, it remains a dissapointing performance - or something like this. I loved the look of this speaker - I loved the superb build quality as well but it would appear that in terms of performance they were eclipsed by speakers made by virtually cottage industry speaker companies - box stuffers if you will. These companies using bought in drivers with nowhere near the resources of B & W at the time got best buy reviews in the issue of that Choice issue and their speakers of similar spec and size were around 25% - 30% less retail price than DM7. I tried to sell DM 7 back in the late 70's - early 80's but could not sell them because they were outperformed by similar sized but cheaper speakers from box stuffer manufacturers. I myself bought an immaculate pair a few years ago to try and reconcile with this model but I have to admit that they were as much a dissappointment second time round as they were the first. I just wish they performed better because I love the looks and build is second to none. However, they were eclipsed then by cheaper similar sized speakers from box stuffers and they are undoubtedly now not even performing to original spec. Perhaps someone has the original review fron Hifi choice. Love to read it again. Once again, many apologises if I came across as confrontational - not intentional at all.

[Bigman80]

I'm very sorry and apologise if my comments have caused distress. I genuinely do not want to upset anyone. However, I thought it woyld be useful to let members know what I know. I definately recall Hifi choice panning these speakers in around '79 -81 in one of their little tests books of the time. Perhaps someone has the review - it went something along the lines of 'for all the high tech input into this design, it remains a dissapointing performance - or something like this. I loved the look of this speaker - I loved the superb build quality as well but it would appear that in terms of performance they were eclipsed by speakers made by virtually cottage industry speaker companies - box stuffers if you will. These companies using bought in drivers with nowhere near the resources of B & W at the time got best buy reviews in the issue of that Choice issue and their speakers of similar spec and size were around 25% - 30% less retail price than DM7. I tried to sell DM 7 back in the late 70's - early 80's but could not sell them because they were outperformed by similar sized but cheaper speakers from box stuffer manufacturers. I myself bought an immaculate pair a few years ago to try and reconcile with this model but I have to admit that they were as much a dissappointment second time round as they were the first. I just wish they performed better because I love the looks and build is second to none. However, they were eclipsed then by cheaper similar sized speakers from box stuffers and they are undoubtedly now not even performing to original spec. Perhaps someone has the original review fron Hifi choice. Love to read it again. Once again, many apologises if I came across as confrontational - not intentional at all.Superb post Charles. Your experience really shone through. Articulated and precise.

More of that please. [emoji4]

[Virkon]

I'm guessing you don't like them Charles.

[57charles]

Love the looks - especially the mk1 and the build quality is beyond reproach but they just never sounded 'right' to my ears compared to the myriad of contempary models from the extraordinary number of speaker producers at that time. We were certainly spoilt for choice.

[Marco]

Superb post Charles. Your experience really shone through. Articulated and precise.

More of that please. [emoji4]

Yes, much better! Stick to discussing the subject, not the poster, and in the process refrain from being judgmental of other people's opinions or decisions, which are contrary to yours :)

Marco.

[Beobloke]

I definately recall Hifi choice panning these speakers in around '79 -81 in one of their little tests books of the time. Perhaps someone has the review - it went something along the lines of 'for all the high tech input into this design, it remains a dissapointing performance - or something like this.

Just for balance, it might be worth remembering that not everyone may agree with these reviews. I have the A5 Hi-Fi Choice that contains the review of the Sony PS-B80 Biotracer turntable and the conslusion is predictably along the lines of "you're paying for all the technology but it doesn't sound that great". Er, actually, to my ears and to the ears of more than a few people I know, it does!

[Marco]

Just for balance, it might be worth remembering that not everyone may agree with these reviews...

Exactly, Adam. Let's remember that subjective reviews, whether printed in magazines or posted on forums, aren't proof of anything, other than the basis upon which the opinions of the reviewer were formed! ;)

Ultimately, the only opinion that matters belongs to the owner of the item(s) concerned [in this case speakers], and whose ears are doing the listening.

Marco.

[Vinyl turner]

Just to add a 'dash' of balance to proceedings;

www.gramophone.co.uk/editorial/review-bw-dm7-speakers

Happy reading.

[Andy1]

Hi steve.
I bought these in the West Midlands. I've been told a 405 will run these nicely but for some reason only known to myself I want more watts per channel so am looking for a 606 or Similar, but I do want a British amp to pair with them. I've gone through my DM7's and given them a proper clean/ check. I think they look amazing! They are marmite for sure. Everyone who sees them has an opinion -good or bad. That I like. Let me know when you get yours and post a pic.. I've missed all of these comments.. need to turn my notifications on!

[Virkon]

Hey there Steve how did you get along with the Dm7?

[Dylanthecat]

I picked up a pair of DM5 yesterday with the kevlar driver questioned in an early response.

I was super inpressed when I tested them against some highly regarded current stand mounts.

I did not hear any age related weakness.

I have passed them on with great reluctance to a friend down on his luck. Despite his serious woes the DM5 had him grinning from ear to ear within a few bars of the remastered N Simone's Funkier than a Mosquitos Tweeter. M

[57charles]

I picked up a pair of DM5 yesterday with the kevlar driver questioned in an early response.

I was super inpressed when I tested them against some highly regarded current stand mounts.

I did not hear any age related weakness.

I have passed them on with great reluctance to a friend down on his luck. Despite his serious woes the DM5 had him grinning from ear to ear within a few bars of the remastered N Simone's Funkier than a Mosquitos Tweeter. M

I had problems with a version of that bass/mid unit which was fitted to my Monitor Audio MA1's. More worringly, the tweeters fitted to DM5 are prone to gradual reduction in output due to drying out of ferro fluid. This is a gradual reduction over the years as the ferro fluid evaporates and gets sticky. Users don't always realise it as it's a gradual process. Chances are they are out of spec though.

[spendorman]

I picked up a pair of DM5 yesterday with the kevlar driver questioned in an early response.

I was super inpressed when I tested them against some highly regarded current stand mounts.

I did not hear any age related weakness.

I have passed them on with great reluctance to a friend down on his luck. Despite his serious woes the DM5 had him grinning from ear to ear within a few bars of the remastered N Simone's Funkier than a Mosquitos Tweeter. M

I have a pair of DM5's, OK speakers in my view, best bit about them is great bass performance for a small (very heavy!) cabinet.

The dried ferrofluid can be removed from a lot of old B&W tweeters, restoring the treble output.

[karma67]

Or just replace the fluid with fresh

[57charles]

I have a pair of DM5's, OK speakers in my view, best bit about them is great bass performance for a small (very heavy!) cabinet.

The dried ferrofluid can be removed from a lot of old B&W tweeters, restoring the treble output.
It's important to replace the ferrofluid if flushing out old because spec will be altered and power handling affected. It's vitally important to replace with same spec ferrofluid and in the exact same quantity. I'm not sure if B&W can or will help with this information. I'd like to think they could but model DM5 is an ancient speaker from another era of this company.

[spendorman]

It's important to replace the ferrofluid if flushing out old because spec will be altered and power handling affected. It's vitally important to replace with same spec ferrofluid and in the exact same quantity. I'm not sure if B&W can or will help with this information. I'd like to think they could but model DM5 is an ancient speaker from another era of this company.

Ideally, yes, but I guess that a lot of these early tweeters that were adopting ferrofluid were existing non ferrofluid ones to which ferrofluid has been added.

I have had no problems removing the ferrofluid of some early B&W tweeters. Better than a tweeter that has little output.

[57charles]

Ideally, yes, but I guess that a lot of these early tweeters that were adopting ferrofluid were existing non ferrofluid ones to which ferrofluid has been added.

I have had no problems removing the ferrofluid of some early B&W tweeters. Better than a tweeter that has little output.
Removing the ferrofluid and not replacing it like for like will alter the balance of the speaker system since the original system including crossover would have been designed to include the response of the tweeter with the ferrofluid. I've tried it myself and generally the characteristics of the speaker tend to become brighter and more strident.

[VanDerGraaf]

On the DM7 front, I am about to let mine go, and as with the above DM5s, I think the ferrofluid needs replacing.
Sad to see them go, despite Charles' opinions on them I happen to think they have a lot going for them.

[system7]

Ye Gods, what is all this fretting about ferrofluid! And its viscosity. :lol:

When it dries out, your tweeter clogs up and stops working. It's happened to me. It's a mixture of iron oxide and oily kerosene.

http://www.bluearan.co.uk/index.php?id=SONFF05&browsemode=manufacturer

That's enough for about 5 tweeters. Clean out the old from the magnet gap and put in the fresh usually. Ocasionally you need to unsolder the voicecoil leads, but this is rare.

It has a 2dB damping effect at either extreme and partially controls the low frequency resonance and provides some cooling to the voicecoil.

[tinear]

Still retain DM7 mk.1 from 1978. Always driven by Meridian 105's.

This speaker caused endless grief.
The original Tweeter would 'blow' (wire-stress when threaded through the doped fabric diaphragm?) - and had a c.5kHz resonance (identified by Peter Tribe when visiting the factory).
The Bass cone assembly would slap into the chamber rear & concertina/unravel the former/coil. The roll surround also originally too shallow.
The ABR initially had a metal slug connector - spider to foam - it would detach/unglue itself - replaced by a flanged plastic version.

Later took the precaution of getting 10 treble diaphragms (mk.2 polyamide - still mostly unused)- & noted some variation in coil windings (B&W considered that had no effect..). A residual problem was the kapton former could 'bubble' due to heating and attaching to the pole-piece (treble disappearing). There was no ferrofluid in the Mk.1 tweeters; wasn't aware it was in the mk.2.

The Bass unit was rather a mass of coloration - later production had doping applied to the cone rear - though the source mostly resided behind that..
Applying a thin epoxy 'veneer' from v/c winding end to cone eliminated much, and improved 'detail' (also has prevented further v/c buckling); but the bass unit is inherently 'sluggish' due to v/c mass (+ plastic former under the dust cover).
By comparison a modern QUAD kevlar bass unit is a Revelation for detail/lack of coloration.

Splitting the x-over had some advantage - as did slightly adjusting the treble resistors for output (the mass of bell-wire leading to the upper rotary adjuster being disconnected).

After all that, it became relatively trouble-free; but driver replacements had easily added 50% to the original (20% discounted) price.

[Handiman]

I've been using Yamaha C2/B2 combo since the late '70's. Only amps I could find to do the job properly.

[Lawrence001]

Nice thread resurrection.

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