Rogers LS3/6 and Leak Stereo 70 combination

[spendorman]

Not tried this combination before, it works really well. What is seems apparent, is the very good midrange. Probably better than any other transistor amp that I have tried. I feed the signal source in to the tape input, this avoids the pre amp.

My LS3/6's have had replacement bass units (Dalesford), so they are effectively early Rogers Export Monitors.

[Wakefield Turntables]

Come on Alex.... :worthless::worthless::worthless::worthless:

[spendorman]

Not much to see really, think I have a look for pics (not that good) that I have put up before.

[spendorman]

Here are the Leaks:

https://c1.staticflickr.com/6/5016/5529888448_1f25143248_b.jpg (https://flic.kr/p/9qE8bh)Leaks (https://flic.kr/p/9qE8bh) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

[Macca]

That tuner is looking lonely. Shouldn't you buy some more of them to match things up? ;)

[spendorman]

17206172071720817209The LS3/6s under reconstruction:

[spendorman]

That tuner is looking lonely. Shouldn't you buy some more of them to match things up? ;)

I did have a second Stereofetic, sold it off years ago.

[Arkless Electronics]

Come on Alex.... :worthless::worthless::worthless::worthless:

I seem to be in a minority in not giving a toss about pictures :D

[spendorman]

I seem to be in a minority in not giving a toss about pictures :D

Most that are interested will probably know that a Stereo 70 is not much to look at. however, I was just being lazy.

[Arkless Electronics]

I have similar (and more) piles of Leak gear like that.... Other than the very good Stereofetic tuner I couldn't recommend any of the rest.... ie the amps...

[spendorman]

I have similar (and more) piles of Leak gear like that.... Other than the very good Stereofetic tuner I couldn't recommend any of the rest.... ie the amps...

Well, I have piles of stuff, mostly in good order. It surprised me how good the Stereo 70 sounds through the LS3/6. To me, my best sounding amp is a Williamson, but mono I'm afraid. The next best is a Radford STA25 III, this is very good. The Stereo 70 is almost up with the Radford.

The LS3/6 speakers are very revealing. They show up differences in amplifiers more than most speakers.

[Virtual-Symmetry]

The Leak 'Stereo 30 Plus' is my fav Leak..

[Arkless Electronics]

Well, I have piles of stuff, mostly in good order. It surprised me how good the Stereo 70 sounds through the LS3/6. To me, my best sounding amp is a Williamson, but mono I'm afraid. The next best is a Radford STA25 III, this is very good. The Stereo 70 is almost up with the Radford.

The LS3/6 speakers are very revealing. They show up differences in amplifiers more than most speakers.

Each to their own. I have several stereo 30 plus, 70, delta 30's, delta 70's and the receivers with the same amps in them. I regard the amps as poor. All of them.
Strangely the original Stereo 30 (not the plus) with awful germanium transistors can sound really good but it's a lottery as to whether you get a good one or an awful one... they vary THAT much!

I've even rebuilt a stereo 30 plus with modern components, bigger smoothing caps etc and set it up very carefully for lowest crossover distortion etc... much better than a standard one but still nothing to write home about. Most SS amps from before about 1980 are pretty meh IMHO... and generally for good technical reasons. No I don't like the 303 before anyone says "but what about the Quad 303" :D

[spendorman]

Four Quad 303's here.

[spendorman]

The Leak 'Stereo 30 Plus' is my fav Leak..

I guess that you know, 30 Plus and Stereo 70 are near identical circuits, mainly higher rail voltage in the 70.

[Wakefield Turntables]

I really like looking at old gear i got a little excited with the smilies. I also have to admit that a set of Spendor speakers has been high on my list of stuff to try for a very very long time. I keep getting side tracked and restoring old decks. :eek:

[Arkless Electronics]

Four Quad 303's here.

Some Spendors here. I'm a big fan of Spendor. We agree on them :)

[Martyn Miles]

17206172071720817209The LS3/6s under reconstruction:

Those transformers look the business.
Wouldn't be out of place in a power supply...

[Virtual-Symmetry]

I regard the amps as poor.

Precisely why i always say 'Do not take a blind bit of notice to half the crap on Hi-Fi forums'. ;)

[spendorman]

Some Spendors here. I'm a big fan of Spendor. We agree on them :)

Yes, have a few of them, about five pairs BC1, one pair BC2, and a pair of Preludes. I also have some BC1a amps.

[spendorman]

I have similar (and more) piles of Leak gear like that.... Other than the very good Stereofetic tuner I couldn't recommend any of the rest.... ie the amps...

Strangely, I only regard the Stereofetic as OK. I much prefer the Rogers Ravensbourne FET2 which is of a similar vintage.

[Virtual-Symmetry]

Yup. I prefer the 'Stereofetic' to the 'Through line 3'

[Bluetone]

Hi Spendorman,

I also have a pair of Rogers LS 3/6's. There's also a replaced bass unit in mine (Kef B110 I think). I've only every chatted with one other person who owns a pair. I'm in Australia, and that guy is in the US. Beautiful midrange on them hey. I had mine recapped, did you recap yours? considering going back and putting nicer caps.

Pics of mine attached.

[spendorman]

Hi Spendorman,

I also have a pair of Rogers LS 3/6's. There's also a replaced bass unit in mine (Kef B110 I think). I've only every chatted with one other person who owns a pair. I'm in Australia, and that guy is in the US. Beautiful midrange on them hey. I had mine recapped, did you recap yours? considering going back and putting nicer caps.

Pics of mine attached.

Hi Bluetone

That's a KEF B200, not the best replacement for your speakers. The midrange will not be as good as the original units for the LS3/6 or Export Monitor.

I have tried the B200, most versions. The original capacitors in the crossover would most likely have been OK as they are not of the electrolytic type.

I can suggest a couple of things that should improve your speakers.

[Bluetone]

Hi Bluetone

That's a KEF B200, not the best replacement for your speakers. The midrange will not be as good as the original units for the LS3/6 or Export Monitor.

I have tried the B200, most versions. The original capacitors in the crossover would most likely have been OK as they are not of the electrolytic type.

I can suggest a couple of things that should improve your speakers.

Still got the original caps. Yeah thanks interested in any suggestions please. What would be a better midbass unit? Thanks

[spendorman]

In my view, the best replacement bass/ mid unit is the Dalesford D100/200. These can be found in 70/80's speakers such as RAM etc. I make a a small adjustment to the crossover that requires two wirewound resistors. The next best unit is the Dalesford D50/200.

The adjustments to the crossover are possibly required because the original LS3/6 bass unit is nominally 15 Ohm, and we are using 8 Ohm units.

Although, it appears that Rogers used the 8 Ohm Dalesford with standard LS3/6 crossovers in the early Export Monitors.

I can supply the crossover mods if you like. I'm not sure if it would be beneficial with the B200 that is in your system. It would likely slightly boost the already coloured midrange of that unit.

[Arkless Electronics]

Yes, have a few of them, about five pairs BC1, one pair BC2, and a pair of Preludes. I also have some BC1a amps.

BC2's here... amongst other speakers I own... The Spendor's were my main speaker until the KEF Reference 105.3/4's came along.

[Arkless Electronics]

Strangely, I only regard the Stereofetic as OK. I much prefer the Rogers Ravensbourne FET2 which is of a similar vintage.

I think I've got one of those Rogers ones somewhere... yes a good tuner.

[Arkless Electronics]

Yup. I prefer the 'Stereofetic' to the 'Through line 3'

Same here and by a very large margin! I really can't see what all the fuss was about with the Troughline. It was probably the best of the British all valve FM tuners and the use of a tuned line local oscillator (the "troughline") gave it excellent frequency stability for the time. In comparison to a modern tuner though it's a non starter....

[Bluetone]

ok thanks for the tips. I will try to source the Dalesford driver. Out of interest, how does your LS 3/6 compare to your BC1's do you have a preference?

[spendorman]

My LS3/6 (now really early Export Monitors) are preferable to both my BC1's and BC2's. They have better controlled bass than the BC1, midrange as good as BC1, and possibly slightly better integration of the units.

Also better midrange than the BC2.

I did try the BC2 bass unit in the LS3/6, the Dalesford unit gave better midrange.

I also tried the BC1 bass unit, felt the Dalesford was better overall.

Many other units tried including nearly all the versions of the KEF B200, bass was fine, midrange too coloured. Similar applies to the B&W DM4 and DM2 bass units.

[Bluetone]

Good to hear. Sounds like you've done some extensive testing of Bass options. I think our chances of finding an original pair of Rogers BBC bass loudspeakers are very slim. Still would love to hear the fully original for comparison. Will chase down a pair of those Dalesford's thanks

[Virtual-Symmetry]

Be careful Alex, you might get ridiculed for owning all the speakers you do & owning a hand full of the same amp over slight variation in production run ;)

[spendorman]

Be careful Alex, you might get ridiculed for owning all the speakers you do & owning a hand full of the same amp over slight variation in production run ;)
Yes, one might get: "slight variation in production run"

But, Virtual-Symmetry, you must suspect that I have many different makes and models of amp.

[spendorman]

Good to hear. Sounds like you've done some extensive testing of Bass options. I think our chances of finding an original pair of Rogers BBC bass loudspeakers are very slim. Still would love to hear the fully original for comparison. Will chase down a pair of those Dalesford's thanks

Even if you did, they are a delicate item. You might need a supply of them! I guess that people used them with amps that were too powerful. Actually, similar can happen to BC1's, especially the earlier ones with a lower power rating.

[Bluetone]

Even if you did, they are a delicate item. You might need a supply of them! I guess that people used them with amps that were too powerful. Actually, similar can happen to BC1's, especially the earlier ones with a lower power rating.

Yes welll now all three people including myself that i know who have ls 3/6s dont have original mid bass units. So must of been a very delicate unit.

[Bluetone]

Have you ever measured frequency response of your ls 3/6s. Apologies for hijackingnthe thread to ls 3/6 topic. I don't get the opportunity to chat with many people who also have them

[Virtual-Symmetry]

Yes, one might get: "slight variation in production run"

But, Virtual-Symmetry, you must suspect that I have many different makes and models of amp.

Yeh i know. But certain people on AOS are anal about such habbits

[spendorman]

Have you ever measured frequency response of your ls 3/6s. Apologies for hijackingnthe thread to ls 3/6 topic. I don't get the opportunity to chat with many people who also have them

Although an Engineer, to me in this field, measurements are not God. In the past I have heard many speakers that were designed, perhaps using computers, and measured to the nth degree, and have sounded rubbish.

So no, I have not done extensive measurements.

Good to chat about LS3/6. It only took me in excess of 10 years to collect the bits and put mine together! Well, there were a few pauses along the way!

I first bought empty cabinets and most of the crossover bits from eBay.

You are probably aware that the special crossovers allow close matching of individual units sensitivity, also adjustment of input impedance.

I can provide the crossover diagram, I have posted it on the Yahoo Spendor Group site.

[Bluetone]

Although an Engineer, to me in this field, measurements are not God. In the past I have heard many speakers that were designed, perhaps using computers, and measured to the nth degree, and have sounded rubbish.

So no, I have not done extensive measurements.

Good to chat about LS3/6. It only took me in excess of 10 years to collect the bits and put mine together! Well, there were a few pauses along the way!

I first bought empty cabinets and most of the crossover bits from eBay.

You are probably aware that the special crossovers allow close matching of individual units sensitivity, also adjustment of input impedance.

I can provide the crossover diagram, I have posted it on the Yahoo Spendor Group site.

Hi no didnt know about the matching thing, whats that? Yes please share the crossover schematic thanks.

[spendorman]

Hi no didnt know about the matching thing, whats that? Yes please share the crossover schematic thanks.

The label on the back of your speakers says 15 Ohm, Rogers also supplied 8 Ohm. The brown input wire was moved to a different tap on the large autotransformer. I think it was moved to tap 5, but not absolutely sure. I would tend to leave the brown wire connected tap 1. This is for two reasons,

1/ Most replacement bass units will be 8 Ohm, and moving brown wire towards tap 5 will decrease the nominal impedance well below 8 Ohms.

2/ moving the brown wire towards tap 5 will increase the voltage drive to the whole speaker system, making it appear more sensitive, it will also be easier to blow the whole speaker with excess power. I suppose if using the speaker with a very low power amp, say 5 to 10 Watts, some benefit may be had by moving this brown wire.

The voltage applied to all the drive units can be adjusted individually, but the Celestion HF1300 is the one that as standard is well attenuated, as it is in the Spendor BC1 and BC2. The difference here is that in the BC1 and BC2, the attenuation is done by a fixed tapped inductor, with the LS3/6 we can adjust in 0.5 dB steps by means of the multi tapped inductor/ auto transformer.

If you PM me your email address, I will send you the standard crossover diagram and my slight modification for when using the Dalesford D100/200 bass unit.

[Bluetone]

Excellent Alex. The Ls3/6 are my most treasured speakers. Very excited about tweaking them to perform to their best. Thanks

[spendorman]

PM received, emails with info sent.

Let's hope that you find the Dalesford units an improvement. A friend has early Export Monitors, he has tried other bass units and found the original Dalesford units the best.

[spendorman]

One slightly negative point, looking at your photo, it appears that your baffles have had the bass unit hole enlarged (not that neatly) so that the B200 can be front mounted. The original units were back mounted. I would tend to correct this when fitting the Dalesford. This might then show the roughly cut hole when viewed from the front of the speaker. Making new front baffles seems a bit of a nuisance, repairing the originals may be possible.

[Bluetone]

Yeah I was going to ask you about that, is a bit of a shame. I wonder if the hacked out hole is not too large to prevent the Dalesford from being back mounted. Otherwise would need to cut the hole slightly larger and a clean circle and install a ring of ply to the correct dalesford size. A quick look around for the Dalesford D100/200 is not yielding much, are they also fairly difficult to find?

[spendorman]

Yeah I was going to ask you about that, is a bit of a shame. I wonder if the hacked out hole is not too large to prevent the Dalesford from being back mounted. Otherwise would need to cut the hole slightly larger and a clean circle and install a ring of ply to the correct dalesford size. A quick look around for the Dalesford D100/200 is not yielding much, are they also fairly difficult to find?

You might get away with it, hopefully the hole is not too big. Your ring Idea is good, especially if you are handy with wood. With patience and some matt black paint the repair could be invisible.

Dalesfords do turn up, I think I mentioned in RAM speakers, some other too like WAR. Can't offhand think of other, anyone help? Put a search into eBay for RAM, for Dalesford, and save them. You should get some automatic replies.

[spendorman]

D50/200 Here

http://www.ebay.co.uk/itm/Western-Audio-Research-vintage-British-Hi-fi-Speakers-WAR-Dalesford-Peerless-/291790799381

I have tried the D50/200 in the LS3/6. It's the smaller magnet version (still quite big), has slightly sweeter mid, slightly less sensitive, and marginally inferior bass compared to the D100/200.

[Bluetone]

D50/200 Here

http://www.ebay.co.uk/itm/Western-Audio-Research-vintage-British-Hi-fi-Speakers-WAR-Dalesford-Peerless-/291790799381

I have tried the D50/200 in the LS3/6. It's the smaller magnet version (still quite big), has slightly sweeter mid, slightly less sensitive, and marginally inferior bass compared to the D100/200.

Do you think the D50/200 would be a big enough step up from the Kef I'm currently using or should I just hold out for the D100/200? saved the ebay searches.

[spendorman]

Do you think the D50/200 would be a big enough step up from the Kef I'm currently using or should I just hold out for the D100/200? saved the ebay searches.

The D50/200 in my opinion is a much nicer sounding unit than the KEF. Probably slightly less sensitive, may need the HF1300 attenuated a step, easily done. I would try as is first though.

A saved search for D100/200 may not yield much as the unit part number may not be described in the listing.

[Barry]

I listened to The Rogers BBC Studio/Export Monitor speaker many years ago (~ 1973), where it was powered by either a Quad 33/303 combo or (more likely) a Quad 33/405.

Being slightly pedantic, the BBC Studio Monitors are NOT LS3/6s but are based on the BBC design. The Roger's speaker was available in two versions: 'Standard' - a two way design using a Celestion HF 1300 tweeter, conforming exactly to the LS3/6 specification; and 'Special', wherein a third drive unit was added, a Celestion HF 2000, to extend the frequency range. This latter version was approved by the BBC, but it was never given a BBC designation; nor to my knowledge was it used by them.

The original Studio Monitors used bextrene cones with paper voice coil formers, made in house by Rogers. These proved to be unreliable and were replaced by bextrene drive units made for Rogers by Dale. With the Dale units fitted, and a necessary change made to the crossover network, the speaker was renamed the Rogers Export Monitor.

At the time I thought them very good indeed and considered them as an alternative to the Quad 57s as a more 'room-friendly' speaker. In the end I didn't go through with the idea and bought a pair of Quads the following year.

[Arkless Electronics]

I listened to The Rogers BBC Studio/Export Monitor speaker many years ago (~ 1973), where it was powered by either a Quad 33/303 combo or (more likely) a Quad 33/405.

Being slightly pedantic, the BBC Studio Monitors are NOT LS3/6s but are based on the BBC design. The Roger's speaker was available in two versions: 'Standard' - a two way design using a Celestion HF 1300 tweeter, conforming exactly to the LS3/6 specification; and 'Special', wherein a third drive unit was added, a Celestion HF 2000, to extend the frequency range. This latter version was approved by the BBC, but it was never given a BBC designation; nor to my knowledge was it used by them.

The original Studio Monitors used bextrene cones with paper voice coil formers, made in house by Rogers. These proved to be unreliable and were replaced by bextrene drive units made for Rogers by Dale. With the Dale units fitted, and a necessary change made to the crossover network, the speaker was renamed the Rogers Export Monitor.

At the time I thought them very good indeed and considered them as an alternative to the Quad 57s as a more 'room-friendly' speaker. In the end I didn't go through with the idea and bought a pair of Quads the following year.

To be even more pedantic it couldn't have been a Quad 405 in 1973 as they were first sold in (IIRC) 1976;)

[spendorman]

I listened to The Rogers BBC Studio/Export Monitor speaker many years ago (~ 1973), where it was powered by either a Quad 33/303 combo or (more likely) a Quad 33/405.

Being slightly pedantic, the BBC Studio Monitors are NOT LS3/6s but are based on the BBC design. The Roger's speaker was available in two versions: 'Standard' - a two way design using a Celestion HF 1300 tweeter, conforming exactly to the LS3/6 specification; and 'Special', wherein a third drive unit was added, a Celestion HF 2000, to extend the frequency range. This latter version was approved by the BBC, but it was never given a BBC designation; nor to my knowledge was it used by them.

The original Studio Monitors used bextrene cones with paper voice coil formers, made in house by Rogers. These proved to be unreliable and were replaced by bextrene drive units made for Rogers by Dale. With the Dale units fitted, and a necessary change made to the crossover network, the speaker was renamed the Rogers Export Monitor.

At the time I thought them very good indeed and considered them as an alternative to the Quad 57s as a more 'room-friendly' speaker. In the end I didn't go through with the idea and bought a pair of Quads the following year.

Hi Barry, it's not just based on the LS3/6, it conforms to the LS3/6 spec. See attached scan. I have more info that I have not attached, almost from the horse's mouth, the son of one of the designers. There may be some doubt about the added supertweeter.

But it's possible that the model as you say with the supertweeter does not conform to the BBC spec.

I bought one of the first 405's, 1975 or was it 1976!

17271

The Early Rogers Export Monitor were the LS3/6 / Rogers Monitor using Dalesford bass units, my friend has a pair. Later Export Monitors used a cheapened crossover without the autotransformer, cheaper cabinets too.

PS attachment is almost unreadable after uploading, I will provide something better.


https://c7.staticflickr.com/8/7388/27163144814_faad4ad3e5_h.jpg (https://flic.kr/p/HojdB1)Rogers (https://flic.kr/p/HojdB1) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

[spendorman]

17272This is from one of the designers, via his son:

[spendorman]

Back to the Leak Stereo 70, Got a bit of hiss from it. It's standard, all original, but some years ago I checked the output stage bias etc.

Took the plug in PCB cards out, wiped the contacts with a cloth with some Servisol Super 10 on it, put the cards back, all quiet now.

Still pleased with the sound.

[Barry]

To be even more pedantic it couldn't have been a Quad 405 in 1973 as they were first sold in (IIRC) 1976;)

Actually it was 1975; so I probably heard the Rogers Export Monitors in 1976. It was a long time ago ("and I was very,very drunk").

[Barry]

Hi Barry, it's not just based on the LS3/6, it conforms to the LS3/6 spec. See attached scan. I have more info that I have not attached, almost from the horse's mouth, the son of one of the designers. There may be some doubt about the added supertweeter.

But it's possible that the model as you say with the supertweeter does not conform to the BBC spec.

I bought one of the first 405's, 1975 or was it 1976!

17271

The Early Rogers Export Monitor were the LS3/6 / Rogers Monitor using Dalesford bass units, my friend has a pair. Later Export Monitors used a cheapened crossover without the autotransformer, cheaper cabinets too.

PS attachment is almost unreadable after uploading, I will provide something better.


https://c7.staticflickr.com/8/7388/27163144814_faad4ad3e5_h.jpg (https://flic.kr/p/HojdB1)Rogers (https://flic.kr/p/HojdB1) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

That is exactly what I said in my post and confirmed by the Rogers publicity brochure you show. The 'Standard' model conforms to the BBC specification for the LS3/6; the 'Special' model with the additional tweeter, was approved by the BBC but wasn't used by them (they were quite happy with the LS3/6 response of 15kHz), nor was it given (to my knowledge) an "LS" designation. According to the brochure I have, the 'Special' (called the Rogers BBC Studio Monitor) has a frequency response of 40Hz - 25KHz (+/- 3dB).

The model I heard was the three way design with an autoformer in the crossover.

I bought my first 405 in 1977.

[spendorman]

Label from a Rogers BBC Monitor:

17282

So the plot thickens, not that it matters really.

[Barry]

Worse than that, my Rogers' brochure (for their "BBC Studio Monitor" speaker) states in the second paragraph:

"Based on a design of the British Broadcasting Corporation's research department, the speaker is the result of many years research into speaker cone behaviour, the most significant aspect of the design being the main drive unit employing a special plastic cone. The speaker is produced under licence from the BBC and conforms to their specification LS3/6, but, with the important addition of a third drive unit, a modification exclusive to Rogers."

So how can it conform to the 2-way LS3/6 design and yet have a third drive unit fitted? Confused? I am! :scratch:

[spendorman]

Sorry, my attachment at post 57 didn't work, redone now. 57, how appropriate, 57's were mentioned by you earlier on. Two pairs of them here.

I think it's said on he Mark Hennessy site that there is some confusion over this model!

My crossovers had the tweeter connected in the wrong phase, both crossovers! It's supposed to be out of phase with the bass unit.

[Bluetone]

Very interesting commemts Barry. Interesting that the letter from Spencer Hughes on Hennesy's page, spencer refers to the 3 way and 2 way versions both as the ls 3/6. From spencers comments it seems to me the two way version was a proto and the ls 3/6 proper was the 3 way and the 3 way was used at bbc. This is backed up by spencers comments on relative durabilty of the bc1 over the ls 3/6 saying very few if any ls3/6 wouls stull be surviving, this comparisin makes sense to the 3 way version to me.

http://www.markhennessy.co.uk/rogers/spencer_hughes.htm

[spendorman]

Very interesting commemts Barry. Interesting that the letter from Spencer Hughes on Hennesy's page, spencer refers to the 3 way and 2 way versions both as the ls 3/6. From spencers comments it seems to me the two way version was a proto and the ls 3/6 proper was the 3 way and the 3 way was used at bbc. This is backed up by spencers comments on relative durabilty of the bc1 over the ls 3/6 saying very few if any ls3/6 wouls stull be surviving, this comparisin makes sense to the 3 way version to me.

http://www.markhennessy.co.uk/rogers/spencer_hughes.htm

Yes, I just read that, 3 way model still referred to as LS3/6

[Bluetone]

Just linking to Marks page. This is the only single source of info on LS 3/6 I can find. Take a look at section on ls 3/6. Spendorman you should send markbthat brochure and any other info. This stuff ahould be captured in one spot, important history in my opinon.

http://www.markhennessy.co.uk/rogers/others.htm

[spendorman]

Bluetone, I might send Mark that brochure and other documents, I think I put all or some of it on the Spendor Yahoo Group. Incidentally, My friend's son works at the BBC and was trained by Mark. Also, Jim Rogers was a family friend, I got to visit the London Catford factory quite a few times between the mid 60's and early 70's.


Latest, I have contacted Mark to see if he agrees that the info should go on his site.

[Bluetone]

Bluetone, I might send Mark that brochure and other documents, I think I put all or some of it on the Spendor Yahoo Group. Incidentally, My friend's son works at the BBC and was trained by Mark. Also, Jim Rogers was a family friend, I got to visit the London Catford factory quite a few times between the mid 60's and early 70's.


Latest, I have contacted Mark to see if he agrees that the info should go on his site.

Wow Spendorman amazing connections you have there! Hey wanted to ask you did you try the Studio 1 midbass driver in your experiments?

[spendorman]

Wow Spendorman amazing connections you have there! Hey wanted to ask you did you try the Studio 1 midbass driver in your experiments?

Hi Bluetone, no, haven't tried the Studio 1 midbass driver. Looks like it might be suitable though.

This may be of interest, think LS3/6 / Export Monitor is mentioned:

http://www.g4dcv.co.uk/ls35a/rogershistory.html

Going back in the day, or should I say many decades back, I used to get prototype speakers from the Rogers factory for home trial, eventually, unfortunately, they had to go back. I don't remember a bad model.

[spendorman]

Two small things extra that I have done, a thin ring of foam round the inside of the port, similar to the first Spendor mod to the BC1 port. Also I have added some BAF (Bonded Acetate Fibre) wadding to the inside of the cabinets. This tighten up the bass marginally.

[Barry]

Just linking to Marks page. This is the only single source of info on LS 3/6 I can find. Take a look at section on ls 3/6. Spendorman you should send markbthat brochure and any other info. This stuff ahould be captured in one spot, important history in my opinon.

http://www.markhennessy.co.uk/rogers/others.htm

I had forgotten Mark's page. Very interesting, largely definative, but still somewhat ambigious regarding the connection between the LS3/6 two-way design and the 3-way Rogers Export Monitor.

Certainly the rear information plate shown confirms the speaker to have a specification corresponding to the LS3/6 (eg. the power handling and the frequency response), but does the speaker have only two drive units, or three?

Sorry to be banging on about this, but I would be very surprised if the BBC would allow their designation to be used for one of their designs that had been substantially modified by Rogers. Rogers themselves in the publicity brochure say the 'Special' version of the BBC Studio Monitor (with three drive units) is 'approved' by the BBC. That may only mean that the BBC were content with having their name included in the model name: "The BBC Studio Monitor", not that it still conforms to the specification of the LS3/6.

[spendorman]

Whatever the history, I think it's clear that adding a supertweeter, Coles 4001G in the case of the BC1/BC2, HF2000 in the case of the LS3/6 / Export Monitor, is a good thing. When they are removed, something seems missing, but it's subtle, especially with ageing hearing!

[Barry]

Whatever the history, I think it's clear that adding a supertweeter, Coles 4001G in the case of the BC1/BC2, HF2000 in the case of the LS3/6 / Export Monitor, is a good thing. When they are removed, something seems missing, but it's subtle, especially with ageing hearing!

Agreed. :)

[spendorman]

And the label in post 57 says 3 unit, the crossover diagram for the 3 way says "LS3/6". We will probably not get to the bottom of this, some of the people concerned with the speakers at the time, are sadly no longer with us.

[Bluetone]

And the label in post 57 says 3 unit, the crossover diagram for the 3 way says "LS3/6". We will probably not get to the bottom of this, some of the people concerned with the speakers at the time, are sadly no longer with us.

yeah I think you're right, may remain a mystery.

[Barry]

And the label in post 57 says 3 way, the crossover diagram for the 3 way says "LS3/6". We will probably not get to the bottom of this, some of the people concerned with the speakers at the time, are sadly no longer with us.

The label in post 57 says three way and boasts a wider frequency response, so it is the Special version of the BBC Studio Monitor. It does not mention LS 3/6. The circuit diagram for the crossover has been drawn by hand; it is not a BBC drawing, so the title LS3/6 is suspect.

But as you say the uncertainty will probably never be resolved, and at the end of the day is not really important. The 3-way Rogers Studio/Export Monitor is a very good speaker and were I able to find a pair in good condition would buy them for my second or third system.

[spendorman]

And then, of course there is this:

http://stirlingbroadcast.net/ls36.html

[Virtual-Symmetry]

Ive always stayed clear of Monitor Type speakers

[Bluetone]

Hi Spendorman,

There's a couple of other replacements I'm considering to maximise my chances

1. The Swisstone, bextrene, 11 Ohm driver used in the Export monitor (I guess before the Dalesford unit?)
2. The Swisstone, bextrene, 8 Ohm driver used in the Studio 1

see attached images. What are your thoughts. Would the export 11 ohm one be better as its closer to 15? I think I did read that the swisstone unit were believe to be superior to Dalesford but I don't know

172951729617297

[Bluetone]

An interesting twist in the mystery of the LS3/6 2 way vs 3way

Taken From "BBC's Home service Just what does the BBC use to monitor the output of its many studios"

http://www.g4dcv.co.uk/ls35a/pics/BBC's_home_service.pdf



"The original LS3/ 6 was a two-way design, flat
to about 14kHz, which is all very well if you are
monitoring stereo broadcasts which have no
information above 14kHz but can be a problem in
a TV studio if you are listening for a line whistle at
15.625kHz. The LS3/6 is now obsolete but the
cabinet design lives on in the Rogers Export
Monitor and the Spendor BC1 and BC2 designs"

and also this in the same article

"Taxation
But there was another factor influencing the
design and that, believe it or not, was Purchase
·Tax. It was of course known that the Celestion
HF1300 in the LS3/6 had a natural roll-off above
14kHz and the addition of a third driver to the
design would not only improve the measured
frequency response but also make the speaker
exempt from Purchase Tax (as all three unit
speakers were at the time). Rogers Loudspeakers
(the Jim Rogers - Rogers Loudspeakers Co.)
added a Celestion HF2000 to the design without
altering the existing cross over but exploiting the
natural roll-off of the HF1300 and adding a simple
filter for the H F2000 unit. Referenced against a
standard LS3/ 6 there were mutterings about
phase anomalies but the public preferred a
response to 20kHz. I have recently heard of
American and Japanese audiophiles turning the
clock back and wiring the super tweeter out of
circuit or removing it entirely"

[Bluetone]

Here's a link to the full review of the Rogers BBC monitor in the July 1972 issue of Studio sound

http://www.americanradiohistory.com/Archive-Studio-Sound/70s/Studio-Sound-1972-07.pdf
(http://www.americanradiohistory.com/Archive-Studio-Sound/70s/Studio-Sound-1972-07.pdf)


Interesting comparison between the Rogers and the BC1, the reviewer couldn't really pic a clear winner. Freq response curve in there too. Interesting that the Rogers was more expensive than the BC1 an the Quad ESL. The price of the 3 way with stands was £96.31 , the 2 way without stands was £45

[spendorman]

Hi Spendorman,

There's a couple of other replacements I'm considering to maximise my chances

1. The Swisstone, bextrene, 11 Ohm driver used in the Export monitor (I guess before the Dalesford unit?)
2. The Swisstone, bextrene, 8 Ohm driver used in the Studio 1

see attached images. What are your thoughts. Would the export 11 ohm one be better as its closer to 15? I think I did read that the swisstone unit were believe to be superior to Dalesford but I don't know

172951729617297

Hi Bluetone, I believe that the Dalesford pressed steel chassis bass unit was used in the Export Monitor right from it's introduction, and measuring the DC resistance of a friends early Exports Monitor's bass units, which we believe to be original, they would appear to be 8 Ohm nominal impedance. His speakers have the removable backs and the same crossovers as our speakers.

The Swistone Bextrene 8 Ohm unit may well be an alternative, I have never come across one.

[spendorman]

An interesting twist in the mystery of the LS3/6 2 way vs 3way

Taken From "BBC's Home service Just what does the BBC use to monitor the output of its many studios"

http://www.g4dcv.co.uk/ls35a/pics/BBC's_home_service.pdf



"The original LS3/ 6 was a two-way design, flat
to about 14kHz, which is all very well if you are
monitoring stereo broadcasts which have no
information above 14kHz but can be a problem in
a TV studio if you are listening for a line whistle at
15.625kHz. The LS3/6 is now obsolete but the
cabinet design lives on in the Rogers Export
Monitor and the Spendor BC1 and BC2 designs"

and also this in the same article

"Taxation
But there was another factor influencing the
design and that, believe it or not, was Purchase
·Tax. It was of course known that the Celestion
HF1300 in the LS3/6 had a natural roll-off above
14kHz and the addition of a third driver to the
design would not only improve the measured
frequency response but also make the speaker
exempt from Purchase Tax (as all three unit
speakers were at the time). Rogers Loudspeakers
(the Jim Rogers - Rogers Loudspeakers Co.)
added a Celestion HF2000 to the design without
altering the existing cross over but exploiting the
natural roll-off of the HF1300 and adding a simple
filter for the H F2000 unit. Referenced against a
standard LS3/ 6 there were mutterings about
phase anomalies but the public preferred a
response to 20kHz. I have recently heard of
American and Japanese audiophiles turning the
clock back and wiring the super tweeter out of
circuit or removing it entirely"

Thank you, not seen that write up, but I already knew about the Purchase Tax and the line whistle thing.

[spendorman]

Here's a link to the full review of the Rogers BBC monitor in the July 1972 issue of Studio sound

http://www.americanradiohistory.com/Archive-Studio-Sound/70s/Studio-Sound-1972-07.pdf
(http://www.americanradiohistory.com/Archive-Studio-Sound/70s/Studio-Sound-1972-07.pdf)


Interesting comparison between the Rogers and the BC1, the reviewer couldn't really pic a clear winner. Freq response curve in there too. Interesting that the Rogers was more expensive than the BC1 an the Quad ESL. The price of the 3 way with stands was £96.31 , the 2 way without stands was £45

Not seen this before, interesting. Took a while to scroll though, in the end did a Ctrl+F to find Spendor. It starts at page 79.

It does mention that the BBC approved the addition of the third unit,

I will have to try my BC1's again. I have early models with Alnico magnet,through to the late models with the ceramic magnet ones with the large port partly filled with thick foam.

[Barry]

Here's a link to the full review of the Rogers BBC monitor in the July 1972 issue of Studio sound

http://www.americanradiohistory.com/Archive-Studio-Sound/70s/Studio-Sound-1972-07.pdf
(http://www.americanradiohistory.com/Archive-Studio-Sound/70s/Studio-Sound-1972-07.pdf)


Interesting comparison between the Rogers and the BC1, the reviewer couldn't really pick a clear winner. Freq response curve in there too. Interesting that the Rogers was more expensive than the BC1 an the Quad ESL. The price of the 3 way with stands was £96.31 , the 2 way without stands was £45

I have that edition of Studio Sound magazine, bought initially for the review of the Quad electrostatic, but was the start of my subscription to the magazine for many years.

Refering to the review of the Rogers BBC Monitor, it is interesting that the designation LS3/6 is not mentioned. Only that the Rogers BBC Monitor was a development of the LS3/4 to a floor-standing speaker using a rectangular cabinet. It seems the BBC Research Department accepted Rogers modification of the original design in using a third drive unit to extend the response to 25kHz, yet it is not clear if the BBC continued to designate the new three-way unit as an LS3/6.

[spendorman]

I've got it, we shall unofficially name the three unit version the LS3/6a. lol

In my view it a was a bit misleading when Rogers called speakers LS1, LS2, LS2a, LS5 LS6 LS7 etc. etc. Many people thought that these were BBC designed speakers. Not to say that they are bad speakers, I have some LS7's, quite like them. The LS2's I have don't get used much, but not bad.

[Bluetone]

Agree should be reserved for the BBC orignanted models only. I also have the LS2 and the Studio 1a.

[spendorman]

Agree should be reserved for the BBC orignanted models only. I also have the LS2 and the Studio 1a.

The Studio 1a looks similar to the LS7 with bigger cabinet and Bi-Wiring facility. The LS7 bass unit has a massive magnet.

[Bluetone]

Yeah Studio 1a is a very nice speaker. Listening to it right now.

[spendorman]

I prefer to Celestion HF1300 / supertweeter combination to the tweeter in the LS7. How do find that combination to the tweeter in your Studio 1a?

[Bluetone]

Much prefer the bbc monitors, just that upper midrange for vocals is still the one of the best I've had. There is decent deep full bass in the Studio 1.

[spendorman]

The B200 should give you pretty good bass in the the BBC monitors, adding a small amount of extra damping inside the cabinet, and the foam ring in the port, should help in firming it up a bit. It's the mid of the B200 that lets the side down a bit.

From memory, I think that the Dalesford bass unit has its mounting holes near enough in the same place as the B200.

[Bluetone]

yeah I actually re did te foam inside the Studio 1a cause it had disintegrated to rubble and it made a big improvement. How much damping did you add, how did you add the foam to the port?

[spendorman]

yeah I actually re did te foam inside the Studio 1a cause it had disintegrated to rubble and it made a big improvement. How much damping did you add, how did you add the foam to the port?

Funny how that foam only sometimes disintegrates. I bought a pair of Tangent RS2's, nice speakers 8" Bextrene Audax and KEF T27 in a compact cabinet. Inside one speaker the foam had turned to powder, had to use a suction cleaner to get it out, the other speaker, foam was fine.

I would suggest trying about half filling the free space of the cabinet with something like BAF wadding.

Foam ring around inside of port, I will look for a photo. This ring reduces the chuffing noise that a port can generate. It really needs to be glued in, otherwise the air movement can blow it out. I used Pritt Stick. Easy to remove if necessary, and won't dissolve the foam.

Foam port ring can be seen her on these Spendor BC1's:

http://www.mats-enterprise.co.uk/roseweb/frntofflrg.jpg

Another pic:

http://www.canuckaudiomart.com/details/649026065-spendor_bc1_speakers_matched_serials_restored/images/499402/

[Bluetone]

I discovered this image of one of the first ls3/5 protoypes. Just wondering if that is the 2 way ls3/6 also pictured?

Also I've got a second pair of rogers bbc monitors headed my way (picture attached). These are early versions (serial no.175) with the gold grill cloth woth orignal stands.

[spendorman]

Interesting pictures, never seen that LS3/5 photo before.

It would be nice to see pictures of your new speakers (inside and out) when you receive them.

[spendorman]

https://c1.staticflickr.com/6/5622/30899767720_07a14ae4b3_z.jpg (https://flic.kr/p/P5vopS)Rogers (https://flic.kr/p/P5vopS) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

Made the pic a bit bigger etc. Looks a bit like the port is in a different position, the HF1300 is mounted low down, and possibly there is a supertweeter there (HF2000?)

[Bluetone]

https://c1.staticflickr.com/6/5622/30899767720_07a14ae4b3_z.jpg (https://flic.kr/p/P5vopS)Rogers (https://flic.kr/p/P5vopS) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

Made the pic a bit bigger etc. Looks a bit like the port is in a different position, the HF1300 is mounted low down, and possibly there is a supertweeter there (HF2000?)

Yes Interesting I thought the same that it looked to be 3 way based on the driver above yhe midbass appearing quite close. Yes will take plenty of pics inside and out when I get them. I already note it has a slightly different rogers badge than my othe pair. Just hoping the midbass drivers are origi al and working on them, we'll see.

[Bluetone]

This is an interesting thread with somw videos taken at the bbc loudspeaker design facility. One of the videos taken in the storeroom shows the ls3/6 I think.

http://www.harbeth.co.uk/usergroup/showthread.php?1837-What-s-it-like-to-be-working-at-the-BBC-anechoic-chamber&

I cant check the video on my phone right now but I think this is the one.

[spendorman]

Great stuff, thank you for posting. Only trouble is I want to see more!

[Bluetone]

No problem. I stumbled on this video a coupkle fo years ago and had been trying to locate it ever since. Yes i know, me too. I'm tempted to email the poster to see if he has any more videos. i think the last video on that first page (KW Part 1c) the very first speakers that Derek Hughes goes for, i think are the LS3/6's what do you think?

[Bluetone]

i would have loved to have access to that storeroom and carefully audition them all. that facility has gone now, I wonder what became of all that history. i think i read there was an auction of all the gear.

[Bluetone]

fascinating that the LS3/5a came from trying to make a scaled down model of a concert hall and hence scaling down the speaker to produce scaled up higher frequency.

Looking at that image I posted earlier again i think it might be dubious that that is an LS3/6 just looking at the proportions. is seems less slim and tall than the Rogers bbc Studio monitor and the prototypes in the storeroom.

[spendorman]

No problem. I stumbled on this video a coupkle fo years ago and had been trying to locate it ever since. Yes i know, me too. I'm tempted to email the poster to see if he has any more videos. i think the last video on that first page (KW Part 1c) the very first speakers that Derek Hughes goes for, i think are the LS3/6's what do you think?

Yes, by the cabinet, slightly recessed back, beading around front edges, speaker connector.

Also title:

"Rooting around in the stores: LS3/4, LS3/6 and LS3/1 and LS5/5 monitors"

[Bluetone]

...and the grill that can't be removed ha

[spendorman]

...and the grill that can't be removed ha

Early BC1's had the grilles bolted on, nuts inside the cabinet. I have several pairs like this.

[Bluetone]

Hi all, so I just received my latest pair of Rogers BBC studio monitors. These are in near mint condition. With the original bass drivers, both working great. Serial #174 and #175.

Well they sound beautiful. Any spare time ive had the past couple days I listen to them, usually till very late at night.

So they are clear as bell as you'd expect. But the big suprise for me is that bass driver. They've got this lovely, deep, woody tone to them. There is this nice delicate balance to them: really clear and sweet at the top suppprted by that smooth, deep woody bass. There's something special about the smoothness of the transition of the bass driver to the midrange too.

So clear for vocals, great for acoustic, clasdical and jazz. There's quite startling moments when listening to them when you can separate out individual vocalists. Or a string instrument just suddenly comes to life out of one of speakers to one side.

Will post more pics soon.

Do we think those 2 x 1 mfd caps on the supertweeter are electrolytics? 1882818829188301883118832

[Firebottle]

Do we think those 2 x 1 mfd caps on the supertweeter are electrolytics?

Great pics :)
The caps look suspiciously like Mullard 'mustards', so named because of their colour. Almost certainly to be polyester dielectric, not electrolytic.

If you do think of changing them fit some Polypropylene caps.

I've used Mullard mustards in my Goodmans Mezzo that were a hit at MiBO :cool:

[spendorman]

Turning green here, they look totally original. You are lucky. How many pairs have you got?

All the capacitors are original in mine and they still measured OK.

Are yours set to 8 or 15 Ohms? Aparently 25 Ohms is possible too. Mine are set to 15 Ohms.

Look forward to see more pictures.

I applied the original Spendor BC1 port mod to mine, a small foam ring inserted in it, also a put a little extra damping inside the speaker. This firmed up the bass a tiny bit.

[Bluetone]

Great pics :)
The caps look suspiciously like Mullard 'mustards', so named because of their colour. Almost certainly to be polyester dielectric, not electrolytic.

If you do think of changing them fit some Polypropylene caps.

I've used Mullard mustards in my Goodmans Mezzo that were a hit at MiBO :cool:

Cheers. If polyester then likely to still be ok?

[Bluetone]

Turning green here, they look totally original. You are lucky. How many pairs have you got?

All the capacitors are original in mine and they still measured OK.

Are yours set to 8 or 15 Ohms? Aparently 25 Ohms is possible too. Mine are set to 15 Ohms.

Look forward to see more pictures.

I applied the original Spendor BC1 port mod to mine, a small foam ring inserted in it, also a put a little extra damping inside the speaker. This firmed up the bass a tiny bit.
Thanks Spendorman I've been looking for years for a pair that were all original and that I could get sent to auatralia. It was a masssive gamble as I didnt know they wete functional or not. I got lucky, very happy.

[Firebottle]

Cheers. If polyester then likely to still be ok?

Yes, if they sound good there is no real reason to replace.

[spendorman]

Probably already mentioned, but worth saying again, in my view, good replacement for the original bass unit is the Dalesford D100/200. This then effectively makes the speaker into an early(ish) model Rogers Export Monitor.

To preserve your bass units, perhaps try changing the tappings on the transformer to give the optional 25 Ohms impedance as stated on the data sheet. That is unless you are using very low power amplifiers.

I use various amps, e.g. Radford STA25 III, Quad 303, Quad 405-2, Quad II's, A&R A60, Technics SU-V303, Class D TPA3116, Luxman L-200, and others.

[Bluetone]

Probably already mentioned, but worth saying again, in my view, good replacement for the original bass unit is the Dalesford D100/200. This then effectively makes the speaker into an early(ish) model Rogers Export Monitor.

To preserve your bass units, perhaps try changing the tappings on the transformer to give the optional 25 Ohms impedance as stated on the data sheet. That is unless you are using very low power amplifiers.

I use various amps, e.g. Radford STA25 III, Quad 303, Quad 405-2, Quad II's, A&R A60, Technics SU-V303, Class D TPA3116, Luxman L-200, and others.

interesting so I suppose these bass unit were so frequently damaged was due to the low power handling? So does using the 25 Ohm tap restrict the power to the woofers? Yes I guess I'm going to try to be careful with them as well.

[spendorman]

Changing the input impedance tappings on the transformer will affect the the sensitivity of the whole speaker. The higher it is set, the more protection is given, but the sensitivity will be lower. Yes, the bass unit was a bit delicate.

Perhaps if the input impedance is set to 15 Ohms, leave it at that. It will give some protection.

[Martyn Miles]

Hi all, so I just received my latest pair of Rogers BBC studio monitors. These are in near mint condition. With the original bass drivers, both working great. Serial #174 and #175.

Well they sound beautiful. Any spare time ive had the past couple days I listen to them, usually till very late at night.

So they are clear as bell as you'd expect. But the big suprise for me is that bass driver. They've got this lovely, deep, woody tone to them. There is this nice delicate balance to them: really clear and sweet at the top suppprted by that smooth, deep woody bass. There's something special about the smoothness of the transition of the bass driver to the midrange too.

So clear for vocals, great for acoustic, clasdical and jazz. There's quite startling moments when listening to them when you can separate out individual vocalists. Or a string instrument just suddenly comes to life out of one of speakers to one side.

Will post more pics soon.

Do we think those 2 x 1 mfd caps on the supertweeter are electrolytics? 1882818829188301883118832

It's interesting to read your findings on the Rogers LS3/6 speakers.
Back in '76 it was a choice between a pair of these, or Spendor BC1s.
I went for the BC1s.
If I recall correctly, there wasn't much in the price although the Rogers came with stands.
Spendor stands were about £25.
I bought a pair from Horns in North Oxford.

[spendorman]

"Do we think those 2 x 1 mfd caps on the supertweeter are electrolytics?"

No, none of the capacitors are electrolytic.

[Bluetone]

"Do we think those 2 x 1 mfd caps on the supertweeter are electrolytics?"

No, none of the capacitors are electrolytic.

Thanks, then I will leave them alone.

[Bluetone]

Very pleased with this find...does anyone know how to upload pdf's? it wont let me cause its 200kb.

[spendorman]

Looks interesting.

Put on Photobucket, Flickr etc. then provide link to it.

[Bluetone]

Ok here is a link to the pdf.

https://drive.google.com/file/d/0BwQgb6CMkpaobVhIbUJETG5BaDg/view?usp=drivesdk
(https://drive.google.com/file/d/0BwQgb6CMkpaobVhIbUJETG5BaDg/view?usp=drivesdk)

Lots of interesting points in this to discuss.

[Bluetone]

So

- The ls 3/6 is identical to the ls 3/4 except for the cabinet shape. There is a white paper available for the ls 3/4 which I will updload too.
-the ls 3/6 was nominally 25 ohms
- the BBC paired it with a 25 watt amp (25 watts into 25 ohms?) Which was designated the AMI/20 preamp and AM8/11 power amp.
- They designated the hf unit the Ls2/5 while the bbc developed bass unit was called the ls 2/4.
- however I'm pretty sure in the white paper on the ls3/4 speaker that I have they refer to the bass driver as the ls2/2 which is puzziling if both soeakers are supposed to by identical with regards to driver and crossover

[Bluetone]

Looks like the am8/11 power amp was a quad 50d.

[spendorman]

Interesting stuff.

The AM8/11 appears to be a Quad 50D, some on ebay recently:

http://www.ebay.co.uk/itm/BBC-AM8-11-QUAD-50D-AMPLIFIER-GOOD-CONDITION-WORKING-COLLECT-ONLY-2-/182316199389

The 50D has an output transformer.

[spendorman]

He calls these BC1, but I reckon they are most likely LS3/6:

http://www.ebay.co.uk/itm/Spendor-bc1-active-speakers-/252689836020

But are they?

[Bluetone]

Interesting. I thunk I read somewhere they did a powered version of the ls 3/6. The cabinet is definetly right although that spec seems to indicate it was a generic cabinet they may have used for different projects. At least one bass unt has been replaced with a bc1. The other has a white surround but the basket and terminals are different to my bbc bass drivers. Very intwresting

Here is a listing from a week ago of the same ones from a different seller. This new seller is trying to flick them for a tidy profit. There are pics inside in this listing

http://m.ebay.co.uk/itm/291913144891

[Martyn Miles]

He calls these BC1, but I reckon they are most likely LS3/6:

http://www.ebay.co.uk/itm/Spendor-bc1-active-speakers-/252689836020

But are they?

I've been in touch with the seller and he posted more pics.
I initially wondered if they were 'one off' BC1s as they were
up for auction as SB1s.
No bids yet...

[spendorman]

Looks very much like the early Spendor 25 Watt built in amp. I have a single BC1a that has a similar amp.

[Martyn Miles]

It's interesting that these 'LS3/6s' & 'Spendors' are originally from Kingwood Warren.
There is a video on the Harbeth Users Forum, which shows Derek Hughes and Alan Shaw
looking at and discussing the various speakers stored there.

Early LS3/6s and Spendors...
All sold off now and on the market by sellers hoping to make a profit.

[spendorman]

There are still some LS3/5as at the BBC, mainly in storage broken, blown tweeters, at least that's what my friend's son told me on Christmas day, the son is an Engineer at the BBC.

[Bluetone]

It's interesting that these 'LS3/6s' & 'Spendors' are originally from Kingwood Warren.
There is a video on the Harbeth Users Forum, which shows Derek Hughes and Alan Shaw
looking at and discussing the various speakers stored there.

Early LS3/6s and Spendors...
All sold off now and on the market by sellers hoping to make a profit.

Yes thats a fascinating couple of videos we have linked to those videos. Funny that Derek hughes pulls out an Ls3/6 on a tour of the storeroom and is stumped as to what it was.

Yes I do hope there is a chronologically ordered collection of these important speakers somehwhere at the bbc still.

[spendorman]

I suppose a lot reading this thread will know that the Celection HF1300 originated from a GEC unit. From the mid 80's to the early 2000's I worked at GEC, but we had nothing to do with speakers then.

Scroll down a bit to see tweeter:

http://soundup.ru/index.php?option=com_content&id=2580:gec-genalex-fr-bcs-1851-8-aluminum-cone-speaker-1852-tweeter

[Bluetone]

I've been in touch with the seller and he posted more pics.
I initially wondered if they were 'one off' BC1s as they were
up for auction as SB1s.
No bids yet...

Can you please upload the additonal images? Curious to see more. Thanks

[walpurgis]

I suppose a lot reading this thread will know that the Celection HF1300 originated from a GEC unit. From the mid 80's to the early 2000's I worked at GEC, but we had nothing to do with speakers then.

Scroll down a bit to see tweeter:

http://soundup.ru/index.php?option=com_content&id=2580:gec-genalex-fr-bcs-1851-8-aluminum-cone-speaker-1852-tweeter

There was an early version made by Celestion before the HF1300 designation arrived. I have a pair, but they are boxed and tucked away so I can't check the model number. They were metal bodied and painted gold, with a recessed phase plate.

Coles also produced a similar tweeter.

http://i67.tinypic.com/dy9ngw.jpg

And Fane made a tweeter based on similar principles.

http://i63.tinypic.com/a0do45.jpg

[spendorman]

I knew of the Coles 4000 as in your pic, never owned any, but I seem to remember it being said that they were not really up to the standard of the HF1300.

The Fane one looks interesting, never had any of those either.

[walpurgis]

I've had the Fanes, they sounded rather nice.

[spendorman]

My age is showing, I put "Coles tweeter" in to a search for Google images, did not really get the results I expected.

[walpurgis]

These are the early Celestions. Model T718. It's funny, I thought they were gold, but they are silver (Cadmium plated I think). Memory playing tricks.

http://i65.tinypic.com/312v9g4.jpg http://i65.tinypic.com/flwuw7.jpg

[spendorman]

Never seen those models before.

[walpurgis]

They are 8 ohm.

I have a pair of earlier metal bodied HF1300 in 16 ohm too.

http://i67.tinypic.com/65bs4y.png

[spendorman]

They are 8 ohm.

I have a pair of earlier metal bodied HF1300 in 16 ohm too.

http://i67.tinypic.com/65bs4y.png

These look like the HF1300's in my LS3/6

<a data-flickr-embed="true" href="https://www.flickr.com/photos/41679262@N02/29302983266/in/dateposted/" title="DSCF9577 (2)"><img src="https://c3.staticflickr.com/9/8480/29302983266_58981d21fd_z.jpg" width="640" height="480" alt="DSCF9577 (2)"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>

[spendorman]

They are 8 ohm.

I have a pair of earlier metal bodied HF1300 in 16 ohm too.

http://i67.tinypic.com/65bs4y.png

These look like the HF1300's in my LS3/6, also 16 Ohm.

https://c3.staticflickr.com/9/8480/29302983266_00f1b41b3a_k.jpg (https://flic.kr/p/LDps2q)DSCF9577 (2) (https://flic.kr/p/LDps2q) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

[walpurgis]

More of a meeower than a tweeter. :D

[spendorman]

About the size of a woofer though.

[Barry]

So that's what became of Schroedinger's cat!

[spendorman]

So that's what became of Schroedinger's cat!

Unfortunately, she's in the "dead state" at the moment, but we had some good times.

[Bluetone]

Here are some more pics of my speakers as promised...

https://drive.google.com/open?id=0BwQgb6CMkpaoUEYwSzZSaVBmNEE
https://drive.google.com/open?id=0BwQgb6CMkpaoa0JXVkFhTmVGZHM
https://drive.google.com/open?id=0BwQgb6CMkpaoOWx2S1FZNWZhY1E
https://drive.google.com/open?id=0BwQgb6CMkpaoYmRBY0JudE13NlU
https://drive.google.com/open?id=0BwQgb6CMkpaoTTNtYlFmLXBHRXM
https://drive.google.com/open?id=0BwQgb6CMkpaoSWMwZGU0aVZ2Vms
https://drive.google.com/open?id=0BwQgb6CMkpaoT1MwV004TzV5bXc
https://drive.google.com/open?id=0BwQgb6CMkpaoblJjaGNra1Nkbkk
https://drive.google.com/open?id=0BwQgb6CMkpaoMzl6d29ZVkNTNTQhttps://drive.google.com/open?id=0BwQgb6CMkpaoMzl6d29ZVkNTNTQ
https://drive.google.com/open?id=0BwQgb6CMkpaoMkctS0RMVEp6Mlkhttps://drive.google.com/open?id=0BwQgb6CMkpaoMkctS0RMVEp6Mlk
https://drive.google.com/open?id=0BwQgb6CMkpaoQXM0RWJ5UGQ5dUEhttps://drive.google.com/open?id=0BwQgb6CMkpaoQXM0RWJ5UGQ5dUE

[spendorman]

Very nice, in very good condition, thanks. You were very fortunate to get them in that condition.

Have you checked the white bass unit surrounds? It's likely that they suffer the same issue as the white BC1 surrounds, shrinking.

How do they compare with your other speakers?

[Bluetone]

..Spendorman I agreem, I think those speakers on EBay are definetley Powered LS 3/6.

-Although the BC1 started life as a 2 way the early BC1 2 ways look totally different and always with a round bass port
-They are basically identical cabinets to the BBC LS3/6 spec
- I did read somewhere they did a powered version of the LS 3/6
-If you look closesly at the pics you see the 4 orignial mounting holes of the old BBC bass drivers.

So I'd say these were powered LS3/6 which the original BBC bass drivers died in and were repalced with BC1 bass drivers.

Well spotted.

[Bluetone]

Thanks. Yeah I did take a look at them couldn;t see anything nasty going on. What do I need to look for with regards to Shrinking? Thanks.

Yes so they definetly outperform the other pari I have that had Kef bass units. They have a lovely deep woody bass and that clear as a bell midrange. Great for vocals, acoustic, classical. I am paranoid about blowing the woofers so I play them very nearfield at the lowest volume I can, they work nicely up close. They won't be the speakers I listen to daily, I'll take them out every now and then for a careful listen I think.

[spendorman]

The white material tends to shrink, therefore inhibiting and limiting the cone excursion, and thus affecting the bass performance. Untimately, it can pull the voice coil off center.

I have worried about the input transformer stressing the amplifier, as it's almost a short circuit to the amplifier at DC, therefore if an amp has a lage DC offset (fault), high current would flow, possibly damaging the amp, or tripping the protection circuits (if any). But, this same transformer may in fact protect the bass unit from damage, it being a shunt for any unwanted DC from the amp.

In practice, I have had no problems with any amps that I have used with my speakers. But it's probably sensible to check your amps for excessive DC offset anyway. All one needs is a multimeter.

[Bluetone]

ok yeah I think I read somewhere that the surrounds were fabricated from sheet material and formed into a semicircular shape, over time the stress has relaxed and they return more to their flat sheet shape. Is that what you mean? I wonder if anything can be done to fix that.
Ok will measure DC offset

[spendorman]

Yes, you put it very well. There has been talk of car brake fluid softening the surrounds, I have not fully read all the posts on it. There are some on the Yahoo Spendor Group.

[Bluetone]

Just measured the Freq response of Left and Right BBC monitors. Pretty well withing 5 db for most of the range, not bad after all these years.1896118962

[spendorman]

A lot of the variation is probably due to the room.

[Bluetone]

Hi all it's been a while, thought you moght like this.

To the left, looks to be an LS 3/6 with an HH AM8/12 amp. I think this is one of the BBC studios in Manchester. Photo is from '76

[spendorman]

Hi there, thanks for this most interesting, says a man watching a youtube video about electrostatic speakers, my LS3/6 / Export monitors doing the sound.

https://www.youtube.com/watch?v=HmwEh5P3D54

1976 eh, had just completed 8 years at college and got my first full time job as an Electronic Engineer in a big company.


PS. Can we have a better image than that which you posted?

[Bluetone]

Well I got it here from one of these papers

https://archive.org/details/bbc-monographs

They are worth a look through, you can search by year. Havent gone through exhaustively but there may be other images of LS 3/6's. The original image was about as grainy, although I did take a screen shot of it. I think one can pay to download a higher res copy. Will try to locate which issue I found it in.

[Bluetone]

...It's in the March 1st 1976 issue (3 days before I was born). page 35 :)

[spendorman]

Well I got it here from one of these papers

https://archive.org/details/bbc-monographs

They are worth a look through, you can search by year. Havent gone through exhaustively but there may be other images of LS 3/6's. The original image was about as grainy, although I did take a screen shot of it. I think one can pay to download a higher res copy. Will try to locate which issue I found it in.

Can you just email me the photo you have? Save me searching. You should have my email address already.

[Bluetone]

Dont seem to have your email address. message it to me if you like

[spendorman]

Dont seem to have your email address. message it to me if you like


Thank you but got this when sending you a message;

"The following errors occurred with your submission

"bluenote has chosen not to receive private messages or may not be allowed to receive private messages. Therefore you may not send your message to him/her."

[Bluetone]

hmmm thats strange. well i just sent you a message with my email adress.

[walpurgis]

hmmm thats strange.

Looks as though you've opted not to receive communications in your personal settings. You should be able to amend this if you choose.

[spendorman]

hmmm thats strange. well i just sent you a message with my email adress.


I found your email on my PC and sent you a message on that email address.

[spendorman]

Hoping that this will be a little clearer

https://farm5.staticflickr.com/4885/45362846234_f959eb644b_o.jpg (https://flic.kr/p/2c7yrLw)LS3_6 (https://flic.kr/p/2c7yrLw) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

[Bluetone]

much better thanks

[spendorman]

Incidentally, a friend has been through many speakers including LS3/5a, Spendor BC1, B&W DM4, Harbeth P3ESR, Tannoy Classic Dual Concentrics, and fairly recently got some Rogers Export Monitors. He's fairly happy with these, similar to BC1's but slightly better controlled bass.

[Bluetone]

interesting to hear his experience against those other speakers. For me I have a pair of big 4 way JBL4343's which I love the big enveloping sound and punch. But the Rogers BBC studio monitors are just nice for acoustics and vocals, particularly playing nice clean vinyl. The low end is suprsingly deep and surrounding and has a nice smoothness to it, vocals and highs are as clear as a bell bit not harsh. With good placement you can get a nice big sound stage. They are a really good companion to the big JBL monitors because they are so different. I'll listen to say pink floyd on the big jbls and say Nick Drake or some classical on the Rogers.

[spendorman]

interesting to hear his experience against those other speakers. For me I have a pair of big 4 way JBL4343's which I love the big enveloping sound and punch. But the Rogers BBC studio monitors are just nice for acoustics and vocals, particularly playing nice clean vinyl. The low end is suprsingly deep and surrounding and has a nice smoothness to it, vocals and highs are as clear as a bell bit not harsh. With good placement you can get a nice big sound stage. They are a really good companion to the big JBL monitors because they are so different. I'll listen to say pink floyd on the big jbls and say Nick Drake or some classical on the Rogers.

I have some Tannoy HPD315's for blasting! Also my home-made speakers containing EMI 14" x9" (cast chassis), Audax mid, Celestion HF1300, and Coles 4001G, can blast pretty well! They are also pretty good.

[hornucopia]

These....
are quite nice. Cost a lot in 70s! (Not that I got them then, I had the original Sandwiches.)
Funny; I ended up running a Vegetarian Sandwich cafe (well, rolls actually)
The 3090s have an Isodynamic super tweeter, like the Wharfedale headphones I use.
Jerry's recently got a set of the 'phones too. Had mine since 73.

[Martyn Miles]

To revive this thread, I would be interested in information about the Dalesford drive units.
There doesn’t appear to be much on the Internet.

[57charles]

These....
are quite nice. Cost a lot in 70s! (Not that I got them then, I had the original Sandwiches.)
Funny; I ended up running a Vegetarian Sandwich cafe (well, rolls actually)
The 3090s have an Isodynamic super tweeter, like the Wharfedale headphones I use.
Jerry's recently got a set of the 'phones too. Had mine since 73.

I wasn't aware that the unit to which you refer as a 'super tweeter' was indeed a super tweeter - I believe it's the same isodynamic tweeter Wharfedale fitted to the upgraded Dovedale SP2 and the new model Teesdale SP2. I believe the Dovedale SP and Airedale SP ( there was no Airedale SP2 with the isodynamic tweeter, incidentally) were fitted with that horrible squawking purple tweeter which was also fitted to the Leak 2075's - the previous version of your 3090's.

[spendorman]

To revive this thread, I would be interested in information about the Dalesford drive units.
There doesn’t appear to be much on the Internet.

Hi Martyn, I've emailed you the Dalesford drive unit data sheet.

[Pharos]

I have two pairs of the Isodynamic headphones, for which I made calf-hide earpads in the mid 80s.

They are a little cheaply made, and veiled, but bought in about '72 so perhaps to be expected, but at the time a breakthrough if you couldn't afford the Pro 4AAs. I also have some spare transducers.

[Martyn Miles]

I have two pairs of the Isodynamic headphones, for which I made calf-hide earpads in the mid 80s.

They are a little cheaply made, and veiled, but bought in about '72 so perhaps to be expected, but at the time a breakthrough if you couldn't afford the Pro 4AAs. I also have some spare transducers.

A friend bought a pair and I quite liked them and wondered if to buy a pair.
In the end I bought a pair of PWB electret headphones in a sale and preferred them.
Do any Forum members recall the PWBs ?

[Barry]

A friend bought a pair and I quite liked them and wondered if to buy a pair.
In the end I bought a pair of PWB electret headphones in a sale and preferred them.
Do any Forum members recall the PWBs ?

Yes they were a very good headphone design - before Peter Belt went off on a tangent with all his pseudo science and dubious audio accessories.

[our_john]

I've got Swisstone woofers in my LS3/6s. My understanding is these were developed by the 'new' Rogers team (after the collapse of the Jim Rogers team) around 1977-78 as they weren't happy with the sound quality of the Dalesfords. Swisstone was the off-the-shelf company they bought at the time due to some issues with the ownership of the Rogers name. They had managed to get hold of the equipment necessary to build these in-house. In essence, the Swisstones are at least as good, if not better, than the original units but far more durable. After all, the new Rogers team comprised developers of the 'original' LS3/6!

For your interest my speakers are currently in for servicing, as shown here...
https://m.youtube.com/watch?v=F8JRlEUJ0Ys

[spendorman]

Very interesting, but the repairer got several things wrong including the type of tweeter and supertweeter. Tweeter is Celestion HF1300, and supertweeter is Celestion HF2000. I don't think KEF had anything to do with this speaker.

The low DC resistance of the speaker is because of the autotransformer.

[walpurgis]

Not sure why he regards them as sealed speakers. They're not!

[spendorman]

Not sure why he regards them as sealed speakers. They're not!

Agreed, possibly he meant that the port has not much effect. As the cabinet size increases, the difference that a port makes decreases. In a very big cabinet a port will not make much difference. I think I remember reading this in a GA Briggs book (G A Briggs of Wharfedale).

[spendorman]

I have never owned genuine LS3/6 bass units, but I think the magnets on the originals are much bigger than on the Swisstones.

[walpurgis]

I think I remember reading this in a GA Briggs book (G A Briggs of Wharfedale).

I read that too, at tech college around 1972 :). I have sections of one that was in bits, still very valid.

A port with no tube to extend it has to be smaller to obtain comparable Hemholtz resonance. Tubes tend to be used as they make the port flow more laminar, avoiding the bass 'chuffing' which can be detected on some Rogers and Spendor speakers.

[spendorman]

as late as 72! I was at tech from 1968 to 1975!

[spendorman]

I'm thinking of trying Richard Allan HP8B in the LS3/6, massive magnets.
https://live.staticflickr.com/65535/50813259903_172f6e1e67_z.jpg (https://flic.kr/p/2kqceRZ)RA- (https://flic.kr/p/2kqceRZ) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

https://live.staticflickr.com/65535/50813258568_3e50c6e6d3_z.jpg (https://flic.kr/p/2kqcesY)RA (https://flic.kr/p/2kqcesY) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

Also considering the bass driver from LS7, massive magnet again, but a Polypropylene cone.

[Pharos]

If those pictures are of the same unit, it looks more like bextrene because of the hand painted coating which poly did not need.

I'm also surprised at the apparent quality of a Richard Allen unit being so good.

[spendorman]

If those pictures are of the same unit, it looks more like bextrene because of the hand painted coating which poly did not need.

I'm also surprised at the apparent quality of a Richard Allen unit being so good.

Yes, the Richard Allan is Bextrene. Richard Allan made some very nice units. Rogers used them in some of their earlier speakers.

The Polypropylene unit I was referring to was the Rogers LS7 unit.

[spendorman]

Just received the Richard Allan HP8B 8" bass units from a friend. 1.3 Tesla magnet, Bextrene cone.

https://live.staticflickr.com/65535/50835858062_79f63dbed2_c.jpg (https://flic.kr/p/2ksc4vq)RA HP8B (1) (https://flic.kr/p/2ksc4vq) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr

https://live.staticflickr.com/65535/50835047468_fcf2f050d7_c.jpg (https://flic.kr/p/2ks7UxE)RA HP8B (2) (https://flic.kr/p/2ks7UxE) by A60man (https://www.flickr.com/photos/41679262@N02/), on Flickr