My Beveridge Electrostatic Speaker System

Kcin

Active Member
Mar 27, 2016
184
87
28
Canada
#1
Hi all,
I had the pleasure of speaking with @Ron Resnick today. Ron, I must say that I've met many enthusiasts over my over 30 years in this hobby but I don't think I've spoken to anyone as gracious and engaging.

Ron encouraged me to introduce my system to the group in a little more detail after having a great discussion around his choices around the building of his new system- which should be--- absolutely fabulous.

While certainly not state of the art anymore, I am a little reticent to post about them among a group with such high standards - I believe that the Beveridge Electrostatics still perform at a very high level of resolution and do things that are still not approachable by many transducers today at any price.

I wrote, a little while ago, a short story on my speakers & system - which have a bit of personal history- to a member of the local audio group.





Here's the story:

The Beveridge Model III speakers are the last true wave launch full range speakers the Harold Beveridge produced in the early 1980’s. Beveridge was a Canadian that studied Engineering at McGill University in Montreal and was hired by Raytheon to design Radar systems and electronic counter measure systems for the US military programs.

He was a genius. In his retirement from Military work he used what he learned from radar wave technology and adapted it to his love of electrostatic speakers.

I heard the very same speakers I own today at local audiophile’s place when they were current over 35 years ago. He ran them with an Audio Research D79 and SP 6 with a Goldmund Studio Turntable. ( this system 35 years ago would give most current systems a run for their money!) This was the height of state of the art at the time.

When that needle dropped to the record way back then I knew that everything I was trying to accomplish with tube electronics ( not cool back then) and even my Acoustat X’s and model 3’s was a waste of time. They had left an impression on me that I could not duplicate for over 30 years of trying along with listening at dozens of audio shows and multi-kilobuck systems .

Through chance, those speakers were still local and were sold just one more time to another audiophile that the original owner had kept in touch with. Once I heard they were available I had to have them at almost any cost. The second owner was in his early eighties and he was happy to have them go to someone who could appreciate them.

Beveridge’s original efforts were constant charge electrostatic panels where the sound waves were forced through a wave guide to disperse at 180 degrees across the room. These are not dipoles so the room does not impact the sound launch from the speakers a la Martin Logan, Sound Labs, Acoustat etc. The speakers point at each other directly facing!

These panels were fed by dedicated built in servo Output Transformerless (OTL) amps that directly charged the panels at +/- 2000vdc to modulate the audio signal. No step up transformers to step up the audio signal as in Martin Logans, Sound Labs or Quads etc. The audio signal was fed directly from the plates of the tubes to the stators of the electrostatic panels with no transformer losses on the speaker nor audio output transformer for the tube amplifiers.

The signal could not be clearer. Other added benefit: lab grade silicon high voltage wires to carry the polarizing voltage to stators as well as the audio signal that rides on it. No expensive speaker cable trials anymore.

The cost of these units in the late 70’s was over $15K – hideously expensive. Beveridge was forced to eliminate the integral OTL amps and develop a step up transformer based full range model to compete at a lower price point. These are the Model IIIs that I have.

The Model IIIs have two 10” woofers upward and downward firing in a hemholtz configuration with a 6’6” line source electrostatic element in front with a wave guide to disperse the sound about 180 degrees.

To Beveridge’s credit, although the Model IIIs were a compromise to his original design,- no OTL amps- they had the same type of step up transformer as all electrostatics have- he designed the unit so that the elements of the electrostatic panel and the woofers could be driven by 1 amp or bi-amplified with an internal crossover or bi-amplified with an external crossover.

Not leaving well enough alone. I abandoned the internal woofers and deployed a pair of modern subs with internal amp with 200wpc each on the subs.

Subwoofer technology has advanced tremendously in 30 years.

Roger Modjeski who was a young engineer at the time working with Beveridge designed a Direct Drive tube amplifier to eliminate the internal cross over and step up of the Model IIIs .

It is passively 1 st order high pass limited with a single copper V cap to allow everything from about 100Khz up to the panels and I feed the woofers everything below that through a second output.

So effectively, I have the electrostatic panels driven by +/- 2kv directly with no step and no audio output transformer from the tube amps. The only other amp I have had that approached this purity was the Berning ZOTL 270.

If you’ve ever heard an electrostatic panel driven by an OTL amp you’ll get ½ the story… the other half is that the step up in the speaker is eliminated as well- big difference in resolution and clarity.

Pretty complex but I am optimizing it and it sounds real nice. The difference with the Beveridge is its ability to hang an instrument in space it is a bit uncanny. Add this to the low mass diaphragm of an electrostatic -no step up transformers or audio output transformers of any kind and you get a very pure output.

The heart of the analog system is the 150lb 3 box Aesthetix Io Eclipse with volume controls.

No required line stage no step up transformers no extra cables for greater purity- it drives low output cartridges no problem. I have spent years optimizing the tube choices it is exceptionally quiet.

For up front transducers I’ve have added the Clearaudio Goldfinger Statement- I also have on hand the Lyra Atlas, Lyra Etna SL and the Koetsu RSP.
The table is the Brinkman La Grange with Kuzma 4pt and Brinkman 12.1 The room is about 18x 40 purpose built with 9 1/2’ ceilings.

Thanks for listening to this long story of this relatively modest system by today's standards. Even though the Beveridges are over 30 years old they are still widely coveted today and many have them in top class systems across the world. Very few of them were produced as they were built by hand but those that survived still make some great music today.
 

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Last edited:
May 30, 2010
15,427
665
113
Portugal
#2
Great to read about a Beveridge model III - many decades ago I listened to a pair - the passives, not the amplified - but they were not in prefect conditions and could only play a low levels. The image I retain is that they were astonishingly clear. Do you still have the original diaphragms in your speakers?
 

Kcin

Active Member
Mar 27, 2016
184
87
28
Canada
#3
Hi Microstrip,

Still the original diaphragms which are, knock on wood, in perfect condition. The previous owner used to power them at 80% of +/- B+ so I think this saved things as well as a very conditioned environment.

These will play 94+ db easy with the woofers and and the crossover but I don't listen that loud , no fireworks or odd quirks at all.
 

BruceD

VIP/Donor
Dec 13, 2013
985
45
28
#4
Yes indeed a wonderful transducer--heard it many time in the early 80s--I worked in Orange County at ER and would often drive down to take and pickup gear /discs for demos/etc from Sheffield labs house in those days!

I'd pop into Harolds "Den" for quick listen--Rodger Modjeski was often present -- I recall when he was evaluating the pair for Julie Andrews in MirrorBall finish--ha!:D

Amazing his concept of the Speaker facing one another across a room but oh my goodness the Music floating in space--transfixed the listener:b

BruceD
 

Al M.

VIP/Donor
Sep 10, 2013
4,580
375
83
Greater Boston
#5
Fascinating story, great system and room!
 
May 20, 2016
81
4
8
Torino - Italy
#6
Fascinating story, great system and room!
Wow! wonderful speakers... I had a pair of Model 3's for a few years. Purchased used in California and later rebuilt in electrostatic panels by Rick Beveridge.

When I was forced to transfer me into a small apartement I decided to sell them; they are here in Italy in the collection of Mr. Stefano Zaini who own also a pair of Model 2's.

Life is strange sometimes... just two years later I had again the chance to have a larger listening room but the Beveridge's have gone... :(

My best
Marco
 

Kcin

Active Member
Mar 27, 2016
184
87
28
Canada
#7
Yes indeed a wonderful transducer--heard it many time in the early 80s--I worked in Orange County at ER and would often drive down to take and pickup gear /discs for demos/etc from Sheffield labs house in those days!

I'd pop into Harolds "Den" for quick listen--Rodger Modjeski was often present -- I recall when he was evaluating the pair for Julie Andrews in MirrorBall finish--ha!:D

Amazing his concept of the Speaker facing one another across a room but oh my goodness the Music floating in space--transfixed the listener:b

BruceD
VERY cool!
 

Elliot G.

Industry Expert
#8
Wow. I had no idea that anyone still had a working pair of the Beveridge. Back in the day I worked at Lyric in NYC and we were a Beveridge dealer. That was a long long time ago LOL
 
May 30, 2010
15,427
665
113
Portugal
#9
Wow. I had no idea that anyone still had a working pair of the Beveridge. Back in the day I worked at Lyric in NYC and we were a Beveridge dealer. That was a long long time ago LOL
As far as I remember Beveridge used aluminized Mylar diaphragms - much more stable and long lasting that Mylar coated with resistive materials. The fact they are not full range and only operate in the comfort zone of electrostatics also helps. The model III electrostatic element was known to have much better built quality than the 5 or 6. To be told only at Audiophile Anonymous sessions - a good friend has in storage a pair of Beveridge's, missing the electrostatic elements. Several times I considered buying the beautiful wood boxes to rebuild them, fortunately I stopped at the research phase... :)
 

Kcin

Active Member
Mar 27, 2016
184
87
28
Canada
#10
As far as I remember Beveridge used aluminized Mylar diaphragms - much more stable and long lasting that Mylar coated with resistive materials. The fact they are not full range and only operate in the comfort zone of electrostatics also helps. The model III electrostatic element was known to have much better built quality than the 5 or 6. To be told only at Audiophile Anonymous sessions - a good friend has in storage a pair of Beveridge's, missing the electrostatic elements. Several times I considered buying the beautiful wood boxes to rebuild them, fortunately I stopped at the research phase... :)
Yes, the aluminized mylar and constant voltage vs. constant charge operation make the Beveridge speakers more robust. The stators are an epoxy/carbon type element that are cast into a profile- quite elaborate.
 

JackD201

[WBF Founding Member]
Apr 21, 2010
11,317
276
83
Manila, Philippines
#11
This is the very speaker that jolted my high end awakening back in 1984. My buddies would sneak us into their Dad's music room and play our tapes on his gold Dragon. Ahhhh to be 14 again!
 

Ron Resnick

Site Co-Owner, Administrator
Jan 25, 2015
6,590
1,003
113
Beverly Hills, CA
#12
Thank you very much for starting this thread, Nick. And thank you for your kind words! I enjoyed our conversation very much!

What a beautiful room!

I am extremely intrigued by the idea of driving electrostatic panels driven by +/- 2kv directly with no step and no audio output transformer. Could this direct drive technique be applied to Martin-Logan CLX Arts? Could it be applied to ribbon drivers?
 

Kcin

Active Member
Mar 27, 2016
184
87
28
Canada
#13
Thank you very much for starting this thread, Nick. And thank you for your kind words! I enjoyed our conversation very much!

What a beautiful room!

I am extremely intrigued by the idea of driving electrostatic panels driven by +/- 2kv directly with no step and no audio output transformer. Could this direct drive technique be applied to Martin-Logan CLX Arts? Could it be applied to ribbon drivers?

Ron,

For certain it could be done with the Martin Logans. The polarzing voltage and capacitance of the panel come into play. You can use different types of tubes dependent on the current requirements for the panels.

I have modified mine to experiment with the QUAD USA monitors and it works, I have not spent the time to vet out how to deal with my ESLs because they have different requirements for the treble and bass panels.

This technique has been used on Acoustats as well. Martin Logans are really no different.

Since you are in California I would suggest that you could get in touch with Roger Modjeski he can certainly design something custom for ML easily . One of the local fellows here has CLXs and they are phenomenal for what they do well. He has CJ amps on them.

I don't currently have a good pic of the amp but it all looks very "experimental" in the picture attached below the Otari- It has been totally reliable over the almost 3 years I've been using it. You really won't find an amp like this commercially available because of the perceived risks of the high polarizing voltages going through wires on the floor. With a dedicated room and careful dressing of the cables there is no danger as its relatively low current.

I will soon be looking at mono blocks to make things tighter looking.

Thanks.
 

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Ron Resnick

Site Co-Owner, Administrator
Jan 25, 2015
6,590
1,003
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Beverly Hills, CA
#14
Very interesting! I think we should get our ML owners on that!

What is sitting under the tape deck? Is that an external tape repro amplifier?
 

BruceD

VIP/Donor
Dec 13, 2013
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28
#15
Thank you very much for starting this thread, Nick. And thank you for your kind words! I enjoyed our conversation very much!

What a beautiful room!

I am extremely intrigued by the idea of driving electrostatic panels driven by +/- 2kv directly with no step and no audio output transformer. Could this direct drive technique be applied to Martin-Logan CLX Arts? Could it be applied to ribbon drivers?
Agree looks a superb setup and listening room--Kudos!

If I could drive my stacked Dayton Wright XG-8lll's by hooking directly into the primary of the Transformer with Bridged Electro Research A75's ( had this combo for 2years)-- the same method on ML CLX's should be

an easy push over:)

I'd think--no?

BruceD
 

Kcin

Active Member
Mar 27, 2016
184
87
28
Canada
#16
Very interesting! I think we should get our ML owners on that!

What is sitting under the tape deck? Is that an external tape repro amplifier?
Hi Ron ,

Its a deHavilland 222.. I modified the Otari to run direct out - my tube rerpro unit design still sits on a bench and I go back to it once and while to muddle away at completing it. The 222 stands in until I can compare my design to it- best man wins. I had JRF relap the heads on the Otari and I brought the rest of the unit up to standard with new caps, cleaning etc.

I have a limited number of tapes as I assess how deep I wish to go in the tape realm.....looking for a Studer I should of got involved years ago when they were further away from the spotlight
 

Kcin

Active Member
Mar 27, 2016
184
87
28
Canada
#17
Yes Bruce,

ML would be easy with a direct drive amp against the DW requirements!,

DW was a Canadian as well and he built those speaker a short drive up the road from me. They were certainly an experience as well. A few of them around here still working after 40 years .

What is it with Canadians and Electrostatic speakers anway?
 
Mar 4, 2011
41
2
8
#18
There is a Model 2 for sale in Chicago area. I think listed on the 'gon
 
May 30, 2010
15,427
665
113
Portugal
#19
Thank you very much for starting this thread, Nick. And thank you for your kind words! I enjoyed our conversation very much!

What a beautiful room!

I am extremely intrigued by the idea of driving electrostatic panels driven by +/- 2kv directly with no step and no audio output transformer. Could this direct drive technique be applied to Martin-Logan CLX Arts? Could it be applied to ribbon drivers?
You have a manufacturer in Holland who sells this type of amplifiers for Martin Logan - see http://twinstaticaudio.com/elektronica/twin-otl/ Unfortunately Soundlab's seem to be out of the range of these amplifiers - they need around 9-12 KV HV with around 8kV peak to peak voltage.
 

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Oct 15, 2010
130
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Kidneystone-on-Trent
#20
Back in the 1970s, I auditioned the Beveridge 2SW. It had very little in the way of dynamic range (it distorted at ridiculously low spls) and very little going for it in general. After the audition, we switched over to Linn Isobariks which outperformed the Beveridges in every way.
 

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