My Beveridge Electrostatic Speaker System

MRJAZZ

[Industry Expert]
Jan 21, 2014
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#41
Hi folks, As you can see I have posted some photos of my pseudo bevs. Due to my inexperience with computer usage, they didn't transmit the way I intended. However, you can see the main listening room system with the proper arrangement for Bevs. The speakers are a bit over 6' tall with a 1'x4' ESL mid/tweeter array within the top cabinet . The mid woofer is in a separate cabinet below. The other pictures are of an smaller prototype using a similar lens but only 2' high. The high end worked very well but the blend with the mid woofer was not good enough w/o DSP, so I am redesigning the low end to be more like the big speakers. Nevertheless, you can see what the lens looks like in the rough so to speak.
Unless I missed it, where do you source the 1’ x 4’, ESL panel from....or are you DIY....?
Thanks....
 
Jul 30, 2019
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#43
Sounds like a great effort. I'd love to see pictures.

My Bevs are highly modified with direct drive amps which really transforms them especially when you cross them over to modern subs as you do. 100 db is not a problem.

Congratulations
The Beveridge lens is an interesting concept. Looking at the original patent drawing of the lens we see the lens takes the planar wave output of the diaphragm and attempts to convert it into a hemi-cylindrical wave form by having the planar wave front travel through a network of separate waveguide channels which converge to a hemi-circular opening. The theory is that because the length of each channel is equal , each "filament" of sound will reach the circular opening at the same time creating a circular wave front. But if you look at the shapes of each channel, they are all different in width and cross-sectional dimension, making the speed of sound in each channel different. There is no way each "filament" of sound can converge to the projected circle in phase. The design, in my opinion, is dead in the water before it begins. There may be a way to re-design the lens so that all the filaments of sound converge in phase, computer simulations to the rescue ? :)
 

Janek36

New Member
Jun 13, 2019
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#44
Theoretically you may be correct but I'm not sure it makes much difference as sound transmitted by virtually any speaker has phase discrepancies most of which the listener cannot detect unless they become excessive. Also, Room acoustics have significant effects on phase response. In a practical sense one can walk around the front of a functioning Beveridge lens and not be able to hear beaming at all. Amazingly, in the original Beveridge 2SW's that effect was a true 180 degrees. Additionally when listening in a room playing a Beveridge speaker system or its equivalent one becomes aware of a wall of sound which is both very prominent and in my experience different than that produced by other electrostatics or non-esl panel speakers. I have lived with Quads, double Quad 57s, Soundlabs as well as various dynamic speakers, none of which produce the sense of depth or panorama that the Beveridge lens does.
 
Likes: Kcin
Dec 9, 2018
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#45
My late father had Beveridge system 3’s with the lenses facing each other with a semi-circular sound stage produced.
Whilst you intimate the theory is dead in the water, have you ever listened to a pair? Maybe the premise is incorrect to begin with?
I can only go off personal experience
 

Kcin

Active Member
Mar 27, 2016
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#46
Any multi- driver box has phase anomalies especially off axis. Compound this electrically with crossover networks and you have an interesting soup.

Conventional electrostatics that have a back wave radiation 180 deg out of phase have it swirl around and mix with the forward wave or at lower frequencies cause cancellation.

I have not read the patent for Beveridge- I am sure the design is full of compromises like any other engineering initiative. As any well executed design, the decisions made are optimized for result and cost.

The concept is certainly unique and innovative especially when you look at things like the rf motional feedback system for the diaphragm, commercial execution of direct drive, the unique polarizing of the stator system and of course the lens. All this over 40 years ago.
 
Jul 30, 2019
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#47
My late father had Beveridge system 3’s with the lenses facing each other with a semi-circular sound stage produced.
Whilst you intimate the theory is dead in the water, have you ever listened to a pair? Maybe the premise is incorrect to begin with?
I can only go off personal experience
Hi, yes I have heard them , twice, at a friends house who had an old pair that he used to play around with, he had the enclosures removed so that you could see the lens and transducers. I want to be clear hear, I mean no disrespect to the late Mr. Beveridge , he was a true genius in every respect . I only question technical details because I am an engineer myself. The sound that I heard coming from the lenses did indeed fill the room with sound but they did not image at all, no matter how they are oriented in the room. The lenses only give the illusion of creating a true cylindrical wavefront, I am not trying to be critical just for the sake of being critical, I hope someday someone may take the basic idea of the lens and improve on it using advanced software to design a lens that is superior.
 

gian60

Well-Known Member
Apr 17, 2016
1,727
500
113
#48
One shop in Italy audioantiquary has one Model 3,one model 2 and one model 2 with sub on sell,perfectly restored in all
 

MRJAZZ

[Industry Expert]
Jan 21, 2014
208
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#49
Hi, yes I have heard them , twice, at a friends house who had an old pair that he used to play around with, he had the enclosures removed so that you could see the lens and transducers. I want to be clear hear, I mean no disrespect to the late Mr. Beveridge , he was a true genius in every respect . I only question technical details because I am an engineer myself. The sound that I heard coming from the lenses did indeed fill the room with sound but they did not image at all, no matter how they are oriented in the room. The lenses only give the illusion of creating a true cylindrical wavefront, I am not trying to be critical just for the sake of being critical, I hope someday someone may take the basic idea of the lens and improve on it using advanced software to design a lens that is superior.
Back in “The Day “, I owned two pairs of BEV III’s , and I disagree that “ They did not image at all”...... of course it all depends on how one would “define” correct sound field creation (Imaging)....I thought they imaged very well in the sense of creating an illusion of musicians, especially on large orchestral assembles, existing in a “Natural” acoustic perspective...... pin point..hardly.....but laser like imaging is the exact opposite of how I would describe “good imaging”.......
Cheers....
 

Kcin

Active Member
Mar 27, 2016
188
88
28
Canada
#50
One shop in Italy audioantiquary has one Model 3,one model 2 and one model 2 with sub on sell,perfectly restored in all
Gian, if you are close, I would be interested to hear what you think of the Model 2 Beveridge in this shop!
 

Kcin

Active Member
Mar 27, 2016
188
88
28
Canada
#51
Back in “The Day “, I owned two pairs of BEV III’s , and I disagree that “ They did not image at all”...... of course it all depends on how one would “define” correct sound field creation (Imaging)....I thought they imaged very well in the sense of creating an illusion of musicians, especially on large orchestral assembles, existing in a “Natural” acoustic perspective...... pin point..hardly.....but laser like imaging is the exact opposite of how I would describe “good imaging”.......
Cheers....
Totally agree, very good to excellent in natural space illusion. Certainly not full range in the day. However, that is totally possible today with modern subs & careful placement . In fact, the subs will support the imaging component of the total package. Additionally, the subs will support getting clean extended dynamic range to levels that we expect today.

The other aspect is transparency. Especially with direct drive and no step up transformer for the sators and no step down transformers for the amps. Totally wipes the window on sound clean. The DD unit for my modified III's is tube input and driver further improving, in my opinion, Beveridge's original DD with a SS input.

If nothing else, Beveridge is a unique perspective on the creation of the illusion.
 

gian60

Well-Known Member
Apr 17, 2016
1,727
500
113
#52
Shop is 350 km and don't go,also always too traffic.
Shop is very very serious and this 3 model are 100% restored also inside.
you can see audio antiquary.com

the most expensive model 2 has the original sub included,the cheapest is without sub
He has 2 sub Janis to sell
 

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Kcin

Active Member
Mar 27, 2016
188
88
28
Canada
#53
Shop is 350 km and don't go,also always too traffic.
Shop is very very serious and this 3 model are 100% restored also inside.
you can see audio antiquary.com

the most expensive model 2 has the original sub included,the cheapest is without sub
He has 2 sub Janis to sell
That is is a 3 1/2 drive without traffic ... too far. Looks like an interesting shop. Funny, seems to be a few Beveridge fans in Italy.
 

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