The Shure V15 V with a Jico SAS/B stylus VS The Soundsmith Hyperion MR and Lyra Atlas SL

There is dipolar and there is bipolar.  The difference is important.  In one case, where we are talking about two subwoofers mounted into opposite sides of a cabinet, the rear or opposite side firing woofer will cancel cabinet movement that might have been induced by a single subwoofer.  In the other case, the cabinet will wobble because the two subwoofers are taking turns rocking it back and forth, because they are 180 degrees out of phase.  I always forget the semantic distinction, but I'll stick my neck out.  In a dipolar subwoofer, the two woofers are out of phase with each other, which is undesirable also because it results in phase cancellation. In a bipolar subwoofer, the two woofers are in phase.  In that case, the motion of the two drivers on opposite sides of the cabinet cancel each other out, and there is also no phase cancellation. So bipolar subwoofer good. Dipolar subwoofer not so good.

@bdp24 Roger was a smart guy. 100 Hz is right. The only problem was he only had analog filters to use and 24 dB/oct or 4th order was the steepest he could go without penalty but it is too slow and you will get subwoofer coming through in the midrange. At 100 Hz the slowest filter you can use is 8th order or 48 dB/oct and you can only do that cleanly in the digital realm. I have been using dipole speakers of one sort or another exclusively since 1978. I have been using subwoofers since 1978 and not able to find a satisfactory commercial subwoofer I started building my own somewhere around 1990. You might want to look at the link below. Just so we get this straight. Dipole subwoofers will make bass, real crappy bass. The problem for most people is that bass is difficult to evaluate especially by ear because a lot of it you do not hear, you feel it. After decades of measuring subwoofers I know what low bass should sound and feel like. You would too if you had been studying the problem for 30 some odd years. 

@richardbrand First of all what you are talking about is not a dipole, but a bipole and in that regard you are speaking to the choir. You might take a look here  https://imgur.com/gallery/building-resonance-free-subwoofers-dOTF3cS I happen to think the KEF Blade is a fine sounding loudspeaker, just odd looking.

@lewm The problem with stacking 57s is an 8 foot Sound Labs. You get a full range line source that is indestructible with a much better dispersion pattern. If I were operating on a shoe string I would look for a pair of used Acoustat 2+2s or even better 3+3s. 

@rauliruegas I was wondering when you were going to turn up. I think inferior is a little too strong, but of all the cartridges that were available I'm sure there were better. Before MC my last high output cartridges were B+Os before that were Stantons and Pickerings. I'd have to go way back to trip over a V15. Call it nostalgia or just the desire to fart around. Back then my system was not remotely near what it is today. So, it is fun to hear what we were listening to back then. Now, What cartridge is mounted in your turntable at this moment??

@mijostyn

I did not mention dipole nor bipole! The Quad ESL-63 was called FRED as it is a Full Range Electrostatic Dipole - the rearward bass radiation is out of phase, since it comes from the same plane as the forward bass. FRED is logically a single driver but is manufactured as four adjoining panels.  The ESL 2905 has two additional bass panels, making four bass panels per speaker.

The Gradient subwoofer designed for the ESL-63 had one forward and one rear facing driver, but they were offset, not co-linear. The Duntech Thor had a single driver and had to be spiked to the floor to provide a semblance of stability for the ESL-63 it piggy-backed.

It makes sense to stack ESL 57 speakers vertically, but not the ESL-63 and later models. That would have introduced another point source to cause cancellation and reinforcement interferences! But if one could align them so the apparent sources one foot behind the plane of each speaker were in the same spot, you would get a bit more volume. You might even manage three or four aligned to that point source ... thereby creating a true Bipole from equal Dipoles.

@lewm: If you want, take a look at the dipole woofer system in the Linkwitz LX521, or go onto the GR Research website, where you can see the dipole sub Danny Richie and Brian Ding of Rythmik Audio co-designed.

Siegfried’s dipole woofer is a W (or M, same thing) dipole frame, each woofer mounted on it’s own baffle, the baffles mounted in the frame 90 degrees offset from one another. In the GR Research/Rythmik dipole sub, the woofers can be mounted in M/W frame fashion, or in an H-frame, the latter more common. In an H-frame, the woofers (two or three, the user’s choice) can be mounted facing 180 reversed from each other (one cone facing the listener, the other with the rear of the cone facing the listener), or all facing forward. What makes it a dipole woofer system is not how the woofers are mounted in regard to each other, but that the output from both the front and back of the woofer propagates into the room, the front and back waves being 180 degrees apart. In fact, you can build an ob/dipole woofer system using just one woofer.

Yes, those front and rear waves---being of opposite polarity---meet on both sides of the dipole frame, with resulting dipole cancellation. A loss of output is therefore inherent in the ob/dipole sub. There’s no free lunch! But once you’ve heard an ob/dipole sub, you’ll know why people are willing to accept that design penalty in exchange for the sound quality produced by the sub.

For many years, I considered the sound QUALITY produced by the big Magnepan woofer panels (two of the panels in the 3-panel Tympani models, and the current MG30.7) to be the best reproduction of low frequencies I had ever heard (Harry Pearson agreed with me). Well, the GRR/Rythmik OB/Dipole woofer system sounds very similar to the Maggies. Brain Ding characterizes it as sounding "lean". The question is: is it lean, or are "normal" woofers "fat"? The ob/dipole sub reproducing an upright bass (or the lower registers of a grand piano) has to be heard to be believed! The "texture" of the fingers plucking the bass strings is clearly audible, with no added "weight" or "pluminess."

To offset the dipole cancellation, Brian Ding installs a dipole cancellation compensation circuit into the plate amp that comes with the OB/dipole sub kit. That of course means the power amp must provide more power than it would sans the compensation circuit. Power is cheap, and the woofers used are pretty sensitive/efficient. The sub also features Ding’s patented servo-feedback control of the woofers, which is what drew Danny Richie to Rythmik Audio. Danny was already marketing an ob/dipole woofer, and the idea of mating it with servo-feedback sounded like an idea worth exploring. It was.

I’ve owned servo-feedback woofers mated with planar loudspeakers before---the Infinity RS-1b, and this sub is a whole ’nother matter. State-Of-The-Art reproduction of low frequencies! Audiogon member @jaytor has the GR Research/Rythmik woofer system, with four woofers per side (left and right channels). Crappy bass? Uh, no.

Guys! All I was trying to do was to establish the definitions of bipole and dipole. But I must say I’m curious about a “dipole cancellation compensation circuit” or whatever Mr Ding calls it. I remember reading about subwoofers using two woofers in one sealed cabinet driven 180 degrees out of phase so there’s no back pressure build up in the closed box. That’s supposed to have its virtues too.

Listening to Big Band Monk on my Beveridge system where bass comes from my home made transmission line woofers. For me TL is the most undistorted bass imaginable but doesn’t go down to 10 Hz.

@lewm: Like you, transmissionline loading of woofers for bass reproduction holds a special place in my heart.

In 1971 my hi-fi education took a giant leap upward when I was first exposed to: 1- ESL loudspeakers, and 2- TL woofers. The ESL was the original Infinity Servo-Static I, as well as the ESL tweeter (made by RTR) array in the ESS Transtatic I. The TL woofer was also the design of the woofer in the Transtatic. ESS (this was before they introduced their Heil models) installed the well known KEF B139 woofer in a pretty long transmission line, and the KEF B110 midrange driver in a short one. David Wilson used that KEF woofer and the RTR ESL tweeters in his original WAMM loudspeaker.

Hearing the bass reproduction afforded by the Transtatic revealed to me that the bass of the AR-3a and Rectilinear III (two of the best box speakers of the late-60’s/early-70’s) was somewhat lacking. I was severely lusting for a pair, but at $1200 they were out of reach. In 1982 I saw a pair for sale in The Recycler (a weekly buy/sell rag published in Southern California) for $400, and snapped them up. One of the B139’s had been replaced with an imitation B139, so I gave ESS a call to get a real one. They had one woofer left, and for 39 bucks it was mine! I still have them, sitting in my spare room (along with a pair of Magneplanar Tympani T-IVa’s, acquired from Kent at Electrostatic Solutions).

And like @mijostyn, I love ESL’s. If I had the dough and a big enough room (and a capable amplifier), I too would own SoundLabs. In his review of the Eminent Technology LFT-8b and 8C planar-magnetics, Steve Guttenberg states that he doesn’t like ESL’s, finding them to sound a little "threadbare", lacking body and substance. Or as Art Dudley might have put it, lacking full "color saturation". I suppose I can understand what Steve means, though I don’t share that opinion. Speaking of the ET LFT’s, in the reviews Steve also states that he prefers them to every ESL and Magnepan he has ever heard. I'll bet he hasn't heard the Sanders ESL, imo a great loudspeaker.

I’m not on the Eminent Technology (or Sanders) payroll, honest.

@richardbrand You were talking about balanced force woofers which are bipoles in the context of speakers which are dipoles. As you correctly mention 57s are dipoles. There is a huge difference. The dipole nature of panel speakers is not the same issue as dipole subwoofers if you remove the low bass from them. Like every other dipole woofer they stink at it. There rear wave of a panel loudspeaker, at least above 200 Hz is relatively easy to control, below 100 Hz  you are totally helpless. Unless you can get panel loudspeakers 10 feet from the front wall, in order to achieve the best image, the rear wave has to be partially absorbed by at least 50%. People frequently prefer the sound without absorption, it is brighter, more airy and louder. It is also far less accurate and at times painful (sibilance). @bdp24  As far as subwoofers are concerned, low bass is omnidirectional. The rear of the subwoofer driver is just as omnidirectional as the front. Take two enclosed subwoofers and play a 30 Hz test tone. Walk around the room. As you move the bass will get louder and softer due to room modes. As you get close to walls the tone will get louder. This is barrier effect. Now wire one of the subs backwards 180 degrees out of phase. Now as you move around the room the tone goes from almost entirely gone to extremely loud. Where this happens changes with frequency. An open baffle subwoofer is exactly the same as two out of phase subwoofers, actually worse because in open baffle designs the drivers are inadequately braced. Put your hand on one while playing a 20 Hz test tone at 85 dB. It will be shaking and that is distortion. At some frequency, depending on the effective mass of the system, it will shake so badly you will be able to see it. This is the resonance frequency. There is absolutely no way you can overcome this. You can only live with it and the best way to live with it is to avoid dipole subs like the plague. 

I think what Steve Guttenberg is trying to express is that playing full range ESLs will not go all that loud and because they are dipoles, the low bass is compromised. They are also very difficult to drive and the amps used make an extreme difference. Look at the monsters Roger Sanders uses to power his speakers. Once you take 100 Hz and down away from ESLs it is a whole different story. Roger crosses to his transmission line woofers at 250 Hz using a dBx driverack. Without those frequencies it is harder to saturate the transformers and the diaphragm has a lot more room to go loud, very loud given enough power. I have no problem hitting 105 dB, ear splitting levels. At 95 dB they might as well be playing at a whisper in terms of distortion which is an order of magnitude below any planar magnetic or dynamic loudspeaker. I guarantee "threadbare" would never be a term anyone would use to describe my system or Roger Sanders speakers including Mr. Guttenberg. If anything he would think my system had too much bass and my response would be to compare it to live performances and not other systems. The only problem with Roger's speaker is it is extremely selfish, it beams like crazy. People sitting outside the listening position get no direct high frequencies.  The ETs are good speakers, better than most, but IMHO the Magneplanar 3.7i is even better. That ribbon tweeter is fabulous, arguably the best tweeter made. The ET's tweeter is too wide which will cause it to beam.  I once had a pair of Tympany IIIs. It was with great fortune that I met my wife at this time giving any other speaker a reasonable WAF. She loves the Sound Labs as they blend right into the room. People don't even notice them at first. 

Every audiophile should read Roger Sanders White Papers. https://www.sanderssoundsystems.com/technical-white-papers

Every one of those subwoofers you mention is challenged by bad enclosures and their bass is colored.  There is no such thing as too many drivers in a subwoofer system. The more surface area you have working for you the lower will be distortion levels. INHO the minimum is two 15" drivers or four 12" drivers. 

@lewm A dipole cancellation compensation circuit? Talking about wishful thinking. How many bad ideas does it take to make a good one?

The subwoofer design you mention is just as bad as the open baffle subwoofer except the drivers are more adequately braced. Like the open baffle subwoofer the only virtue it will have is terrible bass. Using drivers in phase at opposite ends of a symmetrical enclosure cancels Newtonian forces, the enclosure does not shake and the drivers brake each other improving transient response. The drivers have to have high BL products and very stiff cones, preferably aluminum to prevent paradoxical flexing. You also want drivers with a shorter X max and stiffer suspensions for the same reason. 

OMG! I once owned Tympani 1Us and then Tympani IIIs. Those were my only forays outside of the ESL paradigm since 1973. Without the ribbon tweeter, magnepans were dead sounding, utterly lifeless. It’s frightening to think how closely our bouts with audiophilia coincide, and yet how profoundly we differ with respect to digital processing and room equalization.

@lewm  My assessment of the Tympanies matches yours. I also took a foray into ribbon speakers with the Apogee Divas, also a big mistake. It was back into Acoustat 2+2s until the Sound Labs came along. 

You mentioned being fond of live performances because of the dynamics. The only difference between us is I chased those "dynamics" using subwoofers. Once you realize (get hooked on) the benefits of subwoofers it is a very short hop to digital processing. You are already toying with the idea of subwoofers. I know for an absolute fact that if you listened to my system for just 15 minutes you would be 100% onboard. 

I’m on board and have been for years. I just don’t want the extra clutter and complexity. Whenever I get close to pulling the trigger, my inner self says, "Nah. My Sound Labs do excellent bass, though I would not argue that very low bass could be better. I just don’t care enough. My Bev system has better bass, as good as I could want. In my own opinion, a system I have heard locally with stacked Quad 57s that have been modified by removing the electronics and direct driven from EMIA tube amplifiers with only one transformer at the interface outperforms my long time friend’s Acoustat 2+2s by a long shot. But with those mods and upgrades to the Quads, this is no surprise. I think that Quad system may also incorporate subwoofs, but I am not sure. The owner demoed the system at the Capital Audio Fest (coming up soon) with the stacked pair. At home he uses stacked triplets. If he is there this year (along with Dave Slagle his close friend), I will report.

I did not quite say that I am fond of live performances "because of the dynamics".  I said that on the frequent occasions where we attend live performances, what is striking in comparison to any home audio system is the dynamics of live music, as opposed to pinpoint imaging, which was the subject of that discussion.  I once had a saxophonist come to the house and stand between the two SL speakers while playing a tune in our living room (aka, the listening room for the Sound Labs). Well, actually she happened to be visiting and had her sax on hand and was kind enough to play for us.  That was informative.

@mijostyn 

Have you managed to try out the recommended capacitive loading ( 250-300 pf ) on the Shure yet. I am interested to know the results.

Re Tympanis - I had a pair traded years ago, spent more time repairing them than listening. Fortunately found someone that thought they made very good screens for their parlour.

@lewm stated "Hearing is believing ".

I stopped taking description of Audio Equipment's end sound as a guidance many many years past. I have been much more interested in being able to encounter sound and form my assessments, as a result of the impression that had been made. 

Isolated / Insular Listening experiences leaves an individual quite limited in their experiences of sound being produced from recorded music replays.

My friend who tinkers with the 57's will be informed of the design for Quad 57 mentioned by @lewm, maybe I can hear one, especially as I donored 2 x 57's to support their own array method used.     

Now that I have a powered subwoofer between my Quad 2905 speakers, I realise I could have got away with 2805s (or their replacements with fancy wood trim, the 2812). The trick has been to adjust the level of the subwoofer such that I cannot tell when it is switched on, but can tell when it is switched off - I know that makes little sense, but perhaps you understand me. It is like adding, say, cinnamon to Italian savoury dishes, not so much you can taste it, but it still adds something to the flavour.

Doggie, wait a bit for Mijo to tell you that you must use a stereo pair (or quadruplet) of subwoofers to reach Nirvana. Actually I agree stereo subs have some advantages. But I am not in a position to criticize.

I’m munching on the idea that my Sound Lab 845 PXs “blend right into the room”. Perhaps if my listening room was a gymnasium or an aircraft hanger. Guests who don’t know any better think I’m planning a rock concert when they see the two black monoliths, each measuring 8’ x 3’, in our living room.

@mijostyn 

Which version of the Hyperion are you using? I noticed that Soundsmith now has two variants of the Hyperion. I have the previous Hyperion MK II Contact Line which is absolutely amazing. This new Micro Ridge variant of the Hyperion sounds like a great match. 

Dear @mijostyn  :  " So, it is fun to hear what we were listening to back then. Now, What cartridge is mounted in your turntable at this moment?? "

Well I don't do it just for fun but for the MUSIC overall presentation.

Several vintage cartridges are a true challenge and even can outperforms to some top today MC/MM/MI cartridges and you can't know till you listen with your today system. Shure is not a reference for what I'm talking about, far away from there.

I'm listening: Audio Technica AT-ML160-LC/OCC (MM), Audio Tecnica AT 36 ( VLOMC ) and the surprising LOMC Empire MC5.

Both AT are " something "and the AT 36 has new cantilever and stylus due that my original one had not by a mistake from me but its cartridge motor is just a beauty..

Everthing I do in my system is in favor of MUSIC enjoyment always. 

@lewm  "  what is striking in comparison to any home audio system is the dynamics of live music, as opposed to pinpoint imaging, which was the subject of that discussion.  "

Absolutely rigth an that dynamics is developed thank's to the very fast transient response of instruments in a live MUSIC.

R.

My Limited Experiences of having been able to hear Quad ESL Speakers in use with a Subwoofer, is that the carefully matched ESL>Subwoofer is is a set up that had a addition of Bass that is detectable, but certainly not an improvement, the Bass being noticeable does not augment the ESL as a Speaker it merely produces a unique type of Bass presentation in conjunction with another Speakers unique Bass presentation.

Remove the Bass from the Subwoofer as a influence on the ESL Bass and what is left is a Speaker functioning with a Bass that is satisfying and not effected by a Bass that is seemingly an anomaly.

It is because of this sensing that the Subwoofer is an anomaly, that has drawn my attention to a Ripole Bass and the Figure of Eight Radiation the Ripole produces. The design seems to lend itself to be much less detectable as a Separate Source for a Bass Driver coupled with the Bass from the ESL.

@dogberry

@mijostyn

I bought an 18" Velodyne servo-controlled subwoofer to replace my Duntech Thors, back when my main speakers were Quad ESL-63. One undoubted advantage is that, by relieving the Quads of low bass, they can play much louder before their protection circuits come into play.

The bigger Quad ESL-2905 has about twice the bass panel area, and does not really benefit much from the Velodyne, which ticks by on level 3 out of 60. Most of what I play is orchestral and the only instruments that go really deep are organs (and maybe venues?)

Oops, I forgot the revolutionary Australian Stuart and Sons 108-key piano which extends the 'normal' piano range by two octaves, all the way down to 16-Hz.  Those low strings add sonority even when playing standard repertoire. The bridge design provides downward rather than sideways coupling, and the pianos are much brighter than popular European heavyweights.

I share with @lewm and @mijostyn admiration for the Magnepan ribbon tweeter, which is found in the Tympani T-IVa’s. The planar-magnetic midrange driver of the T-IVa (unfortunately single-ended), however, is somewhat veiled, especially in comparison with just about any and all ESL’s as well as the p-m midrange driver of the Eminent Technology LFT-8b and 8c, which is of push-pull design and construction, a big deal.

There are a group of guys active on the Planar Speaker Asylum forum who replaced the T-IVa’s midrange driver with eight of the fabulous NEO 8 p-m drivers, which with a little fiddling fit into the slot in the frame of the T-IVa’s for that Magnepan midrange driver. Mated with the Magnepan ribbon tweeter and the two Tympani bass panels (Harry Pearson made his "super speaker" using those bass panels with the Infinity EMIT and EMIM drivers), the resulting loudspeaker is reported to be significantly more transparent than the stock T-IVa.

While the Eminent Technology LFT-8b may not be up the level of the SoundLab ESL’s, they cost only $3200 a pair. That is just about the same price as a pair of Magnepan MG1.7i’s (also with a single ended midrange driver), which imo (and that of Steve Guttenberg) is not in the same league as the LFT-8. One problem with the LFT-8 is that the crossover point from the p-m midrange driver to the ribbon tweeter is located at 10kHz, with 1st-order filters. Those filters characteristics coupled with the short wavelength of 10kHz leads to the inevitable comb filter behavior of the driver interaction. I trust I don’t have to explain comb filtering. I’d love for Danny Richie to get a hold of a pair, and design a crossover with filters at, say, 2 to 3kHz.

Guttenberg found the sealed enclosure 8" woofer of the LFT-8 to mate very well with the planar-magnetic driver, but an 8" woofer can be expected to play only so low, and not at lifelike spl. However, since the crossover point between the woofer and midrange driver is at a very low 180Hz, the GR Research/Rythmik Audio OB/Dipole Sub (you can disregard the opinion of @mijostyn---he hasn’t heard it)---which is capable of playing up to 300Hz---can be substituted for the stock woofer. The resulting combination provides 100% open baffle/dipole operation, with deep, clean reproduction from 20Hz to 20kHz. Guttenberg found the sound of the LFT-8 to possess the best characterisics of ESL’s and planar-magnetics, without their (in his opinion) failings. Since getting my pair of LFT-8b’s, my Tympani T-IVa’s and QUADS have been relegated to a spare room.

@dover yes, I listened to it most of the day yesterday. The sound was definitely less harsh, better, but after listening to 5 records that I know really well I best describe the overall performance as flat, flat in terms of excitement and visceral involvement, less dynamic than todays best cartridges. It is also way more sensitive to surrounding electro magnetic fields resulting in more background noise than all of my other cartridges. It is also more microphonic than all of my other cartridges. How it compares to other $500 cartridges I can't say. The high output cartridges that I have listened to lately including the Clearaudio Charisma and the Soundsmith voice are superior in every way sonically. The Soundsmith Voice was also playing through the phono stage of the DEQX Pre 8 in a system centered around Magico S7s and the pair sounded wonderful. This is not the fault of the phono stage. My other cartridges, all low output are played through a Channel D Seta L Plus which I am thrilled with. 

@audioquest4life It is the new microridge version and I have absolutely no complaints. It and the Lyra Atlas Lambda SL are, in my system the two best cartridges I have ever used. I am going to try the My Sonic Lab Ultra Eminent EX as it has the lowest impedance of any cartridge I know of. The Seta L will do both voltage and current mode. In current mode the cartridge with the lowest impedance wins and I am betting that it will outperform the Signature Platinum, a good cartridge, but not as exciting as the Hyperion or the Atlas in my system. 

@pindac That is an assumption that is simply not true. You can not compare the reproduction of very low frequencies with higher frequencies. Matching subwoofers so the system is completely unified is not easy. It is not any more difficult with dipole speakers as long as the crossover point does not go much over 100 Hz. The benefit in terms of distortion and headroom/dynamics in ESLs can not be overstated. 

@lewm Acoustat 2+2s run correctly with subwoofers out perform 57s in every way and you have to throw a Javelin at them to cause any damage. I used a single Sowter 1:100 transformer on each one along with my own adjustable bias supply. Their one weakness is their horizontal dispersion is very limited almost as bad a Roger Sanders speakers. 

@richardbrand  That is some piano.

Next time you try subwoofers please use at least two. Not only will your ESLs play louder, but if you cross higher at 100 Hz, distortion levels in the ESLs will drop noticeably. The problem is getting the subwoofer to disappear. At 100 Hz you have to use very steep filters at least 8th order. The only way to do this cleanly is in the digital realm. The benefits far outweigh any detriment. There is loads of low bass in good classical recordings. Large indoor venues breath at low frequencies, then there is the Tympany, Organs and massed strings. In order to get realistic low frequency performance in a residential space 20 Hz has to be boosted up to 10 dB. This will cause serious problems in most speakers, but not subwoofers. Done correctly subwoofers will give you the FEELING of a live performance while improving the performance of the main speakers. Unfortunately, it is much easier to screw things up then get the desired result and the manufacturers do not help.

@bdp24 You definitely do not want to mention comb filtering around me, it could put you in mortal danger. I spent two months trying desperately to stop it as it was confusing the computer in my DEQX preamplifier. The solution required about 50 hours of shop work and you can see it on my virtual system page. It was initially designed by Dr Roger West. I modified the design by making it a foot wider and using 8" wedges instead of 6" wedges. Dr West calls it SALLIE, Sound Attenuation of Low Level Interference Effects. They worked. 

@lewm The Sound Labs makes that impression on everyone who sees them. Nobody is use to seeing monoliths like them. Just because they are HUGE does not mean they make great low bass. They make great mid bass. I stand by my opinion. Just 15 minutes listening and I will change your approach to HiFi forever especially since you are already 75% of the way there.

Mijostyn, I always get the impression that you read but do not take the time to understand what I and others write. How can you really know that Acoustat 2+2s outperform a stacked Quad 57 with all the modifications I described? I am quite sure you’ve never heard the Quad system, because it is one of a kind. Whereas, I have many hours listening to both the modified Quads and Acoustat 2+2s. Yes, I am offering a subjective opinion based on some aural data. And then you add in that if by chance the Acoustats were found wanting, it must be because they were not properly driven. Your mind is closed.

Then in your last paragraph you tell me what I already candidly admitted about the bass response of my Sound Labs, even keeping in mind that we once calculated that my speakers have a greater radiating area than yours and so almost assuredly do better in the low bass than yours do without subwoofers. At the same time, I recognize that you went for the smaller panels because you knew in advance you were going to use subwoofers. You got the right version for yourself, and I got the right version for myself. Nothing wrong with that, and I am sure you have more extended bass response than I do. I still sleep at night.

Seems you are hearing the Shure V15 in much the same way that I heard the V15 in my system 40 or so years ago (probablyi version III); flat response but dry and a bit dull.  I didn't keep it for very long. This does not mean that all vintage cartridges are inferior to very expensive modern LOMCs, categorically, at least in my opinion.

@mijostyn My Velodyne 18" subwoofer is digitally controlled, with digital crossover and servo control of the cone for under 0.5% harmonic distortion.  It has 8-band parametric equalisation and 1250-Watts RMS power.  If I am not careful, it rattles the windows and brick walls too much.  It adds about two octaves to the Quad 2905 but most of that is felt, not heard.  Like you, I am a big fan of walking around to see how the audio image holds up.

On swept tones, the sound is dreadful as various room modes kick in.  Additional subwoofers would help, but musically I am in my own sort of heaven!

@mijostyn Assumption ? Please Clarify 

I usually am doing my best to share only my experiences had and an very subjective assessment will be attached, if I feel it is worth the mention.

As always, I don't expect anybody within the Current Thread to endorse my input, it is quite obvious the common posters are not able to cojoin.

My Input is directed to the onlookers of the thread or future thread visitors, who  might get some value from the content added. 

I was once a Visitor, then a Regular Onlooker and developed into a valuable contributor.  

@lewm You apparently do not listen to me either Lew. I was one of the very first people in the entire world to mess around with stacked Quads. It was the brainchild of Mark Levinson and John Curl. It was called the HQD system. Levinson marketed an Oak stand that held the stacked Quads with a little window in the center for the Decca Ribbon tweeter. I'm sure you can find a picture. We had the full system set up at Sound Components in Miami. I have talked endlessly about the poor reliability of both the Quads and the Decca. It was powered by six  25 watt class a amps. God knows how much power they put out in B mode. I have WAY more experience with Quads then you will ever have. I have taken them apart, exchanged elements and blown them up a second time. On the other hand you have no experience with Acoustats. Granted, the methods supplied by the manufacturer to drive them were somewhat crippled, but the panels were genius. They were the first ESL panels made that you could not burn out. All they needed to shine was a good transformer, the right amp and subwoofers.

@richardbrand Having low bass is a lot of fun. Digital electronics do make it much easier to to get to the point where the subwoofers are invisible while still supporting the low bass. I promise you that if you get a second and digitally high pass your main speakers you will be even more amazed by a factor of four. 

@lewm Which reminds me, I find your speakers to look fat and bulbous (Captain Beefheart). The dimensions are wrong, but take just four inches off the girth and they become graceful. Screw the bass, it's WAF that counts. Anyway, go here https://www.stereophile.com/content/mark-levinson-hqd-loudspeaker-system. The article mentions a dealer in Florida. That was us and we did have them sounding great....for a few minutes until we blew something. The system was doomed from the start. It was way too difficult to set up and way to fragile. You are right, I have a very closed mind. 

@pindac The way I read your comment above was  if you used a subwoofer that radiated like the main speakers, both dipoles, it would be easier to integrate the subwoofers correctly. That is the assumption that is not true. It is logical to think that way, but subwoofers and main speakers are apples and oranges. The considerations for the best performance are vastly different. 

Stacked Quad 57s were hardly the brainchild of Mark Levinson or whosis. I am 10 years older than you, and I first heard stacked Quads in the home of one of my patients, when I was an intern, in 1970. He drove them with a Marantz 7C preamplfier (when the term "preamplifier" automatically meant built in phono stage) and Marantz 9 amplifiers. Harmony House in Manhattan also had them back then. Mark Levinson was a kid at that point in time. He can take credit for the HQD system, I agree. What you are not hearing me say is that the stacked Quad 57 system that I heard locally a few years ago was comprised of speakers wherein the onboard electronics, courtesy of Peter Walker in his attempt to turn them into a point source, were gutted and so too was the OEM audio transformer. In place of that stuff, Dave Slagle devised a tube amplifier with an output transformer that could directly drive the panel. In other words, only one transformer at the interface. And that transformer can have wider bandwidth and lower distortion than typical transformers used to couple tube amplifiers to ESLs, because the ratio of the two impedances, the output impedance of the tube output stage (which is very high, not like our OTLs that are designed to have a low output Z) vs the input impedance of the panels, are more nearly the same. Plus, Dave wound it himself. Like I also said, that system, owned by a local guy and unique in the world so far as I know unless Dave has built one or two for others, can play very loud and with very low distortion and may in fact incorporate a subwoof in its base. Like I also said, I have many hours listening to my friend’s Acoustat 2+2s. There is no contest at all. As I also said before, the guy who owns the aforementioned system uses stacked Quad 57 triplets at home, but he only saw fit to bring the doublet to CAF. So, you have a system with markedly enhanced durability in its ability to play at high SPLs and bandwidth, with reduced distortion even below that of the base Quad 57. It’s awesome; trust me.

Oh yeah, the reason the Sanders ESL amplifier is so large is because it has to develop the voltage to drive an ESL.  Most SS amplifiers are good at current (i.e., driving low impedance speakers) but not so good at voltage.  ESLs require voltage except at very high frequencies, which is why in general a tube amp is a superior match. OTLs are better yet, of course.

The most important point for me as a result of the recent Posts, is that a Speaker that is not fat off 70 Years being entered into the Market Place has serious support for it's Capabilities.

I often find 57's for sale in the UK, where a Pair can range between £300 - £1000

Most will be offered to be listened to under the guise they are quiet when charged.

The Last Pair I bought was not the prettiest, but were quiet and cost £120. There were the Donor Models referred to.

In my own home the Family call them the Wash Boards, fortunately I have my own Laundry Room   

https://www.facebook.com/marketplace/item/371140325552580/?ref=search&referral_code=null&referral_story_type=post&tracking=browse_serp%3Aed91271f-5755-4621-8851-eb130e7996ed

https://www.facebook.com/marketplace/item/1028071632350338/?ref=search&referral_code=null&referral_story_type=post&tracking=browse_serp%3Aed91271f-5755-4621-8851-eb130e7996ed

Dear @richardbrand   : " My Velodyne 18" subwoofer is ..."

Wel, you can be sure that 2 subs always is better than only one listening at the prefered seat position.

I own Velodyne too but with better wooferbuild material: pulp/paper.

R.

@mijostyn   : Velodyne comes with the high-pass filter as the one that use richard.

R.

Ah, so much to take in.  Yes, my Velodyne has stereo high pass digital filters which is how I relieve my Krell / Quad ESL-63 / ESL-2905 of having to play low bass.  It is also old enough to have a pulp/paper cone but if the servo mechanism is good enough, who cares?  The only things stopping me adding more are: the cost; the space; the fragility of my home; the fragility of my partner; the neighbours and ROI.

The original Quad ESL is often known as the ... ESL.  But it is totally different in concept, design and implementation to the later Quad ESLs which have factory designation not less than 63.

The original ESL, aka ESL-57, uses a curved panel (much later this was apparently "invented" by Sound labs) to give an approximation of a line-source, albeit horizontal.  Like modern stadium systems, these can be stacked vertically.  Stadium so-called line source systems are curved in the vertical dimension to get them to emulate a point source!  It is of course rather hard to bend a flat panel in two dimensions simultaneously.

The ESL-63 and later models use fancy electrics and shaped electrodes to get a truly flat panel to emulate a point source.  It makes no sense at all to stack them, nor to remove the electrics which are their unique raison d'etre in my opinion.

I am not certain, but if the Quad 57 is curved at all, it is curved in the vertical plane, not in the horizontal plane.  And anyway, Sound Lab ought not to claim to be the first to curve an ESL in the horizontal plane, because Martin-Logan did it first with their flagship CLS model, albeit in a problematic way.  (They used curve stators with the diaphragm suspended inside a curved "sandwich"; thus when the diaphragm moves toward the listener it wants to stretch, when it moves away from the listener, it is looser than in the rest position.)To be fair to SL, I doubt they ever did claim to be the first to curve an ESL.  Sound Lab uses flat facet segments arranged in a curved array, thus avoiding the inherent issue with the M-L CLS but also perhaps fairly described as not a true curve.. Also, "ESL" is a generic acronym for ElectroStatic Loudspeaker.  In my lifetime, I never heard the Quad 57, so numerically named for the year of its introduction, referred to as an ESL57, but I certainly can be wrong on that. We just say "Quad 57".

On the "line source" descriptor, it was my impression that Peter Walker incorporated time delay into electronics mounted inside the speaker so as to create the radiation pattern of a point source, not a line source. Again, I would be happy to be corrected if that is bad info. Whether that was a good idea or not is also open to question.

@lewm Yes, the Quad 57 (your nomenclature) is indeed curved in the vertical dimension, which effectively focusses the sound on a horizontal line behind the speaker.  Most other speakers claiming 'line source' have a virtual line which is vertical!  

We now recognise the 57 as having three panels in a d'Appolito configuration, though unusually this is horizontal with a central treble flanked by two bass panels. Get off-center, and the bass panels start to differ in path-length, meaning there is a very small sweet-spot.

When the Quad 57 was re\eased in 1957 it was just the ESL.  Sound Labs "The Complete White Paper" states "The electrostatic speaker art was in its infancy when Sound Lab started business back in 1978" which is a bit rich considering Quad sold 54,000 pairs of the original 57, starting 21 years earlier.  I have many other quibbles with the white paper, especially when it groups dynamic speakers as point sources, which most certainly aren't.

Only the ESL-63 and later had the radiation pattern of a point source.  Whereas the 57 has a very small sweet-spot (sideways!) speakers that emulate a point source have a very large listening area.  The ESL 63 is often reported as the world's most accurate speaker, since it has a very light diaphragm, effectively no cabinet coloration, no crossover colouration, and a coherent radiation pattern with no cancellation / reinforcement interference patterns if reflections are ignored..  The 2905 has amplifier-like distortion measurements.  And if it doesn;t play loud enough for you, you can just sit closer!

Note that I am not claiming it is the world's best speaker, just very accurate.  Peter Walker's perfect amplifier is "a straight wire with gain".  The 63 and later aim for the same neutrality "If you don't like what comes out, pay more attention to what goes in" he said.

@lewm See, you learn something everyday. I've still blown out more Quads than you:-) We both own extremely similar loudspeakers, I suspect for a reason. Acoustat 2+2s driven by one big transformer and crossed to subwoofers at 100 Hz sound exactly like our speakers except their horizontal dispersion is worse.....much worse. I also believe it is the job of the step up transformer to convert current to voltage. IMHE, and we both use OTL amps, the amps that drive ESLs best are SS amps with HUGE power supplies. For whatever reason, the Bricasti M28's do a better job of it than the MA2s. I like the MA2's midbass better, but I tend to push them hard the result being a steady drain on my tube supply. They are great amps suited to a less stressful existence. The Bricasti amps are the most bullet proof amps I have ever used. If they do not like something they simply turn themselves off. Reboot them and you are good to go. They also are amazing at protecting loudspeakers. If they detect any clipping either their own or any other unit in the chain they turn themselves off immediately and this includes digital clipping. I burned out two transformers clipping the MA2s.  I do believe Acoustat was the first to curve an ESL in the horizontal plain. The X which came out in 1978 had three panels angled about 15 degrees to each other giving a horizontal dispersion of 30 degrees. The 2's and the 2+2's only had 15 degrees of horizontal dispersion, but it was better than 0 degrees (at high frequencies)

@rauliruegas You are correct! The Digital Drive Plus series has a high pass filter.....a 1st order one. Definitely better than nothing...if it is being used. I use a digital 8th order filter on both low and high pass sides. @richardbrand are you using the high pass filter??  I agree that Roger West could have stated that position more accurately. Dr West did advance the art of ESLs. ALL dynamic drivers are point sources unless you stack them in a linear array with the right spacing between drivers and that has never worked well in home HiFi systems. It has been tried unsuccessfully 3 or 4 times by Infinity, Nearfield and others. This results in a big impressive sound lacking in fine detail and image specificity. Most line sources, like Maggies, Apogees and many ESLs are crippled because they are not tall enough to extend the line source behavior below about 250 Hz. A proper residential line source has to extend from floor to ceiling or it loses it's line source behavior at the frequency matching the wavelength of the speaker's height. The power projection stops at the frequencies it is most needed. Now, what you are talking about is a co-axial point source which has absolutely no advantage over non co-axial point source speakers that are spaced closely together until you are a foot from the loudspeaker. In doing the variable diameter point source Quad was trying to improve dispersion characteristics at high frequencies. My assessment of modern Quads is there are dynamic speakers that outperform them in many ways resulting in a better listening experience particularly at levels above 85 dB. 

Funny how coincidences happen. As i read this, I was going through a box of interconnects and found two unused Shure V15-IV MRs. I was given when I worked at a studio. We had purchased several of the "new" Shure CD players for doing transcription work and they came with these carts. Just wondering, my bedroom system has a Music Hall classic w/an Ortofon 2M Bronze that has around 250 hrs on it. Does anyone have an option if the Shure may be a worthwhile replacement? 

This thread has evolved as if the Shure V15 was the sine qua non of vintage high output cartridges. It’s surely not that, in my experienced opinion. Far from it. But if you try it, give an NOS cartridge that must be minimal 30 years old at least several hours playing time before you judge

Mijostyn, if you’re talking about the Sound Lab OEM backplate on a Sound Lab speaker, with its power robbing parallel resistance and its very low midrange impedance, then yes perhaps an SS amplifier is better suited to overcome those handicaps. But if you want best sound, you remove those kludges, then Z and efficiency go way up and an OTL kicks ass. If you don’t agree, that’s fine, but please stop telling me what I would like.

To add a bit to the ESL plus OTL paradigm, Sound Lab, by using two audio step up transformers, one for bass and one for treble, and by therefore using a passive crossover between them, are somewhat unique in spoiling the natural match of ESLs to OTLs, because of that midrange impedance dip thus incurred. Scuttlebutt was and is that SL use solid state amplifiers (Parasound JC1s, it is said) to voice the speaker and so are ignoring the problem, essentially, for tube aficionados.  Historically, ESLs like Quad, KLH9, Jantszen, Acoustat, original CLS by M-L were high impedance speakers well suited to OTLs.  Then M-L revised the CLS (which came to be known as CLS II) such that impedance was lowered considerably, to suit the rising popularity of SS amplifiers, I guess.  I traded in my beloved CLSs for the CLS II on account of the favorable publicity but without knowing what M-L had done to the impedance curve; the CLS II sounded awful with my Futterman OTLs. Sound Lab "borrowed" the two transformer idea from Acoustat, actually, in the 90s.  So I don't know when Acoustat were driven via only one step-up transformer as you mention.  The earliest Acoustat I recall was the Acoustat X, a giant panel that was direct driven by an on-board amplifier, which I heard once but cannot remember aurally.  That was in the mid to late 70s.

richardbrand, Though no one ever told me this, it was my assumption that the Quad 57 is curved in the vertical plane, because it was designed to sit only a few inches off the floor.  So they devised a stand that leans the speaker back a bit to tilt it upward, and to further enhance radiation to the height of a listener's ears, they curved the panel.  I imagine that all this was to accommodate the smaller listening spaces of typical UK houses and apartments.  They never dreamed of stacked pairs as part of the original design intent.  I would guess that the last thing anyone thought about was how the vertical curve would focus the rear radiation. 

Also, now I think of it, you are probably correct.  The 1963 speaker was called "ESL63".  It falls trippingly from the tongue.  The ESL63 is the only Quad speaker I ever owned. I didn't love it as much as some others. I just don't recall the 1957 speaker being referred to as ESL57, but if you say so....

@richardbrand   : " old enough to have a pulp/paper cone but if the servo mechanism is good enough, who cares?   "

It cares any one that knows in deep about best bass range build material subs, not all material gives us the same bass quality level.

Btw, my Velodyne's came with the servos too as yours.

R.

On ESLs and OTLs: Rich Brkich is rehabbing a pair of Joule Electra VZN 160s for me to use with my Stax F81s. Will report back on this thread in a few weeks if it's still so far off topic.

@lewm Come on Lew. You know you are preaching to the choir. I use essentially one 1:100 transformer to drive my Sound Labs just as I did the 2+2s and they sound exactly the same except for dispersion and output capability. The midbass of the Sound Labs might be superior. Forget about the stock back plate, everything except the bias supply has been ripped out. Nothing in the signal path is original. I should also note that the frequency response curve of the modified Sound Labs is not correct and has to be equalized to get the desired curve which is not flat. You are doing something different by keeping the bass transformer hooked up. 

@maxson Don't worry about it. It's my thread and it can go anywhere it wants. 

Dear Mijo, of course I do know how you now run the speaker, I was only referring to the stock circuit.

@lewm To be fair to Dr West, he had to conjure up a way to make the speaker work with a variety of amps and rooms. I think for most people his solution is a reasonable compromise. Most people are not like you and me. They think we are crazy ripping apart $40K loudspeakers as if we know better than the designer:-)

$40K!!!! Is that what my speakers cost now? I agree with you, almost. I think Dr West had to conjure up a way to make his big panels with relatively wide spacing between stators and diaphragm (thus permitting better reproduction of low bass but also decreasing efficiency) work. So he had to use the bass transformer with its very high turns ratio (by hearsay only it is 1:250) and high bias voltages (before you bought yours, I think, they were having problems with leakage of the stator insulation due to the high bias voltages; my M1s died from that malady and SL gave me a good deal therefore on the 845PXs) in order to move the diaphragm at low frequencies, but that wasn’t a good idea for mids and treble, so he added the separate treble transformer. And that necessitated a passive crossover (for those who would not bi-amplify), and that produced the problematic impedance curve for tube amplifiers. It isn’t inappropriate to drive the stock speaker with a solid state amplifier, IMO. The only thing I never understood is why they chose such a low value for R (depending upon the date of manufacture, anywhere from 5 to 8 ohms based on informally acquired data) in the RC network that comprises the high pass filter. If they used a higher value resistor (e.g., 10 or even 20 ohms) that more nearly at least matched the inherent Z of the panel at mid-frequencies, much of the problem with tube amplification could have been ameliorated.

@mijostyn

"Now, what you are talking about is a co-axial point source which has absolutely no advantage over non co-axial point source speakers that are spaced closely together until you are a foot from the loudspeaker."

I beg to differ.  Where did the foot come from?  Whenever two separated sources play the same frequency (eg in cross-over regions) there is reinforcement and cancellation interference, as explained and animated here Discover the Surprising Flaw in Center Channel Speakers (youtube.com).

"In doing the variable diameter point source Quad was trying to improve dispersion characteristics at high frequencies"

The diameter does not vary - it is fixed by the speed of sound as it radiates from a virtual point.  Mind you, the stators are only static in the mechanical sense.  Electrically they carry the varying signal.  The moving membrane confusingly carries a static electrical charge.  I think one of the problems Quad tried to address was the cancellation and reinforcement interference experienced from different parts of a large panel.  They deliberately reduced the high frequency dispersion pattern, in ways I do not understand but probably in the delay circuitry.

"My assessment of modern Quads is there are dynamic speakers that outperform them in many ways resulting in a better listening experience particularly at levels above 85 dB"

Agreed.  I prefer my KEF Reference 1 at high levels.  These look like a two way speaker, but have two concentric drivers handling mid and upper frequencies.  Modern recordings seem to have more high-level transients, which trip the Quad protection circuits!

THIS is the dipole/planar loudspeaker I find myself lusting to hear. At $17,000/pr I can’t buy them, so it’s purely academic.

https://youtu.be/KQh66jM7aLE?si=ia3J7sKU7Eh9Z-MT

@bdp24 Interesting speaker with a few obvious problems. The tweeter is too wide which will cut down on it's horizontal dispersion at very high frequencies, the space in the middle is also a problem and the tweeter is not long enough, it will beam vertically. The Magnepan tweeter is a much better design. Like you I would like to hear them. 

@richardbrand you need to learn more about speaker design. The foot comes from the wavelength at the crossover point. If two drivers are closer together than 1/2 the wavelength at the crossover frequency they function acoustically as one driver. Woofers can be farther apart than midrange drivers and midrange drivers can be farther apart than tweeters. Tweeters have to be very close together which is the major problem for speakers trying to make line sources with stacked drivers. What you are succumbing to is lay assumption and as we all know assumptions are the mother of all f-ups.   Quad was trying to improve dispersion. Stick with your KEFs

@lewm Actually, I think they are $45 K now. I can say definitively that bi amping the transformers does not work. It is impossible to keep the amps from interfering with each other. I tried every permutation.

Our OTLs do a fine job of driving these speakers particularly in the midbass and midrange. They are not so hot in the treble. Because of the high output impedance the treble starts rolling off at best at 12 kHz. I know because I have measured it. On the bright side most older guys can't hear up there anyway. Solid state amps are more prone to having difficulty in the very low bass due to the high impedance of the speakers down there, but they go easily up to 20 kHz. The solution to this problem is to use a VERY big solid state amp. The JC 1+ does a fine job of driving these speakers as long as you keep the impedance of the interface up above 2 ohms. The Bricasti M28s also do a fine job. It is entirely possible that I might be selling my MA 2s. I have not made up my mind yet.