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So based on the discussion below, I emailed RM himself. He was kind enough to respond, twice. Seems he does/will make direct-drive amplifiers, and he inferred that it would be no problem to make one for the Sound Lab speakers, or any other ESL, I guess. He does not do mods to the Beveridge amplifiers at this time, however.The URL for the vendor who sells his DD ESL amp is below.
I am not sure that 4000V is enough to get decent bass response from a Sound Lab speaker. Sound Lab uses a bass step-up transformer with a turns ratio of 1:200 or 1:250. However, I think RM meant to imply that he can fiddle with the voltage capability; I think.
Edits: 12/31/13Follow Ups:
www.twinstaticaudio.nl
das link mussen sie putten in der box
or whatever they say over there
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
Thanks. Do you know of anyone who has actually used those amps to direct-drive an ESL? The price is nice; I wonder if it is "per pair" or for each monoblock.
I think it is actually a stereo amp.
Lew
Most of the wider spaced panels take 5kv..My acoustats did and I think my Beveridge did as well but can't remember.My Martin Logan monliths took 3kv and the new CLXs I have I think are 3kv
Some people like second order distortion in their tube amps,some people like honesty in their tube amps. I like honest!
The Bev voltages are known, because of the amplifier schematic. It's 3200V across from one stator to the other, but as you may know the Bev mylar does not require a polarizing external bias voltage. Most think that the mylar bias supply in the full-range Sound Labs puts at least 5-6kV voltage on the mylar, or maybe even slightly higher. This at least suggests that a DD amplifier for a full-range Sound Lab speaker will need to put a lot of voltage on the stators, also because of the reputedly wider than average space between stators and diaphragm. That is the problem, so far as building a direct-drive amplifier for the SL speakers goes. I am not at all equipped to say that 4000V (the spec for the RM dd amplifier) would be insufficient, without having tried it. Would love to try it.
Edits: 01/06/14
Hi Lew,
I plan to use the RM DD amps to drive the Model 3s I acquired. The panels are the same as in your Model 2sw's.
The natural crossover point for the 3's is 200hz it may be lower with the 2sw's . The 18db/ocatave is good; the higher the better so as not to mesh any midrange to the subs at all.
The RM crossover and sub system is 24db/ocatave with variable output for the line array and woofer with set frequency cards that are replaceable in the unit. It is solid state. Given his interest in this and advocacy for it, I would ask him about the crossover in the Bev and Dahlquist to see if there would be a reasonable belief for improvement.
Marchand makes tube crossovers and there is an ARC crossover for sale here on the trader. Bryston makes a very flexible SS crossover as well as Pass .. both are very expensive. The case work and flexibiltiy are expensive in these models.
Regardless, the separate cross over and subs are going to be miles better than the internal woofers and crossovers of the 3's . They should now approach the model 2's.
I like the idea of dealing with RM as he had a hand in working with Bev & is familar with the speakers. He is an avid electrostat proponent so he has perspective which I hope will follow through in his design.
RM suggests the crossover will mate well with the Beveridges as he designed the system for electrostatics. If you read his forum at Audio Circle he is and advocate of outboard crossovers with attenuation for each element of a speaker array with separate amplification. He even will build a 2 or 3way passive crossover into an amp chassis to drive each element of a speaker. I think he is on the right track.
I will run the crossover from my Aesthetix IO with volume controls and 2 supplies. I don't have a transistor bass amp yet .. but I don't think this is overly critical. I will run the line arrays initially with the Futterman and Berning.. then decide on what to do with the DD mono or stereo.
Thanks
I apologize for reposting, but it does seem relevant at this point. After having my Stax F83's rebuilt, I realized that my NYAL OTL3 was not working well in the bass----at least the combination wasn't working. Perhaps it was because the Stax's drop to 4 ohms in the bass. Based on advice from this forum, including Lew, I decided to try a subwoofer, since I liked the rest of the range very much. I ordered RM's crossover and subwoofers, along with an inexpensive used SS amplifier. I won't deny that there were some tradeoffs, but overall I am extremely happy with the result. The woofers integrate well with the speakers, the midrange and trebles sound better to me, not worse, and I am more confident in the longevity and robustness of my system. Roger says these new woofers are much better than the ones included with the original Beveridge's.
on the woofers and X-over, not that I would want to dump my home-made TL woofers.
Sorry, is this a question/request to me?
Sorry if I forgot to add a question mark.
Dear Lew,
As AJ says, RM's crossovers are solid state, with adjustable crossover points achieved by interchangeable cards and with level controls for the high and low pass filters on the front. There is unfortunately no bypass switch. RM looked at the frequency response of my speakers and recommended a crossover point at 100HZ, to avoid a resonance peak at around 60 HZ in the response curve supplied with the Stax speakers. This works well for me, the transition does sound seamless, to me and and several experts. The woofers are sealed, and quite small, with a resonance above the crossover point, which I think means that they roll off in response as the frequency decreases, which RM compensates for in the crossover. They seem solidly made but bare-bones; the grill cloths are not removable and the connection in back is via banana plugs. One needs about 100 watts per channel to drive them. It was convenient for me to set these up because I already had a spare set of speaker cables running under the floor.
I will quote for you a couple of things I got from RM about his woofers.
1) from an email to me:
there is nothing to measure and no right setting. Just let your senses be your guide. If the close woofer seems too loud turn it down. (N.B. this is not possible using his crossover; my amp has volume controls for each channel.) You need to stop listening to "everyone" and listen to me if you want to simplify your audio life.
I have found the low frequency level control to be the most usefull control in my system. Other owners of my woofer systems agree.
The woofers are 8 ohm, polypropylene cone, rubber (not foam) surround that will not rot. Their sensitivity at 100 hz is 89 db, decreasing 12 db /octave below that. The EQ precisely compensates for this rolloff.
From material on audio circle (about his ELS system):
The system consists of a mirror imaged pair of electrostatic panels, two sub woofers and an electronic crossover (24 dB/octave Linkwitz-Riley at 100 Hz). The speakers are designed to have a high WAF (wife acceptance factor) and will not dominate you room. Custom cloth and wood finishes are available. The Electrostatic Line Sources are 54 inches high, 15 wide and 2.5 inches deep. The base is 18 x 12 inches and is removable for shipping. The sub woofers are 12 x 9 x 7 inches. The crossover has calibrated level controls for the sub and the line source. These controls provide easy application of any two amplifiers of any gain plus a very handy way to change the bass balance with out affecting the lower midrange. The crossover is designed so that no male vocal can be heard from the woofer alone. Therefore, it can be placed where most convenient and/or most efficient. This design came out of many years of careful study and experimentation. The system is priced at $12,000. This includes the pair of line sources, two woofers, and electronic crossover. .
Pictures of the crossover and woofers will follow in a separate post. It is not quite true that one can hear no male voice from the subs. I find the bass to be fast and musically satisfying but not room shaking. Not as dry as the speakers alone but more tuneful.
Here is a photo of the crossover (along with my preamp and tuner).
How do you like it? I bought a 6LX/P that I got very reasonably, because it came with no outboard PS. (The LX differed from the LE in that aspect; the LE has an on-board PS.) Since then, I had to send it to Stan Klyne for some mods to the phono stage, and, while he had it, he's upgraded the voltage regulators, etc. Plus, I re-capped it myself. I also had to build the outboard PS, which is not quite ready for prime time. Thus, I have yet to hear my 6LX/P. Been using a Quicksilver preamp so far with the Bev system. The Q is excellent; I wonder whether I will like the 6LX better.
I've had this preamplifier for ages. Had Stan upgrade it once. I think it is a very good performer--delicate pure highs, good dynamics, excellent focus and imaging. Very flexible phono stage, two line-level outputs. The phase inversion relay failed and Stan says he can't get replacements, so i live without that. I hated trying to figure out which way each record was recorded anyway.
So far as I know, the 6LX does not even have a phase reversal switch. The question of "correct phase" is as controversial among audiophiles as is religion among certain ethnic groups. I don't subscribe to that school, at least with my bipolar ESL speakers in my room. No one can hear a difference when I toggle the phase reversal switch on my MP1. There are good theoretical reasons why it should not make much difference, especially if one is using multi-way speakers and given the fact that recording engineers back in the day paid no attention to it, such that every cut on every LP could be different from the one before and the one after, with respect to phase.
It's an SK5. Back in the day when I bought it, a big deal was made of phase reversal.
You were supposed to listen carefully to each recording and figure out if the recording engineers had things right or not and then use the switch to compensate as necessary.
Peter J. Moncrieff of IAR wrote copiously about it. I eventually gave up on it. I don' t like to spend time on A/B comparisons; there is too much music out there and not enough time.
All the PS and decoupling caps are new Silmic electrolytics which need time to break in. But after about 2 hours, sounds excellent with a Grace Ruby cartridge driving the phono section.
I'm just wondering if you have any further impressions to share about the Beveridge and/or the Klyne. I might suggest that, to take advantage of the Klyne's excellent phono stage, you try
a moving-cartridge with it. The Klyne and, I expect the Beveridge, should excel in image presentation and focus, which are perhaps a slight weak point of the Sound Labs. Have you ever tried a Van den Hul cartridge?
You did not complete your description of the cartridge type, "moving cartridge". I presume you refer to "LOMC" types. Yes, I do plan to try that. I am very interested to try the unique capability of the Klyne circuit to equalize the output of an LOMC into a 47K load, so you don't have to load down the cartridge to 100R or so to achieve a tame hf response. Stan Klyne tells me that my current phono section, after he completed his work, is "very nice" but still a step slightly below his latest max effort. But he indicated the difference between what I have and his best max effort would be narrowest with MM or high output types. I do plan to try it with my Urushi or the Ortofon MC7500, soon. But right now it is sounding so great with the Grace Ruby that I am loathe to change. I may mount the Ortofon in my RS Labs RS-A1 tonearm this weekend (the goofy looking Japanese tonearm), so I can run two tonearms on my Lenco.
When I re-capped the Klyne, and also when I built the Power Supply for it, I used ELNA Silmic II and Nichicon Muse electrolytics. So all those parts were new at the start of my listening. Plus Stan installed the new voltage regulators and new parts on the phono board. Per Stan's recommendation, I leave the PS power up 24/7, using the Mute switch as cut-out. Thus I have heard a steady improvement over the last week. It's really a kick now, and a great match with the Beveridges. All in all, the Klyne lives up to the legend.
Needless to say, the PS I built is way way overkill, a huge 250VA toroidal transformer, Schottky diodes, and a CLC filter. I like to think it gives my unit an advantage over others, but I can't know that.
I don't think any preamp I've ever heard will outperform the Atma MP1 with LOMCs, however.
I have a Koetsu rosewood MC with a Mitch Cotter stepup but I sure miss my F9E Ruby.I do have two Grace F9E bodies that need stylus but I would love to get the original OEM stylus unless Soundsmith can hook me up with a reasonable facsimile thereof.
Some people like second order distortion in their tube amps,some people like honesty in their tube amps. I like honest!
I probably love the Grace Ruby more than it deserves to be loved, but I keep going back to it nevertheless. About a year ago, I bought a second one off eBay; on that one the cantilever/stylus had been literally ripped out of its red removable stylus assembly. However it appeared otherwise to be NOS. I sent it off to SoundSmith and it came back with a new ruby cantilever and one of their OCL styli. I have not auditioned it yet. But your answer is "yes"; SoundSmith can replace your ruby cantilever with ruby plus a new stylus, but it won't be elliptical. I went for the most expensive of two options for styli. Cost $350. The lesser one is $250. If you really prefer elliptical, talk to them about it.
I can't get away from the Bev system. I must have listened for 4-5 hours yesterday alone, which is unusual for me. The Klyne is getting better as its PS breaks in. (I built it myself.) I also replaced every one of many electrolytic capacitors on the audio chassis, and those need to break in as well. It was unimpressive for the first hour, but since then it's giving a very "full", rich sound; I would never have identified it as a solid state device if blinded. The Quicksilver preamp sounded more like SS, if anything, on this same system. At some point, I would like to try my MP1 on this system. The MP1 is "king".
I probably love the Grace Ruby more than it deserves to be loved.
I don't think so and here is why.My friend brought over his Grace F9E ruby mounted on the head shell and we mounted on my same sumiko arm and set it up for his cart by weight,balance and Anti skate and the difference between my Koetsu Rosewood thru the Mitch Cotter step-up was not as much as you would expect..I didn't do the test on my big Martin Logans but I did do it on the full range ribbons,well full range from 270 on up but the point is,they were much more alike than they were different.
Yes,the Koetsu had an edge in some areas but nothing that would justify the price difference..I think if we worked with the setup a little more on the Grace,it would probably be very close to equal to the Koetsu..
Some people like second order distortion in their tube amps,some people like honesty in their tube amps. I like honest!
It's been in storage for about a year, but I have no doubt that the Grace Ruby is at least as good. Like you said, better in some areas and not as good in others, would be my guess. I also have an Ortofon MC7500. Ditto for that one too.
Oh yes
Very familiar with it.
Some people like second order distortion in their tube amps,some people like honesty in their tube amps. I like honest!
Thanks for the news. Let me know what you think after more listening. Is the Klyne the only solid-state preamp you like so far?
At least. If not longer.
I agree. I got my son and wife to listen to music while I toggled the phase switch on the MP1, such that they could not know whether I had altered the phase or not. We used a variety of sources and genres. In the end, neither of them could hear any difference one way or the other. But there are those who do swear by its importance. It may well be that bipolar speakers obliterate the differences, if any.
And here is a photo of one of the subwoofers, tucked under a small table.
Without a doubt there are possibly better ways to go than what I am listening to now. I kept myself on a strict budget. Would I rather have bought a tubed Marchand crossover w/24db/octave hi and lo-pass slopes? Yes, indeed. But they cost more than $2000, and Marchand would not even return my emails, anyway, when I wrote him to inquire. At the time I was putting this together, I was not even sure I would like the Bev speakers, did not want to go overboard on cost.Turns out, the Dahlquist is absolutely superb, altho 24db/octave is superior to 18db/octave, if you worry about phase shift.. But I would like to upgrade the hi-pass x-over that lurks inside the 2SW amp chassis along with the Bev built-in woofer amp, which I am totally bypassing. Problem is that no one has the schematic for the Bev x-over.
A general comment on electronic crossovers: For decades, I've stayed away from them, because prior to that time I never met one that I could love. Back then, they all colored the sound to one objectionable degree or another. I am willing to believe that modern design and parts can do better, but I am only willing to tolerate the idea for supplementing the bass response, as for the Bevs or any ESL or a monitor type spkr.
Edits: 01/01/14
I understand completely with regard to investment without a solid basis for keeping the speakers.
I am in the same boat. The Beveridges are one of my most memorable audio experiences but 30 years have past and I am not sure that the same astonishing presentation will be presented today. I am sure the Soundlabs are a more robust presentation with a more seamless balance... but budget plays a role for me as well and I am not prepared to make the investment in audio today that I have made perhaps 20 some years ago. So the Bevs will go for a spin and I am sure they will present some virtues that can be judged accordingly.
The RM system is reasonable and will also be able to be worked into my Quad set up. I also have never particularly liked the idea of complexity but I am hopeful this combination will be better than stock.. everyone I have spoken to or anything I have read verifies this for the Beveridge woofer/crossover in the System 3.
It is a shame manufacturers don't value inquiries on their products. I have had many poor customer experiences in audio along with many good ones. Given the state of the high end and the economy in general it amazes me that business would treat their customers this way. If you are going to have a website I think a response in 24hrs for a boutique mfr. is reasonable and necessary...and if you are going away as chief cook and bottle washer an auto response back of when you can expect a reply is easliy accomplished.. sorry it is a pet peave of mine.
Sounds like you have your cross over network well set up. The internal passive crossover should be easy enough to discern and upgrade with different parts for different flavour.. going all active would be nice to try to see if the benefit is real or not. If we were closer I would lend you mine in return for a listen to those Sound Labs!
So far as I can tell, based on rumor and direct inspection, the internal X-over in the 2SW is active, not passive. If I get the urge strongly enough, I will try to trace the circuit, but the circuit seems to be quite complex insofar as the lo-pass side becomes the input voltage amplifier for the in-built woofer amps. I can also say this: the 2SWs give the Sound Labs a run for the money, at least. I could live with either and not miss the other. You will be pleased with the Model 3s and direct-drive.
to get it to the equivalent of 200 watts or so. Is that realistic with current tubes? The good news is that one only needs 28 mA into 28Kohms :)
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
It may be true that you need more than a 4000V swing to drive the SL's adequately, but not because of Watts, I don't think. Once you remove all the power sucking components in the back plate and now also eliminate inefficiency associated with a step-up transformer, I think the speakers will be very happy with much lower Watts, more like 50W or less. I think (emphasis on "think") the extra volts are needed to make the diaphragm respond, because I am told that the SLs have an unusually wide gap between stator and mylar, so as to permit deep bass response. That's why you need that huge bass step-up transformer that SL uses. If 4000V is fine for a Quad, I doubt it is sufficient for a full range Sound Lab speaker. But I would yield to RM of course, in terms of knowledge on this subject, assuming he knows the ins and outs of Sound Lab speakers.
Edits: 01/01/14
I am just going off of good old ohms law. if you put 200 watts across 4 ohms you get a voltage swing of about 28.28V multiply that by 200 to 250 and you get the 5700 to 7000 volts :)
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
With no audio step-up, the impedance of the panels is much, much higher than 4 ohms. In fact, I measure about 25 ohms at 1kHz using a 1:90 step-up with no RC network, which means that the intrinsic Z of the panel is way up there in the thousands. (I am thinking it would be 25R times the square of the turns ratio, or 8100 X 25.) With the Sound Lab crossover network, yes, Z is as low as 4 ohms, at certain frequencies. But even with their massive bass transformer, Z does rise at low frequencies way above 4 ohms; I think I got around 50R at 50Hz via the SL bass transformer.However, your basic premise that increasing V necessitates an increase in power, all other things being equal, is of course correct. My only point was that I do not believe Power has to be anywhere near 200W. Because, for a big enough V swing, the current demand is nominal when you're driving the panels direct.
I edited this to change "your" into "you're" (you are). An error I commonly make in a first draft.
Edits: 01/01/14
I used it as a nominal number with the crossover...i know it is not really 4 ohms and not a real impedance but rather capacitive reactance....and and and but just to estimate what would the voltage swing be on the amp and on the panel...gets you somewhere in the ballpark.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
So my point was that 4 ohms is not the operative impedance of the panel with nothing between the stators and the amplifier outputs.
Anyway we both agree that more than a 4000V swing afforded by the RM amplifier shown in the advertisement is probably necessary to drive a Sound Lab with authority. The question is whether RM can get it up to 5 or 6kV, or whether he agrees with us that more V is needed and why.
Hi Lew
Work continues on my Beveridges and I have ordered a crossover and subs from RM. The DD are in sight for the New Year.
I am not sure how how he would vary the polarizing voltage required in his amps for various speakers- this would be another question for him.
I am interested in DD'ing the Quads ( 57 & 63s) to compare to the Beveridges.
From his website :
"Hi,
I am bumping this topic to go along with the discussion on direct drive for all ESLs, including mine. In the process of making a pair for my speakers I have found how to adapt them to the QUAD 57, 63 and all that have followed. They also will drive the largest 8 panel Acoustats, all Beveridge systems, Sounds Labs and a host of others "
Looks like he claims it can be done..........
Sounds like this would involve a high-voltage hookup between the amp and the speaker. If you recall the old powered Acoustat, the reason it was powered (amplifier built-in) is they could not sort out a way to make the amplifier not be dangerous otherwise.
was Dayton Wright. The massive (a 150 lb. chunk of metal resembling a large power amp) power supply/step up transformer unit had very heavy hardwired output cables to each speaker that made heavy duty automobile jumper cables look a little dainty :-) Those cables were I believe 15 ft. long, transmitting up to 15 kV in the case of the XIM-11 professional model PS/xfmr unit. The much more common XIM-10 consumer model put out a mere 9 kV :-)
Naturally with today's safety regulations such a thing would never fly. But fortunately Mike Wright must have known what he was doing because I never heard of anyone getting fried.
"Ideal" audio product characteristics:
- Esoteric and dangerous (John Iverson, anyone?)
- Expensive
- Unavailable
Well, DWs were available back in the day.
Brian
Brian,
One year at CES, one of my audio friends, retired OBGYN MD Gary Vart walked into the Dayton Wright room, and they had their ESLs powered by these huge solid state Dayton Wright audio amplifiers. Gary is pretty sharp, so he followed the speaker cables off the speaker back to their non-public sleeping room, and low and behold, he found out they were using Paoli 60Ms to drive the on-display ESLs, NOT their own amps !!
Dr. Vart got kicked outta the display suite !!! He was Editor of an audio rag based outta St. Louis, but this is the first time you will see this in print I suppose. Pretty funny, eh ?? No reason NOT to tell me the truth from Dr. Vart !!
Jeff Medwin
John Iverson used to sleep at my apartment, drink Jack Daniels, in LA when he came in from AZ.
Sounds like, from what you wrote, that the mylar bias supply AND the audio step-up transformers were both also located outboard. Is that correct? If so, therefore, the DWs were not directly driven. That doesn't detract from your point that they were potentially dangerous. Those cables would have to be very thick, as you suggest. Any resistance would potentially drop the voltages to possibly ineffective levels. Back in the day, I heard the DWs once or twice. I always thought they sounded like what they were: vibrating gas bags. But I never noticed the huge umbilicals or the outboard electronics box.
In a way, I miss those days of outrageous audio innovation and experimentation, where crazy products like that would actually make it to market. The Beveridge speakers are no exception.
It is the insulation...at 7KV you only need like 30 mA to put 200 watts on the panel. so even if the cable serial resistance wold be 10 ohms the voltage drop on the cable would be negligible, a bigger problem would be the characteristic impedance of the cable at the higher frequencies. but that is all resolvable and a simple engineering problem. It would drive the cable nuts even more nuts that one could not change speaker cables :), In any case i would make such amps mono blocks with short cables connected to the backplate with a connector that would shut the apm down if the cable is disconnected, and would not allow physical removal till the panel is fully discharged. I know it would need some sort of control in the backplate. all that is solvable and can be made totally safe, the question is how much of an improvement would one get, and how much would it cost to build.
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
No disagreement that it's voltage, not current.
The company in Europe that also makes a dd amplifier for ESLs is Inoxx or Innoxx. Something like that. They do think in terms of an externally mounted amplifier, and they do use short thick wire and some very interesting connectors that are probably safe with the very high voltages involved. Still, it's no wonder that ESL-makers shy away from direct-drive in the US. (For that matter, EU safety rules are even stiffer than here, altho the lawyers there are not as interested in liability claims as they are here.)
is only 3000 V pp. so that is way below what is needed...they list a 5000 v pp but no info on the site...
dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.
quote by Kurt Vonnegut
I've emailed them on the subject of driving Sound Labs. I did get one or two responses that each stimulated me to ask more questions. Finally, the line went dead. No response to my last question, sent about 3 months ago. I was asking about their higher voltage amplifier.
At the outset, they had a complete misconception of how the Sound Labs work, telling me that they were a 3-way speaker. I then had to describe the circuit, etc.
In a way, I miss those days of outrageous audio innovation and experimentation,..................
yes...yes Lew in some ways those were the days.....thanks to all for the info on the Beveridge ESLs..............the bais could be outboarded?
I think the bias in the SoundLabs gos up to 7KV........
Based on info from the one guy I know of who actually bought an instrument to measure the bias V on his Sound Labs, right at the panels, you are absolutely correct; I think he measured 7 to 8kV!!!
Just to clarify, because I am not sure what you meant, the mylar on the Bev panels is conductive and not subjected to a bias V at all. The mylar is instead driven by the dd amplifier in concert with the stators. Don't ask me how or why this works as well as it does; I am still thinking about it. But I think this has a lot to do with the fact that my speakers are still working, all 3 individual panels in both spkrs, after 30 years. The Bevs panels are quite reliable.
Lew.... the outboard bias in my other post.........was for the Soundlab an a DD amp.....then the DD amp may work at lower V.......
Funny about the QS preamps an amps..........
your point about the ...The Quicksilver preamp sounded more like SS
Over the yesrs i have had guys beg me to help them get the QS preamps to sound like a tube preamp....but like most of the ARC preamps...I dont get it... lay out look vary good ..part Q is high.....dont sound like glass to minny........
So is it the top end an uper mid... that makes the Beveridges sound diff than the soundlabs would you say?
On the Quicksilver preamp: To a large degree its sound can be tuned by the choice of capacitors. There is some unit to unit variation in the RIAA network, so far as I can tell, because the schematic that Mike Sanders sent me shows slightly different capacitor values from what is actually in my unit. My unit has four .022uF capacitors (two per channel) for RIAA. I replaced them all with Russian SSG types. OMG, what a fantastic improvement. Those are wonderful capacitors. Then also the coupling caps between phono and linestage and between linestage and output make a big difference. However, there are two things in the circuit design that may make it lean toward an SS sound. One is the NFB in the linestage. Another are the zeners used in the PS. I toyed with the idea of revising the linestage to get rid of the NFB, but I did not want to destroy the pristine originality of my unit. Plus, it does sound excellent, and it certainly is not "lean" or harsh sounding. Just a little more toward SS vs "tube". Another upgrade that I did perform on mine was to ditch the 12AU7 at the input to the linestage, in favor of another 12FQ7. (Which is to say that my linestage now uses two 12FQ7s and one 12AX7.) The latter is a much better sounding tube, and I can hear a big improvement. (12AU7 is not my cup of tea at all, no matter how fancy the brand or the vintage.)
I have not heard my SLs in a while, but my impression is that the Bevs do have a subjectively more extended top end. A lot of this may have to do with the way you listen to the Bev. Speakers are sideways facing each other, and I sit only about 7 feet away from a straight line that could be drawn between the lenses of the two speakers. There is a brick wall about 6 feet behind, at the rear of my room, from that same straight line. The SLs are in a much bigger room, are operating in true bipolar, and are farther away from my listening position. HF response will appear to deviate much more, depending upon where you sit or stand.
maybe some thing like this...........
You'd have to have the amplifier within a foot of the speaker and use very well insulated wires and connectors to do it with an outboard amplifier. The Bev amps in the Model 2 and 2SW are built in to the base of the speaker, just as was done for the Acoustat X.This makes it a pain in the ass to work on the amplifiers or to analyze faulty operation; you cannot access the circuit at all when the amps are installed, and in turn the amps misbehave (oscillation), if the speakers are not connected, not to mention the fact that you've got 3200V in your face.
Edits: 01/01/14
When you wrote, "..The DD are in sight...", do you mean to say that you are going to use RM's DD amplifiers to drive your Beveridge speakers? If so, which model of Bev? My Bev DD amps work fine driving the Bev 2SWs. I use the hi-pass filter built in to the 2SW amp chassis. Then I take a separate output from my preamp and use it to drive a Dahlquist DQLP1 electronic crossover. That gives adjustable crossover frequencies from 40 to 100Hz w/18db/octave slope. I use 100Hz, after experimenting with 80Hz. The lo-pass output of the Dahlquist drives an old Threshold S200 amp, which drives my home-built Transmission Line woofers (KEFB139s in a stereo pair). I am very happy with the bass support, and the crossover is audibly seamless.
The only changes I would like to make are to figure out the schematic of the Bev crossover so as to either do away with it (wonder if I could get away with a simple passive first order hi-pass filter) or improve upon it and to figure out a way to tweak the Bev amps a bit. But they are VERY prone to oscillation due to the high impedances in the drive circuit, so one must proceed with caution.
I guess the RM crossover would interest me. Do you know much about that? Is it all tubes?
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