Tubes or Solid State

[Leporello]

Since the current setup uses a step-up transformer to boost the voltages, don't we already have very high voltages on the stators?
We see this when a stator seal cracks or peels away and arcs to the diaphragm.

The main difference vs direct drive is the risk of having that high voltage in the cables between the amp and the speaker; that's where the real problem lies.
I dealt with this conundrum in my design for the Monoray line by having a custom Kevlar-wrapped 'umbilical' cord to carry the signals (and any LV power) needed by the speakers. Using sealed locking connectors, an amp output relay that only closes once the connections are validated as safe. My direct-drive amp is a power-DAC like some of the NAD DDFA amps but with beefy modern power FET devices.

See the brochure PDF I wrote for more details: https://cdn.imagearchive.com/martinloganowners/data/attach/15/15199-MonorayBrochureFlat.pdf

The stepped up audio signal from a normal ESL driver transformer system could be harmful or lethal under unlucky circumstances, and you should always use caution when working inside the electronics, especially if feeding an audio signal. All the direct coupled tube amps I have seen use plate voltage for the DC bias, which is very dangerous. That could be mitigated somewhat by using a grounded anode arrangement with the cathode floating at -2000V or so, but I have not seen this. The Hermeyer 'stats, referenced in the Sanders white paper, had bare metal rods as stators, at transmitting tube plate voltage. No infants or pets should ever be in the room with them!

The Acoustat panels, when they went with direct coupled tubes, used insulated wires as stators inside plastic supports (fluorescent light diffusors were the material of choice for home made versions). So quite a bit of isolation between the user and high voltage. ML panels use perforated metal with propitiatory insulation--probably safe but I'd be nervous about touching both sators at once with a signal applied, let alone with both floating at transmitting tube plate voltages.

I have long believed the ideal setup for driving ESL's with tubes would be a single, low turns ratio transformer between the tube plates and ESL stators. Low turns ratio transformers are easier to build with less flux loss. Stepping the signal down to an 8 ohm nominal impedance then back up to high voltage to drive the 'stats just doesn't make engineering sense to me.

 

[JonFo]

ML panels use perforated metal with propitiatory insulation--probably safe

I saw the process at the Kansas factory during our MLO tour in 2007. It starts with flat perforated metal sheets, then runs through a curving press to give them the 30-degree arc, and then hangs them on a charged line that goes through a powder coating booth. Then they go into a baking oven to set it. I think it was a fairly standard silica-based powder coat material. It is able to insulate the high voltages as long as it's not cracked or peeled away.
From my efforts at separating the old panels for my sidewall installation, the coating is pretty resilient and can handle rough treatment without (visual) harm.

 

[Ercana]

Quite afraid to speak after persons speaking of OTL amps directly coupled to ESL stators. This could obviously be the best technical solution to eliminate many parasite capacitors and inductances, but in a world made for electromagnetic transducers, this is not a path paved with roses. After all, I decided to use the 4 ohm output of all amps with my refurbished Aerius which goes down very quietly to 2 ohm and less at 20kHz. The new Peerless woofer with its big 82uF PP cap accepts this drive and gives everything needed to sustain the electrostatic counterpart. At the 4ohm output, The Aerius (not-i) are giving a great sound with any of the tube or silicium amp that I have tested (Audio-Research, Yamaha and even the tiny Jolida Jd-202a). Fifty watt per channel are more than sufficient in those conditions, and no 6550 or EL34 were harmed.

 

[Bodyslam]

I have long believed the ideal setup for driving ESL's with tubes would be a single, low turns ratio transformer between the tube plates and ESL stators. Low turns ratio transformers are easier to build with less flux loss. Stepping the signal down to an 8 ohm nominal impedance then back up to high voltage to drive the 'stats just doesn't make engineering sense to me.

I agree with this, and have thought so for a long time. But I have never heard of anyone actually trying it.

Of course it would require a custom designed transformer. There's nothing you can buy off the shelf that would cover all the requirements. I once asked Tim de Paravicini whether he would make a pair for me so I could use his amps to direct-drive my panels. That was neither the first time nor the last time he called me an idiot.

In any case, I have been driving my Monolith panels with Tim's 549 250-watt tube amps for decades. Out of all the gear that has come and gone from my system, it's the only gear that my wife has forbidden me to sell. I'm pretty happy with it too.

 

[Rich]

Tubes can be awesome with ESL’s. Just depends on the design of the tube amp and in particular the beefiness of its power supply. I have powered my Martin Logan Summits with a Conrad Johnson Premier 140 tube amp for years with sublime results. Interestingly, though, the same amp gives out trying to power my KLH Model Nine’s (full range electrostats). So it depends on the design of the amp, and the load presented by the speakers. You just have to find a match that works. Martin Logan’s are better for a lot of tube amps due to their hybrid nature. Full range electrostat can present a more difficult load.

 

[amey01]

It starts with flat perforated metal sheets,

Do you know what metal per chance?

 

[Leporello]

I once asked Tim de Paravicini whether he would make a pair for me so I could use his amps to direct-drive my panels. That was neither the first time nor the last time he called me an idiot.

Nice. He couldn't or wouldn't do it, so he insulted you.

Plitron used to make toroidal transformers for tube audio applications. There was once a project in Audio Amateur Publications--I think it was AudioXpress, after Audio Amateur, Glass Audio and Speaker Builder merged into one--that used Plitron toroids, and a ring of 6550/KT88 tubes, half for each channel. I read it during my many tube-curious phases, but when I finally got serious, the Plitron parts were no longer available. Plitron had merged with another company and they now concentrate on where the money is, switching power supply applications. Previously they had advertised in Glass Audio. I had written to them about a custom tube to ESL transformer but didn't get a reply.

 

[Ercana]

Do you know what metal per chance?

Aerius panels are made of steel. I glued some magnets on the wood to avoid the slow descent of my Aerius panels

 

[Ercana]

Nice. He couldn't or wouldn't do it, so he insulted you.

Plitron used to make toroidal transformers for tube audio applications. There was once a project in Audio Amateur Publications--I think it was AudioXpress, after Audio Amateur, Glass Audio and Speaker Builder merged into one--that used Plitron toroids, and a ring of 6550/KT88 tubes, half for each channel. I read it during my many tube-curious phases, but when I finally got serious, the Plitron parts were no longer available. Plitron had merged with another company and they now concentrate on where the money is, switching power supply applications. Previously they had advertised in Glass Audio. I had written to them about a custom tube to ESL transformer but didn't get a reply.

Menno Vanderveen makes elevation 1:50 and 1:75 transformers for ESL in the Netherlands (EU)
click here : Tubes and ESL transformers Vanderveen

 

[Trn335]

My $.02. I've been using a Primaluna Dialogue Premium for two years to drive SL3's. I've tried to get this to work. I rebuilt the SL3s (new panels and such). I made room adjustments. Added autoformers. Tube rolled, tried different speaker taps, different front-ends. Nothing helped. I just wasn't getting the magic out these speakers that I'm used to. Dull and lifeless, mushy, no punch, no air.

The best sound I've ever gotten out of these speakers was with a Wadia CDP direct to a Pass Labs X150, many years ago. I still have the Pass (serviced in the meantime) and last week decided to put it back in. I bought a Schiit Freya+ to drive it (I like it best in passive mode so far) as I no longer have the Wadia. Bang! There we go. Clearly, there is a synergy between these speakers and the Pass amp. (So much so that I bought another one for vertical bi-amping, as a Christmas present to myself).

Primaluna has been mentioned on this forum many times. A lot of users. If they're happy with it, good for them. In my experience, this is not enough amp for these speakers. They don't play well together. I think two years of use is enough of a trial. I haven't tried other tube amps though I've been close to buying an OTL on several occasions. I don't think I'll be trying them now or any others for that matter. YMMV.

 

[Jeff Zaret]

My $.02. I've been using a Primaluna Dialogue Premium for two years to drive SL3's. I've tried to get this to work. I rebuilt the SL3s (new panels and such). I made room adjustments. Added autoformers. Tube rolled, tried different speaker taps, different front-ends. Nothing helped. I just wasn't getting the magic out these speakers that I'm used to. Dull and lifeless, mushy, no punch, no air.

The best sound I've ever gotten out of these speakers was with a Wadia CDP direct to a Pass Labs X150, many years ago. I still have the Pass (serviced in the meantime) and last week decided to put it back in. I bought a Schiit Freya+ to drive it (I like it best in passive mode so far) as I no longer have the Wadia. Bang! There we go. Clearly, there is a synergy between these speakers and the Pass amp. (So much so that I bought another one for vertical bi-amping, as a Christmas present to myself).

Primaluna has been mentioned on this forum many times. A lot of users. If they're happy with it, good for them. In my experience, this is not enough amp for these speakers. They don't play well together. I think two years of use is enough of a trial. I haven't tried other tube amps though I've been close to buying an OTL on several occasions. I don't think I'll be trying them now or any others for that matter. YMMV.

As a FYI and $.02 more, I have been using a Pass Labs 150.8 on my CLSiiZ with great success for many years. I think it is the best I have had.

 

[Tmort]

Primaluna evo 400 tube preamp with a Sanders Magtech powering my panels works very well! I’ve heard it before that tube amps don’t seem to work great with stats, that’s why I’m getting the “tube” on the front end!

 

[amey01]

I’ve heard it before that tube amps don’t seem to work great with stats, that’s why I’m getting the “tube” on the front end!

Definitely true in theory. But same could be said (in theory at least) for a tube preamp being at a disadvantage to drive a SS amp input stage. A good, well-designed amp (or pre) will drive anything in its path, whether it uses valves or transistors. Plenty of people here have great success with valve amps as well as preamps.

Valve amps are also at a disadvantage for any speaker - simply because they're voltage devices, not current devices. Speakers need current - hence the need for output transformer - which in an ideal sense should be avoided. No one in their right mind would put an output transformer in the signal path if it wasn't an absolute necessity. But you make the compromise for output transformer for a different set of benefits (eg. inherent linearity of valves, or their more sympathetic distortion profiles).

Don't forget - Stax (for one example) specifically design **VALVE** amps for their ES headphones. And they're extraordinarily good too. Each to their own, but if it's good, it will work well.

But hey - it's all about compromises. No two of us reach the end-goal the same way. We make compromises in different areas and I don't doubt any of us don't achieve great sound in the end. Some better than others obviously - but we all get there one way or the other.

 

[Lightloopy]

VTL MB 450's for me - controlled SL3's and now 11A's with big, effortless, organic sound. Happily addicted.
Have a great holiday.

 

[pjr300]

I agree with this, and have thought so for a long time. But I have never heard of anyone actually trying it.

Of course it would require a custom designed transformer. There's nothing you can buy off the shelf that would cover all the requirements. I once asked Tim de Paravicini whether he would make a pair for me so I could use his amps to direct-drive my panels. That was neither the first time nor the last time he called me an idiot.

In any case, I have been driving my Monolith panels with Tim's 549 250-watt tube amps for decades. Out of all the gear that has come and gone from my system, it's the only gear that my wife has forbidden me to sell. I'm pretty happy with it too.

This made me laugh! Tim was a unique character. Back about 1983 I spent a few months with his 509 monoblocks and they were glorious (once they warmed up).

I have smaller speakers than you (the ESLs) and a small tube amp is working well (Unison Research from Italy, a 40w single-ended Class A tube integrated) and the performance is great, but i definitely wonder if I'm missing something by not using SS with the ESLs.

 

[StimpyWan]

My $.02. I've been using a Primaluna Dialogue Premium for two years to drive SL3's. I've tried to get this to work. I rebuilt the SL3s (new panels and such). I made room adjustments. Added autoformers. Tube rolled, tried different speaker taps, different front-ends. Nothing helped. I just wasn't getting the magic out these speakers that I'm used to. Dull and lifeless, mushy, no punch, no air.

The best sound I've ever gotten out of these speakers was with a Wadia CDP direct to a Pass Labs X150, many years ago. I still have the Pass (serviced in the meantime) and last week decided to put it back in. I bought a Schiit Freya+ to drive it (I like it best in passive mode so far) as I no longer have the Wadia. Bang! There we go. Clearly, there is a synergy between these speakers and the Pass amp. (So much so that I bought another one for vertical bi-amping, as a Christmas present to myself).

Primaluna has been mentioned on this forum many times. A lot of users. If they're happy with it, good for them. In my experience, this is not enough amp for these speakers. They don't play well together. I think two years of use is enough of a trial. I haven't tried other tube amps though I've been close to buying an OTL on several occasions. I don't think I'll be trying them now or any others for that matter. YMMV.

I use a Schiit Saga tube preamp, into an Aragon 2004 MKii power amp, which drives my ML EM-ESL speakers. While I like my Saga pre, I also like to tweak. So, I upgraded the Saga's stock Wima output capacitors with Mundorf EVO Oils poly caps, bypassed with AudioCap film and foil capacitors. That upgrade expanded both the width and depth of the sound stage, plus improved system transparency. Not hard to do the mod, if you have decent soldering skills, though there are 4 output caps in the Freya, and you might have to study the cap's measurements to see which would fit in there? Oh, the caps are 2.2uF 250V.

 

[amey01]

, but i definitely wonder if I'm missing something by not using SS with the ESLs.

Definitely you are. But also in reverse, you'll be losing something too by using SS too. Something different no doubt.

A gain in one set of factors will mean a loss in another set.

It's never about what's best. Everything's a compromise. It's about finding the set of compromises which best suits you.

 

[audioxcel]

hello all, wondering if anybody else is driving their speakers (Quest) with a tube setup, I was told by my Amp company tubes are not meant to drive electrostatic speakers, however, I've been driving them for the last 10 years this way until a tube burnt out. Is this true should I consider a Solid State System?

I think that at the end of the day, it comes down to using whatever amp sounds best to you. I have had the same pair of Sequels that I bought new a few months after they were originally released. They are on their 3rd set of panels.

Over the years I have used quite a few amps and some have sounded better than others including a Tandberg 3016A (220w), M-L No. 23.5 (200W), ARC CL60 (60W) and currently an ARC D70 MKII (65W). I started with a Tandberg 3012A 100W integrated amp and tried quite a lower priced solid state amps by Carver, Boulder and others. I stayed with the 3012A a couple of years before moving up to the 3016A with a 3008 preamp.

Then, I made a big jump to an original CAT SL-1 Reference preamp now have a (Signature MkIII) and decided to try tube amps. I bought a used ARC CL60 which I did not expect to drive the Sequels based on everything I had read. Wow, I had really liked the Tandberg 3016A; it sounded very clean, natural and well controlled. But, I now realized that I had been missing the "live music sound" that the ARC delivered.

Like all audiophiles, after a few years I decided to try to get something closer to "real". I bought a Levinson No 23.5. It was nice and the bass control was to die for. But, I felt that I just didn't "feel" as good as I did the the little ARC "but the bass".

I decided to try to sub KT88s for the 6550s in The ARC because i had read the KT-88 have more slam. Sure enough, I was getting deeper and more controlled bass. I went back and forth with the Levinson and ARC over the next week. It was close with the Levinson winning by a very, very small margin on the bass but overall the ARC still made me "feel better". So, I sod the ML No 23.5.

I had a power surge one day and blew some grid resistors in the CL60. It also developed a mechanical "knocking" sound that I could not isolate. I decided to try a different amp. I bought an bigger ARC VT 100 MkII. It was nice but not as "live" as the CL60 had been. Then i bought a D70 MkII. It is a glorious amp and I love it. I am going to try it with some KT88s soon but it is a keeper.

It drives my speakers without a problem (I use a self-powered Mirage BPS400 sub too) and has everything I can hope for at this stage of my 78 years where my HF hearing is less than my golden ears days.

So, as I said at the beginning, I think that it really comes down the whatever sounds best to you. If the amp will drive your speakers and you like the sound, that is the amp you should use.

 

[Trn335]

Definitely you are. But also in reverse, you'll be losing something too by using SS too. Something different no doubt.

A gain in one set of factors will mean a loss in another set.

It's never about what's best. Everything's a compromise. It's about finding the set of compromises which best suits you.

Absolutely, what best suits your ears...in your room. In all fairness, this system is now in a large space (17x38x10) so there's a minimum volume level to get everything working together optimally. 44w/ch (tube or otherwise) won't get you there. That being said, when the system with the Primaluna installed was in a smaller room, it didn't sound particularly good either. I just don't think it has enough power/headroom to get these speakers going even at low volume. Not knocking Primaluna - I've got it now in a vinyl setup in my studio driving some original (rebuilt) L100's and it's a entertaining combination. The only thing missing from that room now is a cable spool coffee table and cinder block shelves. (IYKYK)