Tube amp forethought

good time to try tube power. many products now self bias and new production tubes are cheap, abundant and very high quality. I don't know if those speakers are candidates for tube amplification but others will chime in. you will get lifelike tone, imaging and sound staging from a good tube rig. I own a PrimaLuna and have been using tube amps for decades. This is the best I've owned in terms of reliability, value and most importantly sonics.

Look for a used Bedini 25/25 for your Quad ESL 57 speakers. One of the best matches.

Check out the Audio Research Documents page. They have biasing instructions for most all their classic amps. Usually, although there are exceptions, all you need is a small insulated screwdriver, a meter that can read millivolts and the restraint to keep one hand in your pocket when the amp is live. For the most part biasing is setting the standing current for the output tubes by measuring the voltage across two points while adjusting a pot with the screwdriver.

Usually you bias after the initial tube install and then after an hour or so of warmup. The manufacturer will have recommended bias values. Run it for a week or two and repeat. After that you should be good checking it every few months. You see a deviation your not comfortable with its time to look into new tubes.

Self biasing is for people who'd buy a self driving sports car. I get the convenience and all but why even bother when you can get a mini van.

Nothing against people who like mini vans or have to have one. You're just looking to get from A to B with minimum fuss. I guess like self biasing. Just not as involving to me.

@jperry +1 - I used a Bedini 25/25 with my Quad 57's for years. The only tube amps I found comparable were the Futterman OTL's (I still have 3). An alternative choice would be a nicely restored Quad 303. The 57's are voltage-limited. They will be damaged with more than 20 volts (50 watts). 

If you are still insistent on a tube amp, the Dynaco ST 70 (either vintage or new) is a good match for the 57's.

I was yet another QUAD ESL/Bedini 25/25 user for years, but if and when I put my QUADS back into service it will be with a Music Reference RM-10. Roger Modjeski used the QUAD as his load when designing that amp. He has offered in in two versions: as a 35/35w Class-A/B, and as a 25/25w Class-A.

@bdp24  +1 Sounds good!

+2 for the Music Reference RM10 MkII.  I've enjoyed one as my primary amp since 2011 w/no issues - in fact never shorted or even worn out a tube (knock wood).  I swapped tubes a couple times to hear if they were wearing out and had them tested.  Biasing is easy, rock steady and never needs adjusting.  The newer 25 watt version is self-biasing.  I owned 5 tube amps prior and this is my keeper.  Take the plunge!

Biasing is not that difficult.  Just requires patience and a multi-meter.  Many amps are self biasing which is great.  Plug in the tubes and go.  

There are a lot of different tube types out there. 6550 or KT88 amps are popular because they deliver a lot of power and the tubes are usually inexpensive.  

EL34s deliver a more traditional sound profile that you would expect from a tube and it is the classic PRaT but they aren’t as powerful.  

845/211s deliver AMAZING soundstages but the tubes can be unreasonably expensive, they run at such a high current you want to be cautious who you buy from as build quality really matters.  

300B/520Bs tend to have lush mid ranges that many find massively addictive.  Gorgeous sound with lots of detail, many seem these the ultimate tubes.  They usually are in SETs (single ended triodes) and are low power, 10w.  I can think of a push-pull that delivers 40w and some parsley SETs that deliver 18-28w.  

Triode, pentode/tetrode, ultra-Linear, etc are different writing configurations that have to do with the amount of power going through the tube.  

In general (some will argue this and there are exceptions) triodes sound the most tubelike.  Triode’s deliver the most detail and tend to have the most dimensional soundstage but you get a lot less power out of a triode and often, bass will suffer  and be a bit flabbier.  Some tubes can only be configured as triodes like the 845.

Pentode/tetrode gives much more power with a more linear frequency response and much tighter bass but usually at the expense of fine detail.  This is not always true as you can design a pure pentode that can deliver detail and a fine soundstage like the McIntosh MC275.  Amps with a pentode/triode switch 

Ultra-linear modes tend to be a little less powerful than a pentode, deliver tight bass and a bit more detail.  When you hear someone say that a tube amp sounds solid-state it is almost always in Ultra-Linear.  

There are great, detailed explanations of the circuit types out there.  I am making generalizations here.  I am also trying to keep this simple as I am not sure you care about circuit design.  

There are always exceptions and there is a matter of taste.  I have a pair mono-blocks that are 6550 based.  I love them in triode and found tetrode disappointing.  People have challenged me and said I am crazy, they only listen in tetrode.  

Personally, I like 845s the best of all tubes.  I am addicted to a massive and dynamic soundstage.  Others love lush mid-ranges.  Others love that classic PRaT style sound and some want a more solid state sound with a more dimensional soundstage.  

Full disclosure I am the importer of a very high-end line of amps and we happen to sell triode amps almost exclusively.  I have a couple that can be configured as pentodes/ultra-Linear.  I rep the line because I love it’s sound profile and prominently sell 845s and 300Bs.  My biases are obvious though and hopefully this is still helpful.  Good luck!

Let me start off saying that I love tubes, particularly as they pair with the mainly acoustic jazz music I enjoy most. My main system until recently has included tubes in most of my components (amps, preamps, phono stage). I’m going to throw out a suggestion since you characterize your aspiration as a retirement system - which, all things equal I’d want to be as versatile and trouble free as possible w/o sacrificing the sonics you crave.

Consider a Pass Labs Class A amp and pair it with tube gear up the line - a XA25, XA30.5, or XA30.8 (if lower power is required consider the First Watt line as well). What I have found that by replacing my all-tube amplifier with a Pass XA30.8 is that I’ve retained everything I like about tube sonics - the warmth, sweet mids, smooth lack of grain, and fluidity yet gained immense detail, bass slam, depth/width of soundstage, lower noise floor and imaging - it simply digs so much deeper and plays a wider variety of music in a much more compelling manner. The overlay of tubes in my line and phono stage provide such a complimentary accompaniment that I really feel like I have found the "secret sauce" that works for me.

I never found things like biasing tubes to be a chore and in fact enjoyed the engagement with the equipment. But the reduced maintenance associated with much less tube replacement and dealing with inevitable tube noise has been welcome.

Just an idea to consider - good luck with your fun project.

Three-easy, basically you are right but guys our age have a romantic passion for tubes. Who knows, maybe it is the smell of hot power tubes.
kgvteran, everybody is forgetting about our friend Mr Karsten. His amps (Atma-Sphere) are ideally suited for driving ESLs. I have been running ESLs of decades and his output transformerless tube amps are the only ones I would consider for the job. Actually, I am in conversation with him about having a pair made. He is even going to put a custom trigger in mine so I can turn them on remotely!  http://www.atma-sphere.com/Products/#M-60
These are the ones I would get for driving Quads.

If you don't mind the lack of a mono amp behind each speaker (thereby requiring only very short speaker cables---I used one-footers---though long inter-connects, one reason why it's great the M-60 is balanced, as long as your pre is as well), an S-30 (a stereo amp) is sufficient for a single pair of 57's. The speaker was made to be powered by the original QUAD tube amplifier, a 15w/ch design.

Roger Modjeski used the QUAD as his load when designing that amp.

We still use a Quad 57 in the shop today when we test amps we build or repair. If the 57s in question have the Zener clamp boards (an upgrade as they were not supplied at the factory with them) this prevents any over voltage condition within the panels and stops stator-to-stator arcing. So you will have more amplifier options at your disposal.

He has offered in in two versions: as a 35/35w Class-A/B, and as a 25/25w Class-A.

What might be one of the best kept secrets is the original RM-10s ran up to 15 watts in Class A and if you light load them you pretty nearly had a Class A amplifier.

I run my 57s with either the RM-10 or Atma-Sphere M-60s, but just picked up a Harvard H3 (Futterman) that Roger Modjeski and I will restore so it will be interesting to here this amp on the 57s when we are done.

Uh, is it just me? I don't see anything in particular about the ESL57 in the OP- just Quads.


So ESL63s or any later model like the 989 could be in the mix.


My experience with the Quads has been that you really have to watch it with the ESL57 because it really can't take much power. I've also seen updates that include protection circuits.


The ESL63 could take more power. We found that right about the point that our MA-1s were going to overload was also the point that the original protection circuit would energize. We also found that due to the way the amp interacted with the impedance curve, it could drive the ESL63s with greater volume than any other amp we tried.


The later Quads have been used with both our M-60s and MA-1s. Only the ESL57 has the low power limit issue.

Now if you are worried about the speaker no longer being made or that sort of thing, the ESL57 and 63 have a lot of support in the aftermarket- new diaphragms, power supplies and the like are available through various rebuilders. But you also have other alternatives like Sound Lab who arguably makes the state of the art in ESLs.

Ralph darn it. Don't complicate things. I'm trying to get him to buy your amps and you are spending all his money on Sound Lab's speakers.
kg, just in case you are interested the Quad equivalent Sound Lab would be the 545:)

I've said it before but don't mind saying it again: Tubes are more fun. These days I use an original version Schiit Freya into a Dennis Had Inspire "Firebottle HO" (12wpc more or less depending on tubes) with 99db efficient speakers. The detail this rig digs out of recordings, the physical beauty of the tubes themselves (no user biasing with these components, but my previous amp, a great sounding Jolida 502p, had user biasing and I liked doing that), tube rolling (unlike transistor rolling which isn't a thing for most people) to change things a little sometimes...all fun...with a couple hundred watts of (2) REL subs to assist. There are no tube subs (or ARE there?), but RELs do use the tube amp signal so there's that. Having said all this I am planning to get either a Pass XA25 or a much less pricey Schiit Aegir to see if I'm imagining all of this so called "fun." The Aegir got a great review in Stereophile recently so that got my attention.

@wolf_garcia 

Having said all this I am planning to get either a Pass XA25 or a much less pricey Schiit Aegir to see if I'm imagining all of this so called "fun."

I think the XA25 may surprise you. I'm a tube guy myself but wow, the Pass Class A stuff is amazing and digs pretty deep into the sound.  To me it's like tubes on steroids but not overcooked or unbalanced.  Just more of a good thing.

I hope the OP will consider Ralph's (Atma Sphere) amps. They are really wonderful pieces of equipment that in general need only to be biased (very easy) and then just work as they should. (Though if anything does happen, you are only a phone call away from assistance- though in my many cases, it was something I did- But, Ralph seems to always nail down the problem quickly.

Re: Pass amps
To add fat to the fire...
I also use an Ayre MX-R, and have to say they really are a nice compliment to my MA-1's. Smooth, detailed- mmm-Good.

Bob

I recently watched the Guttenberg "audiophilliac" interviews with Nelson Pass and really enjoyed 'em. Pass, Atma Sphere Ralph, the Schiit guys, Dennis Had...all refreshing and hip as...well...you know...

Overwhelming to say the least !
:0)
i have been into Home audio since my good friend was spinning Kiss destroyer through a HK receiver and small Advents, my guess 1976ish/1977. I was smitten !!! Blown away by the orange glow of the receivers light and the music coming out of those little Advents was glorious to say the least. I had a panasonic portable 8-track player, and a home “all in one” unit.
this changed everything, i HAD to have this sound in my life.

40yrs later, just putting the finishing touchs on my 3yr build of my HT, and im just thrilled at the thought of new gear getting me even closer to my music, excited is to say the least, im taking notes !!!!

thank you all for the great 1st hand knowledge on tubes and esl’s.

Now, please continue. I have no idea of which Quad, but it will be, im not afraid of rebuilding, im a tweakahaulic

Picked up a VTL st-85, impressive power and lovely tube sound.

Btw, how many ESL models did Quad make, i found these:

57
63
988
989
2812
2912
2805
2905

Kg, it must be around 6 by now. The current ones are the ESL-2812 and 2912. They are now owned by a Chinese company somewhere in Shenzhen and they are made in China.  The 2912's are something like $14,000. At that money the clear choice would be the Sound Lab 545 which is about the same money but is a seriously better loudspeaker in all respects and it is made here in the USA. 
The first Quad was the 57 and you definitely want to stay away from those. They are way too fragile. Next is the 63 which is much more reliable than the 57 but some would argue do not sound as good as the 57. I think that is probably romantic brains talking. Then there are a few in the middle which have a good reputation but I have never experienced them so can not comment on their sound. By then I was deep into Acoustats and not really paying attention to other ESLs. Acoustat is out of business. You see them pop up once in a while. Most of them have been broken up into parts. They were relatively inexpensive and audiophile hobbyists bought them up and tried to rearrange them into speakers they thought would sound better. A clean pair of 2+2's would be a real snag.
Sound Lab speakers come up on rare occasion but most of their owners consider them permanent purchase. Where else you going to go?  

Everything you need to know about the  glass bottle.

http://ken-gilbert.com/images/pdf/taste_of_tubes.pdf

Good information and history. 

I have long assumed that when anyone used the term the QUAD ESL they were of course referring to the original electrostatic model Peter Walker introduced in 1957. All other QUAD modes are referred to by their model designation---63, 989, etc., even the reissue of the original (a while after that model had been discontinued), named the QUAD 57.

I would also suggest Atma-sphere amps. 

If you are considering Atma Sphere, I would also ask that you consider Sound Lab speakers.
Ralph holds them in high regard-which is saying something. At least, to me.
Bob

You don’t say if you have a ssd system now. I got into tubes via an Audible Illusions pre-amp. There are used ones available at modest cost. Tube pre-amps make a huge difference in sound.

SSD ?

nos tubes sound better have a lower noise floor and last longer than modern tubes
i see people get pricey tube gear and leave the chinese/russian mediocre tubes than they preach to swap every year scared of them to fail (ps audio)...
some modern amps like the schiit freya comes from the factory with microphonic tubes and people think it's part of the magic .(it actually is because all tubes are at least a little microphonic but those stock tubes are really crap ,the darkvoice 336 has a hum in one channel and people live with it) 
once you get the amp let it settle for a couple of weeks  with the stock tubes .then try to make a judgment about the sound what is missing or too much .than swap'em all without looking back for nos (made in uk,usa,germany or holland) with the sonics that you would like to add.i like mullard tubes ,ge's are nice as well .enjoy!

Room size, music taste, budget, near field, hearing? 

Room size: 13’x19’x vaulted ceiling
music taste: LarryCarlton jazz, SteelyDan, i will begin dabbling in some classical
near field: speakers will be 8’ from LP
Hearing ??? My hearing roll off at 14Khz

When my original version Freya arrived a couple of years ago with its stock "mystery tubes" (actually NOS Russians) they were very quiet, and displayed no microphonics. Hardly crap. I ordered a set of new version Tung Sols anyway and they sounded fine and very quiet but I wondered if NOS anything else would sound better. I eventually bought bunches of NOS Sylvanias and GEs, and decided the GEs were a little more to my tastes. Note that all of the tubes I mentioned sounded and performed fine, no microphonics or noise, just slight tonal differences as one would expect. The various Russian power tubes I've used in both my previous push pull and current single ended power amps have performed brilliantly, and really lasted...KT88s, 120s, 77s, 6550s, etc., including my current faves 7581As. 

@kgveteran So you're young enough to want the volume pretty loud! If not, the 57s will easily sound loud enough in your room, particularly if not full of soft furnishings. There's a guy in NH that will refurb a pair of 57s for a few big ones. Pros: Exquisite sounding, fast, responds to system upgrades like you wouldn't believe, louder than you might guess, what bass there is clean and fast, magical midband, transparent and sweet. Cons: May not be loud enough, needs protection circuit if you like to crank it, 7" wide sweet spot only suitable for dedicated listening. 

@clio09, though I have yet to bring my old Quads up here from SoCal, I couldn't resist the near mint RM-10 Mk.2 that has been listed here on Audiogon for a coupla weeks. As the Quads don't need (and in fact can't withstand) more than what the amp produces from it's 4 ohm taps, I'll be hooking them up that way for lower distortion and longer tube life. I'm stoked!

@bdp24 that was a good score on the amp. It looked really clean. FWIW Roger uses the 8 ohm taps with his RM-10 but as he would tell you, try it both ways and use the tap you like best.

Thanks @clio09, I'll do that.

Kinda seems like this thread dropped off the face of the earth. Here's my .02 - I put together a retirement system incorporating tubes (in the preamp) and Quad ESL 2805 speakers. I previously used ESL 63 speakers, and they are wonderful. After some futzing around with SS power amps I put a Quad 909 in the system to power the 2805s because it won't be destroyed when I trigger the clamp circuit. I also use and enjoy an Innersound Electrostatic amp, which is capable of driving rediculously low impedences. It is a Beast with loads of instantaneous power but it doesn't like dumping all its power in a microsecond when the clamp boards are triggered.
For high volume listening (ya' know, when ya' just gotta get above, 95 db or so) I use JBL 4430 studio monitors. Which are just about perfect "all rounders". Yes I know there are other speakers out there that equal or better the JBLs.

It seems the OP wasn't buying the tube lore - posted a few days later looking at a Krell KSA250! 

How about a SS amp paired with a tube pre?