Crazy idea from a CHEAPSKATE (Me) - Low powered tube amp?

[soundacct]

Damn..... I have to change my friends for more appreciative group of people....when they come over and I try to explain a reason for my madness they look at me in this funny way, like I just escaped from mental institution....

Oh, I get my share of that too!

But really, what's more insane? My next door neighbor with his 5 bedroom house for 2 people and an un-driven convertible in that 3 car garage, or an "insane" audio enthusiast with a few thousand dollars worth of stuff built to last a lifetime?

I say sell that convertible and turn that place into a sound studio!

 

[Gordon Gray]

Has nothing to do about "probing" and everything to do with defensible / constructive member comments to help you.

I assume that's why you are posting?

Best,

GG

 

[soundacct]

Has nothing to do about "probing" and everything to do with defensible / constructive member comments to help you.

I assume that's why you are posting?

Best,

GG

glad to hear it. so much of communication is lost over text.

yes, exactly why I am posting.

And though I am rather surprised at the numerous comments attached to guests being in my house (it was only an example meant for illustration folks!) I have also received some very excellent information and especially lots of links, so thanks everyone!

I am not personally convinced that my Aeons are particularly difficult to drive based on personal experience, it also doesnt escape me that 3-15 watts isnt all that much power. That's good to know, because now I'm looking at saving up for 30 or more watts, maybe something like a dynaco st-70 . I may still get a low powered SET, but likely for another project. Of course I'll still try them on the ML's if i do get one.

 

[InterMechanico]

If you want the answers you seek, you must run the gauntlet (and survive)


I want to try a tube pre-amp/amp combo at some point too. I'm going to go used and set a budget of 3-5 K. In other words, I'll be saving my Christmas money lol

 

[soundacct]

If you want the answers you seek, you must run the gauntlet (and survive)


I want to try a tube pre/pro combo at some point too. I'm going to go used and set a budget of 3-5 K. In other words, I'll be saving my Christmas money lol

Ah some humor, thank you!

I am a newcomer in someone else's home, and given my eclectic interests, this isnt my first time in this situation, so not entirely unexpected. but your observation is quite astute! very well put.

3-5k ought to land some decent shiny stuff...I'll be going the other way by keeping my B&K SS preamp which I paid $100 for because the previous owner broke one of the RCA ports and it had a nasty 60Hz hum. I jiggled that silly monster cable he had plugged in, saw it was broke off...20 minutes and some solder later all fixed!

As for my Aeon's - that was a fluke. Craigslist local selling for $450. Mercy sale. He priced too low and he knew it, so the guy was like interviewing perspective buyers as if to make sure it was going to a good home. Only after he found out I had a Parasound amp and a B&K preamp did he let me come over and look at it. Next thing you know, he's busting out Mcintosh this, Rogue that, Quad ESl this, Vandersteen that...This guy's collection is worth more than my house. Not rich, but 40 years of passion for audio lands you some pretty nice gear.

But I gotta ask, what sort of used gear are you looking at for 3-5k (I think Canadian-US exchange is more or less 1:1 right now, correct?). I think you can get some very, very nice gear for that assuming you already have your ML's

 

[Spike]

Mr. Ralph Karsten of Atma-Sphere describes in pretty well here in favor of tubes:

Common Amplifier Myths
Paradigms in Amplifier Design

In short, "Thus there is no way that a transistor amp can be described as linear if it is subject to these problems and that is one of the reasons why transistor amps produce so many amusical colorations."

Basically, as I mentioned before, one can construct any argument in favor of one's belief. It all comes down to whether the product in question suits your needs/taste. I cannot tell you that a tube amp will fit your need. What I might describe as natural or non-piercing characteristic may well be due to the fact that the high frequencies are rolled off. This characteristic might be dull or lifeless to someone else. Only you can make that decision!

 

[soundacct]

Mr. Ralph Karsten of Atma-Sphere describes in pretty well here in favor of tubes:

Common Amplifier Myths
Paradigms in Amplifier Design

In short, "Thus there is no way that a transistor amp can be described as linear if it is subject to these problems and that is one of the reasons why transistor amps produce so many amusical colorations."

Basically, as I mentioned before, one can construct any argument in favor of one's belief. It all comes down to whether the product in question suits your needs/taste. I cannot tell you that a tube amp will fit your need. What I might describe as natural or non-piercing characteristic may well be due to the fact that the high frequencies are rolled off. This characteristic might be dull or lifeless to someone else. Only you can make that decision!

Spike, you are a fountain of information!

Agreed. The limits of my experience with tube audio is the guy I bought my Aeons from. Read above - of course it sounded, well...magical!

I think my ML's sound spectacular on my SS amp. But I want to experiment with different music, different sounds, different volume levels, and so on.

oh, and tubes just look cool.

 

[Gordon Gray]

Good luck with your venture.

I hope it works out for you and you are happy with the results.

GG

 

[soundacct]

Good luck with your venture.

I hope it works out for you and you are happy with the results.

GG

Thanks Gordon!

Well to tell you the truth, trying different combinations is almost as much fun as having good results...so my odds are good!

 

[InterMechanico]

Have you considered going with a tube pre-amp/SS amp combo to get the sound you want?

 

[soundacct]

Have you considered going with a tube pre-amp/SS amp combo to get the sound you want?

Yes, that is a strong possibility, do you have any good value for the money recommendations?

I have a pretty decent B&K solid state preamp - that's why it isnt higher on my list of things to upgrade. But since this insane hobby is all about experimenting, the only part I dont see myself changing out would be my ML Aeon's (except possibly for an even better set of logans, that is). But for how little I paid for these things (used on craigslist), I'm planning on being buried with them.

 

[InterMechanico]

I have literally no experience with tubes, so I'm not the person to give a recommendation. Poke around a little on the site, and look at some of the members systems (that use tubes). I'd bet you'll get some good ideas. Good luck and try before you buy!

 

[Gordon Gray]

Hi sound,

Selling my CJ. See classifieds. Only SS pre CJ made but has the CJ "house" sound, which is basically a warmer, tube like presentation.

GG

 

[soundacct]

Selling my CJ. See classifieds.

GG

Thanks Gordon,

I think I'll stay on course for a good entry integrated tube amp. Though your CJ looks like a notch or two nicer than my B&K, I think my amp is the weak point at the moment (equipment-wise).

Thanks though - she's a beauty!

 

[Pneumonic]

Hi, Spike

Pneumonic, you are focusing on the low impedance at high frequencies to argue against the case for tube amplifiers and you're conveniently leaving out the high impedance part.

Keep in mind that my response to the OP was only to highlight some of the technical reasons why using a low powered tube amp to drive stats might be a problem. It wasn’t to debate the pros and cons of driving them with either SS or tube amps.

FTR, while I do drive my stats with SS amps these days much of my lifetime spent with my Logans has been with tube power amps driving them. High powered ones typically.

Let's focus on the high impedance at low frequencies for the time being. Let's say that the impedance will be 64 ohms at low frequencies and the solid-state amplifier in question is rated at 200 watts per channel into 8-ohms. This same amplifier will do:

1. 100 watts into 16 ohms
2. 50 watts into 32 ohms
3. 25 watts into 64 ohms
4. 12.5 watts into 128 ohms

Basically, about 1/10th of its power around the lower male vocal range, if its power supply is robust enough to deal with such a wild range of impedance swing. This frequency range is still considered critical since it falls into the sensitive audible range for human hearing. Just base on this pure fact, the solid-state amplifier does not look too attractive, does it? This is where the output transformers come in to address the impedance swing and the taps are configured as nominal overall impedance, not to be looked at as a narrow range.

It is voltage that is most important when driving an ESL. Well, current is also required ….. to drive electrons onto the stators to produce the voltage but it’s important to note that as the impedance rises (in your example) the current required becomes less. So the power required becomes less. As a result, any competently designed amp will find it quite easy to drive a high impedance load because it doesn't have to do much work (ie very little power will be required to be used).

Technically, there is no difference between a SS amp and a tube amp when faced with a low f/high Z condition. Both will have much lower output impedance than the input impedance of the speaker …. meaning their frequency response will be fairly linear. A tube amp is probably going to have a 4 ohm output impedance while a SS amp will have an output impedance of less than one ohm. When faced with an impedance of say 500 ohms, the difference in output impedance between the two types of amplifiers is effectively insignificant.

 

[Pneumonic]

Mr Sanders described it here pretty good: esl-amp

or here: tubes-vs-transistors

In short: "In short, tube amps can't drive ESLs linearly, cleanly, without clipping, to high output levels. So why put up with all their problems of heat, cost, maintenance, and unreliability when a properly-designed, solid state amp solves all these problems?"

That is certainly to the point! Thanks.

 

[Pneumonic]

I'm not sure I understand the capacitive load part. Isn't that precisely why there's a transformer inside the speaker? To present the amplifier with a load it is designed to drive and step that up to the very high voltage that charges the panel? If all we needed was good control over high voltages, why bother with all that power? Why not build half an amp and skip all the heavy and expensive power gain stages?

It's because we're trying to get the speaker to do work (make NOISE!! Yeah!), correct? Work takes power...voltage and current are two sides of the same coin.

Though I've killed my share of brain cells between electronics school and now... am I missing something?

Keep in mind that while the step up trannie steps the amp voltage up (based on its turns ratio) it also transforms the impedance lower (by the same turns ratio) as well as increases the inductance and capacitance (by the same turns ratio). It is this capacitance that is potentially troublesome …. enough to cause some amps to misbehave or even to become damaged.

It really is a mixed bag for the trannie; for the most part it makes the load much more difficult to drive as it lowers impedance and increases capacitance dramiatcailly. However, the trannie is essential to increase the voltage so that the speaker plays loudly.

 

[soundacct]

WOW, thanks for taking the time to highlight the electronics details!

But I still think those points are being placed in a vacuum here (pun intended. perhaps these points might be more relevant if we were driving the stat directly off the tubes with no transformers at all? But with the output transformers of the amp, and the transformer + associated electronics inside the stat it would appear that the point(s) are sort of moot - Proof is in the pudding, every amp i try runs these Aeons as well or better than a standard 4ohm speaker and run cooler than ever. I cant think of an explanation for that other than that these aren't especially difficult to drive.

In short, I believe ML's engineers have done a great job here. And from cruising this forum and others, I haven't noticed a lot of complaints about ML's blowing out tube amps inordinately.

Thoughts?

 

[Pneumonic]

WOW, thanks for taking the time to highlight the electronics details!

The engineering is simple. It’s the explanation that is proving challenging. [wink]

But I still think those points are being placed in a vacuum here (pun intended. perhaps these points might be more relevant if we were driving the stat directly off the tubes with no transformers at all? But with the output transformers of the amp, and the transformer + associated electronics inside the stat it would appear that the point(s) are sort of moot

The "iron"y is the problem is with the "iron". Without those trannies life is very simple from an engineering perspective. Unfortunately, those trannies are needed.

The only way to bump up an amp’s voltage high enough to adequately drive an ESL to loud enough levels is to use a step-up trannie in the ESL itself. Without this trannie, we wouldn’t have enough volts to hear it play properly. This same trannie is what causes the troublesome phase angle, low Z and high capacitance conditions which make for a terribly difficult load for an amp to drive. Unfortunately, you can’t have one without the other.

And, on the amp side, even though we have output trannies which allow for selection of different impedance taps, getting a proper impedance match is impossible due the fact that ESL’s do not have constant impedance across their full frequency bandwidth. Without a proper Z match, we will not get a flat frequency response nor, will we get maximum voltage delivery. And, as math and engineering tells us, ESL’s need as much voltage as they can get.

- Proof is in the pudding, every amp i try runs these Aeons as well or better than a standard 4ohm speaker and run cooler than ever. I cant think of an explanation for that other than that these aren't especially difficult to drive.

In short, I believe ML's engineers have done a great job here. And from cruising this forum and others, I haven't noticed a lot of complaints about ML's blowing out tube amps inordinately.

Thoughts?

Since every setup (gear and room) and listening demands are different, it might simply be that you have never ended up with a listening situation that stressed your amp’s ability to output sufficient voltage to drive your ESL’s to your desired volume level without clipping. Unfortunately, outside of tossing up the signal on a scope/ spectrum analyzer, it's next to impossible to tell if your amp is clipping or not.

Then again, maybe the amp is clipping like crazy and its fr is all over the place ..... it may still sound fine to your ears. All I can really say here is ........ if you are going to listen to any clipping amp make sure it is a tube amp.

In any case, I think powering an ESL with a very low powered tube amp is a horrible idea. About the only thing worse is using a low powered SS amp which ends up clipping (or engaged in protection mode) all of the time.

 

[soundacct]

I admire your convictions!

FYI, I do understand the explanation and I appreciate your time for putting it in words