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Tube Amp with the "Good Kind of Distortion"

MakeMineVinyl

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On that subject, is there any blind data of quality on the whole subject?
Probably but if you're interested enough you'll need to dig it out yourself.
 

Ken Tajalli

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Here is my 2 pence:
I am gonna go on a limb and declare that "Tube sound" is the sound of a tube amplifier with deficiencies.
I don't believe anyone can tell a good tube amp from a good solid state equivalent amp in any blind test.
Those tube amps that do have a sound, are doing something wrong (I am a tube amp user BTW). Otherwise there is no Tube-sound.
Those tube amps with deficiencies can have the following issues, that could be construed as having "Tube-sound":
- limited bandwidth
use of low feedback (purist approach to tube amps) can cause this, specially drooping high frequency response. (warm sound?)
- Lack of punch
certain tube poweramps that use auto-biasing, can have limited transients, so they sound a little soft.
- single ended versions, may have rising even harmonic distortions plus all sorts of other issues, due to output transformer. it is difficult and expensive to make a good output transformer for a single ended amp, because of the large DC current present.
Also single ended amps require extra clean power supply sections
- Balanced tube amp designs, tend not to have even harmonic distortions! if balanced perfectly they tend to have the best sound but it would not be "tube-sound".
- And finally Tubes do not clip like solid states! and when they do, they sound more pleseant - hence the notion " Tube amp watts are bigger" , simply because one can push them into soft clipping and still sound decent, when solid states can sound horrible.
If a Tube amp is designed and built well, it would not have any "Tube-sound" nor any other sound.
Now more knowledgeable friends, can tell me off . . .
 

SIY

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Here is my 2 pence:
I am gonna go on a limb and declare that "Tube sound" is the sound of a tube amplifier with deficiencies.
I don't believe anyone can tell a good tube amp from a good solid state equivalent amp in any blind test. Likely true.
Those tube amps that do have a sound, are doing something wrong (I am a tube amp user BTW). Otherwise there is no Tube-sound.Sorta. There is no defective amp sound specific to tubes.
Those tube amps with deficiencies can have the following issues, that could be construed as having "Tube-sound":
- limited bandwidth Not specific to tubes
use of low feedback (purist approach to tube amps) can cause this, specially drooping high frequency response. (warm sound?) Usually, the effect is more of high output impedance which will alter frequency response differently from speaker to speaker. Also not specific to tubes.
- Lack of punch
certain tube poweramps that use auto-biasing, can have limited transients, so they sound a little soft. I have never ever seen this. Can you give a specific example?
- single ended versions, may have rising even harmonic distortions plus all sorts of other issues, due to output transformer. it is difficult and expensive to make a good output transformer for a single ended amp, because of the large DC current present.
Also single ended amps require extra clean power supply sections
- Balanced tube amp designs, tend not to have even harmonic distortions! if balanced perfectly they tend to have the best sound but it would not be "tube-sound".
- And finally Tubes do not clip like solid states! Tube clipping is worse because of blocking. Not specific to tubes, but there aren't many solid state amps with cap coupling. and when they do, they sound more pleseant - hence the notion " Tube amp watts are bigger" , simply because one can push them into soft clipping and still sound decent, when solid states can sound horrible.The whole "soft clipping" thing is often stated, but not by anyone who has observed tube amp clipping on an oscilloscope.
If a Tube amp is designed and built well, it would not have any "Tube-sound" nor any other sound. Exactly so.
Now more knowledgeable friends, can tell me off . . .
Some comments. You're heading in basically the right direction, but there's still some superstition to pare off. :)
 

Ken Tajalli

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To @SIY
Ofcourse you know more than me.
The issues I mentioned are not specific to tube amps, you are correct, and I am sure they can be duplicated on solid states too.
Regarding the soft clip, this is what I encountered, correct me:
The output tube auto-bias can be as simple as a resistor parallel with a capacitor( + possibly another resistor for local feedback). when high transients come in, the capacitor charge and discharge pattern can cause softening of the transient.
Ever come across such a thing? or am I way off.
 

SIY

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To @SIY
Ofcourse you know more than me.
The issues I mentioned are not specific to tube amps, you are correct, and I am sure they can be duplicated on solid states too.
Regarding the soft clip, this is what I encountered, correct me:
The output tube auto-bias can be as simple as a resistor parallel with a capacitor( + possibly another resistor for local feedback). when high transients come in, the capacitor charge and discharge pattern can cause softening of the transient.
Ever come across such a thing? or am I way off.
When that happens, you get blocking rather than soft clipping. Blocking is particularly obnoxious sounding. If you have access to Morgan Jones's "Valve Amplifiers," this is discussed in several places in the book.
 

0bs3rv3r

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The output tube auto-bias can be as simple as a resistor parallel with a capacitor( + possibly another resistor for local feedback). when high transients come in, the capacitor charge and discharge pattern can cause softening of the transient.
Ever come across such a thing? or am I way off.

The capacitor simply presents a low impedance to all but the lowest of frequencies, thus increasing the gain of the tube because the audio does not have to pass through the resistor (which is there to set DC conditions only). Transients are high frequency, same as the audio. The capacitor appears as a very low impedance - i.e. a piece of wire, and does not have any effect on the transient.
 

Ken Tajalli

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When that happens, you get blocking rather than soft clipping. Blocking is particularly obnoxious sounding. If you have access to Morgan Jones's "Valve Amplifiers," this is discussed in several places in the book.
I shall have a read and refresh.
 
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pma

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- And finally Tubes do not clip like solid states! and when they do, they sound more pleseant - hence the notion " Tube amp watts are bigger" , simply because one can push them into soft clipping and still sound decent, when solid states can sound horrible.
If a Tube amp is designed and built well, it would not have any "Tube-sound" nor any other sound.
Now more knowledgeable friends, can tell me off . .

You easily get much more power from the solid state amp at much lower distortion and much lower output impedance than any tube power amplifier would ever have. Clipping is then a non-issue if you have enough power. And you can add a soft clipping circuit to the ss amp if you wish, but then you only lose clean power. Tube power amps are inferior to ss amps for domestic Hi-Fi system, the only reason I assume is a nostalgy.
 

MakeMineVinyl

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Tube power amps are inferior to ss amps for domestic Hi-Fi system, the only reason I assume is a nostalgy.
Yes, and the government should confiscate and destroy all tube amplifiers and their owners should be arrested. That should end this debate, I truly hope. :)
 

mhardy6647

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Mind you, I am just musing here...
The good kind of distortion, it seems to me, is akin to saying The good kind of cancer.
 

SIY

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Yes, and the government should confiscate and destroy all tube amplifiers and their owners should be arrested. That should end this debate, I truly hope. :)
Someone seriously suggested something much like that. It may have been Arny Krueger. The motivation was preservation of tube stocks and energy consumption. I suspect I could gin up a lot of outrage in some non-audio circles by writing about the latter, maybe rolling in the remarkable amount of toxic chemicals in the tubes.
 

Ken Tajalli

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Someone seriously suggested something much like that. It may have been Arny Krueger. The motivation was preservation of tube stocks and energy consumption. I suspect I could gin up a lot of outrage in some non-audio circles by writing about the latter, maybe rolling in the remarkable amount of toxic chemicals in the tubes.
I once sold a tube amp through eBay to someone in Germany .
After I sent it, it got confiscated and destroyed at customs, because vacuum tubes are considered toxic material and banned from import to EU!
 

antcollinet

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I desperately want a tube amp.

I want one with the good kind of visual distortion.

I think they look cool but I am not prepared to pay the aesthetic tax. I have considered building a box, populating it with old tubes with the heater coils powered - and fitting a class D amp somewhere inside :p
 
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MakeMineVinyl

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Someone seriously suggested something much like that. It may have been Arny Krueger. The motivation was preservation of tube stocks and energy consumption. I suspect I could gin up a lot of outrage in some non-audio circles by writing about the latter, maybe rolling in the remarkable amount of toxic chemicals in the tubes.
Yeah, the toxic chemicals in tubes can join the toxic chemicals in, say, a Tesla. :facepalm:
 

mhardy6647

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I'm old, and my memory isn't very good, but I seem to remember that there were several lower-power chinese products that were built exactly that way. Jim
One of 'em in a box here in the basement (it was passed along to me... OK? :) ).

3xfh6v8s69ct.jpg


Oh, and note the orange LEDs shining up through the vacuum tubes.
:cool:
 

Robin L

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What about the inevitable inharmonic intermodulation distortions? Are they euphoric too?
If you really want "Euphoric" there's a few exotic chemicals that mimic Serotonin I could mention, if you're interested.
 

SIY

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One of 'em in a box here in the basement (it was passed along to me... OK? :) ).


Oh, and note the orange LEDs shining up through the vacuum tubes.
:cool:
Hah, Amir sent me one of those to see if I could improve it. I got it to stop thermalling out and that was all that could be done without ripping out everything and starting over.
 

MattHooper

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Possible, but I'm not even sure "tube distortion" is actually audible, as it has good chances of being masked; do you have measurements that correspond to your type of equipement?
It may work if you don't listen to very varied genres, but from a lot of people, it justs sounds like an excuse to spend money on a cool toy. Maybe I'm cynical, but I don't really believe the aesthetic pretentions.

Objectively, I can't see additional distortion always enhancing the sound, whatever the genre (solo violin, for example?) but I can get wanting a (possibly nostalgia fueled) more 'fuzzy and relaxed' sound.

Sure I can certainly see your point of view!

Insofar as I refer to the sound of a tube amp (e.g. mine), it's meant to be "in principle" - that is to address the idea of why one might want or prefer some distortion in their audio system. So it's "given for sake of argument a tube amp distorts in ways some like...here's why accepting that distortion can be reasonable." The specific discussion of what if anything is actually audible is a different one than I was getting at.

So, again, presuming for sake of argument my tube amp adds a subtle distortion of the type I seem to hear, I find it enhances all forms of music for me - and I listen to a very wide variety (funk, rock, prog, jazz, classical, soundtrack, many different types of electronica, world music, library music, folk...you name it).

Of course if you had my gear to listen to, you may judge it "good on this, bad on that" or "just bad on everything." But...whether a distortion "sounds good with this or that" is a personal value call.

(And fwiw, I don't like the tube amp in my system only because it sounds fuzzy and relaxing, but also because I find it nudges the sound towards more life-like to my ears).
 
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