Cathode Bias confusion

[45]

Gentlemen, the only way to cancel the function (2 stage) is to multiply it by an anti-function. Have you seen any anti-tube? I did not. You can substitute one from another in PP, but the result would be, only DC and even order parts would be decreased.

So what I see on the scope is a miracle?
It's just about even fuctions and the phase of the amplified signal (including its harmonics). It is only about 2nd harmonic and it's not complete cancellation (i.e. not reduced to zero).

PRR tried to explain that in simple words, I think.

 

[Shef]

Gents, I think, the truth is in between, as always.
The carefully picked tubes and adjusted operating points can mutually exclude some THD to the pleasing wow! point of listening, seen that (I mean: heard).
So we are here down to the specific schematics i.e. combination of tubes, voltage, traffos etc etc.
Though, of course, some basics be obeyed. .. that's what we are cookin' of that old technology ))

 

[gabdx]

Using a row of devices with inverted signal can cancel 'something' on your scope like you can built perpetual motion devices, I am sure you can do both.

 

[jazbo8]

It's nothing like perpetual motion devices, inter-stage distortion cancellation techniques have been used since the 30's, perhaps even earlier...

 

[45]

Using a row of devices with inverted signal can cancel 'something' on your scope like you can built perpetual motion devices, I am sure you can do both.

Scope I meant a true analyzer, not even a crap sound card.
If you don't how to do it it doesn't mean that it is not possible. It is just not accessible to you or maybe you have done it by chance without being aware. Who knows...with the total confusion even about basic things you have in your mind eveything is possible!

 

[Wavebourn]

It's nothing like perpetual motion devices, inter-stage distortion cancellation techniques have been used since the 30's, perhaps even earlier...

Yes, for true believers.

 

[45]

Yes, for true believers.

Then can you explain how you can get 0.15% THD @1W and 3% @8W distortion from a 3x4P1LSE, without any other feedback? Scale the power down for your SE and see what you get. Do you get that THD at 0.33W and 2.66W. I don't think so.....And it is not the different OT.

 

[45]

Same identical amp with a (stand alone, very) linear voltage amp instead of ECC82 running at 242V/1.3mA with 100K plate resistance. Only other difference is plate voltage at 283V instead of 263V (that only brings more power).
Distortion never gets down to 0.15%. Even at 0.1W!
So I should believe that increasing the plate voltage by just 20V I will get such striking difference and/or the ECC82 is most linear device in any condition?

 

[Shef]

4P1L is specifically known for being super-linear triode-strapped, I do not get it why somebody turn its worthmost into the worthless. .. or we are talking about personal preferences then.

 

[45]

4P1L is specifically known for being super-linear triode-strapped, I do not get it why somebody turn its worthmost into the worthless. .. or we are talking about personal preferences then.

No better than others. Paralleling tubes makes linearity worse no matter how well they are matched. In fact 2x4P1L in parallel are not better than a 2A3. Here there are 3 in parallel.....

 

[Wavebourn]

4P1L is specifically known for being super-linear triode-strapped, I do not get it why somebody turn its worthmost into the worthless. .. or we are talking about personal preferences then.

Sure, 4P1L is an exceptionally clean, linear tube when triode-strapped. I could use it in an amp with no negative feedback at all, also driving by a loaded on Gyrator triode-strapped very linear tube. It was my first and last attempt to make a high-end amp with no feedback. I documented it here:

One more 4P1L SE