Yes, L-S's calculations aren't to be taken for granted? The text is lacking a reference I noticed so
I understood it was generally accepted as is with most of the old elektronics.
So, in the push-pull amplifier the constitution of the harmonic distortion changes with the output level.
In SE the harmonic spectrum remains unaltered within the linear range, isn't it?
Listeners prefer "the sound" of one amplifier to the other or distinguish a preferred taste of music to
be more or less "acceptable" with a certain amplifier. Although a different subject, it has my attention
and I'm looking for possible reasons.
I understood it was generally accepted as is with most of the old elektronics.
So, in the push-pull amplifier the constitution of the harmonic distortion changes with the output level.
In SE the harmonic spectrum remains unaltered within the linear range, isn't it?
Listeners prefer "the sound" of one amplifier to the other or distinguish a preferred taste of music to
be more or less "acceptable" with a certain amplifier. Although a different subject, it has my attention
and I'm looking for possible reasons.
That section you referred to has all the math derivations so can easily be checked for consistency and accuracy. For me no need for references.
I would be looking for references if he just would have said: 'this is how it is' with no further back-up.
I don't know of any amplifier where the harmonic spectrum does not change with level. It's in the nature of the beast, so to say.
The (non) linearity varies with level thus so does the harmonic spectrum. As it does with signal frequency.
Listener preference is a rich field, very important if you are a company/marketing dept. and want to sell product.
Many reasons for personal preferences have been documented over the decades, and only a few have to do with the objective equipment performance.
Jan
I would be looking for references if he just would have said: 'this is how it is' with no further back-up.
I don't know of any amplifier where the harmonic spectrum does not change with level. It's in the nature of the beast, so to say.
The (non) linearity varies with level thus so does the harmonic spectrum. As it does with signal frequency.
Listener preference is a rich field, very important if you are a company/marketing dept. and want to sell product.
Many reasons for personal preferences have been documented over the decades, and only a few have to do with the objective equipment performance.
Jan
Last edited:
Yes, the transfer curves I posted earlier clearly show the Gm depends a lot on the current, so the perfect cancellation of even harmonics only happens at one specific spot, or note, if you will.
With that being said, I prefer tweaking the balance of the phase inverted rather that messing with the output tubes: easier to achieve, with cancellation of the PI's nonlinearity thrown in free of charge.
With that being said, I prefer tweaking the balance of the phase inverted rather that messing with the output tubes: easier to achieve, with cancellation of the PI's nonlinearity thrown in free of charge.
All class A amplifiers will have distortions that increase monotonically with level (including the B/H slope burble through zero crossing). If you're really interested in learning about push-pull amplifier distortions, a good place to start is to ask why odd harmonics aren't cancelled. I think the answer to that will also give you useful clues about "the sound" of amplifiers.
All good fortune,
Chris
All good fortune,
Chris
Yes, I noticed no permanent cancellation is possible. A couple of years ago member jhstewart9 published a design incorporating cross-coupling between phases. After half an hour I gave up on understanding the different FB loops. He reported very low and consistant distortion.
100% is neither achievable under any circumstances, nor it is necessary. But 90-95% is great improvement, and it is practically not difficult.
Copper losses and leakage inductance don't have to be zero for cancellation. They have to be symmetrical between sides.
An example of perfectly balanced input is two ends of a single transformer winding.