Relationship of amplifier sound to transformer quality?

Two tube power amp designers/builders who say yes are Tim de Paravicini (EAR-Yoshino) and Roger Modjeski (Music Reference). Roger will personally hand wind you one for $1,000. Tim says he can tell you how an amp reproduces bass by looking at the transformer.

Another couple designers (one already mentioned) who think alike are Kondo Audio Note Japan & Convergent Audio (CAT). 
For tube amps the bigger the xformer the better for its bass. In the CAT JL2 the output xformers are 55lbs each (which contributes to the total 180 lbs) & CAT also winds his own xformers.
In s.s. amps the quality & size of the power xformer is important. Shielding the power xformer to attenuate the noise has a big effect on the amp's micro-details. Plitron makes some very good low-noise toroidal xformers. The size of the power xformer has much to do with the max output current of the amp's output stage which in turn has an effect on how difficult a load (speaker) that amp can drive.  

williewonka
1,019 posts
08-04-2016 9:45am
Another factor in transformer selection....
The transformer acts like a reservoir for electrical energy.
When loud, dynamic music (very fast, like drums) is encountered, the energy required to realistically reproduce that instrument is provided initially from the transformer
A small trasformer is unable to provide all the energy and as a result there is a tiny drop in the circuits internal voltage
This is music, the the internal voltage is always changing - not good for an amp
The voltage fluctuations degrade the amps output signal
The Bigger the transformer, the better the amp is able to handle the demand for electrical energy, fluctuations are minimal and the result is better quality music

williewonka, what you have written is simply bad information i.e. not correct. Please don't write incorrect material & misguide the public. it does nobody any good. Your conclusion to use a large xformer is correct  tho'.

The transformer does *not* act as a reservoir of energy. That is the job of the power supply capacitors. Capacitors store charge & if there is a transient in the music, it is these power supply caps that provide the burst of current needed by the amp. The transformer is a conduit for providing current to re-charge these power supply caps. The larger the power xformer, the more current it can handle & the faster the power supply caps re-charge ready very quickly for that next transient in the music.

A small trasformer is unable to provide all the energy and as a result there is a tiny drop in the circuits internal voltage

not correct - a very small transformer cannot handle large currents hence cannot re-charge the power supply cap quick enough. So, the power supply caps suffer a droop in voltage for much longer a time than if a bigger, higher current xformer would have been used.

The voltage fluctuations degrade the amps output signal

correct. it is called amplitude modulation (AM) of the music signal which is a form of distortion due to a badly filtered power supply. 

The Bigger the transformer, the better the amp is able to handle the demand for electrical energy, fluctuations are minimal and the result is better quality music

the conclusion is correct but the bigger xformer is *not* why the fluctuations are minimal. The fluctuations are minimal due to the power supply caps filtering/suppressing power supply ripple. IOW, you could use a very large power xformer & have no power supply caps & you would have huge power supply ripple which would destroy the quality of the music.

williewonka,
thanks much for your clarifying post. Yes i believe that you have done well to redeem yourself. My apologies too for coming down on you so hard. I could have phrased that better myself.
It's hard to know how technical the audience is when trying to explain some this material. I've found that watering it down to suit a non-technical audience can add more ambiguity & confusion rather than stating it in a technical way & later on, based on the questions from the audience, explaning certain sections using more layman analogies. More often than not the audience here at Audiogon is pretty technical & they can stomach quite a bit before barfing but one never really knows...
Your last post shows you clearly understand the virtues of a good transformer in the design of a component....thanks.