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Single vs Dual Power Transformers

Fellow members

I have a question I hope you clarify. I've noticed some excellent stereo amplifiers and integrated amplifiers have a single transformer with dual windings for each channel (Hegel and others) and some have 2 separate transformers, one for each channel. (Gamut and others). Is there true benefit to having two separate power transformers given excellent design elsewhere? Can an amplifier be defined as truly dual mono without separate power transformers? I do realize that the totality of the design is the most important issue, but I would like to know the real benefits if any.
Thank you for your responses in advance.
audiobrian
zd542
5,339 posts
 
I think dual mono, for the most part, is a marketing term. I may be wrong, but to me, a dual mono amp is something like a BAT VK-500. But amps like that are pretty rare.
atmasphere's avatar
atmasphere
7,068 posts
 
The issue is power supply modulation, which can be very difficult to prevent! If the supply has noise (IOW, if the action of the amplifier has caused fluctuations in the power supply) the result can be intermodulations with the other channel running off the same power transformer.

This is why monoblocks usually sound better than dual mono, and why dual mono usually sounds better than a plain stereo amp; intermodulation distortion is pretty audible.
audiobrian OP
96 posts
 
Thank you Atmasphere! If a single power transformer is used, are separate secondary windings for each channel used in all stereo amplifiers or is this configuration in the dual mono or partially dual mono camp? I'm just trying to understand why some manufacturers hype separate secondary windings as complete power supply separation for each channel, despite a solitary power transformer.
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