Evolution 302e Review

[AudioGremlin]

Large toroidal transformers are particularly susceptible to being 'mechanically' noisy when the mains supply is asymmetric and/or has a DC content whereas many EI transformers appear less effected. The 3000VA transformer in my last power amplifier buzzed like an angry wasp at times. I'm amazed at the cavalier attitude of some amplifier manufacturers to these occurrences i.e. Its nothing to do with us attitude. Whereas some other manufacturers embrace the problem and build DC filters into their amplifiers, i.e Bryston, Crown, Krell (I believe) whilst some others do provide a DC filter option to be either retro-fitted or on request with selected amplifiers from Classe etc. Considering almost all advertise low signal/noise ratios, quiet cooling fans (where fitted) and seem to ignore this very concerning and potentially noisy problem. At the elevated price point we pay for high-end amplification I'd have expected the amplifier designers to have covered all of the bases. Perhaps I'm being a bit hard in my attitude as it doesn't occur in all cases, however it is still a problem and remains so!
A point to ponder, does DC filtering of the mains have a negative impact or not?
Thats my rant over with for the time being.

[Mikeoz]

Originally Posted by AudioGremlin

Large toroidal transformers are particularly susceptible to being 'mechanically' noisy when the mains supply is asymmetric and/or has a DC content whereas many EI transformers appear less effected. The 3000VA transformer in my last power amplifier buzzed like an angry wasp at times. I'm amazed at the cavalier attitude of some amplifier manufacturers to these occurrences i.e. Its nothing to do with us attitude. Whereas some other manufacturers embrace the problem and build DC filters into their amplifiers, i.e Bryston, Crown, Krell (I believe) whilst some others do provide a DC filter option to be either retro-fitted or on request with selected amplifiers from Classe etc. Considering almost all advertise low signal/noise ratios, quiet cooling fans (where fitted) and seem to ignore this very concerning and potentially noisy problem. At the elevated price point we pay for high-end amplification I'd have expected the amplifier designers to have covered all of the bases. Perhaps I'm being a bit hard in my attitude as it doesn't occur in all cases, however it is still a problem and remains so!
A point to ponder, does DC filtering of the mains have a negative impact or not?
Thats my rant over with for the time being.

Yeah I love the amp but am slightly disappointed having spent this amout of money that there's a buzz - albeit low level and hardly noticeable. Shame that having spent x thousand pounds I may have to chuck more money at the mains problem otherwise live with it.

I certainly wasn't aware of this potential issue before I bought and it wasn't evident on the lower powered Krell I had previously.

Oh well maybe I should think of it as 'character'

[AudioGremlin]

I was also disappointed to discover transformer noise after spending x amount on a power amplifier. Unfortunately not all DC mains filters do the job successfully. The type that rectify mains and use the DC to create stable & clean AC are good for low current devices like preamps, CD players, audio servers etc. but when you want to use one on a large power amplifier then the size and cost of the mains conditioner becomes very significant.
I believe Macintosh pot their transformers to prevent buzz but I'm not sure if their are any side effects to this i.e. reduced cooling, longevity etc? Maybe a concerted effort to inform manufacturers that if their amplifiers buzz then customers will most likely look elsewhere. Lost sales would be a good motivator!

[Pojuojuo]

Best way to solve this "problem" is avoiding it. Enjoy music and the glorious sound from your amazing Krell amp!!!

[Mikeoz]

Yep you make a fair point - if I understand you correctly