Mechanical hum coming from EVO600
 

I noticed a hum coming from my amp. The hum is not audible from the speaker and it is only when the amp is in standby. I know it is under 5 years old. Now to locate the receipt and figure out what to do because my krell dealer is no more.

Lou... PM me, I'll help you out. ;)

So when you switch the amp on the hum disappears :scratch2:

actually I investigated further and it hums all the time. The other 2 are silent and on the same line. I disconnected the input and speaker cable and still has the buzz sound coming from the top front of the amp... well at least it seams to be, sometimes sound can reflect and fool you :)

I've had a similar problem and Krell service told me this is not uncommon with their larger transformers and is not a fault. Good luck trying to sort it out but I've given up and am just living with it - doesn't impact sound quality on mine and only notice it between tracks.

I'm quite surprised that a manufacturer accepts as normal any mechanical transformer hum audible enough to be heard from the listening position. When I had a NRG401S it hummed intermittently depending on mains DC component, that irritated me! Since changing to Classe I get no mechanical transformer hum I can't even hear the fans at the listening position.

There are several causes of mechanical hum - DC offset , over / under voltage , poor design, faults - difficult to be sure and replacing the transformer won't necessarily fix it.

However what is clear is that a mains problems will be more obvious with larger transformers and that is where manufacturers like Krell have a problem. I've heard of similar issues with other brands with the same unhelpful response.

now that I am very focused on the hum it is something that could be lived with but I suspect it is not normal because I have 2 more of the same amps that are silent. It is possible that the other 2 just hum much less. I will call a Krell tech.

Lou... Speak to Patrick Bresnahan, tell him I said Hi. ;)

Thanks Ivan!