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How deadly is transformer hummm...

Hello Folks,

I recently collected a lightly used (less than 50 hours) Dennis Had - Inspire - "Fire-Bottle." Within some few days, I noticed a humm emerging from somewhere within the chassis of the unit. As the unit was sold in "perfect" condition, I found the humm startling. Mind you, I've discovered absolutely no evidence confirming the sound is compromised; I mostly hear the sound within a couple feet of the amp, when the surrounding environment is silent.

This amp truly is a work of art. Nevertheless, I am now dealing with this 'humm' sound. I bought an Emotiva CMX-2 as a way to deal with DC offset, and this has not impacted the situation to any detectable improvement. Perhaps there is a slight improvement, but negligible. What to do?? Should I just relax, shake it off, and assume the amp will live well, or a down-the-road transformer replacement will simply become part of my experience with this amp? Should I put pressure on the seller to "right" the situation? He claimed, as I asked him, that it was the quietest amp he's ever owned. His add boasted that the fire-bottle exceeded amps from Pass Labs, a Cherry Amp, and one other that escapes memory. The seller has presented all of his communication in the manner of friendly professional etiquette. 

Your thoughts are appreciated. 
listening99
wolf_garcia
6,631 posts
 
Had is cool...https://www.youtube.com/watch?v=xLQsEeBKg1E. And again, don't burn yer face off.
listening99 OP
172 posts
 
Tubes have been removed and the hum persists. Second email out to Had. 
invalid
1,102 posts
 
Atmosphere is there any reason why manufacturers don't use nyloc nuts to mount these transformers. They wouldn't come loose with a nyloc nut.
Post removed 
atmasphere's avatar
atmasphere
11,639 posts
 
Would 248F handle the temperatures within the amp
No worries.
Oh, I will include this marvelous detail about the amp's design: "The transformers are made with grain orientated steel and impregnated with a special anti vibration varnish. Also the chassis of all Inspire products is non-ferrous aluminum."
FWIW, the transformers are 'EI' cores, and all EI cores should be constructed as described above and usually are (often are what is called 'double dipped' in the varnish, which is very helpful in the anti-vibration department). The chassis material will not affect whether a transformer makes noise or not.
Atmosphere is there any reason why manufacturers don't use nyloc nuts to mount these transformers. They wouldn't come loose with a nyloc nut.
Actually they could come loose, since what happens here is that with a enough heating and cooling cycles the varnish can relax a bit. So this might require tightening the end bells down so they don't rattle. Transformers have been made for over 100 years without the need for locking nuts.

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