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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
three_easy_payments's avatar
three_easy_payments
2,097 posts
 

SET amps can inherently be a bit hummy but should not be to the point you can't enjoy the music. I've read reviews of $20K Air Tight 300b's where the reviewer noted hum from the power supply.  With the Line Magnetic 805ia (for example) there are hum pots in the corners for each channel for the output tubes. The reality is more efficient speakers and SET amps can bring out more noise and the LM amps have been designed to help counter this effectively. Sometimes new SET amps will be a little hummy, and then mysteriously it goes away so you may give it some time to settle.

 


listening99 OP
172 posts
 
@mrdecibel 
So, if I open the amp and I'm tightening things, inserting bushings, etc., I will have the amp unplugged, and I'm wondering what I need to do to protect myself from errant charges that might stop my heart... 

My sense is you are pointing to the kinds of bushings that are customarily used along with screws/bolts to aid in keeping them tight...? 

example bushings: http://i.ebayimg.com/images/i/282179420188-0-1/s-l1000.jpg
millercarbon's avatar
millercarbon
12,531 posts
 
To not get shocked, don't create a circuit. No circuit, no shock.
mrdecibel
3,065 posts
 
@listening99....check out Lowes...item # 198831, model # 88577......rubber flat washer...10 pack....I should have stated " washer ". Sorry. These work great. No need to tighten too much, as you want to keep the integrity of the rubber.....
erik_squires
16,186 posts
 
You know crazy simple things can cause DC offset, digital light power supplies are among them.

Turn off everything else in the house and see if your hum goes away.
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