2. amps-preamps
  3. 1321978695

Amp Hum

I know there are several posts regarding amp 'hum' but I wanted to start a new thread regardless.

Have an Audio Research D 90 and SP 12 Pre that I've had for many years. Recently, I've noticed a significant hum coming through the mid's on my speakers. The amp itself has a similar hum from the large transformers and appears to be transferred to the speakers.

I have a dedicated power line and circuit direct to my main fuse box that's less than 10 feet away so I can't think of any interference from outside sources. I also use a PS Audio power port for the outlet.

The hum doesn't fluctuate and is always there. Checked connections and so forth but my set-up is pretty straight forward. I do use a basic Belkin power strip between the amp and pre so I can power up a cooling fan during use. I disconnected the fan and the hum remains.

Any ideas or help would be appreciated.
jamesk58

Showing 1 response by jamesk58

jamesk58 OP
73 posts
 
*(1) Disconnect the input ics from the amp.
Turn on the amp and check for hum through the speakers.

I did this as well and still got hum, so I was pretty sure it was the amp itself. The caps were replace shortly after I bought it (used) back in the mid 80's.

Yes there could be a bad one. Need to find someone in Orange County that can check and replace.

Thanks for the test procedure. I followed the first item and came to the same conclusion but wanted a more educated opinion.
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