2. amps-preamps
  3. 1321838662

VAC Preamp: Is my Phono stage failing?

My VAC Standard LE preamp is exhibiting a loud, strange hum, heard in both speakers equally when MC Phono is selected. However, the hum doesn't show up until about 10 minutes of normal sounding LP playback. It gets louder with volume.

I think it may have to do with the unit getting to a certain temperature, since it starts the process over again if I turn everything off for 30 minutes – quiet for 10 minutes or so, then Wham! a loud hum that has me diving for the mute button!

If I switch the selector to any other setting, such as CD... dead silence. Could it be a phono tube going bad, and if so, how is it in both channels?

Any ideas (aside from calling Kevin, which I will do)?
alonski
alonski OP
158 posts
 
Maineiac, Thanks, I tried having my Phi 200 amp direct to the wall and it sounded great. Then I tried plugging it into a Panamax power conditioner and it sounded like someone threw a wet blanket over the sound. Then i bought the Purepower AC regenerator and plugged the amp into it... WOW, it blew away anything I've heard from this amp. Surge protection of the highest order, clean power, lots of AC headroom for even more attack and a blacker background. A significant improvement from direct into the wall. But, to be fair, I'll A/B it again next time I move the 400 lb. armoire that's in front of the wall plug.

Al, I agree with your speculation on the pathway this rogue hum snuck through. I hope to have an answer on Monday when the electrician comes back.

Thank you both for your insights and help.
Alon
maineiac
649 posts
 
Looks like I've got some research to do on then Purepower. That is interesting to know.
barrelchief
294 posts
 
Glad your problem has been solved.

Sorry to hi-jack your thread.

Maineiac & others.

Don't guess or assume that your homeowner's insurance will cover your gear, in the event of a catastrophe.

Many policies have limits on home electronics.

I have a rider that covers my electronics...audio, tv, computers, etc, with full replacement. Overall, the coverage is not terribly expensive.

It's worth reviewing with your agent.
maineiac
649 posts
 
In talking to my agent about this potential issue, I ended up increasing the overall coverage but was told that, at least for my policy, there was not a limit on specific types of items (i have some other toys too). It is a good question for sure.
alonski OP
158 posts
 
Same here, increased coverage to $50K replacement value, but no special rider. Who do you insure with?
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