A quick question?

I used to have a cj11a and there was some hum. It's nothing to worry about. If you can't hear it from where you sit, why worry. I got rid of the hum when I got a new amp - BAT, and no hum.
Steve

If you have to put your ear to the speaker, it is not a problem. Forget about it.

I'd try to isolate the problem by connecting components in reverse. Ie start with just the speakers connected to the amp with everthing else disconnected. If no hum then add one item at a time. Ie a pre-amp to amp cable, then the other one then the pre-amp, and continue until you get the hum.

May also need to use ac cheater adapters on each component.

Tranformer hum is usually a 60 cycle vibration. If it were the source, the amp will vibrate and the speaker woofer should be quiet.

Other sources of noise can be anything with a motor, flourescent lights, electronic dimmers, items with high/low switches and computers. Try temporarily disconnecting suspect items to see if hum disappears.

Hope this helps. Hum problems can be aggrevating.

Yup, 60Hz floating thru the transformers & into the speakers... I have it from ONE of the two amps, go figure. As it's barely perceptible with my ear glued to a woofer I don't worry.
Or should I? (Sean?)

Thanks guys. All of my interconnects are shielded and I tried a cheater plug on the whole system via my power conditioner. I only hear the hum when I put my ear to the speaker, not at all from my listening position. With every other component turned off the hum was still there with my amp, making me think it's transformer hum.

Did you try the cheater plug on the pre-amp? Also try a shielded interconnect.

A little hum is normal on a lot of tube gear from my experience.

It is for me. I was told that if you can't hear it from your usual listening distance it is not a problem.

If you have any products that make use of a non-polarized two prong plug, try reversing that and see what happens. It might not specifically be the C-J that is humming but a combination of equipment connected to it. Sean
>

are you listening to a digital or analouge frontend? if the latter, some hummin' is commun'. if the former, keep checkin' on such things as the effects of halogon bulbs/dimmers, ac/coax(tv) crosstalk or other sources of rf and associated electronic junk (lots of threads on the application of filters on 'fridge plugs, etc.). if you still can't find your source, i'd advise retunin' your pianos or just try to join in, hummin' along, singin' a song. :) -cfb