Hum problem with Quad

[jazzIII]

Hi,

I have owned this wonderful piece of equipment for two months now. Best sounds I even got... It was dead quiet even at high gain settings until now... now, the gain channels have a very noticeable hum, sounding like when guitar cord is unplugged or you play a single coil guitar with high gain (I have humbucker guitars).

I changed all the tubes to JJ but it didn't help. The amp is from '88 and I don't know if it's even been serviced. Could dry caps be the problem, as I read somewhere? The only thing that bugs me is that the noise started to appear quite suddenly, like something happened to the amp.

Also, I had the Quad next to a window... when the hum first appeared, it had been quite cold for a few days there. Now I moved it to a warmer place and also warming up the amp when playing longer seems to make the hum a bit quieter. The hum also gets louder when I move the guitar close to the Quad, and near the speaker, although it disappears at some points. These would suggest a grounding problem, but the amp was dead quiet in the same setup connected the same way earlier. I play through the effects return of a Studio .22, actually great when you get two graphic EQ's in series.

Hopefully someone can help! Thanks in advance.

 

[jazzIII]

BTW, the transformer or something else in the circuit also hums quite a lot by itself and has always done so, but the amp never picked that up in the beginning. I wonder if now something has gone microphonic.... hope someone can still advise me! Thanks

 

[jazzIII]

Okay just a update if someone was interested/had similar problems,

Lately I noticed my Studio combo has also got more noisy when playing high gain... I think this must be some electricity problem in the house or some device creating interference. My Quad is also the older model without the ground switch, so I figure these older units are just a bit sensitive to varying conditions. I guess it's good to have less gain and learn to play better anyway 8)

BTW, I must add that the clean channel 1 is amazingly musical, even though I bought the thing for gain channels. Especially love single coil tones.

 

[Gregwor]

Have you tried different patch cords and different guitars? One of your cables might have cacked out on you or something in your guitar. Have you tried different power amps other than the .22?

It's possible you have a ground loop happening with the pre and power amp. As an idea, try pulling the ground off of one of the ends of your cable going from the pre to the power amp.

I've been dealing with this crap for a few days now and therefore I feel your pain hahaha

Greg.