Is it me or the Z?

Just got a lightly used Maz Jr. -- my first Z. Everything's just right except for a low hum in the output. Not enough to be a problem on stage, but enough to make it tough to record with. Not the tubes (swapped them all, careful to use a good matched pair of EL84's), not affected by any volume or tone controls, there with or without a guitar plugged in, there with the reverb tank unplugged. Pulled the chassis to look for anything obvious. Anyone else run into this? An old Fender in the same place, same outlet has no hum. Ideas? Thanks.

Orin Crowder

 

Thanks everyone. That's right, no fan in the Jr. I tried two different sets of matched power tubes, Groove Tubes and EI's. I also replaced the rectifier with the same (a Sovtek). Wondering if it could be the output transformer or a bypass capacitor (now I'm getting beyond my knowledge). I did exchange a couple of emails with the Dr. He said he was sure it was the tubes and didn't really encourage me to send it to him (mostly trying to save me some shipping cost, I think).

 

Not sure if this makes sense - a few times last summer (high humidity!) my Maz 18 would hum as soon as I turned it on; the hum would disappear in a few minutes. I suspect that is somehow related to the paper insulation of the transformer - ??(Are you storing it in a damp basement?)

Also, I noticed that, depending on the location, the reverb circuit picks-up some radio station - the amount depending on the reverb level. This could also be the cause of hum.

BTW, none of the two issues above bother me at all.

Alex

 

Thanks again everyone. I'm getting the idea that what I'm hearing is pretty normal, although it's still a bummer that you can't really record at lower volumes without gating. But, as everyone probably knows, the tone and detail and bottom -- the whole Z thing - can quickly make you forget about that small imperfection. It really is quite an amp.