Post by pfo on Oct 23, 2007 15:23:20 GMT -7
Well folks, it's my first troubleshooting question to the forum. Apologies if this has been hashed out before, my searching didn't find a direct answer....
I'm having some noise issues with the reverb on my MAZ 18. The reverb driver tube (V3), as well as the recovery (V4) seem to be making a lot of noise. Playing a low note on the guitar brings about a "jangling" sound, like metal or glass buzzing. Touching the tubes in V3 and V4 helps immensely. Tapping them (or even bumping the amp when the reverb is on) yields a pretty clear "ping" sound. If I turn the reverb knob all the way up, I'll get what sounds like feedback -- at the same pitch as the "ping" sound when I tap the tubes.
Thinking maybe the tubes had become microphonic, I swapped them out for a Telefunken ECC81 (that I know to be good) in V3 and a brand new Groove Tubes 7025 (well, at least I think it's a 7025 -- it's a "12AX7 R-2/ECC83/7025"...) in V4, but the problem persists.
I've read the "Z-Hiss" and "EL-84 Rattle" threads, and a couple others that touch on these topics. I saw that somebody mentioned that those spots are very sensitive to microphonics. Could I have gotten a bunk GT tube?
I'm headed out to the hardware store to look for some silicone washers that might work as tube dampers. I'll be more than happy to return the GT tube while I'm out as well, though it seems unlikely (?) that a brand new tube would be microphonic (but then, what do I know?).
I'm not real familiar with the world of tubes, or guitar amps....I'm not even much of a guitar player. I do know some of the basics about tubes and tube types, but this is the first high quality amp I've owned, and the most tubes I've ever seen in one place. So clearly, I don't have a lot of experience, and would love any input you guys might have.
Thanks!
Pete
I'm having some noise issues with the reverb on my MAZ 18. The reverb driver tube (V3), as well as the recovery (V4) seem to be making a lot of noise. Playing a low note on the guitar brings about a "jangling" sound, like metal or glass buzzing. Touching the tubes in V3 and V4 helps immensely. Tapping them (or even bumping the amp when the reverb is on) yields a pretty clear "ping" sound. If I turn the reverb knob all the way up, I'll get what sounds like feedback -- at the same pitch as the "ping" sound when I tap the tubes.
Thinking maybe the tubes had become microphonic, I swapped them out for a Telefunken ECC81 (that I know to be good) in V3 and a brand new Groove Tubes 7025 (well, at least I think it's a 7025 -- it's a "12AX7 R-2/ECC83/7025"...) in V4, but the problem persists.
I've read the "Z-Hiss" and "EL-84 Rattle" threads, and a couple others that touch on these topics. I saw that somebody mentioned that those spots are very sensitive to microphonics. Could I have gotten a bunk GT tube?
I'm headed out to the hardware store to look for some silicone washers that might work as tube dampers. I'll be more than happy to return the GT tube while I'm out as well, though it seems unlikely (?) that a brand new tube would be microphonic (but then, what do I know?).
I'm not real familiar with the world of tubes, or guitar amps....I'm not even much of a guitar player. I do know some of the basics about tubes and tube types, but this is the first high quality amp I've owned, and the most tubes I've ever seen in one place. So clearly, I don't have a lot of experience, and would love any input you guys might have.
Thanks!
Pete