#1
recently the JJ high gain power valves in my mesa DC-5 packed in, so i put some oldish mesa valves that i had lying around in. since then iv noticed a background noise that is similar to when you try to tune in a LW radio. it is particularly noticable when i bend notes on the lead channel. it was suggested that the culprit might have been a preamp valve going microphonic, but i didn't notice any ringing when i tapped them (btw, they are also JJ high gains, about a year old). any suggestions?
Ibanez RGT42FM w/duncans
Musuc Man JP6, fully loaded
Crybaby 95Q
Boss DD6
Mesa DC-5
#2
A Tube doesn't have to be microphonic to be bad. One tube may be fading away on you. Some old tube testers had what they called a"life test" button that when pressed told you whether the tube was on its way out or not. Basically if the Needle on the meter stayed steady during life test, the tube was still OK even if the transconductance reading was slightly low. If the needle took a dive while pushing the life test button, it meant the tube was going bad.
Try replacing your tubes one at a time to see if it's one that's the cuplrit.
Moving on.....
#3
Quote by el-gilberto
recently the JJ high gain power valves in my mesa DC-5 packed in, so i put some oldish mesa valves that i had lying around in. since then iv noticed a background noise that is similar to when you try to tune in a LW radio. it is particularly noticable when i bend notes on the lead channel. it was suggested that the culprit might have been a preamp valve going microphonic, but i didn't notice any ringing when i tapped them (btw, they are also JJ high gains, about a year old). any suggestions?


Could be the power tubes, since they're old and the noise only started after you put them in. Are you playing near your TV?
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#4
nope, not near a tv! and these vwere only a few months old when i got the JJ's. possible they are on the way out, but i wouldnt have expected them to be. but i will try swapping the preamp valves one by one i suppose for the moment! thanks
Ibanez RGT42FM w/duncans
Musuc Man JP6, fully loaded
Crybaby 95Q
Boss DD6
Mesa DC-5
Last edited by el-gilberto at Jun 25, 2008,