Members Cas Posted December 19, 2005 Members Share Posted December 19, 2005 last time i was playing my Mark IV(more than a month ago) i was getting horrendous feedback even on the clean channel. somebody said on here that it was a peamp tube. I called mesa and they told me the same thing. I just fired it up and now the lead channel is sounding like dog {censored}. I'm gonna call mesa tomorrow but as of now does anybody know what tube(s) would be causing this? Link to comment Share on other sites More sharing options...
Members KCA NOS Tubes Posted December 19, 2005 Members Share Posted December 19, 2005 V1 (furthest from the power tubes) is for the clean channel, V2 (next tube) is for the dirty channel. Link to comment Share on other sites More sharing options...
Members Cas Posted December 19, 2005 Author Members Share Posted December 19, 2005 let me add one thing. when i called mesa the guy told me to check V1 and V2. if v1 is for clean, v2 rhythm2, v3 lead channel, what's v4 and v5. the v5 is the phase inverter yes or no? Link to comment Share on other sites More sharing options...
Members guitarman967 Posted December 19, 2005 Members Share Posted December 19, 2005 Effects loop and the last one before the Power tubes would be the inverter. Bottom line is that it doesn't matter. You just test one at a time be gently hitting them with a pencil or chopstick:thu: Link to comment Share on other sites More sharing options...
Members Cas Posted December 19, 2005 Author Members Share Posted December 19, 2005 what am i listening for when i tap the preamp tubes, cuz i just did and didn't hear anything different. Link to comment Share on other sites More sharing options...
Members fuxtix Posted December 19, 2005 Members Share Posted December 19, 2005 1st off . how long has it been since you changed tubes 2nd . have you changed guitars or pickups or pedals in the last few weeks/months? gibson guitars with stock pickups tend to feedback like stuck pigs. #3 have you changed rehearsal spaces or changed where you physically play at you rehearsal in relation to the amplifier and its transformers. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted December 19, 2005 Members Share Posted December 19, 2005 Originally posted by Cas last time i was playing my Mark IV(more than a month ago) i was getting horrendous feedback even on the clean channel. somebody said on here that it was a peamp tube. I called mesa and they told me the same thing. I just fired it up and now the lead channel is sounding like dog {censored}. I'm gonna call mesa tomorrow but as of now does anybody know what tube(s) would be causing this? If it will feed back w/o anything plugged in,it is more than likely a preamp tube. Swap them out one at a time until you find the one that is bad,probably one of the first two. Link to comment Share on other sites More sharing options...
Members Cas Posted December 19, 2005 Author Members Share Posted December 19, 2005 Originally posted by fuxtix 1st off . how long has it been since you changed tubes2nd . have you changed guitars or pickups or pedals in the last few weeks/months?gibson guitars with stock pickups tend to feedback like stuck pigs. #3 have you changed rehearsal spaces or changed where you physically play at you rehearsal in relation to the amplifier and its transformers. put new preamp tubes in about 5 monts ago. haven't changed anything, switched a few guitars to see if it made a difference it didn't. haven't even played my gibson thru it yet. i don't understand #3 but yes i've played it 3 different places. i thought amps only had 1 transformer Link to comment Share on other sites More sharing options...
Members guitarman967 Posted December 19, 2005 Members Share Posted December 19, 2005 In order to hear the bad tube you should turn the amp's volume up really loud but turn your guitar's volume down. Tap the preamp tubes with a pencil or similar and listen for a ringing that seems to take off into oscillation. If you just hear a high pitched clank then the tube is probably just fine. The bad one will stick out. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted December 19, 2005 Members Share Posted December 19, 2005 Originally posted by Cas put new preamp tubes in about 5 monts ago. haven't changed anything, switched a few guitars to see if it made a difference it didn't. haven't even played my gibson thru it yet. i don't understand #3 but yes i've played it 3 different places. i thought amps only had 1 transformer Most amps have two,a power tranny and an output tranny. Link to comment Share on other sites More sharing options...
Members Daneswede1 Posted December 19, 2005 Members Share Posted December 19, 2005 Did you buy the 12ax7s from Mesa Boogie. I think Mesa Boogie sells Chinese 12ax7s . The CHinese brand sometimes burn out faster and can be incinsistent. YOu may want to get a solid sounding NOS tube like some BRIMARS CV4004s or some RFT 12ax7s thick plates. Link to comment Share on other sites More sharing options...
Members Zakko Posted December 19, 2005 Members Share Posted December 19, 2005 Wierd things happen when power tubes are on their way out. Link to comment Share on other sites More sharing options...
Members Cas Posted December 19, 2005 Author Members Share Posted December 19, 2005 Originally posted by Daneswede1 Did you buy the 12ax7s from Mesa Boogie. I think Mesa Boogie sells Chinese 12ax7s . The CHinese brand sometimes burn out faster and can be incinsistent. YOu may want to get a solid sounding NOS tube like some BRIMARS CV4004s or some RFT 12ax7s thick plates. yes these are mesa tubes, i thought i've been having terrible luck with them but what you're saying could be the reason, probably is. guitarman-i did the tappng thing you told me to do. after tapping every tube, only one sticks out. it sounds pretty similar to the others just way louder. will i know when i hit a bad tube or what Link to comment Share on other sites More sharing options...
Members Cas Posted December 19, 2005 Author Members Share Posted December 19, 2005 update: channels 2 and 3 sound off but the clean sounds nice. perhaps some of my spare tubes are {censored}. damn it. i need a {censored}ing tube tester godamnit :mad: Link to comment Share on other sites More sharing options...
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