fmsoloist
Member
Hey. I'm relatively new to this forum and much electrical engineering knowledge so I'm baffled here:
I just picked up a Mark V. I've had other mesa heads, Rectifiers, a Road King, a 50/50 and even a V-twin. The stuff has always been solid an never had any major problems.
I bought the MK V Used. Its totally mint in and out. the SN is something like 2600 and the date on the inside reads 1/2010.
I put new preamp tubes in and heard an improvement, ridding it of the crackling in channel 1and giving it a bit more gain and balance. It had mesa preamp tubes in it. I got 7 new tung-sol 12ax7 from the tubestore.com and they seemed to be fine.
However after maybe 5-10 hours, the amp is now all of the sudden making a horrible, circuit-bending tone through the speakers. It made it once while I was tracking scratch for a band. I was able to move it to the side, turn off the overhead lights, it seemed to fix it as the noise stopped and I was able to track probably 10 hours with it on most of the time and it never made the noise. Then when I went to play the other day, it came back, in the same place. I switched channels, it went away, then it came back and eventually on all three and nothing I did could get rid of it. I assumed I was just getting interference or dirty power but it did it upstairs in the control room today and I'm very disturbed.
If I let the amp sit it doesn't come on right away, but after maybe 20 seconds-1 minute, sure enough it comes right back and is all over all the channels. none of the tone shaping controls seem to offer any difference or interference, but the sound is different on each channel, very similar on 1 and 2. on three its almost not there but when I play it comes on eventually first like a rumbling then more pronounced. The master and poutput volumes have direct control over it.
I didn't leave it on long with this noise, but I assume its not going to just disappear. Its a rising tone, with or without a guitar input and trying to play through it doesn't gait it away its all the amp can do now. I double checked the order of the power amp tubes and 5U4 and they are all right and seated firmly in place as are the preamp tubes.
The amp worked fine for a while before doing this and a bit after so It can't be a switch thrown the wrong way etc and it does it with and without the foot switch, loop etc in all possible configurations at the proper impedance with different cabinets. Maybe a leaky component, transformer?
I'm really upset with this and need immediate feedback. I'd hate to have to send it back to boogie. I'll call them after the holiday weekend though, regardless. I'm cutting a record for a client and I'm not using jCM2000 for the whole thing. I want to cry. Please help!
I just picked up a Mark V. I've had other mesa heads, Rectifiers, a Road King, a 50/50 and even a V-twin. The stuff has always been solid an never had any major problems.
I bought the MK V Used. Its totally mint in and out. the SN is something like 2600 and the date on the inside reads 1/2010.
I put new preamp tubes in and heard an improvement, ridding it of the crackling in channel 1and giving it a bit more gain and balance. It had mesa preamp tubes in it. I got 7 new tung-sol 12ax7 from the tubestore.com and they seemed to be fine.
However after maybe 5-10 hours, the amp is now all of the sudden making a horrible, circuit-bending tone through the speakers. It made it once while I was tracking scratch for a band. I was able to move it to the side, turn off the overhead lights, it seemed to fix it as the noise stopped and I was able to track probably 10 hours with it on most of the time and it never made the noise. Then when I went to play the other day, it came back, in the same place. I switched channels, it went away, then it came back and eventually on all three and nothing I did could get rid of it. I assumed I was just getting interference or dirty power but it did it upstairs in the control room today and I'm very disturbed.
If I let the amp sit it doesn't come on right away, but after maybe 20 seconds-1 minute, sure enough it comes right back and is all over all the channels. none of the tone shaping controls seem to offer any difference or interference, but the sound is different on each channel, very similar on 1 and 2. on three its almost not there but when I play it comes on eventually first like a rumbling then more pronounced. The master and poutput volumes have direct control over it.
I didn't leave it on long with this noise, but I assume its not going to just disappear. Its a rising tone, with or without a guitar input and trying to play through it doesn't gait it away its all the amp can do now. I double checked the order of the power amp tubes and 5U4 and they are all right and seated firmly in place as are the preamp tubes.
The amp worked fine for a while before doing this and a bit after so It can't be a switch thrown the wrong way etc and it does it with and without the foot switch, loop etc in all possible configurations at the proper impedance with different cabinets. Maybe a leaky component, transformer?
I'm really upset with this and need immediate feedback. I'd hate to have to send it back to boogie. I'll call them after the holiday weekend though, regardless. I'm cutting a record for a client and I'm not using jCM2000 for the whole thing. I want to cry. Please help!
