I have had a crackling noise in my Mark V for months now. It is intermittent but when it does it, it's pretty loud. I've tried to narrow it down but it appears to be in all channels, FX loop on or off, and even when I don't have a guitar plugged into the amp. It seems as though it is mostly at Full Power and 10 watts. I bought a couple of Mesa 12AX7's and one by one replaced each preamp tube. It still crackles after substituting them all. Before I spring for new power tubes, does anyone think it could be a power tube problem? I have heard that they have made some revisions in the Mark V since #4000; better screen printing on the faceplate, new reverb tank; some caps and resistors that improve channel 3. I have several words on my faceplate that have come off. I emailed Mesa and they said I could send it back to them and they would replace the screen printing and work on the crackling. So here's where I need another opinion: Would you buy power tubes to see if it takes care of the issue or send it back, knowing that it might be a power tube and a big waste of effort to sending it, but also, knowing that if I sent it they would replace the screenprinting and possibly update it with any revisions they've made so far.
COULD THIS BE A POWER TUBE PROBLEM?
- Thread starter Gunner
- Start date
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boogieman60
Well-known member
Try this; Put the amp on, take it off standby , Turn up the master volume at about 10:00, and gently tap the power tubes, One at a time.The bad one (If thats what it is) Should make the noise you are hearing, When you tap it..You can try this with the Preamp tubes, Use your Man. to find out which tubes do what, And repeat the procedure. You can save yourself a lot of $$$$ If you learn how to diagnose tube problems.
mejoshee
Well-known member
i'd try a local tech first just for diagnostics. is that an option? you're right, a major pain to ship to mesa (unless you can drive there like some). on the other hand, it's also hard for mesa to diagnose without it right in front of them. if you're going to do something about the faceplate anyway, you might as well send it if you think it'll help, but you can avoid all this if you find it is a power tube. check like how boogieman says. might also just be your cable or guitar, though. have you tried swapping the cables? other guitars? try swapping the connected ends of the footswitch too.Gunner said:
let us know if you end up sending it in and notice a difference once they send it back with revisions (if any). gl with that, sorry i can't offer any more advice.
Thank you for helping!
I tried the tube tapping thing first when I was trying to diagnose the problem. It's not the guitar, cables, or footswitch because it happens without the F/S plugged in or the guitar plugged in. I think at this point I will bite the bullet and buy a pair of Mesa power tubes and swap them out two at a time. I would hate to send it to Mesa if it was just a power tube. I almost hope it's not a power tube because I would like to have the faceplate fixed and any new revisions done on it if I sent it in. 8>)
I tried the tube tapping thing first when I was trying to diagnose the problem. It's not the guitar, cables, or footswitch because it happens without the F/S plugged in or the guitar plugged in. I think at this point I will bite the bullet and buy a pair of Mesa power tubes and swap them out two at a time. I would hate to send it to Mesa if it was just a power tube. I almost hope it's not a power tube because I would like to have the faceplate fixed and any new revisions done on it if I sent it in. 8>)
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Anonymous
Guest
sorry to hear about your problem, my guess will be that one of the outer power tubes is failling. in 90 watts four powertubes are running, 45 watts inner pair are running and 10 watts two outer tube are running (the closest to the rectifier tube) so you mention that in the 90 and 10 watts the crackling is happening therefore my guess is that the one of the outer power tube is failing.Gunner said:
hopes that help.
p.s. try to keep some spare tubes (power, preamp and rectifier) and a couple of fuses. if your problem is the power tubes and you can fix it then ask mesa to send you replacement tubes plus a screen printing (if you are comfortable replacing the screen plate)
good luck
>Photi G<
Well-known member
I saw something that I must correct. 90Watts (Simul-Class) All 4 Power tubes are running. 45Watts (Class A) The OUTER 2 Power tubes are running. 10Watts (Single Ended) The 2 power tubes closest to the rectifier are running.
Most of the time, this odd crackling noise in the V ends up being the Rectifier. Try a different 5U4, or (I'm not sure if anyone's tried this) a 5AR4. But before you go out and buy any tubes, watch this: http://www.youtube.com/watch?v=wSl-l9aWDHw
Most of the time, this odd crackling noise in the V ends up being the Rectifier. Try a different 5U4, or (I'm not sure if anyone's tried this) a 5AR4. But before you go out and buy any tubes, watch this: http://www.youtube.com/watch?v=wSl-l9aWDHw
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Anonymous
Guest
>Photi G< said:
it is in the manual in 45 watts the inner pair tubes are running.......
>Photi G<
Well-known member
salvatruco said:
It's in the Schematic, in 45 watts, the outer pair is running.
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Anonymous
Guest
are you sure you are reading the mark V manual? there is reference on page 3 about 45 watts running the inner pair of power tubes and the schematic on page 62 specifies V8 and V9 running in 45 watts which are the inner pair of power tubes (check the most up to date manual in the mesa boogie site)>Photi G< said:
>Photi G<
Well-known member
salvatruco said:
Yeah, the actual amp schematic conflicts with the production model. On the schematic, It shows the Class AB pair in the middle positions, and the Class A pair outside, like all other Simul-Class amps before it. However, to double-check myself, I looked at some gut shots, and you are right, the Class A/45W pair is the middle two tubes. Sorry for the confusion.
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Anonymous
Guest
No problem :wink:>Photi G< said:salvatruco said:
Yeah, the actual amp schematic conflicts with the production model. On the schematic, It shows the Class AB pair in the middle positions, and the Class A pair outside, like all other Simul-Class amps before it. However, to double-check myself, I looked at some gut shots, and you are right, the Class A/45W pair is the middle two tubes. Sorry for the confusion.
