Maverick 2x12 Mystery Hum...and go...

[Lotustar]

Here's one that even stumped the fine folks at Mesa. I have a 2x12 Maverick that suffers from a low hum. Pretty common right? Turns out it's not. Not in this situation. Quick background. Got this Mav used and it was a little mistreated. I knew it would need some love. First power up after purchase I noticed a strange modulation thing going on when playing single notes at about the 14th fret or so. VERY ANNOYING! This low "note" followed all my other notes around. I figured filter caps. Replaced them and nope. New tubes? Nope. Cone cry? Guess again. Finally took it to a trusted amp tech. He checked everything and even replaced my power chord that had some shorts in it apparently. Get it home and it does sound punchier and has more life but still "ghosting" note. I'm at a loss here. Anyone want to take a stab at it?

List of things tried:
New tubes
New caps
New power chord
Tried different cab/speakers
Different locations to rule out bad power from wall
Nothing plugged into input (guitar, fx, ect.)
Reverb off, eq settings, gain volumes, switches.

It's not so much the hum that bothers me. It's the way it mingles with my notes. It's a deal breaker for sure. This is my second maverick. First one being the short head version. That amp was STELLAR! That's why I got another. My other one never gave me a single problem and I don't want to give up on this one. Help me gurus, you're my only hope.

 

[green_henry]

Are you plugging straight into the wall? Even if you're trying different outlets, that won't necessarily make a difference if there's a common problem at the fuse box or elsewhere. Have you tried going through a power conditioner? Also wondering whether your amp tech noticed the same thing -- if not, then it's even more likely to be an issue with your power source.

Also, are you running anything through the loop and does changing the mix level make any difference? Any difference if you switch rectifiers?

 

[Lotustar]

Are you plugging straight into the wall? Even if you're trying different outlets, that won't necessarily make a difference if there's a common problem at the fuse box or elsewhere. Have you tried going through a power conditioner? Also wondering whether your amp tech noticed the same thing -- if not, then it's even more likely to be an issue with your power source.

Also, are you running anything through the loop and does changing the mix level make any difference? Any difference if you switch rectifiers?

I've tried straight into the wall and will a standard power strip. As far as power conditioners go no I have not tried that. I've heard they don't do much until you get into the high end ones that are like $400. My amp tech said he could barely hear it. But I CLEARLY hear it. It's totally unacceptable. I have tried the amp in different places (work, studio, ect.) and it still does it. Also when I turn the amp on it makes a "zzzt" zapping sound for like a second. I'm thinking a transformer problem in the amp. But shouldnt that have thrown a flag when he checked all the electronics? And yes I have tried both rectifier settings. No change. I don't use the effects loop. May be time to just sell it. I hate to do that though.

 

[afu]

That zzzt makes me think of something discharging to ground.

 

[Lotustar]

That zzzt makes me think of something discharging to ground.

From my research on forums other people seem to think the zzzt sound is normal. I would disagree but I'm not a tech. I def think you are right about a ground problem. That would explain the hum as well if I'm not mistaken. Again though, that's something that should have thrown a flag when my tech ran checks on everything.

 

[lovetoboogie]

it sounds like ripple in the power supply somewhere if you have ruled out speaker(cone-cry)...i have seen these maverick boards badly overheated. make sure the 220uf's are securely grounded and in an extreme case you might want to fly those caps right to the diode/rectifier B+ junction...

check all the 30uf's and don't trust those pads...

additionally, check the power tube pcb...any warping on that from overheating will cause problems...

lastly, the cathode resistor and bypass cap run hot if the amp has been pushed hard on a regular basis...i have seen that solder joint go bad. i mod all mavericks and fly all power supply leads with wire...

 

[Lotustar]

it sounds like ripple in the power supply somewhere if you have ruled out speaker(cone-cry)...i have seen these maverick boards badly overheated. make sure the 220uf's are securely grounded and in an extreme case you might want to fly those caps right to the diode/rectifier B+ junction...

check all the 30uf's and don't trust those pads...

additionally, check the power tube pcb...any warping on that from overheating will cause problems...

lastly, the cathode resistor and bypass cap run hot if the amp has been pushed hard on a regular basis...i have seen that solder joint go bad. i mod all mavericks and fly all power supply leads with wire...

Holy crap I don't even know what some of that means. Lol. But I will def run it by my tech and have him check it out. I have a volt meter and soldering iron but I don't know what to look for....yet. Although I did do a pretty good job replacing my filter caps. Was easy. Thanks for the reply.

 

[afu]

That zzzt makes me think of something discharging to ground.

From my research on forums other people seem to think the zzzt sound is normal. I would disagree but I'm not a tech. I def think you are right about a ground problem. That would explain the hum as well if I'm not mistaken. Again though, that's something that should have thrown a flag when my tech ran checks on everything.

My Harmony amp buzzes and pops sometimes from not having an Earth ground.

The suggestion about the caps is probably right on the money.

 

[Lotustar]

That zzzt makes me think of something discharging to ground.

From my research on forums other people seem to think the zzzt sound is normal. I would disagree but I'm not a tech. I def think you are right about a ground problem. That would explain the hum as well if I'm not mistaken. Again though, that's something that should have thrown a flag when my tech ran checks on everything.

My Harmony amp buzzes and pops sometimes from not having an Earth ground.

The suggestion about the caps is probably right on the money.

So I guess now I need to check all the grounds? I JUST spent $130 with a tech that was supposed to go through the whole amp and make sure it' all good. And it's still not playable.

 

[afu]

If you do it yourself, (disclaimer about electric shock goes here), the big caps need to be drained before you touch much of anything. I would start at the cord input and inspect it going backwards. Good luck, buddy. The power supply is not big, so I hope it ends up being easy.

 

[RR]

...
So I guess now I need to check all the grounds? I JUST spent $130 with a tech that was supposed to go through the whole amp and make sure it' all good. And it's still not playable.

Did you test your Maverick at the tech's shop and point out the problem still exist? Man, I hope he's not those technicians that still wants to get paid even though they didn't fix the problem.

I had a buddy who had an intermittent amp problem that the amp tech thought he fix. When my buddy brought back his amp, the amp tech went through it again and just said : "I can't solve the problem, here's your money back." It was a cheap amp though.

 

[Lotustar]

If you do it yourself, (disclaimer about electric shock goes here), the big caps need to be drained before you touch much of anything. I would start at the cord input and inspect it going backwards. Good luck, buddy. The power supply is not big, so I hope it ends up being easy.

Yea I know all about draining those puppies. I made a jumper with clips on each end and a 10k resistor (I think it was 10k anyway) in the middle. I have replaced all my filter caps. But maybe I need to replace all my caps. bias cap especially.

 

[Lotustar]

...
So I guess now I need to check all the grounds? I JUST spent $130 with a tech that was supposed to go through the whole amp and make sure it' all good. And it's still not playable.

Did you test your Maverick at the tech's shop and point out the problem still exist? Man, I hope he's not those technicians that still wants to get paid even though they didn't fix the problem.

I had a buddy who had an intermittent amp problem that the amp tech thought he fix. When my buddy brought back his amp, the amp tech went through it again and just said : "I can't solve the problem, here's your money back." It was a cheap amp though.

I didnt test it there. I should have. He is known to be a trusted amp tech here so I didnt worry about it. To me it seems that all he did was put on a new power chord and change a couple of preamp tubes. And my rectifier tube still sits really loose in the socket. maybe he just sucks.

 

[BlackBart]

I have a 78 Mark I that was humming with and without reverb turned up and nothing plugged. Only annoying when I stopped playing. I'm thinking 30+ years old, probably needs the preverbial cap job. I wiggled the reverb pan cables, bam! Bad reverb pan connection, no hum now.

YMMV

 

[79fwlthree]

Here's one that even stumped the fine folks at Mesa. I have a 2x12 Maverick that suffers from a low hum. Pretty common right? Turns out it's not. Not in this situation. Quick background. Got this Mav used and it was a little mistreated. I knew it would need some love. First power up after purchase I noticed a strange modulation thing going on when playing single notes at about the 14th fret or so. VERY ANNOYING! This low "note" followed all my other notes around. I figured filter caps. Replaced them and nope. New tubes? Nope. Cone cry? Guess again. Finally took it to a trusted amp tech. He checked everything and even replaced my power chord that had some shorts in it apparently. Get it home and it does sound punchier and has more life but still "ghosting" note. I'm at a loss here. Anyone want to take a stab at it?

List of things tried:
New tubes
New caps
New power chord
Tried different cab/speakers
Different locations to rule out bad power from wall
Nothing plugged into input (guitar, fx, ect.)
Reverb off, eq settings, gain volumes, switches.

It's not so much the hum that bothers me. It's the way it mingles with my notes. It's a deal breaker for sure. This is my second maverick. First one being the short head version. That amp was STELLAR! That's why I got another. My other one never gave me a single problem and I don't want to give up on this one. Help me gurus, you're my only hope.

I have a 1x12 narrow body; it does the same thing. I've had it to a Mesa certified technician in Sarasota and he says it's OK. I don't play it much because of the ghosting notes.....exactly as you described it. My question is: did you ever get it fixed and what was the fix. BTW it doesn't do it until it is fully warmed up in say 20 minutes or so.