My Mark V is irritating me... Snap, crackle, pop...

[MakeAJazzNoiseHere]

My Mark V sounds awesome. It's just a great little amp, I love it!

EXCEPT for when it starts crackling. Crackle, crackle, crackle. And it picks up Mexicans on a CB radio. :think:

I swear I'm not insane, but I fired it up last night and jammed for about an hour and it was sounding awesome, then I hit the "mute" button on the footswitch, switched guitars, and when I un-muted it... <crackle crackle crackle>

You can't hear it so much if you turn the volume up on the guitar just a litle, it kind of makes me think there is a bad ground, I've tried two different outlets (one is an extension cord into a grounded outlet about 4 feet from the main electrical box).

So I'm thinking, bad solder joint on a ground somewhere, it happens when it gets warmed up. WRONG!

I played it ALL DAY today, not a single crackle out of it!

I can't (wont, waste of time) take it in to be serviced if the problem is not reproducible... Thoughts?

[jgcable]

My Mark V sounds awesome. It's just a great little amp, I love it!

EXCEPT for when it starts crackling. Crackle, crackle, crackle. And it picks up Mexicans on a CB radio. :think:

I swear I'm not insane, but I fired it up last night and jammed for about an hour and it was sounding awesome, then I hit the "mute" button on the footswitch, switched guitars, and when I un-muted it... <crackle crackle crackle>

You can't hear it so much if you turn the volume up on the guitar just a litle, it kind of makes me think there is a bad ground, I've tried two different outlets (one is an extension cord into a grounded outlet about 4 feet from the main electrical box).

So I'm thinking, bad solder joint on a ground somewhere, it happens when it gets warmed up. WRONG!

I played it ALL DAY today, not a single crackle out of it!

I can't (wont, waste of time) take it in to be serviced if the problem is not reproducible... Thoughts?

Sounds like a bad instrument cable to me.

[Grandturk]

Leave it outside the back door. I'll be around later on tonight to uh... Get rid of the crackle.

[Grim]

I agree with jg. It sounds like a cable. I used to buy those generic 2$ cables and never even had to play the guitar - I'd pick up radio stations

[MakeAJazzNoiseHere]

Yeah, that's what I thought, seems like a bad cable. And, the cables I usually use are not cheap cables, but they are old.

But I tried a brand new ProCo cable (actually a few) and it did the same thing. I tried another of my old cables, same thing. Plus, I was using the same old cable all day today, no problem... :dunno:

BUT, I have (somewhere) this POS cable with molded ends that came with one of those $150 "stop dreaming and start playing" Squier kits they were giving away at Sam Ash last year... It's the quietest of the bunch once it starts acting up, but it still crackles some.

So, pretty sure it's not the cable... What else? I'm hoping maybe a preamp tube because past that I'm looking at "wait until it fails catastrophically or trade it in and let the next sucker deal with it."

[Grandturk]

It could be a microphonic preamp tube.

[Grim]

It could be a microphonic preamp tube.

+1

[MakeAJazzNoiseHere]

It's doing it again.

It's weird, different things will cause it to stop for a second or whatever, wiggling the input around, touching the metal rails on top fo the amp, touching the guitar's metal volume knob or output jack plate will change the characteristics of the crackling, but nothing really makes it go away.

So yeah, after working great all day I turn it on to play for a little bit and it's buzzing like a sonofabitch again, just to be sure I tried two ProCo cables and two of my old Switchcraft/Belden wire cables and I can't make it go away using any cable, any channel, any power setting, etc.

I wouldn't mind so much if it were reproducible all the time. I can't take it somewhere and tell them to "just keep trying it" until it starts buzzing.

I was thinking of maybe getting a preamp tube (or two) for spares and also to troubleshoot with but I seriously think it's a cold solder joint in the chassis somewhere- I've never heard a preamp tube do anything like this, but then again, if you guys say a bad preamp tube can sound like a swarm of bees and make Mexcan CB radio come out of my amp...

Oh, also, tried several guitars.

This is weird, I mean, I've heard howling and crappy tone come from bad preamp tubes but I don't have enough experience with tube amps to know if it's worth spending $20 for a spare to troubleshoot preamp tubes?

[Grim]

It's doing it again.

It's weird, different things will cause it to stop for a second or whatever, wiggling the input around, touching the metal rails on top fo the amp, touching the guitar's metal volume knob or output jack plate will change the characteristics of the crackling, but nothing really makes it go away.

So yeah, after working great all day I turn it on to play for a little bit and it's buzzing like a sonofabitch again, just to be sure I tried two ProCo cables and two of my old Switchcraft/Belden wire cables and I can't make it go away using any cable, any channel, any power setting, etc.

I wouldn't mind so much if it were reproducible all the time. I can't take it somewhere and tell them to "just keep trying it" until it starts buzzing.

I was thinking of maybe getting a preamp tube (or two) for spares and also to troubleshoot with but I seriously think it's a cold solder joint in the chassis somewhere- I've never heard a preamp tube do anything like this, but then again, if you guys say a bad preamp tube can sound like a swarm of bees and make Mexcan CB radio come out of my amp...

Oh, also, tried several guitars.

This is weird, I mean, I've heard howling and crappy tone come from bad preamp tubes but I don't have enough experience with tube amps to know if it's worth spending $20 for a spare to troubleshoot preamp tubes?

Compare $20 to how much you paid for the Mark V. Then compare THAT to how much you can sell it for with this problem.

[MakeAJazzNoiseHere]

Yeah, it's not really the money.

It's working fine again today, no crackling. So, consider driving to the store to buy a tube and spending several more hours swapping tubes, turning the amp on, waiting for it to happen... Maybe it won't happen again for days, weeks, months, maybe it will.

Seems like an exercise in frustration, when you don't even know that a tube could possibly cause this symptom. Which, I understand that noise could come from a preamp tube, but... Would it CHANGE the crackling and popping to gently touch the metal parts of the amp, or to turn the volume up on the guitar 1/16 of the way?

Seems to me like it's a ground issue in the preamp. Then again, I am not an electronics technician, this is just my best guess based on the behavior. :dunno:

[Vass]

Crackle crackle and picking up shortwave radio (which is I bet what you are getting) sounds like an ungrounded outlet- I know you tried 2 different ones and I assume they are on differn circuits, but did you check to make sure it truly IS grounded? Electricians do crazy shit. How old is the service? Is it an equipment ground or one of those knob and tube type sorta grounds (forget how that works exactly). Has the ac been running during crackle crackle? Other high power consumption items? Maybe you need a power conditioner?

I think rsmacker is an electrician- maybe ask him if it could be power related.


EDIT:

http://www.thegearpage.net/board/showthread.php?t=281178&highlight=tube+shields

otherwise an interesting list of issues that can cause you to pick up radio on your amp. Possible that the crackling is not crackling per se (like noise in the circuit of your amp due to something being wrong) but is instead more broadcast interference?

[Grandturk]

I've got pedals that pick up radio stations, too - so check that out as well.

[MakeAJazzNoiseHere]

It COULD be a shortwave radio or something... It's FINE right now, again.

No issues with the power so to speak, I mean, yeah, I probably COULD use a power conditioner, it's running off of a quality APC UPS with battery backup - and the other line is straight to the wall that I tried. I do get the occasional "click" when the AC kicks on or when you flip a light on, that's understandable and I'm willing to live with it (or I'd get a power conditioner) as far as that goes...

It's when it starts going bzzzzzzzzzzt for an hour straight and only lets up for a few seconds at a time that's got me stumped. Maybe there's some Mexican talking to his family on SW radio... :think:

[Hellbat]

You know you wouldn't have these problems if you used a modeller like an Axe-fx.

[Shawn Lutz]

it also could be the power in your house as well. Does it do it elsewhere?

Sounds like a cable or ground issue with the power at you house. Since it happened after you switched guitars perhaps is faulty wiring on the guitar itself. To isolate the issue see if it happens with nothing plugged in the loop, no effects, no pedals just guitar into the amp.