Mark IV "popping" when amp is cold

[lerxst88]

Well I recently started hearing my amp making weird low pitched popping noises when its first started up. I give it plenty of time for the tubes to warm up and I have a brand new set of tubes in it from Eurotubes. It does it in any power amp configuration and in full and tweed power mode. It almost sounds like someone banging on the opposite side of a wall but I can confirm it's coming from my amp. After 5 minutes it goes away and my mark sings as sweet as ever. Any idea whats going on?

 

[zodiac272]

I'm a rookie at figuring stuff out, but I'd guess it has something to do with capacitors.

scott

 

[lerxst88]

Alright I've been living with this and to my ears the noises are getting worse. I'll turn it on and let it warm up for a minute and its still spitting and popping and occasionally fading in and out of volume! after 5 minutes it sounds KILLER like always and I have no more problems.

Yesterday I left it on and on standby for 10 minutes or however long it takes a non pro to put a set of strings on a guitar and i turned it on and had no problems.

Any ideas boogie-ers?

 

[zodiac272]

Could it be a component that is affected by temperature? something that after heating up has better contact? or how about the tube sockets themselves? Did you call the Mesa factory about this? they may troubleshoot it on the phone for you

scott

 

[lerxst88]

hmm i didnt think of the tube sockets. I'll give that a try!

 

[GD_NC]

My MkIV has been doing the same thing for the last few weeks. It spits and pops for a couple of minutes when you flip the standby switch and then it's back to normal. Once it is warmed up it's perfectly normal.

I figured my tubes were the issue but I haven't taken the time to change them yet. Keep me posted if you find the problem.

 

[GD_NC]

I have a brand new set of tubes in it from Eurotubes.

Did you replace power tubes or the whole set?

 

[lerxst88]

Just the power tubes although I do seem to recall getting some spitting and just happened to have a delay pedal hooked up and I may have heard it repeat the spit leading me to believe it COULD be a preamp tube. I'll mess with it eventually but I barely have time to play as it is let alone debug!

GD NC: you keep me posted too!

 

[lerxst88]

So much for not having time! I guess I'll just have less sleep.

Anyway I tried swapping V1 and still got spitting. I hooked up my delay and set it so i would DEFINITELY hear repeats of anything making noise in the preamp. Quiet as a mouse!

So I tried swapping V5 since it comes after the FX loop and I got SIGNIFICANTLY less spitting. It wasnt a brand new tube so that could account for the few spits I got.

I don't think it's a bad solder joint because I hit the top of the amp enough to where I would think it would induce some spitting (or shut it up!) and the spitting was inconsistent with my pounding. (yeah I said it boogie snobs! You think they make the cabinets out of birch ply for looks? thats what the tolex is for! :lol: )

I would also suggest replacing V2 since it is used for the FX return if the replacing the PI doesnt do anything for you.