Tube amp crackling noise after certain notes

Artjr

Silver Supporting Member
Messages
2,829
i have a JCM 2000 DSL 50 and I'm getting a slight crackling noise after notes. It seems worse the harder I hit the strings. Could it be time for new tubes or clean the sockets?
 

Artjr

Silver Supporting Member
Messages
2,829
I could trade in the Marshall and my CVR for a Fuchs blackjack 21.
 

zenas

Member
Messages
8,759
It really could be a bunch of things! But something real simple to try is just pulling each tube and reseating it back in. Sometimes that's all it takes to get the contacts good again.
Also check the speaker connections.

After the simple stuff and subbing in your spare tubes, try another speaker or cab. Then it's time to go inside.
Hopefully it's something simple.
 

Stratonator

Member
Messages
2,958
Crank the volume and gently tap on every preamp tube with a pencil. If you can hear the tap through the speakers, you have microphonic tubes and that could be the issue.
 

zenas

Member
Messages
8,759
Oh something else to try. (thankfully my brother showed it to me before I ripped into an amp with no problems)
Sometimes just sliding your fingers across the pick guard with make noise. Teles are good for that. Rubbing it with a dryer sheet helps alot.
 

rollyfoster

Silver Supporting Member
Messages
16,093
Only on that amp?

Mine was doing something similar, most noticeably with gain, and it was driving me crazy. Play softly...no problems. Snap the string and there was this weird karangy thing after the note. Turns out I needed to raise my action a little.
 

Khromo

Member
Messages
1,020
I was recently having that problem on a silverface Vibrolux reverb. It was most noticeable after warmup, and while bass notes were decaying. It was very noticeable as the crackling seemed to swell as the notes decayed, and there was nothing to obscure the crackle.

I cleaned all the tube sockets, and it got a little better.

I cleaned them all a second time, and it got still better.

I swapped out the tubes one at a time, and couldn't find the problem.

I tried a new phase inverter, and it was better, but not quite there.

I swapped out V-1 and V-2 for new Tung Sols, and it was finally right.

I am convinced that amp actually needed all five of those processes to get clean. I mean it actually had very dirty sockets and three scratchy preamp tubes all start causing a problem at the same time. I really love that amp, so I stuck with it, but I could imagine getting discouraged and ditching an amp rather than going through all the fixes. Swapping out one tube at a time didn't solve the problem because there were more than one tube creating the crackling.
 

SuperReverb2

Member
Messages
2,992
Have the exact same problem with my ML Hot Rod Deville. Brand new in a box. Started about 2 hours into playing the first night. Play softly. No problem. Dig in or do a double stop? LOUD crackle as the note or notes are struck. Intermittent for the first couple of weeks, then came back in spades. Finally took it to the dealer (hard to stop playing this amp as it really does sound great when it's functioning properly) who promptly sent it to the local Fender approved warranty center. Got an e-mail yesterday it was back, repaired for free, and ready for pickup. The repair tag read. Loose pre amp tube socket. Tube arcing in socket. Re soldered the socket. Replaced the tube. Re biased. Let burn in. Sounds fine. Picked it up after work. Got it home. Checked it over. Looked great. No worse for the wear. Stoked. Mmmmmm. That euphoria lasted about as long as the first note. NOT repaired. Worse than ever. Happens on about ever note now. Super loud crackle as well. Amp is boxed up and going back to the dealer tomorrow. Won't settle for anything less than a new amp now as this one is barely 30 days old. Geez!

Edited to add: Plug the same cable, guitar, and pedals into my RedPlate CDS2 and all is good. Plug into the ML Deville. Crackle city. Heard a few pops and things during my time with tube amps, but this is a first for this. Bizarre.

:)
 

mikef09

Member
Messages
529
I have the same amp and it sounded like it was frying bacon when I turned it on and would be in the background when I wasn't playing. Turns out it was a bad power tube. Got it re-tubed last week and no issues now!
 

Stratonator

Member
Messages
2,958
Have the exact same problem with my ML Hot Rod Deville. Brand new in a box. Started about 2 hours into playing the first night. Play softly. No problem. Dig in or do a double stop? LOUD crackle as the note or notes are struck. Intermittent for the first couple of weeks, then came back in spades. Finally took it to the dealer (hard to stop playing this amp as it really does sound great when it's functioning properly) who promptly sent it to the local Fender approved warranty center. Got an e-mail yesterday it was back, repaired for free, and ready for pickup. The repair tag read. Loose pre amp tube socket. Tube arcing in socket. Re soldered the socket. Replaced the tube. Re biased. Let burn in. Sounds fine. Picked it up after work. Got it home. Checked it over. Looked great. No worse for the wear. Stoked. Mmmmmm. That euphoria lasted about as long as the first note. NOT repaired. Worse than ever. Happens on about ever note now. Super loud crackle as well. Amp is boxed up and going back to the dealer tomorrow. Won't settle for anything less than a new amp now as this one is barely 30 days old. Geez!

Edited to add: Plug the same cable, guitar, and pedals into my RedPlate CDS2 and all is good. Plug into the ML Deville. Crackle city. Heard a few pops and things during my time with tube amps, but this is a first for this. Bizarre.

:)
Had the same thing with a tweed Blues DeVille when they first came out. It had a 4x10 speaker config. Turns out it was a speaker that had a tiny tiny ripple in it.

Plug it into another cab to see if you have this problem. But be mindful of the ohms.
 

keithb7

Member
Messages
1,421
I had similar problem with a vintage 1964 Bandmaster. Turned out to be a solder joint. Probed around with a chopstick in the live amp, touching all connections and found it.
 

Artjr

Silver Supporting Member
Messages
2,829
I fixed it the simple way, and the Custom vibrolux hiss is gone to. Traded both amps for a Fryette Memphis 30.
 

swiveltung

Member
Messages
14,492
I was recently having that problem on a silverface Vibrolux reverb. It was most noticeable after warmup, and while bass notes were decaying. It was very noticeable as the crackling seemed to swell as the notes decayed, and there was nothing to obscure the crackle.

I cleaned all the tube sockets, and it got a little better.

I cleaned them all a second time, and it got still better.

I swapped out the tubes one at a time, and couldn't find the problem.

I tried a new phase inverter, and it was better, but not quite there.

I swapped out V-1 and V-2 for new Tung Sols, and it was finally right.

I am convinced that amp actually needed all five of those processes to get clean. I mean it actually had very dirty sockets and three scratchy preamp tubes all start causing a problem at the same time. I really love that amp, so I stuck with it, but I could imagine getting discouraged and ditching an amp rather than going through all the fixes. Swapping out one tube at a time didn't solve the problem because there were more than one tube creating the crackling.
Yep.... this is actually quite common. ,.... and frustrating. Sometimes one socket or tube will make a few of them microphonic... or the whole board microphonic when you tap it. I got rid of most these problems by going to Mullard RI 12AX7's about 3 years ago. I have bunches of vintage tubes, just get tired of chasing my tail. It's very weird because an amp can sound fine for a while then start this up with old tubes.
 
Messages
16,191
"had it re-tubed" is a term that makes me wonder what a guy charges for changing tubes in an amp.
I did it myself, it's pretty simple.
 

bluejazzoid

Silver Supporting Member
Messages
4,389
I've had that sort of problem before, and in my case putting silicone rings on the tubes helped a bunch. But other things may work depending on whether your problem is actually the tubes themselves being microphonic, or the tube sockets needing to be tightened (or re-soldered), or perhaps something else.
 




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