Annoying crackling sound?

brokenjoe · November 13th, 2009, 07:16 PM

I've got a Pro Jr. that I modded myself that is making some loud crackling noises once it heats up. First I thought it was tubes, but I replaced them with new ones and it's still doing it.

Everything was fine for a few months, but now it's making this horrible sound. It's an intermittent crackle -not feedback- that is about as loud as the note being played. The note is still audible, but it crackles along with it.

It's fine until I've been playing for a few minutes, then it starts it's racket. I've tried plugging it into a different speaker, but it still does it -so that ain't it.

Any ideas?

celeste · November 13th, 2009, 07:39 PM

Quote:

Originally Posted by brokenjoe

I've got a Pro Jr. that I modded myself that is making some loud crackling noises once it heats up. First I thought it was tubes, but I replaced them with new ones and it's still doing it.

Everything was fine for a few months, but now it's making this horrible sound. It's an intermittent crackle -not feedback- that is about as loud as the note being played. The note is still audible, but it crackles along with it.

It's fine until I've been playing for a few minutes, then it starts it's racket. I've tried plugging it into a different speaker, but it still does it -so that ain't it.

Any ideas?

Clean and tighten the tube sockets and pots. Make sure the caps are discharged first!!!

buddywayne · November 13th, 2009, 08:31 PM

When I read the thread title I thought you talking about my singing.

pchilson · November 13th, 2009, 09:06 PM

Check all ground points.

I had an amp once that sounded great for about 20 minutes into playing and then all of a sudden it would produce this loud crackling/screeching sound. It was somewhat random as it didn't always do it. Drove me crazy trying to find the problem.
One day I just went in and resoldered all the ground points and viola, problem solved.

I don't know if there was a cracked solder or maybe a cold solder or what but now I always touch up all ground points as a matter of routine.

6942 · November 14th, 2009, 10:41 AM

I had that problem with a bad tube socket.
Eventually replaced the socket.
And the problem went away.

Steve

muchxs · November 14th, 2009, 01:32 PM

Reflow the solder joints on your mods.

brokenjoe · November 14th, 2009, 02:04 PM

Thanx for all the tips and help guys. I'm gonna have to get back inside it and check/re-solder all of the mods I did.

Although I love my Pro Jr., it's a real PITA to work on. It's REAL tight in there. This was the first experience I've had working with PCBs, so it's probably my solder joints.

The loose tube socket may be at issue, but since they're not screwed in, tightening them is not really an option. These amps are very cheaply made. I'm hoping that that's not the problem.

cousinpaul · November 14th, 2009, 03:41 PM

I had a problem with a Pro Jr shaking the tubes in their sockets when it was turned up loud. You might try the PJ as a head with an ext. speaker to see if it's a vibration thing. As I recall, mine didn't have any cans or clips to hold the tubes in place.

tubeswell · November 15th, 2009, 07:39 PM

Those intermittent pops and crackles are usually voltage changing somewhere in the signal path. If the output tubes are okay (and they probably are if it happened only after you did your mods) then check for solder and of dirty flux residue between traces/trace pads, and also on/in the pots themselves. The trouble with those pots that are mounted on PCBs, is that they can twist and strain the joint when you tighten them up, either affecting the traces or the pots or both. Or you might've got some flux or solder residue causing unwanted voltage leakage on a PCB or inside a pot itself (if you soldered directly onto a pot - esp if it was tipped on its side/end in such a way that that solder could run down into the pot. 2CW

celeste · November 16th, 2009, 09:02 PM

Quote:

Originally Posted by brokenjoe

The loose tube socket may be at issue, but since they're not screwed in, tightening them is not really an option. These amps are very cheaply made. I'm hoping that that's not the problem.

The tightning I speak of it not the socket mounting, but the part of the socket that grips the tube pins. They can get loose, they get dirty.

brokenjoe · November 18th, 2009, 06:11 PM

Quote:

Originally Posted by celeste

The tightning I speak of it not the socket mounting, but the part of the socket that grips the tube pins. They can get loose, they get dirty.

I thank you most heartily for the info. That may have been the cause of my trouble.

I inspected the sockets, made sure the tubes were seated properly, and did a couple of other things that were recommended. The amp works fine now!!

Thanks all!

November 13th, 2009, 07:16 PM	#1 (permalink)
brokenjoe Friend of Leo's Join Date: Mar 2009 Location: Toronto Age: 47 Posts: 2,157	Annoying crackling sound? I've got a Pro Jr. that I modded myself that is making some loud crackling noises once it heats up. First I thought it was tubes, but I replaced them with new ones and it's still doing it. Everything was fine for a few months, but now it's making this horrible sound. It's an intermittent crackle -not feedback- that is about as loud as the note being played. The note is still audible, but it crackles along with it. It's fine until I've been playing for a few minutes, then it starts it's racket. I've tried plugging it into a different speaker, but it still does it -so that ain't it. Any ideas? __________________ "Son, always eat your vegetables.... and stay away from those whole tone scales!!"

November 14th, 2009, 01:32 PM	#6 (permalink)
muchxs Tele-Afflicted Join Date: Aug 2004 Location: New England Posts: 1,560	Reflow the solder joints on your mods. __________________ Take it to a tech.

November 14th, 2009, 02:04 PM	#7 (permalink)
brokenjoe Friend of Leo's Join Date: Mar 2009 Location: Toronto Age: 47 Posts: 2,157	Thanx for all the tips and help guys. I'm gonna have to get back inside it and check/re-solder all of the mods I did. Although I love my Pro Jr., it's a real PITA to work on. It's REAL tight in there. This was the first experience I've had working with PCBs, so it's probably my solder joints. The loose tube socket may be at issue, but since they're not screwed in, tightening them is not really an option. These amps are very cheaply made. I'm hoping that that's not the problem. __________________ "Son, always eat your vegetables.... and stay away from those whole tone scales!!"

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November 13th, 2009, 08:31 PM	#3 (permalink)
buddywayne Tele-Afflicted Join Date: Oct 2006 Location: missouri Age: 64 Posts: 1,262 10 Photos	When I read the thread title I thought you talking about my singing.

November 13th, 2009, 09:06 PM	#4 (permalink)
pchilson Friend of Leo's Join Date: Aug 2007 Location: Loveland, Colorado Age: 52 Posts: 2,339	Check all ground points. I had an amp once that sounded great for about 20 minutes into playing and then all of a sudden it would produce this loud crackling/screeching sound. It was somewhat random as it didn't always do it. Drove me crazy trying to find the problem. One day I just went in and resoldered all the ground points and viola, problem solved. I don't know if there was a cracked solder or maybe a cold solder or what but now I always touch up all ground points as a matter of routine.

November 14th, 2009, 10:41 AM	#5 (permalink)
6942 Friend of Leo's Join Date: Apr 2006 Location: Santa Fe, NM Posts: 2,027	I had that problem with a bad tube socket. Eventually replaced the socket. And the problem went away. Steve

November 14th, 2009, 03:41 PM	#8 (permalink)
cousinpaul Tele-Meister Join Date: Jun 2009 Location: Nashville TN Age: 59 Posts: 246	I had a problem with a Pro Jr shaking the tubes in their sockets when it was turned up loud. You might try the PJ as a head with an ext. speaker to see if it's a vibration thing. As I recall, mine didn't have any cans or clips to hold the tubes in place.

November 15th, 2009, 07:39 PM	#9 (permalink)
tubeswell TDPRI Member Join Date: Jul 2008 Location: NZ Posts: 43	Those intermittent pops and crackles are usually voltage changing somewhere in the signal path. If the output tubes are okay (and they probably are if it happened only after you did your mods) then check for solder and of dirty flux residue between traces/trace pads, and also on/in the pots themselves. The trouble with those pots that are mounted on PCBs, is that they can twist and strain the joint when you tighten them up, either affecting the traces or the pots or both. Or you might've got some flux or solder residue causing unwanted voltage leakage on a PCB or inside a pot itself (if you soldered directly onto a pot - esp if it was tipped on its side/end in such a way that that solder could run down into the pot. 2CW

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