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Kustom 250 Bass sounds great, but lots of crackling! [message #12277]

Fri, 23 October 2009 13:06

ookla the mok
Messages: 6
Registered: October 2009

Junior Member

I tested to make sure it wasn't my cords or the cab rattling... from the other topics I've researched, it seems that this might be a dirty pot/input jack problem or a loose cap.

Does anyone have any troubleshooting advice?

Also, glad to join this forum! It seems like a very helpful informative place.

Cheers,

Kane

[Updated on: Fri, 23 October 2009 14:50]

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12279 is a reply to message #12277]

Fri, 23 October 2009 15:38

chicagobill
Messages: 2005
Registered: April 2003

Senior Member

Welcome to the place.

Is the crackling constant?

Does it only happen when you adjust a control?

Does physically moving of bouncing the amp cause the crackling to increase or decrease?

Let us know and we'll help you figure this out.

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Re: Kustom 200 Bass sounds great, but lots of crackling! [message #12280 is a reply to message #12277]

Fri, 23 October 2009 16:06

oren hudson
Messages: 274
Registered: March 2008
Location: Gastonia, NC

Senior Member

Welcome to the forum Kane. I think that you may be referring to dirty controls and/or jacks. Get some tuner cleaner/lube and give them a good spray. Then work them back and forth and back and forth and back and forth. You may have to loosen up the nut for better access. If that doesn't do it, I've had to remove the chassis form the housing to get a real good shot at the pots etc. The best stuff that I've found is Deoxit or even Radio Shack spray. Good luck. Cool

Cool

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12281 is a reply to message #12277]

Fri, 23 October 2009 16:21

ookla the mok
Messages: 6
Registered: October 2009

Junior Member

It mostly happens when I play certain notes... specific frequencies (mostly low down and high up) make it crackle louder.

It happens on all 4 of the inputs... sometimes it seems like when i switch jacks real quick, it's lesser... but i may be crazy, this isn't sound experimentation.

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12287 is a reply to message #12281]

Sat, 24 October 2009 00:43

oren hudson
Messages: 274
Registered: March 2008
Location: Gastonia, NC

Senior Member

If your "crackling" is just on certain notes, your problem is not with the pots. Generally, this is a sign of cabinet rattle or a bad speaker(s). Cabinet rattles are sometimes real difficult to isolate. I try to get help with someone playing the offending note(s) while I try and locate the problem. Sometimes it takes bracing, gluing or more screws. You might first check all screws to make sure that they're tight and the frame of the speaker is reasonable tight. Don't over tighten the speaker screws. Continue doing the process of elimination and hopefully you'll get your problem in line. Cool

Cool

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12288 is a reply to message #12287]

Sat, 24 October 2009 14:18

ookla the mok
Messages: 6
Registered: October 2009

Junior Member

Ok, so I took the face off and sprayed out all the input jacks and pots with an air can. At first, I thought this fixed the problem. The crackling seems less predictable now....

I tried hooking it up through the line out to a Roland "15 keyboard amp that's rated @ 135w. The same crackling happened, but it differs in intensity/frequency depending on which input i'm using on the 250.

I figure the fact that it's a 15" speaker and a new model should mean it's constructed well and could handle the amp without that crackling. The crappy old peavey 4x10" just seems to crackle more frequently. Maybe it's not just the frequencies of the notes, but the input level and volume i'm pushing through the speakers that's adding to it.

I dunno... What should my next plan of attack/experimentation be? Maybe I'm just bad at pinpointing the problem and explaining it.

Thanks again all for taking time to help me out! I am really liking the sound of these old amps!

Kane

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12289 is a reply to message #12288]

Sat, 24 October 2009 21:34

oren hudson
Messages: 274
Registered: March 2008
Location: Gastonia, NC

Senior Member

Sorry Kane - hard to say at this point for me. Good luck. Cool

Cool

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12291 is a reply to message #12289]

Sun, 25 October 2009 14:21

pleat
Messages: 1452
Registered: June 2004
Location: Belding, Mi

Senior Member

I think we need a little more information. You have the K250 head but what cabinet are you hooking the amp to? The K250 wants a 4 ohm cabinet impedance. You mentioned in one of the posts you are using a peavey 4x10 cabinet? Are you playing bass guitar or will a regular six sting do the same noise. Speaker rattles can be caused by the speaker nuts not being tight or some over tighted to cause the frame of the speaker to bend letting the voice coil rub. Speakers with aluminum dust caps can cause a rattle on certain notes. I had a JBL that drove me nuts until I ran a bead of silicon glue around it.
Another thing you will want to check is the connection plugs that hook one board to the other. This is where most slant metal face amps have problems. Poor connections through the molex connectors.
Does the K250 have the same problem if you run it through a good cabinet. It's a process of elimination but it can be a pain in the mean time.
pleat

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12292 is a reply to message #12277]

Mon, 26 October 2009 06:02

stevem
Messages: 4739
Registered: June 2004
Location: NY

Senior Member

If this is just the basic two channel model K250 with no effects section and the crackling happens on both channels, then the problem most likly is eitheir bad connections on the moldex output connector on the lower non-selectone channel, or the connector on the driver/output stage board.
Secondary problems could be solder connections of componets on the driver/output board, or power supply connections to the two main filter cans or the slip on spade connections to the rectifier bridge or the slip on connections to the output transistor legs or the red hot lead screw down/ mounts on the 4 output transistors.

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12293 is a reply to message #12292]

Mon, 26 October 2009 12:03

chicagobill
Messages: 2005
Registered: April 2003

Senior Member

My first suggestion would be to use a control cleaner like DeOxit on the pots, switches, jacks and the Molex PC board connectors. Compressed air will move the dust and dirt, but will not remove the film and oxidation from the surface of the parts.

If that doesn't clear up the problem, then you need to look into the possibility of loose components on the PC boards, loose or frayed wiring, etc.

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12295 is a reply to message #12291]

Thu, 29 October 2009 17:35

ookla the mok
Messages: 6
Registered: October 2009

Junior Member

pleat wrote on Sun, 25 October 2009 14:21

You have the K250 head but what cabinet are you hooking the amp to? The K250 wants a 4 ohm cabinet impedance. You mentioned in one of the posts you are using a peavey 4x10 cabinet? Are you playing bass guitar or will a regular six sting do the same noise?

The Peavey 4x10 cabinet doesn't have any OHM rating listed. If it were an 8 ohm cabinet, could that be a possible culprit for this crackling noise?

My next plan of attack is to try a 6 string on it and see if that produces the same crackling. If it does, then I guess I'll have to take the amp apart again and check those moldex connectors.

If all of these fail... It's off to my amp tech friend!

Thanks again for all of the responses!

Kane

[Updated on: Thu, 29 October 2009 17:36]

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12296 is a reply to message #12277]

Thu, 29 October 2009 20:55

ookla the mok
Messages: 6
Registered: October 2009

Junior Member

Ok, I've removed the chassis from the tuck n roll case. Ive been testing for the crackle sound with the amp stacked on it's case which itself is stacked on another speaker cab. The crackling is mostly gone! I've only been able to get the crackle on the top channel inputs.

My guess is that there's a loose cap or something else on the top channel's board. All the vibration was obviously not helping. The push/pull bright pot seemed to have an effect on the crackle this time too. How can one tell if a pot is bad?

One step closer!

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12297 is a reply to message #12295]

Thu, 29 October 2009 21:57

oren hudson
Messages: 274
Registered: March 2008
Location: Gastonia, NC

Senior Member

************************************************************ ************The Peavey 4x10 cabinet doesn't have any OHM rating listed. If it were an 8 ohm cabinet, could that be a possible culprit for this crackling noise? [/quote]**************************************************** *************

No - but it's important to know the ohm rating of your speaker cab(s) for optimal performance. Go to Sears or a like place and get you a multimeter. Follow the instructions for the ohms setting. The quickest way to check is to touch the prongs to the speaker jack on the cab or plug your speaker cable in and touch the prongs to the other end of the speaker cord for your reading. I would then make a note of it, or make an attachment sticker to the cab for future reference. Cool

Cool

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12298 is a reply to message #12277]

Fri, 30 October 2009 05:53

stevem
Messages: 4739
Registered: June 2004
Location: NY

Senior Member

About 3 years into the life of my early K250( 71 model) it developed a crackle that turned out to be on solder connection on one of the big orange drop type coupling caps on the top channel of the amp.

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Re: Kustom 250 Bass sounds great, but lots of crackling! [message #12299 is a reply to message #12277]

Fri, 30 October 2009 12:02

ookla the mok
Messages: 6
Registered: October 2009

Junior Member

I'll follow-up with the diagnosis once I get my friend to check the amp's solder connections. Thanks again for all your help everyone!

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