1086 Module Crackling & Popping

Hello

I recently picked up a used 1086 module. It sounds great, except it's started to crackle & pop, especially when i increase my pick attack.

It was working & sounding fine for the first few hours of use.

I've tried changing the pre-amp tubes, to no effect.

I have other modules, the XTC, Blackface, and Clean and have never experienced this problem with them, so I believe it to be narrowed down to the 1086 module.

I'm using a RM20 combo, by the way.

Does anybody know what this is ? I immediately thought it was the pre-amp tubes, but after changing them out and it not having any effect, i'm stumped.

Could it be the power tubes? But why wouldn't I ever hear it with the other modules?

Thanks for any help. I really need to get this figured out, because i'm in the middle of recording some tracks using the 1086 as the main guitar sound, and now I can't continue with the sound like this.

Thanks again!

-Jesse

Well I know on my older Clean, Blaclface and Twin modules I had "crackling"
problems. It was a factory design defect where they installed the wrong value resistor. You can read more about it here. Maybe you have a bad resistor.

http://www.grailtone.com/guitar-tone-articles/randall-modules-clean-modifications.html

Hey Spencer,

Official Randall guy here! Any crackling or popping sound in a module is generally related to a preamp tube this is or is about to go bad. I would suggest picking up a few extra preamp tubes, because this will happen occasionally, plus it's a good idea to change them every 6-12 months if you play alot.

Any questions let me know.
Thanks!

Wow....6 to 12 months!?! I've heard of preamp tubes lasting a lifetime. Do the modules put more strain on tubes than other preamp circuits? How do you define "a lot" of playing? Thanks.

RD/MAN said:

Hey Spencer,

Official Randall guy here!
Any questions let me know.
Thanks!

Click to expand...

really? Someone from Randall tech? say it aint so

Anyone experiencing crackling should make sure their modules are seated securely in the module bay. Bruce commented on one of the other forums that modules that are not firmly/tightly seated might exhibit this kind of problem.

I have a JTM that does not respond to either treatment. New tubes? No improvement at all. I also tried seating it in very tightly, used a screw driver to clamp down (not too hard folks) into the module bay. Snap, Crackle & Pop. Not usable. Randall guy, you need to spend alot more time on these boards. We here are fanatical about the product, but Randall support needs to have a voice here.

I did the Clean Resistor Mod on my JTM Module and it took care of the cracking sound

Well RD man which is it? What you said here or what you said on the HC MTS thread?
RD/MAN
Junior Member

Registered: Sep 2001
Location: Vernon Hills, IL. USA
Posts: 71
Blackface & Clean modules

Guys,

We recently had a part change on the Clean, Deluxe, and Blackface modules. A resistor value at the input stage of the modules was causing an overload to the very front end of the module resulting in a slight crackling or distorted sound that could not be dialed out.
The part change can be made to all the modules, but is really only audibly apparent on the cleaner type modules.

If you have some experience with changing parts its very easy, if not we'll be happy to change the part out for you. Otherwise, any local electronics repair place can change the part in a just a couple of minutes. The below part is available at Radio shack.

Find the part labeled R1 on the far left side of the board middle of the way back. Currently it's a 470 ohm resistor which should be changed to a 150 ohm resistor. This will eliminate any and all crackling you will find in the cleaner modules.

Any questions, please e-mail or contact us. Also please pass the word.



Thanks,
RD/MAN

(800) 877-6863 ext. 5172

If you have the correct resistor value AND have tried different preamp tubes and are still having problems, I'd be inclined to guess that there is something wrong with the module. You might want to check into getting the module looked at by Randall or a qualified tech.

Guys,

The early crackling noise in blackface, Clean, and Deluxe which was identified and fixed back in 2003 was not related to the tubes. If you have any early version of these modules you should check the resistor value at position R1 to see if it is 150 ohm. (brown/green/brown stripes)

150 ohm is correct, but the original value was 470 ohm which caused the module to distort a bit up front.

Crackling in any other module will most likely be related to a bad preamp tube or even the first gain stage tube located on the chassis. If you have a module that is still crackling after changing the tubes then try changing the preamp tube located on the chassis nearest to the front panel input jack. This tube will also need changed periodically as it's the first gain stage for all of the modules.

Hope this helps.

Thanks for posting a response. I am overly sensitive to this topic because of my experience with Randall and said issue with my "clean modules".
Please come back and post more often.

I have had the 1086 for a while and it has always been noisy. It started getting real bad so I took it back to shop where I bought it. They are having a licensed repair guy check it out. He has no RM head to test it so I am curious what he is doing to it.

The very first time I tried the 1086 module was at a randall dealer and the module was "brand new." So I was jammin for about 10 minutes at low volume and then it started popping and crackling and it got worse and worse so they changed out the tubes in the mod and back to normal it was. The 1086 must eat tubes pretty quickly or it was just a bad set. Sounds like its fairly common though.

It turned out to the be input tube on the RM20B, not the tubes in the module.

I believe it was just the gain of the 1086 that made it apparent, because I didn't hear it with a Blackface, Clean, or even an XTC module.

I think the RM20B is pretty rough on it's preamp tubes.

Thanks for everybody's input. I installed fresh tubes and life is good again.