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gk800 growl/bad volume knob question

chriscrob

chriscrob

ozellomusic.com
Mar 24, 2008
383
54
40
Atlanta, Georgia
ozellomusic.com
#1
So i just picked up a gk800 for $250. Its in great cosmetic condition, came with a rack case (ima downsize to half case i think), and as far as I can tell it works fine.

except the knobs. Most of them are crackly. i took the amp apart figuring I'ld clean them but they're stuck to PCB (all my other amps are vintage fenders...not sure what to do with a pcb).

The solder looks and most of them aren't bad (crackles only intermittently when you turn it) but the volume knob (on the left side...pregain volume) is horrible. Sound sometimes cuts out at certain points along its path...especially the lower volumes. When its turned all the way up it seems to be fine.

I think I can replace it myself (i'll do it a little more ghetto with wires running to the pcb...) my question is whether its worth it. i've always heard about the 800's "growl" well its quite growly with that volume maxed and the other master volume turned to taste. I like it but i'ld like to be able to dial in a less growly tone for a different feel. Is this growl because I'm overdriving the tonestack (or whatevers next) with that volume maxed or is it a permanent fixture of the 800? With the volume turned down and the low master up will it still sound like I'm using a fuzz pedal? I don't wanna replace the volume pot if its not gonna change things. not worth the surgery/risk.

(also, which pot should I use?)
 
#2
I don't know - but you may be able to get G-K to send you replacement pots for cheap. I damaged several shafts on a Peavey head a few months back, and Peavey replaced and shipped 4 of them for $10.50. Check that out before you go shopping! :)
 
#3
I'm not sure about the pots on a GK, but I recently had problems with crackling noises on the stacked concentric bartolini's on my active fender cowpoke bass even after spraying pot cleaner down the shaft. A TBer suggested spraying the cleaner into the back of the pot, where there was small opening. it works like new now.
imo, i don't think spraying -- several times -- contact cleaner will hurt.
but what do i know, i'm just the bass player. good luck
 
#4
The pots are probably only dirty and require a good cleaning. I haven't looked closely at the pots on a GK but if there is an opening in the back, a quick shot of aerosol pot cleaner and lubricant (the lubricant part is important apparently) folled by a rapid rotation of the knob will do the trick usually. If there is no opening visible on the back of the pots, I've had success using the same cleaner sprayed on the shaft of the pot (remove the knobs first) while the amp is placed on its back with the shafts sticking straight up. It penetrates down the shaft and into the pot. While you're at it clean the contacts for the effects loop and the input jack.

I wouldn't try to rewire in new pots yourself unless you have experience doing this type of work. You don't want to bugger one of the pcbs. It requires a deft hand with the proper sized soldering gun. See if you can clean them first and if that solves the problems, you're only out the cost of the cleaner. But even if you have to get it to a GK certified tech to replace them, it's probably worth the cost considering the price you paid for it. I'd call GK first before going ahead with anything major.
 

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