Gallien Krueger 700 RB - Crackle, Spit, Buzz [VIDEO]

gotly · #1 06-28-2010, 05:20 PM

My old, beat up GK 700rb has developed a crackle of sorts. It's audible on pretty much all frequencies but is the worst on the lower notes. I'm assuming it's the amp head since I doubt both my cabs (Avatar 2x10 and 2x12 neo) would have the same problem at once, I tried each cab individually and it's exactly the same. Also tried several basses, cords, etc. Even tried a different amp through same cabs and cables so I'm 100% sure the problem is in the amp.

That being said, the sound is really similar to the sound a dirty pot makes, but turning all the dials doesn't seem to make a difference. Kind of a buzzz--pop--decrease in volume--buzzz, etc. Also kind of sounds like a blown speaker.

I'm pretty sure it's one of those "you're screwed get someone to re-solder everything" situations which isn't that bad since I know a guy who knows a guy, but just thought I'd throw it out there to see if anyone had any suggestions before I put some money on it.

Here's a couple videos! It sounds like a bad mic but nope, it's pretty much spot on.

First vid: not as descernable as the second video, sounds horrible in real life. Hooked up to bottom cab only.
http://www.youtube.com/watch?v=ilpcCfYDbFg

Second vid: Different power cable, speakon cable, instrument cable, wall outlet. Now only hooked up to 2x10 (top cab in previous video). It's really obvious how bad it sounds in this video. Notice how it's completely silent when I'm not playing, it's not like a buzz that is present all the time and gets worse the louder I play. I also hooked up a guitar and got the same results.

http://www.youtube.com/watch?v=lVHWs72pdwI

I've already cracked open the amp case to see if there's anything visibly wrong with it but I don't see any scorch marks, missing pieces, loose wires, nothing. I'm pretty handy with a multimeter and a soldering iron but I've never worked on a solid state amp before. It looks more like a computer motherboard than an amp.

Any ideas?

Vic Winters · #2 06-28-2010, 05:36 PM

Try spraying contact cleaner in all the jacks then working a instrument cable in and out.

lbwdog · #3 06-28-2010, 06:34 PM

Also, try tightening all the nuts around the amp's output and input jacks. I had a similar situation with my 800RB, and lo and behold, one speaker jack had gotten loose.

gotly · #4 06-28-2010, 06:35 PM

Quote:

Originally Posted by Vic Winters

Try spraying contact cleaner in all the jacks then working a instrument cable in and out.

I'll give that a try tonight but I've already tried plugging the bass directly into the return jack of the effects loop to bypass the eq and tried both Speakon and 1/4" speaker outputs and it didn't make a lick of difference.

fruity2x · #5 06-28-2010, 06:47 PM

Man I had the same thing going on with my 700RBII. I tryed everything you did, it was under GC warranty so they had me send it to Indy (Spectrum Sound, my closest repair shop) and they told me the only thing they found was a dirty FX loop jack...cleaned it up and it pounds like it used to....no problems 6 mo later.

Yeah, just give it the once over with some contact cleaner (little at a time...don't douche it) and tighten everything up. GKs are tanks...they RARELY just up and die (unless you put the wrong size fuse in....oooohhh say...your mid '70 400b

).

BTW...got the same Avatar stack...how long have you had yours and how you liking it?

gotly · #6 06-28-2010, 08:42 PM

Holy bajeezus it worked! I tightened everything and used half a bottle of Deoxit. I'm not sure which one fixed it but I'm back in action!

Thanks so much!

I love the Avatar stack btw, I get compliments on the tone all the time at gigs and they're featherweight. I've carried heavier heads than these cabs.

fruity2x · #7 06-28-2010, 09:04 PM

Right with ya on that....LOVE mine...they boom and cut and just plain ROCK!!!! And my rack is heaver that ether cab...gonna do something about that next...my back is going down hill fast!!!

basscheez · #8 06-28-2010, 09:09 PM

Glad it's fixed. I was going to ask if it did the same thing if you put the head on the floor, i.e. not being vibrated by the cabinet. That would indicate something mechanical.

lbwdog · #9 06-28-2010, 10:42 PM

Quote:

Originally Posted by basscheez

Glad it's fixed. I was going to ask if it did the same thing if you put the head on the floor, i.e. not being vibrated by the cabinet. That would indicate something mechanical.

Many times, that is what triggers these types of noises. In my case, years of cab vibration and transport had gradually loosened the nut around my output jack. Then, the vibration from playing would affect that loose jack and cause it to sound as if a speaker was blown. With tube amps, cab vibration can excite a microphonic tube as well.

hwystar · #10 06-29-2010, 12:04 AM

Using the same set-up as you have, glad all is well, will remember this if I ever have the same problem, Talk Bass rocks!!!!!!

Bart277 · #11 07-14-2010, 02:20 AM

Had the same problem with my 800RB, came across this post done what you guys suggested and what do u know its fixed. Awesome thanks heaps Cheers.

gotly · #12 11-10-2010, 08:49 PM

It's baaaaaaaaaaaaaaaack!

The crack, buzz, crackle that is.

This time the volume is VERY low. Like 1/4 of what it should be. I re-cleaned, re-tightened everything and it didn't make a difference.

Changed all cords (input, output (both speakon and 1/4"), power cable). Tried with 2 basses and a guitar for good measure. Tried with 2 different cabs.

Here's something that really worries me. I tried taking the output straight from the XLR direct output into my band's PA. The same fuzz, crackle, fading volume persisted. I've attached a diagram of the circutry and there really isn't a whole lot that can go wrong in there.

Here's the shortest circuit path that it can take.

Input jack -> -10db Pad (off or on) w/ Clipping -> Tuning Mute -> Pre/Post EQ switch (selected to pre) -> Level -> Direct Out.

I've cleaned it all, tightened it all. Any clues?

Edit: that picture got resized pretty small. Here's a full PDF of the manual. The schema is near the end. http://www.gallien-krueger.com/manuals/700rb.pdf

Bart277 · #13 11-12-2010, 04:19 AM

Mine came back too! I took it to a amp repair place/music shop here in Perth and they fixed it. I am not quite sure what was wrong but they had to replace 3 parts which were blown. Cost $140. Now it ROCKS again!

jazzyb · #14 11-12-2010, 04:37 AM

Quote:

Originally Posted by gotly

Holy bajeezus it worked! I tightened everything and used half a bottle of Deoxit. I'm not sure which one fixed it but I'm back in action!

Thanks so much!

I love the Avatar stack btw, I get compliments on the tone all the time at gigs and they're featherweight. I've carried heavier heads than these cabs.

Exactly same thing with my 700RB combo, cleaned fx loop sockets and the whole thing sounded as good as new.

lbwdog · #15 11-12-2010, 05:19 AM

Cleaning jacks, tightening nuts, checking cables and connections, etc. is about all you can do unless you have some kind of training in electronics troubleshooting and repair. Beyond that, take it to a qualified tech who has the equipment and knowledge to fix it.

If a problem still exists after performing the simple housekeeping tips above, there's probably a part gone bad and can be diagnosed in minutes with the proper test gear, but danger lurks around the corner for those who have no clue in the electronics field. High voltage can be stored in unplugged amps (especially tubes), so please let a pro handle anything beyond the semi-obvious!

unclejane · #16 11-12-2010, 05:26 AM

Quote:

Originally Posted by gotly

It's baaaaaaaaaaaaaaaack!

The crack, buzz, crackle that is.

This time the volume is VERY low. Like 1/4 of what it should be. I re-cleaned, re-tightened everything and it didn't make a difference.

Changed all cords (input, output (both speakon and 1/4"), power cable). Tried with 2 basses and a guitar for good measure. Tried with 2 different cabs.

Here's something that really worries me. I tried taking the output straight from the XLR direct output into my band's PA. The same fuzz, crackle, fading volume persisted. I've attached a diagram of the circutry and there really isn't a whole lot that can go wrong in there.

Here's the shortest circuit path that it can take.

Input jack -> -10db Pad (off or on) w/ Clipping -> Tuning Mute -> Pre/Post EQ switch (selected to pre) -> Level -> Direct Out.

I've cleaned it all, tightened it all. Any clues?

Edit: that picture got resized pretty small. Here's a full PDF of the manual. The schema is near the end. http://www.gallien-krueger.com/manuals/700rb.pdf

Both of my 1001RB-II's came down with this too, both in about the first 6 months after buying them. Both also eventually winked out completely in the preamp section (i.e. plugging the bass directly into the effects-in showed the power amp to be working fine, but no cigar on the instrument-in. The line-out was dead on both too).

Send your amp back to GK for repair - call the factory directly and they'll take care of you. Mine both required new parts of some kind in the preamp section.

To me that was a very high failure rate; I think GK seemed to have a run of amps with defective parts in the preamps, tho of course they've never said anything about it (they're probably just quietly fixing the bad ones as folks call them in, SOP unless the problem is so bad you just flat out have to do a recall).... Once they fix them, they're solid as rocks - mine give me no more trouble now....

LS

BrentSimons · #17 11-12-2010, 09:54 AM

Hey Guys,
My 400RBIV is doing the exact same things. Buzzing, drops in volume,etc. Problem is cost of repair + shipping to and from GK.

Brent

gotly · #18 11-12-2010, 11:52 AM

Quote:

Originally Posted by unclejane

Send your amp back to GK for repair - call the factory directly and they'll take care of you. Mine both required new parts of some kind in the preamp section.

LS

How much did they charge you for this repair?

BrentSimons · #19 11-12-2010, 03:30 PM

+1 I would like to know too.
Brent

xsamxriverax · #20 11-16-2010, 04:41 AM

you know i've been having this problem too with my 700rbII. i thought it was a blown speaker in my cab and went as far as disconnecting one of the speakers and that got rid of the blown speaker sound, but my tone in my amp is still pretty weak and also when i bring my volume nob down it starts to crackle and pop and the bass boost nob and the other nob in that section are real tight and hard to move maybe this is my problem too, i bought mine about 8 or 9 months ago im thinking i'll take a visit to good old samash in Sarasota, fl and see carlo about this warranty stuff, he's been pretty good to me about everything i've ever bought there, might as well keep the business going with him, thanks for the info guys i really appreciate it, i thought i was alone in this world haha