Amp/Speaker Crackle

[FretlessOnly]

Hey all: I'm getting some static/crackle from my rig, and I've rules out cables, so it's either my cab or amp pots most likely. I have a GK 700RB (~3-4 years old) and it's connected to an older GK 4x10 (no ID on this one, the markings are almost all worn off). The static/crackle isn't terribly loud, but noticeable. It's most noticeable whn I turn up the woofer volume as opposed to the gain or master knobs, and it happens mainly from notes on the A and E strings.

So, it could just be a beat speaker(s). That it mainly happens on lower bass notes (mid E to low E mainly) indicates speaker(s) to me, but I suppose it could also be the pots. I have some deoxit; how should I go about working on the pots? Just remove the knob and wipe the pot shaft, or do I need something more invasive inside the amp chassis?

Is there anything I can do to clean the speaker connections? Or any other suggestions as to cause?

Sorry, I'm pretty knowledgeable on theory and improvisational music, but electronics is my Waterloo.

Thanks,

JM

[jps]

Try a different cabinet with the 700RB and also a different amp with your GK cab to determine which is the culprit first.

[FretlessOnly]

Well yes, that's the obvious troubleshoot, but I was trying to avoid schlepping my rig around to figure this out.

[schoolside]

If it is frequency specific it's probably mechanical, but that would be more of a buzz or rattle rather than a crackle. The easiest place to start is to disconnect the current speaker and run to an external speaker, that will help you narrow it down. If you still have the problem with the external speaker it might be something electrical. Common electrical problems are the input jack working loose or corroded control pots.

[schoolside]

Well yes, that's the obvious troubleshoot, but I was trying to avoid schlepping my rig around to figure this out.

You gotta schlepp!

[FretlessOnly]

I should have added that all of my basses do this, and it's certainly not a truss rod or other buzz/rattle on the instrument. It happens mostly on lower notes, but my Ken Smith, which packs hot soap bar pickups, causes it to happen on higher notes as well.

Alright, a-schlepping I'll-a-go.

[schoolside]

I was thinking buzz/rattle as in loose speaker screws or nuts.

[FretlessOnly]

Oh, OK. But still, and I'm pretty sure about this, the sound is not from the cabinet construction, it's from the signal through the speakers.

[jps]

Alright, a-schlepping I'll-a-go.

Yeah, without the schlepping it is only conjecture as to what the problem is.

[beatlefreak]

The first rule of effective troubleshooting is to eliminate the things that are not causing the problem. Change one thing at a time, keeping all other parts consistant. If the problem is still there, move on to the next part. Without doing this, you'll end up chasing your tail almosy every time.

[chrisdski]

I just went thru this with an Avatar 2x10 cab. Weird sound only on very low frequency, open A to open E mostly. I at first thought it was a bad speaker. Turned out to be a loose wood glue joint in the cab's bass port. I isolated it by eliminating the speakers- unhooking them one at a time and sound was still reproduced (I only have 2- where you have 4). Then squeezed and pushed cab till I found where it eliminated the sound. A couple of 2" deck screws to tighten the joint and it's mint. You describe your sound as a crackle which sounds electrical, but I didn't think my sound was cab material when I started. When a sound is frequency specific (only happens when I play open E etc) I'd start with the cab (make sure you have the head off the cab when testing to eliminate vibration on the head). Just a thought.

[FretlessOnly]

Well, problem solved. I bought a GK Neo 212-II cab to go with my old, beat-up GK 4x10, and now, running them parallel, I've split the now 480 watts (instead of 320W into one 8 ohm 4x10) at 4 ohms (two 8 ohm cabs in parallel = 4 ohms) into two cabinets. The old cab now has more headroom and sounds fine and the new 2x12 is connected to my GK 700RB-II with a speakon cable to allow for the horn and woofers to be bi-amped.

Crystal clear sound, with nice growly mids and beefy lows. The horn makes the highs crisp as a chip straight outta the bag.

I had the master on very low but with a fair bit of gain, woofer and tweeter upstairs in my music room, and my wife said that the plates in the dining room were almost shaking off the walls.

[jps]

my wife said that the plates in the dining room were almost shaking off the walls.

You're not loud enough, then!

[FretlessOnly]

Don't I know it! But I just hung those plates for her last Friday, so I thought I'd let them hang in peace for a while before demolishing them with Lark's Tongues in Aspic or somesuch.

[rickenbrother]

Well, problem solved. I bought a GK Neo 212-II cab to go with my old, beat-up GK 4x10, and now, running them parallel, I've split the now 480 watts (instead of 320W into one 8 ohm 4x10) at 4 ohms (two 8 ohm cabs in parallel = 4 ohms) into two cabinets. The old cab now has more headroom and sounds fine and the new 2x12 is connected to my GK 700RB-II with a speakon cable to allow for the horn and woofers to be bi-amped.

Crystal clear sound, with nice growly mids and beefy lows. The horn makes the highs crisp as a chip straight outta the bag.

John, I'm assuming you really dig that GK Neo 212-II cab?