Crackling rig. help!

[Sturg21]

Picked up a nice condition GK Fusion 550 head and RBH 410 cab with speakon cables. Played it first and it thumped at 2, sounded great. Just brought it home and it's completely crackling on every note like every speaker is blown, unplayable.
Obv I need to bring to professional but was hoping I'm missing something easy here. I tried using different speaker cables but they don't fit into the speakon input (even though it says that 1/4 is fine online). My question is how can I troubleshoot whether its the head or cab? Unfortunately I don't have another cab to plug into. Any info would be better than the current situation of me staring at it angrily. Thnx

 

[abarson]

I recommend that you find out whether you are using the correct Speakon cable for this setup. Both the amp and the cabinet are designed for bi-amping but you need the correct 4-wire Speakon cable to make use of this feature.
If you have the correct 4-wire Speakon cable, set the selector switch on the cabinet to "Bi-Amp".
If you have the standard 2-wire Speakon cable, set the selector switch on the cabinet to "Full Range".

The G-K website is doing maintenance, otherwise I'd add their direct links.
GALLIEN-KRUEGER FUSION 550 OWNER'S MANUAL Pdf Download | ManualsLib
https://united-music.by/pub/manuals/322/RBH_Owner_s_Manual.pdf

 

[Sturg21]

Appreciate that. I’ve tried both bi amp and full range settings. I found manuals online for head and cab. My speak on cables have a +1 on both ends... I’m not sure if that means it’s a 2 or 4 wire ?

 

[abarson]

Appreciate that. I’ve tried both bi amp and full range settings. I found manuals online for head and cab. My speak on cables have a +1 on both ends... I’m not sure if that means it’s a 2 or 4 wire ?

As stated in the cabinet manual, a standard 2-wire Speakon is wired +1 and -1 (2 wires). and would be used for full range. +1 on one end must be connected to +1 at the other end, and -1 must be connected to -1 at both ends. I would notate this in shorthand as +1/-1.

A 4-wire Speakon is wired +1/-1 for the woofer (low frequencies) and +2/-2 for the horn tweeter (high frequencies). This is specifically for bi-amping.

If you don't have a ohmmeter to test them, maybe invest in an audio cable tester.
PylePro - PCT10 - Sound and Recording - Audio Processors - Sound Reinforcement

 

[FunkHead]

Is your speakon cable different from the one you tested it with before for brought it all home?

 

[Sturg21]

It’s set up exactly the same as when I tested. Cables came with it. I’m stumped. Either way you can’t blow speakers with volume under 3 right?

 

[FunkHead]

Maybe reseat the preamp tube?

 

[FunkHead]

Or plug straight into effects return.

 

[Sturg21]

Friend of mine recommenced that, or could be within the input/crossover circuit on the cab?..first big boy rig for me so kinda a crushing defeat right now lol. Guess I'll start with the tube. Thanks for the feedback

 

[spantini]

This refers to more than one issue. May or may not help.

Bad noise/crackling from GK MB fusion 500, help!

 

[Sturg21]

Nice! I tried searching so not to start a new thread cause I figured these amps have been around a while but nothing came up. Huge help thanks,

 

[abarson]

Or plug straight into effects return.

I'm not clear on this advise. The amp input is at instrument level while the effects loop is at line level. These aren't the same in function or operation. It also doesn't help diagnose the location of the noise.

 

[agedhorse]

It’s set up exactly the same as when I tested. Cables came with it. I’m stumped. Either way you can’t blow speakers with volume under 3 right?

I wouldn't say that's true.

This might be a good time to get some help from a qualified GK service tech. Many techs are quite reasonable at charging for such troubleshooting.

 

[abarson]

There might be some dust accumulated in the controls.
Power down and disconnect.
Rotate each control knob back and forth a few times at a moderate rate.
Plug back in and see if the problem remains. Sometimes it's the simple stuff.

 

[Sturg21]

Will be troubleshooting everything I can tonight. And hopefully get a tech on the line tomorrow. To me being a noob it sounds like speakers/cab are a mess. But most everything I read and hear tells me the amp head is where the problem most likely stems from. I just wanna know who's the culprit so I can replace before gig on Friday.. not likely

 

[FunkHead]

I'm not clear on this advise. The amp input is at instrument level while the effects loop is at line level. These aren't the same in function or operation. It also doesn't help diagnose the location of the noise.

This would bypass the Preamp/tube. I could be wrong but I would think if the noise is gone then that would be good info. No? Could also point to bad connection in the effects loop from lack of use?

 

[FunkHead]

Will be troubleshooting everything I can tonight. And hopefully get a tech on the line tomorrow. To me being a noob it sounds like speakers/cab are a mess. But most everything I read and hear tells me the amp head is where the problem most likely stems from. I just wanna know who's the culprit so I can replace before gig on Friday.. not likely

One thing that caught my attention is that you tried both settings (Biamp/Full Range) with same Speakon cable. Not sure if that could damage something but I don't think your Speakon is sufficient for both applications.

 

[Sturg21]

 

[Sturg21]

I just meant I clicked over to full range and the same crackling ... so you're saying I shouldn't have been using the speakon cables when in full range ? maybe that messed something up.

 

[abarson]

I just meant I clicked over to full range and the same crackling ... so you're saying I shouldn't have been using the speakon cables when in full range ? maybe that messed something up.

Speakon is appropriate for either full range or bi-amp. The difference is whether you use a 2-wire or 4-wire cable. See page 3 of your RBH manual.