Mystery Speaker Death

Jubey Monster · #1 11-30-2011, 07:28 PM

Hey guys,

Wondering if anybody with the knowhow could advise what's gone wrong with my setup here. I play a GK 1001RB into a Behringer BB410 cab, and earlier today with nought but a slight staticy fuzz the sound died. The amp is clearly still receiving power judging from the lights on it, bass is ok as I tested on another amp, also tried using a 3/4 inch jack lead to connect the amp to the cab to test whether it was one of the speakon inputs that had fizzed out.

I don't know a whole lot about wiring, fuses, crossovers (the BB410 has a tweeter that I normally keep on, still no sound when I flicked it off) and what not but I'm hoping that it'll be a simple repair job on the part of the local electrician.

Any helpful information or diagnosis suggestions would be most welcome, cheers.

billfitzmaurice · #2 11-30-2011, 07:42 PM

You need to try the cab with another amp and/or the amp with another cab.

basscooker · #3 11-30-2011, 08:35 PM

the speaker knew it wasn't worthy of the amp, so it just quit

basscooker · #4 11-30-2011, 08:40 PM

ok, sorry i could't resist. like bill said, try every pc of the puzzle seperately until you find out which is to blame/ not working right. then you'd maybe get a little better help on how to remedy the issue, or you'd know which pc to take in. is the gk under warranty? does it have an impedance selector? are you using a bona-fide speaker cable? bass need batteries? there's my input {pun intended}

Jubey Monster · #5 11-30-2011, 09:00 PM

Cheers guys, I'm going to take the cab in to the local music store tomorrow and try a different amp on it (I strongly suspect the speaker myself). Everything else seems to operate like normal.

Eric Moesle · #6 11-30-2011, 09:14 PM

I would suspect the cord first, then the cab, then the amp.

The cab being a Behringer sets off warning sirens. They aren't known as the most robust kid on the block, widely considered "disposable" once something goes wrong with them.

johnk_10 · #7 11-30-2011, 09:17 PM

i'd get a 9V battery and touch it to the speaker cable (connected to the cab only) and see if it at least makes a clicking sound.

Jubey Monster · #8 11-30-2011, 10:06 PM

A ha, I did the 9 volt test, I did in fact get a click...

johnk_10 · #9 11-30-2011, 10:38 PM

with a fresh 9V, you should be able to see the speaker cones move pretty well, so the click should almost be a pop/thump. if it's really a quiet click, the voicecoils could be rubbing, but at least we know that there's continuity.

it kinda sounds like it might be the head and not the cab. but who knows?

Jubey Monster · #10 12-01-2011, 12:15 AM

I rather hope it's the speaker not the amp... I really love the GK... I'll still do the test Bill suggested

Jubey Monster · #11 12-01-2011, 12:24 AM

Dug out my old BVT4500H head and plugged it in, works fine, so it looks like the GK head is at fault. Am I best taking this into the local electrician and getting them to check it out?

johnk_10 · #12 12-01-2011, 12:34 AM

just for the heck of it, i'd patch a short guitar cable into the loop of the send and receive jacks to see if it passes signal. also, i'd try clicking the mute button in and out a few times. the GK head's light is blue and not red, right?

Jubey Monster · #13 12-01-2011, 12:38 AM

Yep, it's blue. Do you mean patch the one lead into both the send and return of the effects loop? What should I expect to see (I never use it, only run effects in-line)? Browsing the manual I noticed that it advised against 4 conductor speakon cables. I've used the cable I have with a bunch of different amps, but just for the heck of it, would anyone be able to tell me how to spot whether min is 2 or 4 conductor?

johnk_10 · #14 12-01-2011, 01:15 AM

it doesn't matter whether you've used the send receive jacks or not. plug a cable out of the send and into the receive. that bypasses the switches in the jacks which make contact between the preamp and the power amp.

a two conductor cable will have two contacts and two wires in the cable. a four conductor will have four. it's model # also sometimes written on the ends........

2 conductor (#NL2FC):

4 conductor (#NL4FC)

but if it isn't if you unscrew one of the ends and look at the connections or cable.

Jubey Monster · #15 12-01-2011, 01:30 AM

Unscrewed the speakon, definitely 2 conductor. Adding a guitar cable into the effects loop didn't change the result. Given that the amp "appears" to be working correctly (lights all the right colour e.t.c) is it fair to assume the issue is localised to something like the output stage (for lack of a better term) of the Amp? Thanks for all the help by the way, I've learned quite a bit today.

johnk_10 · #16 12-01-2011, 02:55 AM

it's still hard to say.
you could find out by patching out of the GK's send into another amp's receive (power amp return) to see if the preamp's working. or you could patch out of the preamp from another amp into the GK's receive to see if the GK's power amp is working.

Jubey Monster · #17 12-01-2011, 07:33 PM

Right, sorry, just to clarify, I patch a guitar lead from the effects loop send of the GK to the input (where i'd normally plug in) of my old BVT. Do I need to have a cab connected to each?

johnk_10 · #18 12-01-2011, 07:46 PM

you need a cab connected to the amp that you're using the power section of to determine if it's working.