I need help figuring out what is up with my bass cab

[Chris Toy]

So I recently bought a used SWR Big Bertha 2x15. Long story short I plugged in a 300 watt 4ohm head to test it, and only got noise from the horn.

Opened it up, 9 volt tested both 15" speakers, both are functioning.

The wiring all seems intact and tight, what else can go wrong?

 

[two fingers]

Welcome to TalkBass!!!!

Sorry you are dealing with this.

The simplest thing to do when trouble shooting is to quickly determine what the problem is NOT.

Try another bass, cable, head, speaker cable, etc. Even if you have to drag the cab to a friend's house or a local music store, remove everything else from your signal chain as a possibility.

Hope we can help get this figured out.

 

[Chris Toy]

I have tried with two basses, a different head,a speakon cable, as well as a 1/4" speaker cable, and have plugged the same heads into other cabs with no issue.

 

[two fingers]

I have tried with two basses, a different head,a speakon cable, as well as a 1/4" speaker cable, and have plugged the same heads into other cabs with no issue.

We have some experts floating around here. I'm gonna tag one.

@agedhorse you think you can help a new member out?

 

[bumperbass]

What I found:
Big Bertha's internal (passive) crossover divides the incoming signal into two frequency bands. The
crossover point is 5 kHz (frequencies above 5 kHz are sent to the tweeter, frequencies below 5 kHz are
sent to the 15" speakers).

This is a 2-way crossover. There must be a problem with a solder joint. Most likely, my experience has been either a solder joint or a break in the wire of the coil feeding the two 15's.
Look closer.

 

[Stumbo]

Try run the amp directly to the speakers bypassing the jack and internal wiring.

 

[Downunderwonder]

One has to be suspicious of your 9v testing and how you determined good vs audio testing no good.

 

[bumperbass]

To clarify, I mean a break in the coil's wire as it enters the circuit board.

 

[bumperbass]

One has to be suspicious of your 9v testing and how you determined good vs audio testing no good.

Yeah, but if he got ANYTHING from the battery, he'd get SOMETHING from the head if the speakers were good. Must be crossover.

 

[Chris Toy]

What I found:
Big Bertha's internal (passive) crossover divides the incoming signal into two frequency bands. The
crossover point is 5 kHz (frequencies above 5 kHz are sent to the tweeter, frequencies below 5 kHz are
sent to the 15" speakers).

This is a 2-way crossover. There must be a problem with a solder joint. Most likely, my experience has been either a solder joint or a break in the wire of the coil feeding the two 15's.
Look closer.

Thanks I'll be taking a closer look, it may be beyond my ability to attempt a repair. Probably just gonna take her into a shop.

 

[bumperbass]

Thanks I'll be taking a closer look, it may be beyond my ability to attempt a repair. Probably just gonna take her into a shop.

If you can solder, I think the board is held on by the jacks. You'll have to actually take it out to look at the other side. It's gotta be a connection. He||, send it to me.

 

[Pulverizor]

Try reflowing the solder on all the joints, no skill required lol, assuming you have an iron!

 

[Matthijs]

Maybe a stupid suggestion, but: did you check that fuse?

Before taking a soldering iron to the crossover I'd bypass the crossover first and connect the amp directly to the speakers. That way you'd be sure the problem is in the xover. Although that probably is the most likely cause.

 

[Slevage]

Try reflowing the solder on all the joints, no skill required lol, assuming you have an iron!

This is called the shotgun method.
Not a good way to trouble shoot something.

 

[bass40hz]

I second the fuse check. I ran into a similar issue with a different brand cab, was going to replace the whole crossover for like $170 then I decided to check the fuse (aka "lamp") and...bingo...it was a $2 fix.
Rock on.

 

[chadface]

Maybe someone monkeyed with the wiring and has the tweeter line going to the drivers and vice verse

 

[moogieotter]

Big Bertha is a big ole girl....bouta buck - o - five.

Love that cab. Hope it's an easy fix.

 

[BogeyBass]

If speakers are fine.

There is a connection issue with the board itself. Or connections at the speakers.

Easy fix is remove dam thing wire jack directly to the speakers. Forget about the tweet

 

[chadface]

If speakers are fine.

There is a connection issue with the board itself. Or connections at the speakers.

Easy fix is remove dam thing wire jack directly to the speakers. Forget about the tweet

I second this

 

[bumperbass]

I second the fuse check. I ran into a similar issue with a different brand cab, was going to replace the whole crossover for like $170 then I decided to check the fuse (aka "lamp") and...bingo...it was a $2 fix.
Rock on.

The fuse only protects the horn, and the horn works.