speaker cab troubles

M Sterling · #1 11-07-2010, 04:00 PM

I have a SWR Son of Bertha 1x15 cab that I bought used about a year ago. I got it home from my gig last weekend and when I plugged it in, it sounds like a blown speaker. I took the grille off and I don't see any damage or breaks. I took the back panel off and the fuse inside looked blown so I replaced that. It still sounds the same and I can't determine what the problem could be. Im assuming it is tech time, but wanted to see if you guys had any suggestions of other troubleshooting measures I can take. Thanks!

And I · #2 11-07-2010, 04:07 PM

when you say it sounds like a blown speaker, what does that mean? what sound is it making? to see if the voice coil is blown, take a 9-volt and put the positive end against the tip your speaker cable (will this work through a speaker cable plugged into the back of the amp or do you need to pull the speaker?). you should see the speaker move out. try putting it against the negative terminal on the battery and it should move in. if the speaker moves, it's not blown. does this cab have a horn? it could be some wiring in the cab itself got rattled loose or the crossover is shot or something... if the cab has a fuse, it likely has some sort of electrical stuff inside. and if the fuse is blown, something electrical inside the cab may be bad rather than the speaker itself.

M Sterling · #3 11-07-2010, 04:37 PM

Quote:

Originally Posted by And I

when you say it sounds like a blown speaker, what does that mean? what sound is it making? to see if the voice coil is blown, take a 9-volt and put the positive end against the tip your speaker cable (will this work through a speaker cable plugged into the back of the amp or do you need to pull the speaker?). you should see the speaker move out. try putting it against the negative terminal on the battery and it should move in. if the speaker moves, it's not blown. does this cab have a horn? it could be some wiring in the cab itself got rattled loose or the crossover is shot or something... if the cab has a fuse, it likely has some sort of electrical stuff inside. and if the fuse is blown, something electrical inside the cab may be bad rather than the speaker itself.

As far as the sound goes, it sounds distorted with no low end at all. I tried the 9v battery test and the speaker did not move in either direction. I did hear a pop when I touched the positive side of the battery to the tip and the negative side to the sleeve of the cable. There was no noticeable movement though. I guess this means it's a blown speaker?

craig.p · #4 11-07-2010, 04:41 PM

First, make sure the speaker frame isn't rattling against the baffle board, which could happen if the mounting screws are coming loose.

Then check to make sure the speaker wires aren't dangling onto the back of the cone.

There'll be some type of crossover in the cab to protect the tweeter. It could be something as simple as a single capacitor wired to the tweeter. Make sure all this stuff is still secure, no loose solder joints, etc.

Check to see exactly where the crummy sound is coming from -- either the woofer or the tweeter.

Make sure all the connections inside the cab are good and tight. Also make sure the phone jacks' spring contacts (to the incoming phone plugs' tips) are good and strong. If you're not using the phone jacks, then of course that last one is n/a.

Let us know how all that goes, and we can take you from there.

craig.p · #5 11-07-2010, 04:43 PM

Sorry, was writing that when M.S. was replying. I'll leave it there anyway.

And I · #6 11-07-2010, 04:49 PM

sounds like it might be... but don't take my word as definitive. i'm not 100% sure if the 9v trick works through a speaker cable or if you need to pull the speaker and touch the (v to the speaker leads... i wouldn't try to run any more sound through the cab--that fuse that blew would appear to belong to the horn protection circuit.

the 9-volt to the speaker lead is what Blue Sky had me do when i thought my sub was blown in my studio--it turned out to be the electronics. i think in your case it could be the speaker--that pop you heard was probably from the horn. i'd wait till someone who actually knows what they're talking about chimes in though.

a replacement speaker is $300 bucks. ouch...
http://www.fender.com/products/searc...tno=0078021000

what head were you powering it with? did you have it cranked? any distortion/effects pedals?

M Sterling · #7 11-07-2010, 05:01 PM

I was powering with a little mark 2 and running it with a workingpro 4x10. Lot's of effects (distortion, synth, octave, etc...) but I never crank my amp very high. 300 bucks would not be cool seeing as though I only paid 200 for the cab in the first place.

And I · #8 11-07-2010, 05:41 PM

wow, nice price. they sell for $650 new!

assuming you got it used who knows how the previous owner beat on it...

you can get a 300W 15" eminence speaker for like $120, plenty of other replacement speakers would work fine as well. but again--don't take my word for it that slapping a new speaker in the thing will fix it, i'm no expert.

M Sterling · #9 11-07-2010, 05:47 PM

Yeah, I got it from a good friend who owed me a favor. I should probably just take it into the shop. The thing that gets me is that I can't see any damage on the speaker cone. I don't know too much about speakers (obviously!), so I don't know if this matters or not. Thanks for the help guys!!!

And I · #10 11-07-2010, 05:55 PM

the cone itself might be just fine. there are lots of parts to a speaker that you can't see...

anderbass · #11 11-07-2010, 09:24 PM

Might as well find out if that speakers voice coil is dragging. To do this I use my hands open palm to carefully push the speaker cone in about a 1/3" or so (and then let it back out) several times. It should move smoothly and silent, If you feel or hear any dragging/scraping sensation you've found your problem and the speaker needs reconing or replacement.

m.oreilly · #12 11-07-2010, 09:35 PM

Quote:

Originally Posted by anderbass

Might as well find out if that speakers voice coil is dragging. To do this I use my hands open palm to carefully push the speaker cone in about a 1/3" or so (and then let it back out) several times. It should move smoothly and silent, If you feel or hear any dragging/scraping sensation you've found your problem and the speaker needs reconing or replacement.

this is a simple, telltale test. if blown, you will detect obvious drag. if this is the case, please don't pay $300 for a replacement driver...

lbwdog · #13 11-08-2010, 12:13 AM

Quote:

Originally Posted by m.oreilly

please don't pay $300 for a replacement driver...

+1
Eminence has an extensive line of drivers with all kind of specs. Surely there's one that will work great in your cab.

Jim Campbell · #14 11-08-2010, 04:29 AM

Quote:

Originally Posted by And I

when you say it sounds like a blown speaker, what does that mean? what sound is it making? to see if the voice coil is blown, take a 9-volt and put the positive end against the tip your speaker cable (will this work through a speaker cable plugged into the back of the amp or do you need to pull the speaker?). you should see the speaker move out. try putting it against the negative terminal on the battery and it should move in. if the speaker moves, it's not blown. does this cab have a horn? it could be some wiring in the cab itself got rattled loose or the crossover is shot or something... if the cab has a fuse, it likely has some sort of electrical stuff inside. and if the fuse is blown, something electrical inside the cab may be bad rather than the speaker itself.

just unplug the speaker cable from the head and hold thev 9 v battery to the tip/shaft of the plug....easiest way to test the cab is to try it with a head that you are sure works....

M Sterling · #15 11-08-2010, 06:39 AM

Thanks for all of the responses. I will do the test suggested by anderbass tonight after work. And yeah, $300 is crazy for a replacement. If the speaker is blown I will be looking into another brand for replacement.