Troubleshooting SWR 2x10 Cab

[Matt in TN]

I recently bought an SWR 2x10 Goliath Jr for a steal from a guy who said it had smoked two of his heads three different times and he was tired of fooling with it. I'm a mechanical engineer with some decent electronics experience, and for the price I thought I'd take a risk.

I've got it home now and can find nothing obviously wrong inside - no sign of a short, no burnt wires, etc. There is one nut that is slightly discolored by heat, but it could be from where a connection was soldered on. I've measured the no-load ohms at various places across the cabinet and get around 6 ohms (it's an 8 ohm cabinet). I did find one slightly loose connection and tightened it.

I'm a little nervous about plugging this in to my amp for fear of frying it, but I can't find any reason not to. Is there anything else I can check short of plugging it up and giving it a go? I'm starting to think to poor guy had a shorted speaker cable or something...

[Walking]

I would electrically isolate each of the speakers, check the dc resistance for a short, and connect them to an amp and turn it up slowly playing low e. You can't give them full power because they aren't physically supported by the cabinet air volume. Let get loud enough that the cones are getting some extension.

Once this is done, you might want to disconnect the crossover and horn, replace the 10" speakers, and give it some full rated power playing my favorite E string, as well as hitting the strings to get transients and so forth.

The only other concern is that the crossover has a failed component that shorts out at large signal levels. All I can suggest is turning up the volume on that slowly and listen for problems.

Also, make sure your amp is fuzed. If the amp doesn't have protective circuitry, it could get blown by the speakers--hard to completely eliminate all risk along those lines.

[eastcoasteddie]

How does the seller know it was the cabinet that fried his amp, and not something else? I'm thinking the same thing about the shorted cable...Usually, the amp will fry the cab... like the Goliath II 4x10 I bought on CL. It was advertized as being blown. Supposedly, his amp fried during a gig and it must have sent some wacky voltage to the cab and blew all 4 speakers and the crossover fuse. I never really heard of a cabinet frying an amp.

[Matt in TN]

Follow-up: I added an external speaker jack to my practice amp (all I've got right now) and plugged it up with a 10 Meg Ohm-meter across the terminals. I was hoping by watching the ohm-meter I would know if a short condition appeared before the amp got fried.

Cabinet worked great, with apparently no issues whatsoever. I feel sorry for the guy I bought it from, but I'm doing the happy dance for getting a great cabinet for $75!

I suppose that with more wattage from a larger amp I could still find a problem, but for now I'm calling it good -