Dead gear: the sequel
At my friend Jacline's request, I played a gig at the local art association with a local pianist, who was a monster player with great chops.
Of course, that's when some gear went belly-up.
Sigh.
120v power is a good and wonderful thing. It powers our lamps, our televisions, our computers.
Since the 1940s, it's also powered pro audio gear. The range of sounds available from musical electronics has changed the face of music, and created a sonic palette different from anything that's come before.
The downside comes with the absolute dependence on amplification. An upright bass viol is loud enough to be heard in an acoustic setting; a solidbody bass, no matter how good, is not. So we who play bass, or solidbody guitar, or electronic keyboards, are completely beholden to the MTBF (Mean Time Between Failures) of our gear.
Gear's gotten much more reliable over the years; the MTBF of mid-seventies and mid-eighties gear could be measured in minutes or hours, sometimes, because it was such crap. I think half the reason for the stacks of amps on stage behind power rock bands during the seventies and eighties had more to do with "at least ONE of them is still working" than actually using all thousand watts (or however many).
By the early nineties, gear had both improved in reliability and shrunk in size quite a bit. That's when I bought the Gallien-Krueger bass head I've used since, on big shows and small, loud and soft. It's small, as small as a laptop, small enough to fit into a flapover bag, and very light. It does 150 watts in stereo, and has killer bass tone. I used that amp a lot, and definitely have gotten my money's worth out of it several times over. Of late, it had been getting a bit unpredictable, though - making some odd hums and such, and generally being weird, generating a following tone on some notes. I've managed to make it work each time, variously by analysing and fixing the electronics and sacrificing chickens to the amp gods (the latter being more efficacious on gig day, fwiw; ymmv). Each time, I was aware that I was betting the farm on something which was acting as flaky as a piecrust, and trusting to its continued good nature.
Until Sunday.
I got to the art gallery and loaded in gear - the bass rig, and the jazz guitar rig. Got everything wired together just so. Turned on the bass amp and it...made....a....SOUND. Buzz---brrrp--- then a descending buzz and pure 60-cycle hum, indicating that something had shorted and I was pushing 120v at 60 hz straight through the speakers. It took all of about two seconds to shut the amp off, but in that time, the damage was done - the amp had shorted through and shunted wall power to the speakers. While it still made sound, the speakers were buzzy, and the amp sounded like crap, with no edge and with a preamp which just didn't seem to work properly.
I hacked together something using the acoustic-guitar amp plugged into the blown-speaker 2x10 bass cab at low volume, and it worked for the rest of the afternoon, albeit with a good deal less clarity than I'd like. After getting home, I tested the bass rig and confirmed that both the amp and the speakers were toast - I can get sound, but it does NOT sound good.
I tore the amp apart last night and have confirmed that there's something - one of the chokes, maybe, or the transformer - shorting to the case. I can't conclusively determine where it's shorting but something has to be hitting the case; that's the only path to ground which would affect the speakers, and I'm pretty certain of that. The meter indicated voltage where it belonged and none where it didn't. There are a bunch of ICs on the circuit board that I can't really test, so at this point, the amp is in Schrodinger mode - I won't use it with a known-good speaker cabinet for fear of blowing it up, and I don't want to replace the speakers in the 2x10 existing cabinet for fear of blowing up two hundred dollars worth of kit.
It's frustrating to be unable to diagnose the amp any better than I have to date. If it were a point-to-point-wired tube amp? No problem - I've fixed a few SVTs on the gig for other players by soldering in new load resistors, and have replaced filter caps on Fenders (hint: discharge BEFORE soldering - they hold current for up to three days after the amp is unplugged). If it were an older amp style with discrete transistors or MOSFETs? Yeah, I can kind of diagnose that. But with ICs and op-amps all over the board, diagnostics require skills and tools I don't have. The oscilloscope I couldn't give away on CL can kind of help, but it's too slow.
So it's off to the repair shop, and fortunately, in the Bay Area, there are two approved shops. At both shops, the bench charge is twice the depreciated value of the amp - that's the charge to simply put the thing on the bench, prior to diagnostic and component costs. OTOH, the amp sounds great. OTOH, it's fifteen years old and I could probably get something newer and cleaner. OTOH, I hate to write off a tool if it can be made to work....so, decisions.
I'll eventually recone or replace the two blown bass drivers in the cabinet . For the time being, I've laid hands on a 4x10 cab with a horn, so I can drive the new cab with a low-power acoustic amp that's got a pretty flat response.
Ultimately, though, it's time to either fix the amp or sell it on CL as a project. I've had it for fifteen-plus years, and it's a familiar tool. But if it's going to let 120v have its way with it, or if it is too fried for repair, then it may be time, finally, to write it off and let it go, and replace it, and deal with a newer, larger amp, and deal with the learning curve to dial it in for playing out, and larger size.
....And to consider getting an acoustic bass so that I can play with a mic if need be.....
Of course, that's when some gear went belly-up.
Sigh.
120v power is a good and wonderful thing. It powers our lamps, our televisions, our computers.
Since the 1940s, it's also powered pro audio gear. The range of sounds available from musical electronics has changed the face of music, and created a sonic palette different from anything that's come before.
The downside comes with the absolute dependence on amplification. An upright bass viol is loud enough to be heard in an acoustic setting; a solidbody bass, no matter how good, is not. So we who play bass, or solidbody guitar, or electronic keyboards, are completely beholden to the MTBF (Mean Time Between Failures) of our gear.
Gear's gotten much more reliable over the years; the MTBF of mid-seventies and mid-eighties gear could be measured in minutes or hours, sometimes, because it was such crap. I think half the reason for the stacks of amps on stage behind power rock bands during the seventies and eighties had more to do with "at least ONE of them is still working" than actually using all thousand watts (or however many).
By the early nineties, gear had both improved in reliability and shrunk in size quite a bit. That's when I bought the Gallien-Krueger bass head I've used since, on big shows and small, loud and soft. It's small, as small as a laptop, small enough to fit into a flapover bag, and very light. It does 150 watts in stereo, and has killer bass tone. I used that amp a lot, and definitely have gotten my money's worth out of it several times over. Of late, it had been getting a bit unpredictable, though - making some odd hums and such, and generally being weird, generating a following tone on some notes. I've managed to make it work each time, variously by analysing and fixing the electronics and sacrificing chickens to the amp gods (the latter being more efficacious on gig day, fwiw; ymmv). Each time, I was aware that I was betting the farm on something which was acting as flaky as a piecrust, and trusting to its continued good nature.
Until Sunday.
I got to the art gallery and loaded in gear - the bass rig, and the jazz guitar rig. Got everything wired together just so. Turned on the bass amp and it...made....a....SOUND. Buzz---brrrp--- then a descending buzz and pure 60-cycle hum, indicating that something had shorted and I was pushing 120v at 60 hz straight through the speakers. It took all of about two seconds to shut the amp off, but in that time, the damage was done - the amp had shorted through and shunted wall power to the speakers. While it still made sound, the speakers were buzzy, and the amp sounded like crap, with no edge and with a preamp which just didn't seem to work properly.
I hacked together something using the acoustic-guitar amp plugged into the blown-speaker 2x10 bass cab at low volume, and it worked for the rest of the afternoon, albeit with a good deal less clarity than I'd like. After getting home, I tested the bass rig and confirmed that both the amp and the speakers were toast - I can get sound, but it does NOT sound good.
I tore the amp apart last night and have confirmed that there's something - one of the chokes, maybe, or the transformer - shorting to the case. I can't conclusively determine where it's shorting but something has to be hitting the case; that's the only path to ground which would affect the speakers, and I'm pretty certain of that. The meter indicated voltage where it belonged and none where it didn't. There are a bunch of ICs on the circuit board that I can't really test, so at this point, the amp is in Schrodinger mode - I won't use it with a known-good speaker cabinet for fear of blowing it up, and I don't want to replace the speakers in the 2x10 existing cabinet for fear of blowing up two hundred dollars worth of kit.
It's frustrating to be unable to diagnose the amp any better than I have to date. If it were a point-to-point-wired tube amp? No problem - I've fixed a few SVTs on the gig for other players by soldering in new load resistors, and have replaced filter caps on Fenders (hint: discharge BEFORE soldering - they hold current for up to three days after the amp is unplugged). If it were an older amp style with discrete transistors or MOSFETs? Yeah, I can kind of diagnose that. But with ICs and op-amps all over the board, diagnostics require skills and tools I don't have. The oscilloscope I couldn't give away on CL can kind of help, but it's too slow.
So it's off to the repair shop, and fortunately, in the Bay Area, there are two approved shops. At both shops, the bench charge is twice the depreciated value of the amp - that's the charge to simply put the thing on the bench, prior to diagnostic and component costs. OTOH, the amp sounds great. OTOH, it's fifteen years old and I could probably get something newer and cleaner. OTOH, I hate to write off a tool if it can be made to work....so, decisions.
I'll eventually recone or replace the two blown bass drivers in the cabinet . For the time being, I've laid hands on a 4x10 cab with a horn, so I can drive the new cab with a low-power acoustic amp that's got a pretty flat response.
Ultimately, though, it's time to either fix the amp or sell it on CL as a project. I've had it for fifteen-plus years, and it's a familiar tool. But if it's going to let 120v have its way with it, or if it is too fried for repair, then it may be time, finally, to write it off and let it go, and replace it, and deal with a newer, larger amp, and deal with the learning curve to dial it in for playing out, and larger size.
....And to consider getting an acoustic bass so that I can play with a mic if need be.....