Friday, November 7, 2008

Tranny amps - built like tanks, eh?

Solid state amps used to be so simple. Nice old HHs, Acoustics etc - lovely. Then they started working on getting more and more watts out of smaller and smaller boxes.

I do sigh just a little bit when a bass player comes in bearing some behemoth amp capable of delivering a kilowatt or more (ie it would heat up a one-bar electric fire very nicely). Of course it has fused most of its output devices, and no doubt much else besides. Maybe he bunged it on a padded chair in a pub and blocked up the huge fan which is meant to dissipate all that heat. Pop. Or maybe he shorted the speaker leads - same result. Or maybe it just burned itself up for the hell of it. Well it can usually be fixed, but it does take time and it does cost money guys. Cooling is really crucial for these amps, and if there are twin power amps and only one speaker lead, don't forget to put it in 'bridge' mode - both amps on 5 is a lot cooler than one on 10.

Power supply faults (causing weird combinations of symptoms but usually little or no sound) and op-amp failures (distortion, loss of volume, loss of sound altogether, noise) complete the list of familiar westbound route for solid state amps.

All these things can usually be fixed. However (here follows a bit of a grumble, so ignore it if you like as like many grumbles it is no doubt a symptom of Weak Character) - some recent transistor amps tend to be made of specialised ICs - like computer chips - which are often either impossible to obtain or very expensive. Very recent amps have Surface Mount Technology or SMT, which makes their circuit boards both reminiscent of Solihull from 30,000 feet and also tricky to service. If they go wrong you're meant to approach the manufacturer for a replacement board, which of course gives the faceless, be-suited ones the opportunity to discontinue the board and force you to buy a new amp... which is possibly good for the third world economies that manufacture the things in vast automated plants but is not good for the pocket of the struggling musician or indeed that of his ol' pal Honest Steve the amp repairman.

And from now onwards amps will have to be built with lead-free solder, which melts at a higher temperature than good old tin/lead, does not stick to metal so well, and sets to a nasty matt grey. This is so they amps can be recycled safely. You guys are always just chucking your amps in the bin willy nilly aren't you? All those '68 Marshalls in landfill sites are endangering the environment, it's got to stop.

It's all a bit of a yawn. All of which goes to show how behind the times I will be, until I get a hot air SMT repair station. Then I'll be able to fix your mobile while you're here. Why does that idea seem so hateful to me? Weak Character again.

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