Tuesday, 21 April 2009
Making it safe!
Mucking about with valve amps is fun...but less so when the original manufacturer of my amp project's idea of a safe mains connection was a knotted (for strain relief) length of two core with a 1.5 amp slow-blow fuse in a weedy holder, they didn't have health and safety in 1964 clearly. As a concession to modern use I've chain drilled and punched out a hole in the back of the amp chassis for a three pin euro-socket, added a proper period Bakelite fuse holder and grounded the chassis to boot...that ought to stop all that leaky electricity making a big puddle on the floor that someone can step in!
I keep finding bits of redundant circuitry (left over from it's tape recording origins) in the amp as I work on it and have great satisfaction in ripping it out. Every time I junk something I fire up the amp to check I haven't trashed anything vital and so far so good.
Even though I've used valve guitar amps most of my playing life, their inner workings...short of simply swapping tubes...have always seemed some sort of voodoo to me. I decided that was going to change, so I started reading up on valves and amplifier theory...In fact I've gone a bit mad and burnt the midnight oil more than a few times learning my plate resistors from my cathode bias. This little amp has taught me more already than I can quite believe.
I'm now scouring e bay for a vintage 16 Ohm 12" speaker to go with the little beastie.