About 12 years ago i was looking to learn a bit more about amps and got a kit. This was before the days of ampmaker so I had to import from a company called STF electronics. The website is long gone
It was a 5w champ style with added tone control and master volume.
I built it, it worked well and sounded nice. but my build was quite messy, potentially dangerous and a little noisy so as soon as kids came along it got put away and forgotten about.
I found it today, and i am much better at wiring neatly these days so time to rebuild it
Thankfully i still have the instructions from the kit
paints peeling off in big chunks and surplus PT wires just taped up
and now for something really scary - a proper rats nest of wires... not sure why these never got trimmed back???
That's the starting point. Its now dismantled ready for a much neater rebuild. The wiring on the board is actually okay and the soldering is fine so i think it should go back together well
those pics above are an embarrassment, but it will be nice to see it put back together properly. and I plan on making a proper case for it - i think something fancy in solid wood will be nice
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I don’t mind admitting not everything I have ever done has been perfect.
I seem to remember rushing this with the intention of tidying up once I knew it worked... but once it worked I just never got around to it. Until now.
anyway, its all dismantled now. I put some primer on the chassis front yesterday and sprayed a coat of gold top gold this morning
The board:
The transformers
The circuit
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i guess noise levels will be improved just by improving the neatness of the wiring
also, what’s the best way to deal with the mass of unused wires on the PT? Is cutting them short and heat shrinking the ends enough?
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Also a switch to change the negative feedback (22k resistor from the PT secondary) is usually worthwhile. Use the switch to either change it to a higher value or remove it completely.
Heat shrinking is OK, or alternatively you can run them through the hole into the chassis and terminate them in a suitable terminal block that's mounted to the chassis - nice and neat then.
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You can also have a play with different (or even remove) the 6v6 bias resistor bypass capacitor(s). 50uF seems to be quite common.
and rewired all the PT section. All spare wires have been cut short, heat shrinked and held out the way in the block.
i plugged it in at this stage with the tubes in. The purple jewel light works and the valves are glowing
Its ready for the board to go back in
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If you are going to do it, have it on a SPST switch for a ‘boost’ mode
Rift Amplification
Brackley, Northamptonshire
www.riftamps.co.uk
That amp had very little touch response too - although I think a lot of that is down to the speaker, since it was *much* better through a 4-ohm-wired Marshall 4x12" . Basically the 8" makes it almost totally a one-sound amp whatever you put through it.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
this thread will move onto the cab build shortly. I fancy something in solid wood. I have some lightly flamed olive ash on the way that will work well although I may mix it up with some walnut. I just picked up a dovetail jig and like the idea of contrasting woods in visible dovetails
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I plugged it in to test and it worked, but was really dull. I spent a minute or two fiddling with the controls to see if they helped. They didn't
Then i realised the i was playing the guitar on the neck pickup with the tone all the way down. duh.
It sounds great and all the controls work as they should so I am not going to mess around with the circuit just yet, althoug a switch that gives two voicings is pretty tempting
Lets move onto the box. My main considerations at this point are size and ventilation...I assume i don;t want to make it too small
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It's been a while since I read much on wiring in valve amps, but the following sounds familiar with regard to keeping noise down...
Maintain the twist in heater wires for as long as possible, run them close to the chassis, and don't span one of the wires across the valve base (come in from each side).
Avoid having signal and HT wires running alongside the heater wires - cross over those at 90°.
At the bottom valve, the heater wires to the left look like they could have a bit more twist, and it looks like there are signal or HT wires running alongside for some of the way. If you try raising them, or routing them differently, you might be able to reduce the noise further. Easy enough to check the effect by moving them around while the amp is on (with the aid of a couple of bits of stick or the like, if you want to keep your fingers clear).
Nomad
Nobody loves me but my mother... and she could be jivin' too...
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