Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Building a solid state guitar amp, everything is ready to go except my rail power is too high. I'm running 52 volts and would like to get around 25-30 volts. I'm using a 36 volt power supply w center tap into a full wave rectifier and two 2200uf 50v caps. What's my best solution? Thanks

Please sketch, scan and post your current power supply arrangement.  I can think of at least a couple of quite different arrangements that would fit your description.

The most obvious first thought has to be buy/scrounge/swap a more suitable transformer.

I think so too.   I have been cleaning out the shop, and scrapping some old dead stereo recievers and stuff.  I been saving their power transformers for just such projects.  A dead smallish stereo receiver ought to provide you a reasonable transformer.  For free.


One possibility.  Is your existing transformer by any chance a 120/240v primary one?  You could probably wire the primary up for 240v operation, but feed it the 120v from the wall, and that would drop your 52v to 26v.

Agree that description is not clear.
Please draw your PS as-is including voltages, polarity and whether they are AC or DC.

I did find another transformer with the right voltage I can use if neccessary. But 'Ill draw up the current configuration and try to get that up here this weekend.

There is a trick using SCR's that can be used to reduce the voltage of a transformer for a power supply (see attached).

The gate trigger voltage is obtained from a divider between the transformer peak voltage and the output voltage.  When the output voltage rises there is a point where the voltage on the gates doesn't rise high enough to trigger the SCR any more, thus limiting the output voltage.

It has a few "gotchas" however;

- at higher voltages the gates may need to be protected by diodes

- the output voltage is a function of the gate trigger voltage which is itself a function of the SCR temperature, so this simple circuit may show a high temperature sensitivity

- SCR's and audio generally don't make for good partners and there may be considerable, and objectionable, high frequency buzz in the output