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Re: No load...

If you model with a 5V4GA you'll be pretty close on voltages as the voltage drop should be very similar.

That said, Douglas is correct. Even with a modest load I bet you'll end up with around 475vdc from your supply. My first attempt with the transformer you're using would be converting to a choke loaded supply. Then as Douglas suggested you may need a small cap to raise the B+ to where you need it. I'd bet you'll end up needing around .47 to .68uf.

If you have a modest junk box you can build the power supply into the amp, then clip on various caps until you get the ideal B+.

Remember that without drawing some current, a choke loaded supply will act like a cap loaded supply and still deliver a higher voltage.

Choke loaded supplies tend to sound better imho, but can be a bit more tricky. First you'll need to make sure there is a load at turn-on or the supply will spike to a high voltage initially. A small bleeder resistor will often work nicely. Secondly the choke tends to buzz loudly if run anywhere near ratings. Lastly you'll need a small snubber choke to reduce the stress on the power transformer insulation windings and quiet the buzz. Morgan Jones' book has some nice info on choke loaded supplies.



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  • Re: No load... - Gary Kaufman 07/1/0319:53:15 07/1/03 (4)


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