Hiraga power supply

[audio3]

Hello. I have a problem, anyone help me thank him. I'm building a Hiraga 20w (DIYAUDIOWORLD PCB) with salvage parts, I have a voltage of 27,5V , how can I do to bring it to 21V ?
Thanks

 

[ChicagoJTW]

There are a couple of ways to accomplish this. The simplest would be to insert a power resistor in series with your power supply (one on each side, plus and minus). You might try something around 7-10 ohms initially. The power resistors should be rated for at least 25 watts and should be heat-sinked.

 

[audio3]

Thanks, the other way?

 

[ChicagoJTW]

You can use a regulated supply, though Hiraga generally does not recommend them for his Le Monstre or 20W amp.

Still another means of dropping voltage is to use a bunch of diodes in series. As with the resistors, they will need to be heatsinked.

 

[63781]

It's no big problem running the 20W LeClasse A on 27,5V. In fact the original production version of the amp had 24V supplies, not 21V. At least the one I owned did.

Be aware that the PSRR of the LeClasse A is very low, so the PSU needs to be very stable and clean.

 

[audio3]

Hello. Thanks guys for the answers!
Then I can feed it to 27.5 V, I make some changes to the values ​​of the resistors on the PCB?

 

[juma]

I do it with capacitance multiplier, like this:

An externally hosted image should be here but it was not working when we last tested it.

Rails' voltages will be about 4V lower, the ripple voltage will be decreased by about 50dB and, most important, your amp will sound better.

 

[audio3]

Thanks, I'll try these solutions.
Giorgio