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Dneu2011 6th July 2019 02:42 PM

Power Adapter for ACA Mono Blocks?
I tried digging through the forums and had no luck finding an answer. Do the Pass mono blocks use the same power adapter as the stereo units? I just finished building a pair and below is what I ordered.

MEAN WELL GST120A24-P1M 24V 5 Amp 120W Regulated Switching Table Top Power

Are there other cheaper alternatives to this that have worked well?


Zen Mod 6th July 2019 02:58 PM

if brick is good for stereo amp , it's even better when feeding just one channel

Nelson Pass 7th July 2019 05:12 PM


Originally Posted by Dneu2011 (
Are there other cheaper alternatives to this that have worked well?

The Mean Wells are a little more expensive, but I have found them to be
quieter than most, and they do come with a warranty.

Two issues that you have to deal with on switchers -

The rating of the supply has to be at least the peak current draw of the
supply, not the average.

The switchers use sensing circuits to see if the the load has too low an
impedance, and some of them won't turn on into big capacitors. Others
will deliver limited current until the capacitor is charged.

And of course there is always noise....

MEGA_amp 8th July 2019 12:51 AM

I use one of these to power an ACA, picked up two, one for each channel for MOFO as well, work great, and cheap

LRS-150-24 MEAN WELL | Mouser

xrk971 9th July 2019 06:25 AM

If you want to use a very low ripple linear alternative. The SLB SR PSU can work very well. Under 1mV rms ripple with 4A of current and just requires connection to a trafo. It handles rectification, CRC, and ripple control.

kamco 11th July 2019 07:01 PM

5 Attachment(s)
On the other hand, if you want to do something totally over the top that's impractical from a cost, size, weight and usability perspective...

500VA 30+30 transformer > 25A Bridge rectifiers > 22mh toroidal chokes > 50V 30,000 uf capacitors > LT338 regulators (set at 23V) > 50V 30,000 uf capacitors. Connected to the ACA with Neutrik terminated star quad cable.

Kind of silly for a a measly 8 watt amplifier, but if you have all of parts in your amp-building stash, why not? Thanks to Nelson Pass for the excellent design.


Zen Mod 11th July 2019 07:25 PM

I like overkill


Dennis Hui 11th July 2019 08:32 PM

Nice! Haven't seen a TO-3 regulator in a while.

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