70's Allen and Heath Console PSU build

[Jamie1234567]

Hi, I’m looking for a bit of guidance putting together a replacement power supply for an old 70’s Allen and Heath mixer. The original power supply is missing, but was apparently 24v/2.4A. The desk is set up in a slightly strange way, where 24v phantom power goes to all mic inputs by default. I intend to modify this, so that the channels have switchable 48v phantom power (this should be pretty straightforward).

I’m planning on building an external power supply and have found a nice steel rack unit to house it in. Rather than starting from scratch, I’ve bought a Power One linear power supply module for the 24v (rated at 3.6A) and a small (320mA) Meanwell switching power supply for the 48v phantom power (I intend to use an unused pin of the 4 pin XLR power connection to get the 48v to the desk).

This is my first time working with ‘pre built’ power modules. I’m just wondering if/how much additional filtering I’m likely to need after the power modules or are they pretty well filtered already? Also, I'll use a fused IEC inlet on the power supply, should I also add a fuse to the 24v and 48v or is that not necessary?

Thanks!

 

[Ritchie Paris]

The Phantom P48 power supply must be as pure and filtered as possible, I strongly advise you not to use a switching power supply, it is extremely harmful to the sound in terms of harmonics, moreover a microphone signal is very weak and therefore sensitive to noise.

A linear power supply is therefore strongly recommended and very well filtered, to conclude a linear power supply would also be very healthy for the console itself, it seems to be 24VDC, right?

Do not forget that the power supply is the fuel of the audio signal, so we must never neglect the quality of the latter in terms of ripple.

I know that many here consider that a switching power supply is enough NO!! especially not believe my professional experience.

If you need help...