Euro Oakley - Growth issues

[Pav]

Hi all,
just reviewing power and case requirements for my 2023 Eurorack module build plans -2023.
I currently have a 6U case with 17 modules in with Oakley Euro PSU, and PA30 brick

Current calculation for these is +12 664mA -12 587mA.

I have placed an order for 3 additional modules that would take this to

+12 795mA -12 703mA , that exceeds the PA30 spec , and the 10% contingincy is
totally blown. And there is still panel space to fill up.

So my thoughts turn to the "unrecommended option" of transformer+mains to increase
capacity. The Euro PSU page states you had safely tested it to 1A.

1) Do I assume right that was with a Transformer ?

Now , I have an Oakley Sequencer +85 mA in a separate case with a tiptop happy ending.
so im also thinking I should move to a 9U case and include this.

At present all my pus options seem to suck..
- Doepfer "Low Cost" 9U case has gone up #100 squid to 455 , and adds noise.
- Tiptop Uzeus power boost seems to boost +12 but leaves -12 at 500mA.
- Tiptop Zeus 3 boards probably takes up to the Doepfer price.

- Dual PA30s and Oakley PSUS - not keen on as it takes my tally of floor bricks
to Six ..the carpet is getting warm ! ...and electricity of course is
now so pricey that after my fixed price contract expires, may mean i only switch
on wall of synth for 1 hour a day //tongue firmly in cheek .

Q2 ..having said that how best to drive 9U case with 1.25 Amps of expected current rwuirement
to fill it. ?

How have anyone else ( except Eljay - I know his system :-) solved their growth issues ?

Merry Xmas
Pav

[Synthbuilder]

So my thoughts turn to the "unrecommended option" of transformer+mains to increase capacity.

I'm not saying anything. But if you do it, then use common sense and keep everything at high voltage well and truly out of reach of fingers. Preferably with two layers of something. Doepfer uses a small earthed metal frame covering the already insulated high voltage wiring.

The Euro PSU page states you had safely tested it to 1A.
Do I assume right that was with a Transformer ?

Actually it was with my current limited bench supply. However, electrically speaking a transformer of a suitable rating would have a similar results.

[waldenpotato]

I don’t have experience with them, but would a Power One power supply be an option? They can provide more power. I wonder if you don’t load them to their max if they can stay cool and quiet enough.

But I think these power supplies would still expose your fingers to high voltages.

[Pav]

I will check out this Power1 ,ta.
Im not likely to touch live ac ,. I tried it once but was lucky to be able to drop the power cable which shocked me. Shook me up.

[Synthbuilder]

I will check out this Power1

Just noticed this.

Power One supplies and their clones are good supplies but there are a few important points to note when using them in a modular synth.

1. They latch up really easily on power up. This is because they use a system called current foldback limiting. This is a good system as it actively reduces the amount of current that is delivered during a short circuit to below the current limit. This reduces heat build up in the power supply. However, it does make it more likely to latch up as you switch it on. This is because all those electrolytic capacitors on the supply rails in your modular present a short circuit the moment that power is turned on. This confuses the foldback system and one of the +/-12V rails can fail to power up properly.

It is possible to modify the Power One modules to stop this. But whether you do have this problem will depend very much on how much capacitance is connected across the rails. I've seen some Euro modules have 220uF on their power rails. It's the reason I went from 22uF to 2u2 on my own modules years ago.

2. They hum. Almost all Power One supplies audibly hum when run from 240V. They seem to be much quieter when running from 110V.

3. Exposed high voltages. I used to use modified Power One supplies in ready made Oakley Modular systems back in the early 2000s until I developed my own low voltage designs. However, I put them in a separate earthed metal box and connected them to the modular with a four way Neutrik Speakon connector. Neutrik now do special power connectors for this very purpose.

4. They are not designed to be put into sealed wooden boxes and deliver their rated power output. They need air flow to work at their maximum output, or be mounted on a suitably large metal panel that is exposed to the air.