Power and noise issues

[Gee]

HI!

I have previously asked about noise issues under the “guise” of gain…
That’s when I found out that not all PSUs and modules are created equal in this world:-)

I have had absolutely no luck getting rid of noise when attempting to attach a second unit (both analogue (!) and digital) to the same LIBB bus card…
So, I figure I will put the Percussa in its own 60hp box with it’s own power.

My actual question is what does a bus card actually do, other than distribute power in parallel to multipke outputs? I.e. can I attach the Percussa straight to the power supply unit (that delivers +12/0/-12, obviously), bypassing the bus card? I can’t see from any description anywhere that bus cards do any buffering or stabilising or naything like that?

Thanks,
Girilal

[thetechnobear]

it depends…on the bus board ( * )

sure, at its simplest, a bus board is a ribbon cable (e.g. flying bus systems like tip top)

but reality is depends on the system,

the tiptop systems uses a wall wart providing +15-20v DC, to the power module then regulates this to +/-12v and provides 5v, then indeed a simple ribbon cable connects.

in a ‘fixed’ bus board system, you’ll use a regulated power supply that might provide +/-12v and 5v - however , many of these have some kind of filtering. (basically capacitors) … and for sure, some have more filtering than others. also some bus boards have protection system in them… e.g. to look for shorts (e.g. rev polarity/faults)

here look at the befaco bus board it has the schematics, so you can see what I mean about filtering and regulation.

where all this functionality happens depends on the while ‘power system’ e.g. obviously no electronics in the (flying bus) ribbon cable, so its in the power ‘module’. similarly I suspect that doepfer A100 board is pretty simple, again, probably relies more on the PSU3 for filtering etc.

also aware not all power supplies are equal - there are reasons that the the Doepfer costs more than the meanwell … its not just about power output. basically switching psus are cheaper than linear.

so in theory, sure… you could connect directly, assuming its bipolar and properly regulated .and ofc, if there is no other modules on the same psu… then is filtering needed?

but ofc, to skip a bus board, you’ll need to still somehow ‘rig’ the connectors (often space/ring) to the eurorack ribbon connector…

frankly, bus boards are so cheap, I cannot see why you’d skip…esp, when connecting an expensive module like the SSP

---

( * ) ok, this is only about power… eurorack bus is actually more than power, it has other lines, but I think like many modules, SSP is only using the power lines… and iirc is only +/-12v so no 5v requirement?

[Gee]

Thanks for the extensive reply!

My takeaway is perhaps that I could use s small bus board, just to be on the safe side:-)
… I can’t use the LIBB because a Meanwell and a LIBB bird won’t fit inside a 60HP case…

[thetechnobear]

yeah, this is why the 4ms pods are nice… they have the (small) bus board on the back of the case.

does a meanwell fit in a 60hp rack?

one ‘interesting’ option Ive seen for 60 hp is to use something like the tiptop power module, but mount it on the side/back of the case. you’d not need a bus board for this, since its just uses flying bus (ribbon cables), so you could plug SSP directly into the power module.

all depends what you have / what you want really.

---

edit: oh, just realised, I use 4ms Row Power modules, not the tiptop, but the same applies.
4ms row power is nice, since you can ‘daisy chain’ power.

e.g what I have is.
one 80hp (?) rack with 4ms row power , and a 4ms pod64x (with SSP in it)
I also bought 2 PSUs, which I have plugged in on two different desks.

so what I can do is either :
a) run pod64 with SSP in it, on its own on one of my main desk (w/ daw/computer)
b) daisy chain power , 4ms row power → pod64 when at the ‘audio’ desk with my main eurorack case.
(sometimes I’ll also bring the 80hp rack over to my main desk… and again, daisy chain it)

its a flexible setup… which I find really useful with the SSP, since if Im doing more complex patching, or Im coding, I usually want to do this at my main desk. but ofc, I often want to ‘use’ the SSP with my main eurorack rig.

[Gee]

I will check out the 4ms bus boards…
What I’m trying to do is get the percussa alone in a 60hp and to be able to connect straight to a wall outlet, with an on/off switch. It’s way easier for travel, given weight and other limitations…
And a Meanwell is great for that! (A bit of tinkering and soldering with a ribbon cable is fine by me). That being said, maybe. Bus board in between isn’t a bad idea.
And another 60 hp with the Godfather in it, using the same principle …
The two of them complement each other beautifully for live processing of other sources (voice, hurdy gurdy, Wing Pinger).

But, of course, I would prefer not to blow up my Percussa:-)

So thanks for all the advice and suggestions! Invaluable as always!

Girilal

[thetechnobear]

not sure which meanwell you’re looking at, but they are a bit heavier than wall warts.
… also quite bulky, so the case will have to be either bigger/deeper to fit it in 60hp.

but for sure, I do prefer having power within a case, rather that having a separate wall wart/block.

if you do plan on having 2 60hp cases, daisy chaining power would be useful.
that said… ofc, there is a danger of reintroducing noise…
(though, ive not noticed any when ive done this … but ymmv)

anyway, lots of choices, Im sure you’ll find a cool solution

[Ersatzplanet]

I put mine in a skiff and it is wired directly into a uZeus power supply. No buss connected at all. The uZeus has the “Boosted” wall wart which pumps 3000mA into the uZeus resulting in a lot of extra headroom. The other modules in the case are cionnected via a modified “floating buss” ribbon cable (with a reduced number of connections).