PSU Shootout

Against my better judgement, I recently acquired a fancy and expensive (at least by my standards) EuroRack Power Supply & Distribution Bus. The idea was to replace the beastly old Power One PSU in my travel-rig, as the once-amusing novelty of explaining it to nervous TSA agents has started to wear off. I’ve also found that it has the unfortunate habit of dutifully picking up noise from crap mains and depositing it directly into my signal. This isn’t much of an issue on my home turf, but I’ve encountered some “creative” mains supplies out in the wild. My hope was that a modern device would provide some protection from noise, and also exhibit less gravitational pull while I’m trying to hoist it into an overhead bin or whatever. I’m not sure if I was expecting too much, but I was underwhelmed by the new one, which inspired me to compare it with some of the consortium of power haunting my studio.

What follows is a comparison of four PSU, Distribution, Case, and Ground configurations powering LZX Cadet I (Sync Generator) and Cadet IV (Ramps) modules that are feeding fixed frequency waveforms into a Tektronix 620 scope, creating a Rutt/Etra style video raster.

Configuration 1: “Ol’ Trusty”

PSU: A Music from Outer Space Wall-Wart bipolar power supply, a.k.a. the Ray Wilson special. This is the first power supply I ever made, and it’s powered all sorts of nonsense modules I’ve made over the past 6 years. An AC wall-wart is powering some linear regulators with a series of huge, awesome capacitors. Thorough description of the circuit from the late, great Ray here.

Distribution: Ruin Electronics Buss Board v1.0, made in the austere Canadian tundra by Philip Baljeu. There are 10uF electrolytics decoupling the positive and negative rails in close proximity to each 16-pin IDC connector. This is your basic, solid, no-frills, standard issue bus-board. There are many like it, but this one is mine.

Case: “Woody”. This is a plywood box made from scrap I slapped together to house the “Rutt/Cadetra” I made during my Signal Culture residency. Ironically, it also endured a 3 year stint as the chassis for my Power One PSU, during which time it had a ridiculously overpowered AC fan bolted to its face, and DANGER written across it in Sharpie. It’s back to being a tester Eurorack case again, and a little worse for the wear.

Ground: Welp, the modules are screwed into a strip of wood, so not much help there. Everything is grounded via the bus-board, except the banana/bnc converters (the outputs to the scope) which are grounded to the PSU via a Tayda alligator clip.

Result: This is by far the cleanest raster. Sadly, there are deal-breaking little pips that scan the screen from top to bottom, right to left at high speed. It’s almost not noticeable in a still, but prominent in video. If they weren’t there, this would be the unquestionable winner. Nothing else is even close to the crispness and clarity.

Configuration 2: “KIDS, DO NOT TRY THIS AT HOME”

PSU: A high-amperage, potentially lethal open-frame Power One supply. This is like the kind of thing you’d need to make a Frankenstein’s monster. It would be terrifying if not for the flimsy powder blue chassis that matches so nicely with the 620. This has been my go-to PSU for most of my career as a video artist.

“Good morning TSA agent! Don’t I look nice and non-threatening in my baby-blue costume?”

Distribution: “The fate-tempter”. This is the result overturning a shoe-box labeled “graveyard” onto the bench and grabbing the first things that could be made into a bus-board.

Case: “The free-jazz” (self-explanatory).

“Don’t cross the streams.”
“That would be bad.”

Ground: Gator clippy again, but in a significantly less intelligent configuration this time.

Result: You know, this is pretty impressive given the conditions I put it in. There’s some vertical texture that I’m going to guess is some sort of high-frequency noise. I know this PSU well, and I’ve seen it perform better, but I’m also no stranger to this texture. Honestly, I’m not that mad at this. It’s random and subtle enough that it creates a nice pencil or charcoal effect.

Configuration 3 “The Bouge”

PSU: A Malekko Power EuroRack Power Supply & Distribution Bus, fed by the RECOMMENDED DC POWER BRICK: CINCON ELECTRONICS, TRH100A120 (I copied and pasted the all-caps thing from the Malekko site — I think all the capital letters are meant to indicate to us that the Cincon is made from some sort of special weapons-grade Chineseum). From what I understand, the Malekko seems to be the standard Eurorack video synthesis supply. It uses a switching DC brick *cough*blasphemy*cough* to drive linear regulators. “Utilizing a unique power architecture with switching power supplies cascaded to two pairs of linear regulators, it is designed for low noise and stability“.

PSA: Do not

Distribution: Integrated into the Malekko PSU. “With separate regulator pairs per output section, noisier modules can be isolated from the rest of your rig.” I’m not sure I like the insinuation that some of my modules are noisy, but ok.

Case: This has been my travel case for a little while now. It’s an old camera case that’s been reinforced with an aluminum frame, then drilled and tapped for vector rails. The Malekko has been installed in the case according to the manufacturers instructions.

Look how fancy I am.

Ground: The modules are securely bolted to the rails, which are grounded. The BNC jacks are grounded to the frame and also wired to the PSU with stranded 18AWG. I think this is best-case scenario for grounding.

Result: This is unusable. The best I could get out of it was this paper-towel looking mess, that is unmistakable switching noise. Not impressed. It’s cute as a still I guess, but in action it continuously jitters and scrolls which is totally distracting.


Configuration 4 “The Global Village”

Same setup as #3, but with an old 10-amp power brick I got from eBay to power a bunch of preview monitors for an installation in a bar, where it was left on 24-7 for a few months. Pretty sure this one cost under $20. This is also paper-towelish, but I find the pattern less hideous and it ALSO DOESN’T MOVE ALL OVER THE GODDAMN PLACE. Whatever flavor of switching noise this is (Bounty maybe) is more palatable to me.

Consumer grade?
Better paper towels?

Conclusion: I’m tired. As awesome as it is, I’m too tired to keep dragging the Power One beast around, but it will forever be the first choice in the studio. I hope everyone that comes to see me live likes paper-towels. What’s your favorite brand? Ok, for real though, one other thing that bears mentioning: the Malekko seemed oblivious to mains noise. I plugged lights, a fan, a flatscreen TV, computer, and a camera into the same power-strip, and it didn’t skip an absorbent beat. The same can unfortunately not be said for the straight linear supplies, who can be divas about the kind of power they eat. I’d really love a PSU that has the weight and stomach of the Malekko, with the clarity of the Ray Wilson. Is it out there?