I bought a pair of used Cell 90 cases by Pittsburgh Modular. The power supply that came with each of these was a simple analog supply with a 12 volt AC wall wart that powered a diode bridge rectifier to drive 7812 and 7912 three-pin regulators. For a retrofit I found the Tiptop Audio Zeus Studio Bus. Specs:
- Input voltage range: +15VDC +/-10%
- Output voltage: +12VDC -12VDC +5VDC
- Max output current +12V: 1.3A
- Max output current -12V: 800mA
- Max output current +5V: 300mA
- Output regulation of +/-12V: +/-0.05% Linear discrete design
Although the Zeus is meant to be a part of the Tiptop power system, it works quite well in this application. I reused the existing power inlet and switch, together with a 15 volt DC Meanwell wall supply I use with all my other Eurorack boxes. I had a very specific use for this case. It needed to house a set of modules being moved out of my ‘wave mangler’ Synthrotek portable case to make space for sequencer modules that were too deep for a skiff like the Cell 90. The total power requirements were about 600 ma of +12 and 500 ma of -12. The Zeus could handle that without getting very warm. Still the Cell 90 is a tight case and the Zeus is quite large. So, when drilling holes to mount the Zeus, I added a couple of rows of 1/4″ holes for ventilation. One row is under the Zeus board.
A perspective view.
No modification was needed to the power inlet, a 2.1mm barrel, or power switch. All I had to do was to cut off the original connectors and hook to the Zeus, which has very convenient spring-loaded power connectors. Also I added a banana jack as an additional ground, because I connect all power supply grounds in my system.
Because the Zeus stands on 1/4-inch spacers for ventilation, there is reduced clearance above it for modules. All skiff-ready modules work fine. And there is enough space at either end for up to two 6 HP width deeper modules. Fortunately for me that’s exactly what I needed. The WMD Pro Output is a deep module that fit perfectly at one end.
Then I ran into a bit of a snag. First, a picture of the loaded case.
This is almost exactly the bottom row from the other case, plus M.I. Shades. In theory it should all have fit, but the Cell 90 wasn’t quite 90 HP. It lacked about 2 mm to fit everything, so the 4 HP WMD Quad AAF, which is a part of the Phase Displacement Oscillator system (along with the Triple Bipolar VCA) had to be jettisoned and a 2 HP blank used, for the time being.
See also the updated modules in the Spillover Eurorack post.