We did some noise testing on our Low Loss Distribution Boards.
We've created some high performance distribution boards for Eurorack which feature 5x 1/16" thick copper bars that run the full length of the boards. We feel we've struck the perfect balance of portability/compactness and performance. We are also solving the power cable issue in Euro with these as well. They host 26 'Rabid Elephant' Samtec connectors which are properly gold-plated, keyed, shrouded, latching, and just awesome, in general. They are fully compatible with Eurorack systems.
The Rabid Elephant Low-Loss Distribution Boards intend to reduce or completely eliminate the issues of noise in a modular system. And they do just that. Here's some proof:
Since throwing around theory doesn't mean all that much for the average user, I decided to do what I would call a real-world test. To do this test in this manner would be difficult for many because (1) it was a PIA, and (2) you'd need a solid control for the test and that is not possible in many cases (changing from a ribbon cable to, let's say, a PCB system means other things would need to be changed too... and then our control isn't all that great). Since the boards I've made can be populated with and without the copper bars, I thought it a perfect situation to do a before and after test... without then with the copper busbars installed. Keep in mind that even without the copper bars, these boards are already much better than most distribution systems you'll find.
There are 4x Low-Loss Distribution Boards ('LLDB' from here on out) in my 18U 114HP 'suitcase synth' that I used for this test. The power supply is a dual linear system based on some modified Power One supplies.
I wired up the whole synth with 2 LLDBs without the copper busbars installed. This is the 'before' test.
For the 'after' test, I soldered in the 10x copper bars into the two bare LLDBs and reinstalled everything exactly as it was before.
I put the same modules in the same case locations, same header locations, same patch, same PSUs (linear), same recording levels, same wiring to/fro the busboards,
The results of the test can be heard in clips below. They are recorded right from the synth, into an RME UFX. The first half of the clip is without the busbars installed (just the PCB) and the last half is with the copper installed.
The recording is boosted a whopping +70dB to make the noise very obvious.
Below is the noise test before and after but with no boost... (this is how it would normally be recorded). Not as bad, of course, but it is definitely there. Even at this low level, the high-pitched bleed is indeed problematic and would require a notch filter to remove in mixing... which I did have to do because I recorded something in the time before I put the additional bars in. I can hear the bleed noise *easily* when playing through a PA, headphones, or studio reference monitors. Try it for yourself!
Here are the spectra using Ableton Live's spectrum analyser. The same analyser you'd likely use when mixing a tune inside a DAW:
Without the bars installed:
And with the bars installed:
Here's an A-B video with the spectrum. TURN DOWN YOUR VOLUME IF YOU JUST LISTENED TO THE UNBOOSTED CLIP!:
We plan to manufacture the LLDBs though timing is unknown. We may do a Kickstarter to fund these to get them done sooner as they are not in the standard product pipeline at the moment.
Have fun and be sure to spread love and creativity!