Hey Roonies!

[John Jordan]

Well Tom, without even clicking the link, my interests are piqued.
Thanks!!

[John Jordan]

Tom-

Down loaded pretty much instantly on a Wifi MacBook. It was quite an undertaking on your part and most importantly, you enjoyed the experiment!

Not being a double E major, a lot is most likely is over my head. But... your conclusions reinforce to me how subtle tweak differences are; especially when beginning with a strong foundation of McIntosh components.

[W9TR]

Glad it worked! It’s the first time I’d used One Drive to host a document.

After listening for several hours last night the quiet power supply made a bigger improvement than was first apparent.

Now I have to package it up - it’s put together in (ahem) a utilitarian way.

I’ll add pics of the test setup and quiet supply later today.

[PHC1]

Originally Posted by W9TR

I finished my investigation into RPi noise and created a quiet power supply mod for the RPi.
Here is a link to the results. It's very technical and will take some time to load.
I recommend using a tablet or PC to be able to properly view all the graphs.
I tried it on my iPhone and I had to refresh it once before it fully loaded.

https://1drv.ms/w/s!Am4mUJvVR_bzgcUp...2VbDw?e=hhMC6Y

If there is enough interest I'll turn it into a series of forum posts.

Tom

Interesting experiment Tom. I read it with great interest.

The proof really is in the measured data but the listening part should confirm whether the differences are significant enough to appreciate them by the audiophile ear. Looking forward to your findings.

[W9TR]

This is the money shot.
Massive reduction in noise on the USB output.

The Green trace is the quiet power supply output. Basically thermal noise from the regulator I used.

The Blue and Cyan traces are the RPi USB noise without quiet power supply.

[PHC1]

Originally Posted by W9TR

This is the money shot.
Massive reduction in noise on the USB output.

The Green trace is the quiet power supply output. Basically thermal noise from the regulator I used.

The Blue and Cyan traces are the RPi USB noise without quiet power supply.

Quite the difference.

[clpetersen]

Very impressive, Tom. Appreciate your effort to build as well as share these results. The regulated low-noise supply in your link is hand soldered on perf-board? Kudos!
Not sure I know what a 'USB sink' is -

[W9TR]

Thanks! A USB sink is the thing that draws power from a USB female socket which is called a source.

In this case the USB sink is my DAC.

The quiet power supply is cobbled together from regulator modules I bought on Amazon, and the filter components I soldered together. It works but is pretty crude.

If the listening tests pan out I’ll design a version with newer high-performance regulators on a PCB.