April 27, 2015 Leave a comment
A couple of months ago I stumbled upon the discussion thread for Richard Murdey’s J-Mo Mk. 2 headphone buffer on diyaudio.com. Richard runs RJM Audio (which you should definitely check out if you haven’t already) and is also the man behind the Szekeres VE design that I built a while ago (see this post).
I am not sure why the J-Mo caught my eye, probably the simplicity of it, but it did. Richard already has a nice PCB for the design, but as I thought I could make it a little smaller, substitute some parts for more commonly available sizes and also improve the versatility a bit I decided to “roll my own” boards instead :)
I downloaded the eagle-files that Richard graciously provide for download, ripped up the original PCB file and got to work. The result is here in dual-mono format with amp and regulator on separate PCBs similar to the original. Apart from the revised layout my changes are relatively minor, mainly different component footprints where I thought it made sense and of course different heat sinks.
The rectifier bridge PCB is from my second Gainclone design and was perfect for making the unregulated DC voltage that the Zener regulator requires. The bottom plate in the pictures was just one that I had left over from another project and was suitable for mounting the boards. There is no wiring in the pictures, but the boards were wired up and it does play wonderful music (although feeding it with wonderful music seems to be required… :D)
As usual I didn’t really listen for a long time while it was sitting on my desk in “prototype mode”, but what I heard was good enough that I have ordered a proper mounting plate (i.e. one that fits in a standard enclosure), a transformer and some chassis part so I can give these great boards a “real” home :D