While there are lots of quality kits for preamplifiers, I have never really found a decent way of adding more inputs to a preamp. The existing ones are either of dubious quality, spec'ed like a spaceship, or both.

So I decided to make my own input selector. With relays. And an ESP-32 module! A year, and four revisions later, you can buy it on Tindie for $69.

The entire project is fully open source, no strings attached.

So what is it?

It is a programmable input selector for preamplifiers, the size of a Post-IT note, with:

• Four stereo inputs
• One stereo output
• Mute
• Mains power on/off through a solid state relay control
• Break-outs for all ESP-32 pins

It's controlled by a rotational encoder and IR remote, and you get the great build instructions that you've come to expect from a Muffsy kit.

The PCB, all onboard components, ESP-32, rotational encoder and IR receiver are all included in the kit. You also get the fully functional software for it, as well as the Eagle project files for the PCB.

The benefit of using an ESP-32 is that you can program it yourself, and use other functions like touch sensors, Wifi and Bluetooth.

The silvery screws for the Muffsy Back Panel have annoyed me for quite a while, but it has been surprisingly difficult to find ones that are better.

The screws that come with the B0905 enclosure are countersunk, so they won't fit the back panel very nicely. The silver button head screws that I've been shipping from the start are okay, but a little too big for my taste. They also look a little bit out of place against the black back panel.

Here's what I've finally been able to source, and they will of course be shipped with all new orders:

These black button head screws are just a tad smaller, and they make for a much better look of the back panel.

Not having a good thumb nut for the ground screw on the back panel, and the fact that the screws that come with the B0905 cabinet don't really fit has annoyed me a bit.

That's why the Muffsy Back Panel now comes with a brass thumb nut and four mounting screws.

The Muffsy Back Panel is available  on Tindie.