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.

This project is freely available, and you can have the boards produced yourself. That's not for everyone though, so I've decided to sell the PCBs for the BSTRD on Tindie.

The Bill of Materials on hackaday.io has been greatly improved, and even contains a Mouser shopping cart for all parts except the tubes, tube sockets, LED resistors and transformers.

About 10% of the customers have found it worthwhile to review the Muffsy products on Tindie. 

It's always very interesting to hear what people think, and it is especially rewarding when they are happy.

The reviews, although very favorable, aren't 100% positive. People think that the power supply should be offered as a kit, and that the older PCB only versions aren't sufficiently documented.

You have been heard though. The power supply is now a kit. The older, PCB only versions have all sold out, and have been removed from the store.

I get to interact with a lot of the customers, and I'm really happy that I can be of assistance. Many of these conversations lead directly to improvements of the documentation.

With improved instructions, and a line-up of products that makes it easier than ever to build a complete phono stage, now might be the time to get one for yourself.

If you get all the products from the Muffsy Phono Preamp Tindie listing, you'll save $20 on lowered price and shipping.

The reviews mean a lot to me, and I hope to see more of them. Also, do reach out to me on the contact page if you are in need of assistance or just want to chat or if you have ideas for improvements.

The Muffsy Phono Preamp is made to fit perfectly into a B0905 enclosure without any need for drilling or other modificatons. The back panel has to be made manually though, and here is the solution!

It's a back panel that also fits the B0905 cabinet, and it has everything you need:

• Four gold plated RCA chassis connectors with insulation
• Power button
• Power jack
• Ground screw

Buy the back panel separately at Tindie, or get it with your Muffsy Phono Preamp order.