Phono Preamp Build / by Ryan Morrison

For those of you looking for a high-quality phono preamp, I have discovered a fantastic preamp kit from Muffsy. The phono stage, power source, and back panel can be purchased individually or as a complete kit for $100. The AC wall adapter and enclosure are not provided, but the former is available on Jameco and the latter on eBay. Detailed instructions for assembly and ideas for possible mods are provided on the Muffsy website. Here are my results...

Phono stage (left) and and power supply (right).

Phono stage (left) and and power supply (right).

The build process was fairly straightforward — anybody with soldering and electronics experience can get through it fairly quick. However, there are a couple of issues worth noting:

  • The power supply PCB does not accommodate adequate space for the large capacitors. Despite many attempts to reseat/shift the caps to sit flat, the PCB layout is simply too cramped as evidenced in the photo above by the bulging of the four caps.
  • The screw terminal blocks must be installed with the insertion points facing inwards. This is crucial when using the specific enclosure linked above. The Muffsy instructions stated as much, yet I disregarded this and found out the hard way — I had to remove the terminal blocks and reinstall them. However, there is difficulty whichever direction the terminals are installed. Outward results in an impossibility of fitting the boards into the enclosure, inward results in struggling with other components to fit the wires in the terminals. 
Completed phono preamp with back panel.

Completed phono preamp with back panel.

Minor struggles with the tight PCB layout aside, the greatest difficulty arose with my attempt to save money. Rather than purchase the back panel from Muffsy, I decided to fabricate my own. I managed to do a fairly decent job as seen above, yet my measurements turned out to be somewhat incorrect as pictured below/right in the edge protrusion.

Preamp with enclosure base (left) and fully assembled enclosure with LED power indicator (right). 

Preamp with enclosure base (left) and fully assembled enclosure with LED power indicator (right). 

My finished product doesn't look as good as some of the high-end boutique preamps, but I suppose I can claim function before form. Although I'm by no means an audiophile, the preamp works well, sounds good, and offers flexibility with adjustable gain/impedance. Provided the time, I may quantify performance in a future update/post with tests and a demo video.