JFET Moving Coil (MC) Pre-Preamp Kit
I received the Boozhound Labs JFET Moving Coil (MC) Pre-Preamp Kit a while back and I promptly assembled the small circuit board. I’m a sucker for a simple kit and a hot iron. That is where it all stopped. The circuit board remained complete and laying about for a few years. Recently I required another MC stage because the tube moving-magnet (MM) preamp I had just completed did not work all that well with the Jean Hiraga MC stage I had been using for years. It appeared the Hiraga had too much output and was over-driving the tube stage. So I needed another MC stage.I borrowed a friends Denon MC step-up-transformer (SUT) unit. The system sounded better with the SUT driving the tube MM stage but also sounded a bit dull. This finally pushed me to complete the Boozhound Labs MC Pre-Preamp kit.
The Boozhound Laboratories JFET Moving Coil Pre-preamp kit includes PCB and all passive components to populate the PCB. Four Stand-offs for mounting the PCB are included. You have to provide your own chassis, power supply (12-24VDC), and various connectors. The Boozhound Laboratories JFET Moving Coil Pre-preamp kit features:
- Minimalist circuit using the 2SK170 JFET;
- ~30dB gain;
- Russian K40Y paper-in-oil coupling capacitors;
- Nichicon Muse electrolytic filter capacitors;
- nice quality PCB (made in USA);
- circuit requires external 12-24VDC power supply (batteries work well);
- Assembled dimensions (height with included standoffs): 4 x 2 x 1.625 (inches).
The MC PrePre kit only has a handful of components and for the practiced DIYer the whole soldering chore can be over in less than an hour. Some of the solder pads are quite small so a fine soldering tip and some soldering experience is required. Some solder points I found a challenge and I have been on the cooler end of a soldering iron for over forty years.
The schematic (shown in Figure 1 below) is from the kit assembly manual. If you take a look at the circuit you will see it is very simple. It is basically the Le Pacific MC PrePre designed with the usual Boozhound Lab tweaks. The tweaks I think have been quite smart and I believe have really advanced the basic Le Pacific designs.
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