The instructions are very similar in nature and quality to the power supply's directions. The head amplifier board is the same size as the power supply board but requires a different set of components. I needed a step-up device, and the Muffsy head amp fits my needs very well. These days, I have a moving coil cartridge that generates about 1/10th of that amount-0.4 mV, or 0.0004 volts. That is, it is designed for a cartridge that generates a nominal voltage of 3–6 mV (millivolts that is, 0.003–0.006 volts). I already have a phono preamplifier in my home stereo, but it only supplies enough gain for a typical moving magnet phono cartridge. Just a quick review of my situation before I start on the build. Once the power supply is done, it's time to turn to the amplifier board. A lot of care went into the preparation of the instructions, and I don't recall ever feeling uncertain during the build. These kinds of instructions and supporting images make the assembly process straightforward and low-stress. The idea is that the builder uses the label adjacent to the yellow pad (LM317, LM337, LM78XX) to identify which IC goes where and uses the silver bar to the right of the 317 and 337 and above the 78XX to identify the orientation of the heat-sink tab. The build documentation is quite wonderful with a view of the circuit board showing the locations of the groups of components for each step, along with alignment instructions for the ICs and the large capacitors, and photos showing the correct orientation.Īs an example, the image below shows the location of the voltage regulator components (the pads marked in yellow). The final step-soldering the screw terminals for the incoming AC and outgoing DC-is left until after the amplifier board is completed. Voltage regulator integrated circuits (ICs).Diodes, which rectify the incoming alternating current (AC).The power supply kit instructions suggest carrying out the soldering in several steps: I opted for Muffsy's kit and decided to build it first. Neither the Muffsy phono preamplifier nor the head amp circuit boards incorporate a direct current (DC) power supply, so the would-be builder must either purchase the Muffsy power supply kit or come up with something somewhere else. I also test-fitted the boards and casework. I also verified the parts received-including using my multimeter to check resistor values-against the parts lists on the instructions site. I had lots of room to work, even with the laptop set up nearby (to follow the instructions). This let me use a room fan and the cooktop's ventilation to evacuate the rosin fumes from the soldering. Since I had the house to myself, I repurposed the kitchen island, which is a great height for me and has a nice, old maple butcher-block top. The workspace should be clean, well-lit, and properly ventilated. Several preliminary activities are worth mentioning. I had intended to take a few intermediate pictures and include them in this article, but I got so carried away with my new soldering station and my new soldering skills that I was done before I knew it! Therefore, I've used some images from the instructions pages on Muffsy's site.Īlso, I should point out that all the information on the Muffsy website is licensed under Creative Commons, with the sole exception of the printed circuit board designs, which may not be used commercially without prior approval from the designer. To my great surprise, the build went very well. So, on an unusually bright and sunny Saturday morning, I visited a local electronics supply store, picked up the last items, and started building. I watched the entertaining "how to solder" videos linked on Muffsy's site and realized I needed a few more things-like the thin solder mentioned on those videos and some solder wick. I had the amplifier kit, the power supply kit, the back-panel kit (all from Muffsy), the case (from a very efficient supplier in China), the temperature-controlled soldering station, and the wall wart (from a very efficient supplier in California). About a week after I wrapped up my last article where I talked about needing another stage of amplification to take advantage of my new 0.4mV phono cartridge, all the remaining bits and pieces I had ordered online to build the Muffsy phono head amplifier kit arrived.
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