Phono preamplifiers are required if your main receiver/amplifier doesn’t have a phono input directly. This is because vinyl records have a special equalizer curve applied to them during mastering, and the output level is tiny compared to things like CD players. The Actidamp Mk2 preamplifier is based on a design published in the early 1990s in a Czech Amateur Radio magazine. It has remained a popular choice because it uses commonly available parts unlike some designs based around completely unobtainable ICs.
You can spend a lot of money on phono preamps if you’re chasing the “perfect sound” but I suspect most of us don’t have golden ears. We just want something that works well and that we can build and potentially hack ourselves! Based on LF411 and LM5534 amplifier chips, all the components that affect the RIAA curve and overall sound are discrete and easily swapped out if you want to experiment. The entire schematic is available for your perusal, and you can order just the PCB, or a PCB with all the parts already assembled.
Vinyl’s comeback is clearly more than just a fad, with record sales steadily climbing each year. But with older equipment at a premium, it makes sense to build your own gear where and when possible. It’s great for building soldering experience, and you get a very useful item at the end!
