Overview  Circuit description  Protocol  Parts/PCB

Click on the picture for a larger view Some time ago I designed a small remote control board (see "Remote control receiver" pages). But I wanted a full-function (almost) preamp to replace the "rotary switch in-a-box" I was using. Remote controllable volume was nice, but I needed an input selector as well. As my power amp is very sensitive I didn't need any gain, so I decided to go for a passive preamp. I have a separate RIAA stage, so I didn't need any gain for that either. The result can be seen in the picture on the right... I chose a photo with a pen on top, so you can get an idea about the size. It isn't very big - about 17*11*6cm. You can see the inside view on the parts page. The preamp is based on the same circuit as the small remote control board, but with an added input selector with tape monitor loop and a mute function. The whole thing is assembled on one PCB, so assembly was quite fast and easy. The only difficult part was drilling all the holes for the phono connectors :-). I will describe the circuit in more details on the following pages.

Overview  Circuit description  Protocol  Parts/PCB

Comments? Questions? Just send me an e-mail! Mail: mcs@post5.tele.dk