Wednesday, May 10, 2017


Yet another phono preamp but this time a dedicated MC preamp only. This one also uses the LM833 all bipolar chip. One reason is I like the sound of this chip over the OPA2134 and also it had the lowest noise audible through my high efficiency speakers. This build uses MKT and NP caps which are know for there accuracy and stability of capacitance. These features are essential in a phono stage.

Only two 9V batteries would fit in this tight enclosure. I wanted to get back to my epoxy enamel painted enclosure being cast Al. It looks extra sexy in real life. WBT silver solder and fine silver plated hook-up wire is use throughout. No shielded wire is used. The cct. brd. is a prototype brd. and not a PCB. The differential PS is built onboard. A mix of Vishay and other metal film resistors are used and a machined chip socket. Heavy duty gold plated RCAs on the rear and battery test point at the front.

Sound is solid and balanced. Imaging appears good and instrument separation is obvious. Happy with the sound which is based on a very pedestrian OPAMP but as stated above I like the sound of the chip and it was the quietest in this situation.