MM cartridge preamplifier - open project

Please feel free to download documentation of OPENAMP1, MM preamplifier open project.


Documentation files

can be found in the links below the photo of the assembled board


Assembly instructions and board manual

Bill of materials

Gerber PCB files


Openamp in the Modushop 1U case


Noise, Signal to noise ratio, Distortion

Special emphasis was put on reduction of disturbing noises, hum and buzz.

Noise with OPA134 as an input opamp

With OPA627 at the position of the input opamp, noise is about 4dB loawer.


THD and THD+N for 5mV/1kHz input


THD and THD+N for 4V output voltage at 1kHz


THD and THD+N vs. output voltage at 1kHz, up to 4V


Output voltage swing

Max. output voltage swing is 30Vp-p with 2 x 17V power supply. This assures immunity vs. transient overvoltages at the input. Next measurement shows output voltage swing at 20kHz.




Pavel Macura 12/2012, last edited 03/2023