MM cartridge preamplifier - open project
Please feel free to download documentation of OPENAMP1, MM preamplifier open project.
can be found in the links below the photo of the assembled board
Assembly instructions and board manual
Bill of materials
Signal to noise ratio
Special emphasis was put on reduction of disturbing noises, hum and buzz. The following measurement shows noise level at the preamp output with input connected to Technics SL1200-MkII turntable and Shure M35X cartridge. Noise level is -93dB (0dB = 2Vrms) over 20Hz - 20kHz, unweighted.
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