pre standard one preamplifier

the preamp was designed as a reference preamp for Wilson Audio speakers presentations. The preamp consists of electronics cabinet and power supply cabinet. It is a true dual-mono conception with power supplies separated for the left and the right channel.

power supply voltage is 4 x 22V DC for electronics and 2 x 15V DC for relay circuits. Total filtration capacitance for electronics is 20 000 uF.

the design

just click to the following images to see the full size.

inputs and outputs

the preamp has 3 single-ended inputs, 1 balanced input, 1 single-ended output and 2 balanced outputs. Every input has its own electronic circuitry. The outputs are completely independent (separated circuits) and designed to drive 50 Ohm load (buffered outputs with 50 Ohm output impedance).

the preamp circuitry acts as a low-pass filter to prevent the power amp from intermodulation products with D/A residuals (at CD output). Frequency range is up to 138 kHz (-3dB). Appropriate PCB design and signal shielding is applied not to allow the HF signals pass through the preamp.


inputs                                     3 single-ended, 1 balanced
outputs                                   1 single ended, 2 balanced, all of them able to drive 50 Ohm load
frequency range                    138 kHz (-3dB)
output impedance                  50 Ohm
maximum output voltage        32Vp-p for 10 kOhm load, 15Vp-p for 50 Ohm load
THD                                       0.0007% for 10 kOhm load at 1kHz

Pavel Macura - November 30, 2003