The Ampz pages

These pages describe various types of audio power aplifiers

These pages were made by Stefan Wieman, the text and schematics
were sent to me by Rysanek Frantisek (the "I"person in these pages).
The original author is Pavel Dudek, who published this material 1992 in the biggest local Czech electronics mag.

And here's the new DPaudio pages where they sell these ampz.

About the amplifiers

  • All the amplifiers are "whole symmetric", which gives lower distortion and allows to feed the amp with wide range of voltages : from +/- 5V to the full voltage.

  • The amps have also a soft-clipping circuit, which subdues almost to zero the "transistorish" distortion, when the amp is driven with too strong signal. This, in conjunction with lower supply voltage gives sound similar to vacuum lamps. This needs a deeper explanation, I guess.

  • These amps were designed to be "bimonaural", which means it has a separate power transformer for each channel. That's how they reach >100dB channel separation.

  • Take care of these final pics on construction.

The DPA 220 : 100 W in 4 ohms - bipolar.
The DPA 440 : 200 W in 4 ohms - bipolar.
The DPA 880 : 400 W in 4 ohms - bipolar.

The DPA 330 : 170 W in 4 ohms - FET's.
To come: The DPA 380 : 200 W in 4 ohms - FET's.

Securing module + additional circuits

And more to follow

And some prose of Rysanek Frantisek

You can Email Rysanek Frantisek who sent me this info.

WE-MAN!'s electro page

You can Email Stefan Wieman (for HTML comments) at