I built this integrated amplifier in 1995. It delivers approximately 75 watts per channel, has six line inputs selected via relays, two tape outputs and two variable outputs. Even though it is an integrated amplifier, the preamplifier and power stages are completely separated and are only connected externally via cinch cables. The preamplifier stage uses operational amplifiers as gain stages and to drive a headphone output. The power amplifier stage is based on a schematic published in the magazine Elektor as 'Medium Power Amp'. All boards are layed out and made by myself.

It has been working without problems ever since, but the next amplifier will likely be again split into separate preamp and power amp components, to provide more room in each enclosure, and to simplify the ground wiring.

Mahagony and copper front panel.

Rear side with line inputs and outputs and speaker cable posts.

Top view with open cover. Preamplifier on top, power amplifiers left and right, transformers in the center.

Preamplifier boards, left and right stacked. Bottom board hosts preamp power supply and temperature, DC and overcurrent sensing circuitry.

Power amplifier board with 3 paralleled output transistors per rail. Power supply capacitors and rectifiers are located directly underneith.

Another view of the power amplifier board with the shielded transformers. The power transformer is under the board with the inrush current limiter and line filter.

View from the back with the top cover removed.

Some more technical details: