Amplifier with MOSFET - 230W/8W or 400W/4W  77 Kb
If MOS transistors are no problem for you, this amplifier provides quite good sound - 0.07% max and typical 0.005% THD.

Amplifier with MOSFET - 100W/8W  25 Kb
Not very widely known HAFLER DH-200 MOSFET amplifier - 0.005% max and typical 0.0015% THD from 1 to 100 W on 8W.

Linear amplifier  35 Kb
The great constructor of high quality audio applications Mike Rennardson has developped an output stage, which is linear like a stage, working in pure class "A", but effective like a class "B" stage.

Symmetric amplifier  127 Kb
This amplifier is absolutely simmetric, including the power supply, and contains no negative feed-back at all. After reading the article, you are almost sure that this amplifier tends to the perfecity more than any other. It is made from bipolar transistors and is relatively easy to build. And it still sounds too much like valves. Written in Russian.

2-band tone corrector  4 Kb
Usually 2 and 3 band equalizers do their work utilizing frequency dependent feed-back. I desided to use passive frequency dividers in order to remove any distortions. This fact imposes later amplifying in order to lead the output stage. Attenuation for 10 Hz is 8 dB, for 1 KHz is 44 dB, for 20 KHz is 18 dB.

Passive tone correctors  30 Kb
Several schematics with different characteristics. Written in Russian.

6-band equalizer 
Kit with 2 fourfold op-amps.

Switching power supply for custom power  18 Kb
Only changing the impulse transformer and transistors you can develop custom output power. Written in Russian.

Switching power supply for 30V/6A
Thyristor convertor for 200W consumation. I like this circuit for its simplicity and reliability - a thyristor, a dynistor, a transistor. The author claims that the thyristor will not fry even when the load is shortcut.

Impulse transformers  303 Kb
Teaches you how to choose impulse transformers and gives catalog datas for russian and foreign cores. Written in Russian.

Bass box  8 Kb
Good sound for DIY maniacs. Written in Russian.

BG speakers datasheets  656 Kb
This is a short catalog for many of loudspeakers, made in Bulgaria - bass, middle range, tweeters and wide range speakers. Written in Bulgarian.

Passive Ethernet hub for 3 PC  6.5 Kb
This is a simple passive (using resistors only) Ethernet hub. It can be made for more than 3 computers, but then the signal will be too weak. Written in Russian.

How to make really really good homemade PCBs  42 Kb
A very good guide to producing consistently high quality PCBs quickly and efficiently, particularly for professional prototyping of production boards.

Anti-glitch filter for electrical network  20 Kb
This is a filter, which sits between the power supply network (220V) and the transformer. It neutralizes all kind of abnormal network activities - harmonics, extra magnetizing of transformer, DC part of AC voltage, glitches from electro-motors.

"Jamming" for loud neighbours  15 Kb
The first is made from transistor and 2 inductors - mainly against TV, but with calibration can be used against radio, too. The other 2 schematics are made with a digital chip - SN74LS04 or SN74LS00. They generate far more harmonics, and can interfere with cell phones, sitting on 10-15 meters near these generators.