This document is the manual of 2x90W Stereo Tube Power Amplifier with EL34, model K4040 by Velleman. The document in PDF version contain of schematic diagram, part list, component guide, step by step how to build the circuit. This circuit is for advance hobbysts… 
Stereo Tube Power Amplifier Features:
- Pure valve sound with high quality EL34 valves.
- High quality black and chrome housing.
- Chrome valve socket covers.
- Easy bias adjustment with LED indication.
- Removable bottom for easy access and service.
- High quality capacitors and components.
- Gold plated input and speaker terminals.
- Standby function.
- Soft start circuit for power transformer.
Stereo Valve Power Amplifier Specifications:
- 2 x 90Wrms in 4 or 8W.
- Up to 2 x 15Wrms full class A.
- Bandwidth: 8Hz to 80KHz (-3dB/1W).
- Harmonic distortion: 0.1% @ 1W/1KHz.
- Signal to noise ratio: >105dB (A weighted).
- Input sensitivity: 1Vrms.
- 115VAC or 230VAC / 500VA max.
Download the complete TUTORIAL of 2x90W Stereo Tube Power Amplifier with EL34 from the following link:
Stereo Valve Power Amplifier 1.32 MB
Download Manual