Tube amplifier

 

In 1991 I have build this Tube amplifier and now 16 years later a upgrade was neccessary. It’s not my design but from Radio Bulletin magazine October 1987 by Ir.Menno van der Veen.
The top plate was made from steel with a transparent coating on it, but there where some rust spots on it, so i decided to replace it with an aluminium plate. Made the design with Frontpanel designer from Schaeffer .

 

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tube_amp_4
tube_amp_2
tube_amp_1
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tube_amp_3
tube_amp_4
tube_amp_2
tube_amp_1
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Here are some specs:
Tubes: ECC81, ECC82, 4x EL34  (Each channel)
Transformers: Powersupply Amplimo toroidal 7B649, Output Amplimo toroidal XC462
Frequency range: 5HZ to 125kHz (-3dB, ref.1W @8Ω
Continuos output: 121W (1kHz @8Ω)
Burst output: 156W
THD: 0,78% (1kHz @100W @ 8Ω)
Slewrate: 14,2V/μs (ref.50W @80kHz sinus)
Class A: < 16W @8Ω
Class AB: 16 to 100W @8Ω
Input: 0dBm (0,775V rms) ref.100W @8Ω