• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Please evaluate my new EL34 Amp (waveform attached)

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Hi guys,

Finally I got my El34 amp done. Here are some waveform photos that I shot. Please let me know whether they are good or bad. Thank you! The former 4 photos were with a 3.9 Ohms resistor; the later 4 are with a 4 Ohms speaker. My amp has 8 Ohms tab only, but I have no resistor or speaker with that value so I used 4 Ohms ones anyway. The Oscilloscope has DC 1V/grid on top (measured at input) and DC 10V/grid on bottom (measured at load).
 

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  • resistorload.jpg
    resistorload.jpg
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seems reasonable enough. 1Vp-p in produces 10V p-p out = about 6watts into 4ohms. Pretty loud huh?

The rounded edges of the square wave is due to hf roll off and the sloping top of the square wave is due to lf roll off.
Looks like your generator is a bit soggy at high frequency too - the top trace is the input right?

How does it sound with music?
 
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