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Old 11th May 2010, 08:56 PM   #21
bigwill is offline bigwill  United Kingdom
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These are some nice results! My faith in tube amps has been restored. I hope I can achieve such good figures when I build my amplifier design

I think my simulator adds a lot of high order trash due to the inaccuracies of its tube models...
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Old 11th May 2010, 09:11 PM   #22
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Originally Posted by bigwill View Post
These are some nice results! My faith in tube amps has been restored. I hope I can achieve such good figures when I build my amplifier design

I think my simulator adds a lot of high order trash due to the inaccuracies of its tube models...
Your FFT plots looked like they were from a square wave - can you post up the output waveform at high power for that?
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Old 11th May 2010, 10:03 PM   #23
bigwill is offline bigwill  United Kingdom
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Your FFT plots looked like they were from a square wave - can you post up the output waveform at high power for that?
Sure - here's the waveform of the amp just dipping into AB - looks nice and clean to me. No global feedback either, yet the spectrum is a mess!
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Old 11th May 2010, 10:09 PM   #24
bigwill is offline bigwill  United Kingdom
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Here is the current waveform into each tube
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Old 11th May 2010, 10:15 PM   #25
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Can you superimpose the input signal's waveform (in phase) on top of the output plot. I think you will then see the difference.

P.S. The wave looks more triangular to me.
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Old 11th May 2010, 10:19 PM   #26
bigwill is offline bigwill  United Kingdom
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Here we go, they were overlaid manually by twiddling the scales, I by chance happened to get them lined up nearly perfectly on my second attempt

Green is the input to the driver stage, red is the output current through 8R
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Old 11th May 2010, 10:23 PM   #27
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Okay what does the FFT of the input signal say? Maybe the source of your spectrum problem is the source (no pun meant)
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Old 11th May 2010, 10:29 PM   #28
bigwill is offline bigwill  United Kingdom
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Just figured out how to plot the distortion waveform exactly:
Not too pretty!
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Old 11th May 2010, 10:33 PM   #29
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Thats pretty cool.
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Old 11th May 2010, 10:41 PM   #30
bigwill is offline bigwill  United Kingdom
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Distortion at full power (~25V peak) into 8R, YUCK! I hope real life is more forgiving!
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