• 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.

SimpleSE goes Push Pull

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#21
Tubelab,

With my very limited experience, I have had reasonable success with the Russian EL84 equivalent 6P14P and the EL83 equivalent 6P15P. The 6P15P is especially cheap on ebay, around $25 plus shipping for 8. I know you like cheap and easily obtainable around the world 🙂

Keep us posted!

Cheers,

Chris
 
#22
tubelab.com said:
Yes, I do. I use WinAudioMLS with a 24 bit 192 KHz sound module. I can measure some pretty minute details with that setup. For now it resides in the same computer that I use for the web site, photo editing and my documentation, so it makes it hard to do everything at once. I have gathered all of the components for a dedicated computer for audio analysis and music storage and retreival / playback. I just don't have the time to build it.
Click to expand...

I think you have an HP 8903 like I do (if I noticed correctly from some of your pictures), in which case you could hook the 'monitor' output in the back right up to the soundcard with maybe only a 6-12dB attenuator. The 8903 will automatically scale that output so it's limited to 2V peak (when properly loaded with 600ohms), so you can safely see just the residual distortion spectra without the fundamental (or the entire input signal scaled to 2Vpk when 'AC Level' is selected). It's something I've been meaning to do when i get computer for the workbench. But, just viewing the residual on the monitor output on a scope is useful as well.
 
#23
I think you have an HP 8903 like I do... hook the 'monitor' output in the back right up to the soundcard ...
so you can safely see just the residual distortion spectra without the fundamental.
Click to expand...

Boris, THANKS. You know I have never thought of doing that, but it is an excellent idea. I also have two old 331A distortion analyzers and two 204C oscillators. I used to hook the two oscillators together and chain the distortion analyzers together to make intermodulation measurements (a long time ago) but I had forgotten the technique. I found it in a Hewlett Packard application note from the 1960's. I worked in the cal lab for a major electronics company for several years.
 
#24
Glad to see you working on PP operation of SimpleSE's.
I purchased two simpleSE PCB's out of exactly the same reason, and I am now in the process of building each board before converting them into PP operation using Sowter input trannies. 😀

Doug
 
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