Home build of Mars EL84PP

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Qualityten

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I am a great admirer of Karel Mars' amps and follow his posts with interest.

A while back, noticing that RS Components offers nice new output transformers suitable for a push-pull EL84 amp, I decided to try them.  The SA link for the OPTs is https://za.rs-online.com/web/p/audio-transformers/1237240/ and they are priced at about each.  Model number: D29A09F.  They are 10W, PP designs with 6k6 primary impedance, with ultralinear taps.  20% if I recall correctly.

I first tried them with a design similar to Karel's Mars EL84PP circuit, which I had used before, but my layout was not right and there was too much hum.  The fact that I was using parts from a scrap oscilloscope as a chassis didn't help.  I tried to fix the hum, but without success.  Then I decided to build Karel's circuit and follow his layout as much as I could,  The slots already in the chassis meant that I had to put the valves in the front, and I decided to put the power transformer inside the chassis.  But as far as possible, I followed Karel's schematic and photos.  The result is very pleasing and is playing some smooth Ben Webster jazz as I write. 

I'll put a couple of pics in the following post.

Once again, my appreciation for all that Karel does to help us build and enjoy valve amps.
 

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