James Burke's (Jimmy) Phase Linear Ser I WOPL conversion UNIT # 2

laatsch55

laatsch55

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NavLinear said:
Looking good there Lee - under 200 microvolts of noise - that is a quite a goal.

I'll have some bias brackets ready Monday - the last batch were made with a tip that was too large. My words sometimes fall on deaf ears. Here's some shots of a tranistor pad if you're interested. I have a dozen or so of these made up.

View attachment 9092
View attachment 9096 View attachment 9095 View attachment 9094 View attachment 9093
Click to expand...

Dennis that's choice buddy. Send em on, they'll go in that 700B....
 
NavLinear

NavLinear

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Soooooooo - have you guys locked into the RC values for the zobel network? I've done some reading regarding this and if you go to audio blogs information is all over the place. Seems that something close to 8 ohms for the resistance and somewhere in the neighborhood of 0.1 micro Farads for the cap is what I'm seeing.
 
laatsch55

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Dennis , Joe and I were testing different Zoebels to verify what his Spice was saying. We found that 8.2 ohms, .22 uf was very good for stability, which is what the zoebel does, but not so good for high frequency distortion, so we went back to the .1uf/2-10ohm 3watters on parallel.
 
Gepetto

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If you mean in C20 you don't need anything there to test it Lee unless you are going for a performance run. It is in parallel with C6 to cancel the ESR of that cap. It will run fine without C20 unless you are measuring on your AP.
 
laatsch55

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Gepetto said:
If you mean in C20 you don't need anything there to test it Lee unless you are going for a performance run. It is in parallel with C6 to cancel the ESR of that cap. It will run fine without C20 unless you are measuring on your AP.
Click to expand...

Well, that's what I have is the AP. Go with the .01's ftom the C board??
 
laatsch55

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Powered up with the variac and DBT, no problems, bias is a joy to adjust now, DC offset----minus 9mv left channel, ---minus 11mv right channel...
 

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laatsch55

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Listening to it right now.... Joe, we may have broken that 200 microvolt barrier with this one. Can not hear a thing from infinity on the Spec 1 to 0 db, absolutely nothing. Listening to Patricia, the absence of background noise makes it seem like you are there. Lean back and close your eyes.....and you are....
I believe this may e the quietest ine yet. In 3 days we'll know. But my ears haved confirmed it already. Damn, this is sweet!!!!!!!!!!!!!!!
 

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