EF86 Vp and Vs relationships..PHAT? ringing for PH

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Jonas Gemini
Hey get your own solder
Posts: 210
(9/23/03 10:26 pm)
162.40.96.167
Reply | Edit | Del All  EF86 Vp and Vs relationships..PHAT? ringing for PHAT....
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 Phat,

On an earlier lost post, you mentioned that the EF86 needs to be "biased" or set up in a certian manor with relationship to the Vp and Vs voltages.

I think you said a good setup of the EF86 should be about 90v on the plates and about 85V on the screens, but I can't remember.

With respect to the signal, what is going on if these voltages are not set up this way?

When you have time, can you please give me a complete explaination of the proper way to set up an EF86.

Very Much Ablidged
Jonas
 
1965Strat
I will work on all amps
Posts: 381
(9/24/03 1:53 pm)
67.162.241.43
Reply | Edit | Del  Re: EF86 Vp and Vs relationships..PHAT? ringing for PHAT....
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 I have some experience with EF-86's and here are my experiences.

The voltages that you showed are great for getting the most signal from an EF-86. The sound will be crisp and full of bite.

If you are wanting a more refined sound with less highs, try running about 100V on the screens and about 85V on the plates.

This is my experience... your mileage may vary.
 
Jonas Gemini
Hey get your own solder
Posts: 212
(9/24/03 2:05 pm)
162.40.96.167
Reply | Edit | Del  Re: EF86 Vp and Vs relationships..PHAT? ringing for PHAT....
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 thanks strat,

I plan on giving some different set-ups a try. Also, I would like to know why, or have a good explanation of why the different set-ups yield different tones on the EF86, (and other preamp tubes for that matter). I would find this to be most helpful.

Much Ablidged
Jonas
 
PHATamps
I will work on all amps
Posts: 347
(9/24/03 7:18 pm)
24.220.0.48
Reply | Edit | Del  Re: EF86 Vp and Vs relationships..PHAT? ringing for PHAT....
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 Hey Jonas,

Wow, that was a while back! Time flies like the wind...and fruit flies like bananas!!!

OK, let me see if I can remember how I put it...

If Vp is significantly lower than Vs, then when the grid swings positive, the plate will swing even further below the screen, and the screen will pull more current out of the beam during that half-cycle, causing less plate current, and less gain, not to mention an assymetrical waveform. Dr. Z's Rt. 66 is set up like this, and people rave about its smoky, milkshake-thick blues tone. How much of this is due to the EF86 setup vs. a nice pair of KT66s and a unique tone stack, I don't know.

If Vs is too much lower than Vp, the screen loses some of its ability to attract and accelerate electrons toward the plate, which is the main reason for its existence. Fewer electrons striking the plate with less force = less plate current = less voltage swing across Rp = less gain.

That's the way I understand it anyway. Maybe one of the REAL gurus will step in here and set us both straight!

My Z-28 knock-off sounded best with 90Vp and 82Vs. I guess this setup works better with 6V6EHs, cuz they're naughty little things that like to be spanked...Yeah, Baby!!!
 
GroundhogKen
Moderator de forumus
Posts: 1849
(9/24/03 7:35 pm)
66.67.155.173
Reply | Edit | Del  Re: EF86 Vp and Vs relationships..PHAT? ringing for PHAT....
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 "cuz they're naughty little things that like to be spanked...Yeah, Baby!!!"

 

You can't get anymore technical than that.

Ken



 
 
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