Eros2 with 6BR7 voltage checks and a question

johnsonad · 1543

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Offline johnsonad

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on: February 07, 2021, 05:41:25 AM
I finished the Eros2 build this morning.  I subbed in the 6BR7 for the EF86.  No other mods were made other than a different pair of OPT capacitors.  Voltage checks are listed below.  All are within specs minus OKC/OKD. Wall voltage was between 119v/120v (with a variac maxed out).  My wall voltage sucks..... It sounds great :)

IA: 214.7
IB: 218.6
OA: 163.9
OB: 165
OC: 97
OD: 96
OKA: 98.3
OKB: 97.4
OKC: 2.84
OKD: 2.91

The OKC/OKD voltages drift down slowly as it warms up.

Aaron Johnson

Offline Paul Birkeland

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Reply #1 on: February 07, 2021, 06:34:41 AM
Well, the servo is doing what it needs to do. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline johnsonad

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Reply #2 on: February 07, 2021, 06:43:44 AM
That was my guess.  Seems to be working hard ;) 

So if the OKC/OKD voltages were sub 2v, then the circuit is idling and vis versa?

Aaron Johnson

Offline Paul Birkeland

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Reply #3 on: February 07, 2021, 06:44:57 AM
A class A circuit is always at full throttle.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline johnsonad

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Reply #4 on: February 07, 2021, 07:01:43 AM
Is my build then adding a NOS tank to the servo? 😳

Aaron Johnson

Offline Paul Birkeland

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Reply #5 on: February 07, 2021, 07:04:02 AM
No, the 6BR7 needs a different bias voltage than the EF86.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline johnsonad

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Reply #6 on: February 07, 2021, 11:47:39 AM
Thanks for taking the time to bridge my knowledge gap PB!

Aaron Johnson

Offline BNAL

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Reply #7 on: February 09, 2021, 09:05:49 AM
Aaron,

Nice, another kit. Sounds like your back in the swing of building.

What caps did you use in this build?

Brad Nalitt
Iron Upgraded S.E.X. Amp 2.0
Foreplay III
Quickie w/PJCCS
Eros Phono
Blumenstein Orca Speakers, Baby Benthic Subs
S.E.X.y Speakers W/FT17H Horn Tweeters
Thorens TD 125 MkII W/ Shure M97xE JICO SAS Stylus

Offline johnsonad

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Reply #8 on: February 10, 2021, 02:05:43 AM
Hi Brad,

I had some extra 1uF Solen SM polypropylene film and foil caps for the outputs.

Aaron Johnson

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