Bottlehead Forum

Bottlehead Kits => Eros Phono => Topic started by: johnsonad on February 07, 2021, 05:41:25 AM

Title: Eros2 with 6BR7 voltage checks and a question
Post by: johnsonad 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.

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: Paul Birkeland on February 07, 2021, 06:34:41 AM

Well, the servo is doing what it needs to do. 

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: johnsonad 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?

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: Paul Birkeland on February 07, 2021, 06:44:57 AM

A class A circuit is always at full throttle.

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: johnsonad on February 07, 2021, 07:01:43 AM

Is my build then adding a NOS tank to the servo? 😳

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: Paul Birkeland on February 07, 2021, 07:04:02 AM

No, the 6BR7 needs a different bias voltage than the EF86.

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: johnsonad on February 07, 2021, 11:47:39 AM

Thanks for taking the time to bridge my knowledge gap PB!

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: BNAL 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?

Title: Re: Eros2 with 6BR7 voltage checks and a question
Post by: johnsonad 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.