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January 26, 2020, 04:50:31 AM

Author Topic: Soul Sister with 8k B7  (Read 3085 times)

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Offline xcortes

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Soul Sister with 8k B7
« on: March 27, 2013, 08:58:40 AM »
The original article shows two versions, one for a 15k primary and another for a 5K one. What version or changes would be recommended for an 8k primary. I'd like to keep the current under 18mA because I have RS080 PTs and the C4s takes two.


Thanks
Xavier Cortes

Offline Paul Birkeland

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Re: Soul Sister with 8k B7
« Reply #1 on: March 27, 2013, 10:20:57 AM »
8K would be dandy for the 5842, use a 50.6 Ohm resistor for R1 on your C4S and an HLMP-6000 under the cathode.  The 8K vs. 5K load is going to reduce the available output a bit, but at the same time you'd have potential for lower distortion and a lower noise floor. 

With the 5842, I'd use four 1K grid stoppers, 1 going to each pin available on the socket for the grid connection. 

Do also note that using an MJE5731A in place of the MJE350 is a nice idea, and the note for a heatsink.

A string of 0D3's is a good idea (also suggested in the article), but if you are limited to 18mA, that won't make much sense.  A PT-7 power transformer would accommodate such a circuit nicely.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline xcortes

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Re: Soul Sister with 8k B7
« Reply #2 on: March 28, 2013, 08:29:56 PM »
Thanks a lot Paul,

Do you think I can use a 10k attenuator with this version instead of the 50k?

Saludos
Xavier Cortes

Offline Paul Birkeland

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Re: Soul Sister with 8k B7
« Reply #3 on: March 29, 2013, 04:59:47 AM »
Sure, a 10K attenuator won't cause any issues in that circuit, though it's a bit of a rough load for your sources.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man