Nelson Pass B1 Korg preamp.

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Wardsweb

Nelson Pass B1 Korg preamp.
« on: 22 Sep 2019, 02:18 am »
Once again, a huge thank you to Jeff for helping me take this preamplifier build to the next level. Nelson Pass designed this board around the Korg Nutube 6P1 dual triode. It runs on 29vdc. The original kit spec'd some cheap parts to fit a budget build. I wanted something better. This thing hits way above its weight class.


FullRangeMan

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Re: Nelson Pass B1 Korg preamp.
« Reply #1 on: 22 Sep 2019, 02:54 am »
Nice, seems a minimalist preamp, how it sounds?

Jeff

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Re: Nelson Pass B1 Korg preamp.
« Reply #2 on: 22 Sep 2019, 03:05 am »
Ward,

That turned out nice  :green:  Thanks for sharing.  I'm guessing those RTEs fit right under the board.  Any time on it yet?

Jeff

happyrabbit

Re: Nelson Pass B1 Korg preamp.
« Reply #3 on: 22 Sep 2019, 05:00 am »
Looks lovely.  Ladder or shunt attenuator ?

Wardsweb

Re: Nelson Pass B1 Korg preamp.
« Reply #4 on: 22 Sep 2019, 12:31 pm »
Ward,

That turned out nice  :green:  Thanks for sharing.  I'm guessing those RTEs fit right under the board.  Any time on it yet?

Jeff


The RTEs are fine. I just used some aluminum standoffs a couple mils taller and found a case that would allow the raised PCB. Only time has been for warm up, bias set and a couple of songs. My first impression is good. It is what I would expect from a triode. Not edgy or too bright, very clean and good detail.

Wardsweb

Re: Nelson Pass B1 Korg preamp.
« Reply #5 on: 22 Sep 2019, 12:35 pm »

The RTEs are fine. I just used some aluminum standoffs a couple mils taller and found a case that would allow the raised PCB. Only time has been for warm up, bias set and a couple of songs. My first impression is good. It is what I would expect from a triode. Not edgy or too bright, very clean and good detail.


This is a ladder but I'm finding it a bit noisey when changing volume. It was something I had laying around. I am going to swap it out for an Alps.

RickB

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Re: Nelson Pass B1 Korg preamp.
« Reply #6 on: 3 Oct 2019, 04:52 am »
Nice work, as always, Luther!

I.Greyhound Fan

Re: Nelson Pass B1 Korg preamp.
« Reply #7 on: 3 Oct 2019, 04:30 pm »
Once again, a huge thank you to Jeff for helping me take this preamplifier build to the next level. Nelson Pass designed this board around the Korg Nutube 6P1 dual triode. It runs on 29vdc. The original kit spec'd some cheap parts to fit a budget build. I wanted something better. This thing hits way above its weight class.



Where did you get the plans and board?  We built a Pass B1 and a Pass Bride  of Son of Zen which still has some bugs that are being worked out be a friend.

Thanks,

Larry

Mike B.

Re: Nelson Pass B1 Korg preamp.
« Reply #8 on: 3 Oct 2019, 07:42 pm »
Where is the tube or tubes?

pwag

Re: Nelson Pass B1 Korg preamp.
« Reply #9 on: 3 Oct 2019, 08:00 pm »
Where is the tube or tubes?

On the left side of the PCB next to the white output wires.



Dmason

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Re: Nelson Pass B1 Korg preamp.
« Reply #10 on: 3 Oct 2019, 08:18 pm »
it's a module with a non-bottle triode circuit inside.

Norman Tracy

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Re: Nelson Pass B1 Korg preamp.
« Reply #11 on: 3 Oct 2019, 08:56 pm »
Korg 6P1 NuTube triode



There are two triodes in the glass package.

Korg's NuTube site https://korgnutube.com/en/

USA Distributor http://www.nutube.us/

More info and circuits http://www.pmillett.com/Nutube_buffer.html and http://www.pmillett.com/index.html including this 6P1 triode + class-D amp.


Jeff

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