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B1 with Korg Triode (B1K) Preamplifier PCB + Fairchild JFETs

B1 with Korg Triode (B1K) Preamplifier PCB + Fairchild JFETs

  • 2500

At Burning Amp Festival 2017 Nelson presented a version of a pre-amp using the Korg Nutube dual triode. We now have the latest version of this circuit available in the store complete with Fairchild JFETs and all directly supplied by Nelson Pass.

Please check the following links for more information:

What's included:

  • PCB (5.5" x 3.25", mounting holes 5.0" x 2.75")
  • 8 Fairchild JFETs and tweaking resistors (all direct from Nelson) for just $25

What's not included:

Please note:

  • The board is compatible with both DGS and DSG JFET pin orientation. Use the correct holes for the JFETs you are using as directed in the article "JQ1,Q2 is used for the Fairchild J113's and the KQ1,Q2 fits the 2SK170, 2SK370, and LSK170 Jfets."


Customer Reviews

Based on 36 reviews
Such a nice kit and outstanding results!

I built it in a different box, with remote attenuator (Chinese motor operated ALPS potentiometer)
Being afraid of "too much of a good thing" and having a triode based phono stage, I equipped it with a bypass, so I can run the signal straight or through the Korg, the picture shows the look at the test phase.

As far as I can tell until now, the Korg makes the music sound better to me, but I can switch between streight signal pass and through the amplification.

Once again, would like to thank the designer Mr. Pass and the kit supplier, a wonderful preamplifier! Not to forget the F6 which we at home enjoy on every day basis

Jaap B.
Great preamp

Adjustable harmonics are great. Combined with diy Purifi amp.

Allan K.
Lots of fun to discover!

This is a great preamp kit designed by Nelson Pass, comes with exceptional quality parts, and easy to build. The Korg Nutube 6P1 tube is not just a very cool device to look at, but also a very low power consumption vacuum tube which made it a perfect solution to convert it as a battery-powered preamp. Unlike a regular vacuum tube preamp, the Nutube 6P1 is not interchangeable. Although tube rolling is not possible to this preamp, Nelson adds a feature to adjust audio harmonics by a pair of trimmer pots each controlling the left and right separately. I can experience a different sound stage and 3D space by adjusting the value of the trimmer while the amp is powered on, how wonderful!
The kit already comes with audio grade electronic parts. Chassis is simple but elegant and solid, high-quality parts from Italy. I completed the kit with original parts which sounds very good already, later changed a few electrolytic caps with some polypropylene from the signal path suggested by the group member, this further improved the sound quality.
This little preamp kit is easy to build with lots of fun to discover. Worth every penny!


Sorry, I forgot to post some pictures.
Enjoy your music!


She’s so magazine with First-Watt F4 more than Ba-3 Preamp.
Although her voltage gain is small, she doesn't sound like it.

Thierry M.
very very nice preamp

What a great preamp!
Easy to built and what a sound! I am really amazed about its soundscape: deep, large and full of details...
I recommande it absolutely ! Sincerely yours, Thierry Malarmey-Dorel

david w.
Nutubes are versatile and sound great

I have built two nutube pre amps balanced one in a Galaxy 1U chassis, and one single-ended one built into an ACA chassis to make a Pass DIY integrated. Both of them sound really good and construction was straightforward with no problems except the third time I fitted a Nutube to its circuit board the little legs just didnt want to go into the little holes on the board. I used 3mm Sorbothane sheet to stick the nutube to the board and I have not noticed any microphonic effects. Good job, Nelson and DIYaudio ( thanks to 6L6 for the build guide also )

Dirk H.
Beautiful sounding B1 KORG NUTUBE

The pcb is of very good quality. The diyAudioshop sent it very fast. Included JFETs are matched very well.
How does it sound? - Beautiful! Absolutely no hum or noise. Open wide soundstage. Interesting possibility
to adjust positive and negative 2nd harmonic. Together with my BA-3 poweramp great.
This little soundmachine is a giant!
Dirk / cubicincher

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