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B1 with Korg Triode (B1K) Full Kit

  • 29900


2021-11-17 Stock Availability Update:

We have two options available currently - back-orders and pre-orders.

Back-Orders (Shipping regularly but unpredictably during Dec/Jan/Feb)

Very small batches of B1K kits are coming in regularly but selling out immediately. For your convenience we have started taking back-orders for B1K kits even when they are sold out. Your position in the queue will be locked in, and your kit will ship out to you on a first-come first-served basis. We can't give any ETAs on when back-orders will ship (it might be Dec, Jan, or Feb), but you can now secure your spot in the queue if you really want one!

Be sure to read "How do backorders work?" and note that we do not ship partial orders.

If you won't be able to accept a shipment please email us immediately. We will put a shipping hold your order. Otherwise these back-orders may ship at any time without notice.

Pre-Orders (Shipping estimated April 2022)

We have pre-orders available for black and silver faceplate kits. We expect these to ship around April 2022.

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

Please check the following links for more information:

There are 4 elements to building a complete preamplifier. Purchase the elements separately, or all together as a "full kit" bundle for $299. To build a complete preamplifier you will need:

  1. Korg Nutube ($49.99)
  2. B1K PCB + JFETs ($25)
  3. B1K Chassis ($129)
  4. B1K Completion Kit ($99)

What's in the completion kit?

Everything else you need to complete the project other than the Nutube, PCB + JFETs and Chassis. It's an assortment of bits and pieces that joins the Nutube, PCB and Chassis together, turning the whole things into a "full kit", hence the name "completion kit". 

The included "wall wart" style power adapter supports an input voltage of 90-264V and has a US style plug. If you don't live in the US you will need to obtain a suitable plug adapter.

Each kit contains high-quality audio-grade parts that have been carefully chosen for their suitability for this project.

At the time of writing (November 2021), we're still in middle of a pandemic-related global-supply-chain traffic jam. These are predicted to extend until 2023. While we'd like to have everything match the build guide visually, quantities of some of the parts you see in the guide might not be available right now. In those cases we have included well considered substitutions. You'll have to use a little imagination when following the guide.

Discussion threads / Links:


Customer Reviews

Based on 71 reviews
Nutube pre-amp solved my tube amp desire

I had been thinking about buying or building a tube amp. Then I discovered the Nutube. This was a fun diy build project resulting in a great sounding pre-amp. I plugged this into my ACA and noticed a new dimension to the music.
When I started this project, the completion kit was not available so I ended up sourcing those components. Another learning experience.

Pete Z.
A finicky chip but a hypnotic sound

I bought the PCB (w/jfets) and the Nutube only with the intension of building a more compact unit than the whole kit offered here. I was skeptical that I could avoid the "ringing issues” associated with this Korg but using the forum as a guide and realizing/studying what other folks did this buffer/preamp turned out to have a fantastic and hypnotic effect on what came out of my speakers. I love my regular B1 preamp for its clean and precise sound but this B1K just provides a fullness to my soundstage and beautiful presence to the music. I normally listen to (Classical & Jazz) but the Nutube preamp even makes all the early R&R CD recordings tolerable, removing the harshness that plagued the early non-reengineered LP to CD releases. Nelson Pass stuff never disappoints. The 2nd harmonic effects are just amazing.

Greg P.
good build

I couldn't have enjoyed building this more than I did. I am a big fan of the SP1 tube just because it is different. I have made several builds using the Korg tube, from preamps and amps to headphone amps and buffers. The first B1 that I got was already built but I wanted to hear what one sounded like with this design. I wasn't disappointed. The best description of the sound for me was that it was musical. I could go on about all of the aspects, but I got what I wanted here and that is plenty for me.
Kit build is very good and easy to do. Me being me, I upgraded the volume control to an EIZZ stepped attenuator, and opted to make my own power supply, using toroidal transformer and beefy circuits as well. Note that the photo of the power supply shows it in rough form, and the box was cleaned up afterward. I keep the B1 power switch on and just use a switch on the power supply in the front.... I used shielded silver plated copper wiring throughout the build. In other words I maxed out the component quality. The result rivals any other build that I have owned. I have been horse racing it with another preamp build of mine, but can't decide which I like best. They both have their merits.
The B1 chassis needs some help in the support of the top and bottom plates, since the SP1 will give no easement in handling any vibration. This is easily solved by using a bead of silicone for the bottom plate around the perimeter on the inside. I also opted to use additional damping in the form of Dynamat in strategic spots. The one piece of advice that I would give to anyone building this kit is to use silicone supports for the SP1 board! These are inexpensive and pop into place. They are used for the reduction of noise for computer fans. To get the board to be properly held, I used small O rings that took up the additional space left by the silicone support.

Greg P.
Better than it should be

At the price I didn't expect too much. That is ok, since I had a general curiosity about the SP1 tube, even though I have worked with it in the past. This particular kit is easy, almost self explanatory. That's good, because there are many like myself that will get so far with something, but not all the way, and it is a PaiN to have research the crap out of something just to find a simple yes or no to a question.
So I got the kit assembled, and appreciated the quality parts choice along the way. Once done the result look s very good, and not something that resembles a kit. Finally it is the sound that makes me sigh in relief. It doesn't sound like a kit. It does however, sound like a tube circuit. In fact it sounds more tubey than most anything I have built in the past. For me, that was the goal, or at least one of the key points.
You will realize how positive this review is by the fact, I am building another one. This with a few upgrades... yes, because I can.

Pat C.
Awesome little Preamplifier

I enjoyed building this pre amp, it was not difficult especially with the instructions available at diy forum..... great job guys!
I made the top cover with my cnc laser in acrylic and painted the underside, I left a window to see the Nutube, I then laser etched the writing in mirror image on the bottom so it looks nice at night with the letters glowing with the Nutube lite....
And it sounds really nice, I liked it so much I built another one but this time with a different case and remote control volume and input selector with 3 inputs....

Gilles A.
An amazing kit and a great sound

The kit is quite easy to set up, and the tuning too if you go smoothly. I encountered a microphonic issue that I solved by placing a small ball of Patafix under the Nutube. I think it could be useful to isolate the PCB from the chassis because I have a very slight ringing noise when I turn the potentiometer (audible through the headphones). Finally, I placed the switches behind the front panel for aesthetic reasons. I had some worries because the input wires are not shielded, but in reality there is no residual noise. Now I will probably connect it to an F5 (to be built) for two reasons: the simplicity of the schematic and the class A operation. Many thanks for the useful guide.

Dan P.
Great kit, lovely sound

The Korg NuTube kit was a joy to assemble. An easy build, I spread it out over two days (through ps test on day 1). Everything powered up with all test points in spec and no problem setting a stable bias on the triode. The sound is a great complement to a DAC with a low noise and high dynamic range output. It seems to soften the edges but also gives it a fuller, more detailed but still bright sound. This preamp seems to make the rolled-off nature of vinyl at the high and low end as well as the midrange coloration more obvious. I am using this with Klipsch bookshelf speakers (RP-150M) and an ACA; I may compare this preamp to a passive preamp for playback of vinyl in future.

Good Fun!

Nice kit. Enjoyed the build. Very decent sound. Only issue was to find manual for final adjustments.
Will build more of these 🤓

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