KORG Nutube B1 Preamplifier... with a Twist!

[drp1003]

Hello AK world,

I recently built a preamp kit: the Nelson Pass-designed KORG Nutube B1 preamplifier. Which is available to buy at the DIYAUDIO STORE.

Hold on a minute, I didn't buy the whole kit which includes a chassis, wiring, and everything else one would need to build a completely functioning preamp. But instead I just bought what I needed, then proceeded to create my own preamp.

Allow me to explain:

I bought from the DIYAUDIO STORE one KORG Nutube vacuum tube, the preamp PCB with matching JFETS, and finally I bought the ALPS potentiometer PCB. That thing gets soldered to the bottom of the ALPS pot so that you can then solder wires to it without damaging the pot itself, and it also makes soldering wires to it a lot easier.

What I did not buy was the chassis or the completion kit. The completion kit comes with everything you need to - well - complete the kit: the ALPS pot, switches, RCA inputs, wiring, electronic components like capacitors resistors and transistors, and a 24volt wallwart-style power supply.

You can GOOGLE "KORG Nutube B1 preamp" and plenty of photos will pop up showing a completed unit. DIYers have already posted build videos on YouTube as well.

If you look at the photos below, then you will see how big of a difference my DIY Nutube B1 preamp kit differs from the DIYAUDIO STORE's Nutube B1 preamp kit.

I bought a chassis, RCA inputs, a MEANWELL power supply, a 120VAC switch, an ON-OFF-ON switch, and an AC power cord receptacle from AMAZON. I had the wiring already at hand, and an LED bulb as well. I bought some rubber feet from ACE hardware.

Here's where things get interesting. Instead of building the preamp with two line level inputs as per the instructions, I built mine with one line level input and one PHONO STAGE input. Yes! My KORG Nutube B1 preamp kit has a phono stage residing INSIDE the chassis! If you look closely at the photos, you can see another PCB (phono PCB) sandwiched between the power supply and the Nutube's bright green printed circuit board.

I had a TCC TC-750 external phono preamp laying around. I used it every once and a while but not enough. I modded it years ago to improve the sound. It sounds fantastic. But I never really got to use all that often. It was kind of a shame really. But not anymore!

So what I did was unsolder the RCA inputs and the power plug receptacle from the phono preamp PCB, and then I soldered on wires instead. Then wired it up to the switch and the ALPS volume pot and the RCA inputs. You might be wondering how noisy it is. Phono preamps can get noisy. I'm happy to say that it's no noisier than any other phono preamp that's built inside the chassis of a typical vintage receiver. Heck, it's even quieter! I run the ground wire that connects from the turntable/grounding screw to the MEANWELL grounding screw located on its chassis. Quiet as a mouse!

The MEANWELL power supply outputs 24vdc, 12vdc, and 5vdc simultaneously. The Nutube B1 PCB uses 24vdc. The TCC TC-750 PHONO preamp uses 12vdc. I'm gonna in the future add BLUETOOTH. And it will be powered buy the 5vdc.

Three inputs: line level, phono, and bluetooth (later on) !!!

All this stuff packed tightly inside a pretty small aluminum chassis. LOL!

I have a volume knob coming from Amazon. Should be here soon!

That big power switch you see on the front of the chassis turns off the AC power coming in from the outside. When I throw that switch, power gets killed at the 120AC level so that the power supply gets turned off.

The other smaller switch is the input selector switch. It's an ON-OFF-ON switch. I can mute the sound coming in from the two sources. NICE!

I have a 3-D printer. I designed and built the blue chassis cover you see on the back. It supports the RCA inputs, the turntable grounding screw, and the AC power cord receptacle.

I bought the electronic components that populate the Nutube's PCB from MOUSER along with the ALPS volume control potentiometer. It's an ALPS RK27. The finest volume control every made!

Did I mention the ALPS VOLUME CONTROL!!! WOW!

I. NEVER. KNEW. that something like an ALPS volume potentiometer could be so effective! Holy Crap! Wow! Blue Velvet! I'm sold!

Anyway, enough about that...

How does it sound? It's better than anything I've ever listened to. Freaky amounts of presence. Very detailed. Lots of depth! I thought I knew what depth of soundstage sounded like. That is until I listened to music on this baby. Yikes! I'm at a whole new level of soundstage presentation.

I have this thing hooked up to a pair of ICEpower monobloc amps. I built a pair using the ICEpower 125asx2 modules bridged to mono. They make 250 watts at 8ohms. They sound great as well, and can power nearly any speaker with ease.

This was a fun build. Nelson Pass is a genius!

 

[Dr. Ears]

Hello AK world,

I recently built a preamp kit: the Nelson Pass-designed KORG Nutube B1 preamplifier. Which is available to buy at the DIYAUDIO STORE.

Hold on a minute, I didn't buy the whole kit which includes a chassis, wiring, and everything else one would need to build a completely functioning preamp. But instead I just bought what I needed, then proceeded to create my own preamp.

Allow me to explain:

I bought from the DIYAUDIO STORE one KORG Nutube vacuum tube, the preamp PCB with matching JFETS, and finally I bought the ALPS potentiometer PCB. That thing gets soldered to the bottom of the ALPS pot so that you can then solder wires to it without damaging the pot itself, and it also makes soldering wires to it a lot easier.

What I did not buy was the chassis or the completion kit. The completion kit comes with everything you need to - well - complete the kit: the ALPS pot, switches, RCA inputs, wiring, electronic components like capacitors resistors and transistors, and a 24volt wallwart-style power supply.

You can GOOGLE "KORG Nutube B1 preamp" and plenty of photos will pop up showing a completed unit. DIYers have already posted build videos on YouTube as well.

If you look at the photos below, then you will see how big of a difference my DIY Nutube B1 preamp kit differs from the DIYAUDIO STORE's Nutube B1 preamp kit.

I bought a chassis, RCA inputs, a MEANWELL power supply, a 120VAC switch, an ON-OFF-ON switch, and an AC power cord receptacle from AMAZON. I had the wiring already at hand, and an LED bulb as well. I bought some rubber feet from ACE hardware.

Here's where things get interesting. Instead of building the preamp with two line level inputs as per the instructions, I built mine with one line level input and one PHONO STAGE input. Yes! My KORG Nutube B1 preamp kit has a phono stage residing INSIDE the chassis! If you look closely at the photos, you can see another PCB (phono PCB) sandwiched between the power supply and the Nutube's bright green printed circuit board.

I had a TCC TC-750 external phono preamp laying around. I used it every once and a while but not enough. I modded it years ago to improve the sound. It sounds fantastic. But I never really got to use all that often. It was kind of a shame really. But not anymore!

So what I did was unsolder the RCA inputs and the power plug receptacle from the phono preamp PCB, and then I soldered on wires instead. Then wired it up to the switch and the ALPS volume pot and the RCA inputs. You might be wondering how noisy it is. Phono preamps can get noisy. I'm happy to say that it's no noisier than any other phono preamp that's built inside the chassis of a typical vintage receiver. Heck, it's even quieter! I run the ground wire that connects from the turntable/grounding screw to the MEANWELL grounding screw located on its chassis. Quiet as a mouse!

The MEANWELL power supply outputs 24vdc, 12vdc, and 5vdc simultaneously. The Nutube B1 PCB uses 24vdc. The TCC TC-750 PHONO preamp uses 12vdc. I'm gonna in the future add BLUETOOTH. And it will be powered buy the 5vdc.

Three inputs: line level, phono, and bluetooth (later on) !!!

All this stuff packed tightly inside a pretty small aluminum chassis. LOL!

I have a volume knob coming from Amazon. Should be here soon!

That big power switch you see on the front of the chassis turns off the AC power coming in from the outside. When I throw that switch, power gets killed at the 120AC level so that the power supply gets turned off.

The other smaller switch is the input selector switch. It's an ON-OFF-ON switch. I can mute the sound coming in from the two sources. NICE!

I have a 3-D printer. I designed and built the blue chassis cover you see on the back. It supports the RCA inputs, the turntable grounding screw, and the AC power cord receptacle.

I bought the electronic components that populate the Nutube's PCB from MOUSER along with the ALPS volume control potentiometer. It's an ALPS RK27. The finest volume control every made!

Did I mention the ALPS VOLUME CONTROL!!! WOW!

I. NEVER. KNEW. that something like an ALPS volume potentiometer could be so effective! Holy Crap! Wow! Blue Velvet! I'm sold!

Anyway, enough about that...

How does it sound? It's better than anything I've ever listened to. Freaky amounts of presence. Very detailed. Lots of depth! I thought I knew what depth of soundstage sounded like. That is until I listened to music on this baby. Yikes! I'm at a whole new level of soundstage presentation.

I have this thing hooked up to a pair of ICEpower monobloc amps. I built a pair using the ICEpower 125asx2 modules bridged to mono. They make 250 watts at 8ohms. They sound great as well, and can power nearly any speaker with ease.

This was a fun build. Nelson Pass is a genius!

It looks like you did a great job!

 

[skywave-rider]

Love it! I just built mine, but used the full kit. I admire your version. Setting mine up got a TP8 voltage problem, so no listening yet.