[HiGHFLYiN9]

Let me try to break it down. I assume there will be new iterations of the NuTube, and hopefully other companies will throw in as well, but this is for the current Korg NuTube.

NuTube Pros:
Perceived warmth and harmonics of traditional tubes
Low voltage (safer for DIYers, easier to implement in battery powered circuits as power will last longer and filament does not have to be starved)
Smaller form factor than traditional tubes
Longer life - 30,000 hours
Does not generate notable heat like traditional vacuum tubes

NuTube cons
Notably more microphonic (sensitive to vibrations) than tubes typically used for audio. There are suggestions from Korg on how to reduce this
No current ability to "roll" like socketed op-amps or tubes. You can mount it on a socketed carrier, but there are no other Nutube types to try
Pricier than current production driver tubes ($49.99)

Is the Korg NuTube going to take over tube audio? Nope, but it's a unique product design and should implement well in products that require its advantages.

 

[HiGHFLYiN9]

.. double post, please delete.

 

[coinmaster]

Hmmmm, I wonder. With the right circuit and careful biasing this tube can be very linear.
I've cooked up a masterpiece of a design for this tube I guess I'll find out when I wire it up.

 

[silverfishla]

I'm really starting to enjoy my Senn HD650's with this amp.

 

[pmillett]

Let me try to break it down. I assume there will be new iterations of the NuTube, and hopefully other companies will throw in as well, but this is for the current Korg NuTube.

NuTube Pros:
Perceived warmth and harmonics of traditional tubes
Low voltage (safer for DIYers, easier to implement in battery powered circuits as power will last longer and filament does not have to be starved)
Smaller form factor than traditional tubes
Longer life - 30,000 hours
Does not generate notable heat like traditional vacuum tubes

NuTube cons
Notably more microphonic (sensitive to vibrations) than tubes typically used for audio. There are suggestions from Korg on how to reduce this
No current ability to "roll" like socketed op-amps or tubes. You can mount it on a socketed carrier, but there are no other Nutube types to try
Pricier than current production driver tubes ($49.99)

Is the Korg NuTube going to take over tube audio? Nope, but it's a unique product design and should implement well in products that require its advantages.

That is a very good summary, I agree...

Pete

 

[eixe]

Hi everyone, happy owners of a Nutube device, or experienced with electronic.

I have completed the NuHybrid Headphone Amplifier, checked Everything, read this thread for questions and answers, and guess what ?
I writes you because the voltage can't reach 11V between Ground (test point 3) and both L/R Outs (tests points 1/2). Going from the minimum, it stuck at 6.09V, with R17 and R18 (1Kohm) at the most.
An important fact is from 5.5V to 6.09, the glow gradually turn off.

I did not run complete listening test for now, but double checked everything (components value and position, welds) multiple time and here I am.
I got music in my kamikaze headphones, it sounds okay except a buzz wich the pot's grounding have not totally eradicate. I guess this is another trouble wich will wait for the enclosure time.

I have purchased the Mouser's shared project from P. Millet website, and the PCB+Nutube from himself, so their is no unrecommended part, except ins and outs (RCA, 1/4, DC jack, and switch), and a temporary 100K pot laying around. I did this part accordingly to the recommandation for Silverfishla's interrogations (posts #167-#168)

Here are the active components I got :
2N3904BU *2 : BJT NPN Transistor General Purpose
2N7000 : MOSFET N-CHANNEL 60V 200mA
UA78M33CKCS : Linear Voltage Regulators 3.3 V 500mA Fix Pos Voltage Regulator
Opamp 551, 6P1 Nutube.

My power supply is a switching type 24dc capable of 1.5A, with the + centered.

I hope this bunch of infos will help you to help me !

Thanks for your attention.

 

[silverfishla]

Hi everyone, happy owners of a Nutube device, or experienced with electronic.

I have completed the NuHybrid Headphone Amplifier, checked Everything, read this thread for questions and answers, and guess what ?
I writes you because the voltage can't reach 11V between Ground (test point 3) and both L/R Outs (tests points 1/2). Going from the minimum, it stuck at 6.09V, with R17 and R18 (1Kohm) at the most.
An important fact is from 5.5V to 6.09, the glow gradually turn off.

I did not run complete listening test for now, but double checked everything (components value and position, welds) multiple time and here I am.
I got music in my kamikaze headphones, it sounds okay except a buzz wich the pot's grounding have not totally eradicate. I guess this is another trouble wich will wait for the enclosure time.

I have purchased the Mouser's shared project from P. Millet website, and the PCB+Nutube from himself, so their is no unrecommended part, except ins and outs (RCA, 1/4, DC jack, and switch), and a temporary 100K pot laying around. I did this part accordingly to the recommandation for Silverfishla's interrogations (posts #167-#168)

Here are the active components I got :
2N3904BU *2 : BJT NPN Transistor General Purpose
2N7000 : MOSFET N-CHANNEL 60V 200mA
UA78M33CKCS : Linear Voltage Regulators 3.3 V 500mA Fix Pos Voltage Regulator
Opamp 551, 6P1 Nutube.

My power supply is a switching type 24dc capable of 1.5A, with the + centered.

I hope this bunch of infos will help you to help me !

Thanks for your attention.

Hi, something about the posts 167 and 168...there is a section in there where Pete says to use the green wire and white wire to connect the on/off switch. That didn't work for me. The amp didn't turn on. I wired it with the other wires like in this pic. I'm not sure if Pete was mistaken, or my amp is on the verge of blowing up (just kidding) but the way I wired it, worked.
Otherwise, everything else, I wired as instructed on those posts.
Maybe someone else could chime in, since I should have clarified that or asked back at those posts.

 

[eixe]

Thank you for clarifying this point. Visibly the farthest pad of the PCB leads nowhere or on the ground plane. So I wired it anyway, as the BOM's switch. However the two other pads seem to be on a single path for the power, on the other side of the PCB.

Yet I have no clue for the Bias problem, this goes far beyond my present electronical knowledge.

This is actually a very pleasant project to do, and the VFD is inspiring for some original enclosure design, as I can see on this thread.

 

[pmillett]

Hi everyone, happy owners of a Nutube device, or experienced with electronic.

I have completed the NuHybrid Headphone Amplifier, checked Everything, read this thread for questions and answers, and guess what ?
I writes you because the voltage can't reach 11V between Ground (test point 3) and both L/R Outs (tests points 1/2). Going from the minimum, it stuck at 6.09V, with R17 and R18 (1Kohm) at the most.
An important fact is from 5.5V to 6.09, the glow gradually turn off.

I did not run complete listening test for now, but double checked everything (components value and position, welds) multiple time and here I am.
I got music in my kamikaze headphones, it sounds okay except a buzz wich the pot's grounding have not totally eradicate. I guess this is another trouble wich will wait for the enclosure time.

I have purchased the Mouser's shared project from P. Millet website, and the PCB+Nutube from himself, so their is no unrecommended part, except ins and outs (RCA, 1/4, DC jack, and switch), and a temporary 100K pot laying around. I did this part accordingly to the recommandation for Silverfishla's interrogations (posts #167-#168)

Here are the active components I got :
2N3904BU *2 : BJT NPN Transistor General Purpose
2N7000 : MOSFET N-CHANNEL 60V 200mA
UA78M33CKCS : Linear Voltage Regulators 3.3 V 500mA Fix Pos Voltage Regulator
Opamp 551, 6P1 Nutube.

My power supply is a switching type 24dc capable of 1.5A, with the + centered.

I hope this bunch of infos will help you to help me !

Thanks for your attention.

If the Nutube is no longer lit when you get 6.09V on the plate, then there can only be a couple of things wrong...

Did you verify that the 24V supply is really putting out 24V? Measure the voltage to ground at both sides of R10. It should read close to 24V at both ends.

Also double check that R5 is 40.2 ohms, not k, and that R13 and R14 are 475k.

Pete

 

[eixe]

40.2 ohms, not k

R10 is 40K2 on mine. Thank you Pete Millet for your quick expertise.

I'll get back to you with a completed amp, in a nice enclosure I hope.

Have a nice day.

 

[pmillett]

R10 is 40K2 on mine. Thank you Pete Millet for your quick expertise.

I'll get back to you with a completed amp, in a nice enclosure I hope.

Have a nice day.

Hang on, 40k2 might be right. Let me check. Can you measure the voltages on it?

 

[eixe]

I get 17,2V, between "in and out" of R10. Is it the voltage drop caused by R10 or the voltage out of R10 (with a voltage drop of 6,8V in that case) ?
The schematic says it should be a 40.2R resistor instead of 40K2.

 

[pmillett]

I get 17,2V, between "in and out" of R10. Is it the voltage drop caused by R10 or the voltage out of R10 (with a voltage drop of 6,8V in that case) ?
The schematic says it should be a 40.2R resistor instead of 40K2.

OK, 40.2 ohms is correct. I forgot that this node also feeds the input buffers. So if you have 40.2 k there, you'll get too big of a drop. That's your problem.

 

[szpunk]

I buy the "Buffer" version...and later i want to use it to drive my headphone. I tried connect the buffer to my A47 headphone amp first, OMG, Huge distortion which i only get the sound...Yes, gain too high i know.

So i bulid the OPAMP current buffer follow the Nuhybrid Headphone AMP schematic. It's no distortion this time, but i got continuous noise floor. I did bypass the output mosfet follower, no effect, then i replace the input MOSFET 2N7000 with 2N3904, OK, i can enjoy the music now!

 

[2oobz]

I just built the headphone amp. Surprising headroom and power. My favorite build is still the Jonokuchi, but I digress. The nutube is definitely microphonic with a high frequency tone for the first few second after startup or if you touch the tube. Has anyone worked out a mod to subdue the microphonics?