Anyone built this Korg Nutube guitar pedal project?

[microbailey]

Wondering if anyone has built the Korg Nutube pedal design in the article below yet
https://www.rs-online.com/designspark/d ... ube-basics
and if so how does it sound?

(I hope that URL hasn't broken any forum rules )

--microbailey

[Ice-9]

I have thought about messing around with a nutube design but I can buy 3x 12ax7 valves and a nixie psu for the same price so gave it a swerve until the price comes down a bit.

[microbailey]

I have thought about messing around with a nutube design but I can buy 3x 12ax7 valves and a nixie psu for the same price so gave it a swerve until the price comes down a bit.

Yeah price is a bit steep right now. I saw the Nu Tube Screamer and then that article and it got me wondering.

[ppluis0]

Hi Folks,

Why not explore the possible uses for old (and CHEAP) TV tubes ?

I recently built a preamp using the triode section of an ECF80 (6GJ8 in USA) and the gain is reasonable using 12Vdc to supply.

Those TV tubes can be found in huge quantity and also combining triode and pentodes in the same bottle.

Cheers,
Jose

[RnFR]

Hi Folks,

Why not explore the possible uses for old (and CHEAP) TV tubes ?

I recently built a preamp using the triode section of an ECF80 (6GJ8 in USA) and the gain is reasonable using 12Vdc to supply.

Those TV tubes can be found in huge quantity and also combining triode and pentodes in the same bottle.

Cheers,
Jose

feel free to post schematic/demo/anything!

[Frank_NH]

There is some experimentation with NuTube circuits going on at the Guitar FX Layouts site:

http://tagboardeffects.blogspot.com/201 ... drive.html

So far, one person has gotten the Nuverdrive+ to work and said it sounded good, but the NuTube is apparently somewhat fragile (his tube broke at the junction of the glass and one of the legs) and subject to some microphonic noise if not sufficiently cushioned. I think there are possibilities to reimplement some of the Runoffgroove type amp sims with NuTubes, but at $50+shipping per tube, it's still a bit too expensive (though I may get one just to play around with).

[ppluis0]

feel free to post schematic/demo/anything!

Hi RnFR,

Recently I build a clone of an Orange Micro Terror ( viewtopic.php?f=2&t=22030&p=267139&hilit=micro+terror#p267139 ) but instead a 12AX7 successfully adapt for the preamp section an oddball (and CHEAP !) tube.

The ECF801 is a dual section tube used mainly in black and white TV tuners. Here is their datasheet: https://frank.pocnet.net/sheets/010/p/PCF801.pdf If you look at the diagram of the Micro Terror you find that the cathodes of both triode sections of a 12AX7 are connected directly to ground. The resistors and condensers surround this tube are of the same values than those indicated in that diagram.

This TV tuner tube ALREADY have connected internally its two cathodes, but one section is a triode and the other a pentode. (If you tie together the pins 6 and 7 acting as a anode you have a pair of triodes in the same bottle). This tube is normally disregarded due the fact that both sections can't be used separately.

Look further: the Butler tube driver also can be built using this tube instead to a 12AX7 since both cathodes are connected at the same circuit point in these pedals. This tube is 6mm shorter in height than 12A..7 family and have a better response in starved anode operation. IMHO

The heater runs at 8.5 V and draw 300 mA so you need an adequate power resistor in series to adapt to the supply that usually will be from 9 to 15 Vdc in pedals using tubes at low voltages.

In few days I promise to post some pictures in another thread to not derail this subject referred to Korg Nutube

Cheers,
Jose

[koldman]

So far I've only heard the nutube tubescreamer THROUGH tube amps.
How does it sound into a solid state amp?

[BurchSung]

Hi...this Korg tube appears to be small signal only, suitable for a preamp but nothing with more power than that. I am looking for a future with carbon nanotube cathodes with a negative work function for small signal amplification. There was work being done on low-temperature and room-temperature cathodes, but it all got swept away in the semiconductor juggernaut. I would like to see the noise figures for the Korg tube. If it is running in a temperature-limited rather than space-charge limited regime, the noise will be higher and a triode just might act like a pentode.