mixer | julebykiarr

Topomixmix mixer module Nutube 6p1 schematics and simulations.

Here are the Schematics for the Topomixmix mixer module with the Korg Nutube 6P1 Triode. I used EasyEda.

THE LM358 ARE JUST FOR THE SIMULATION, YOU CAN USE 072 OR 5532. I ALSO USED A UA776CD BECAUSE I SCRAPPED AND OLD SOUND CARD….

If you guesss why single triode… this is not a cyrclotron…. and I had a half Nutube available. Just half. Don’t ask.

I’m still learning about frequency response simulations, and I have to thanks Rezzonics and this project by Andifierman here if I was ever able to reproduce the Nutube triode in SPICE simulator.

So, this is just one part of a modular mixer that goes into Topolona.

EDIT / LAST VERSION 1.4 – SINGLE TRIODE INVERT THE PHASE – IN 1.0 AND 1.1 TRIODE PHASE IS MIXED INVERTED.

The Nutube can not accept much more than 1v p-p at input. Or it can but it will go into distortion mode. While the dry signal has plenty or input-throughput room to bear with.

VERSION 1.4

SIMULATION RESPONSE ON TWO SINEWAVES

8hz 1A and 16Hz 2A on inputs A1 and A2.

Master volume (yellow) at 50%, the 2A sine get distortion in the Tube. Output is phase correct.

Lowering the input to 1A each, and adjusting master gain and mix with wet prevalence, the distortion remain subtle in presence. Tube bias on A1 is at 50% of 22k and 5v.

Adding at 10k resistor after the 22k trimpot, the response of the tube is clearly visible.

In spite of the additional 10k resistor, an alpha pot could be used. Or. A cv input IC for to control the bias and a pot. Or just a couple patchbay patchpoints because I run out of space long time ago in the Topolona…

////// following with previous sch. /////things have changed since v1.0…

The wet and dry signal get mixed at a B10K pot. I have added a 1k resistor after the pot, and a couple 10R resistor before it. the response gets much better.

Also in sch 1_1 the voltage bias is 4.5, trimmed / divided at 50% by the 22K trimpot, while the filament is stepped down to 0.6 input to allow max threshold.

SPICE simulation 1_1 Sine wave 8Hz 3A input. Blue is mix signal pre final gain. Orange is final out at 1.5 Gain pot value (R9 is a B10K in reality). MIx pot dry prevalence.

MIx pot Nutube prevalence (wet signal) same 3A source sinewave

Upgraded 1_1 Schematic.

Here 1st simulation and sch. v 1.0

SPICE schematics 1.0 and a 60Hz sinewave 1A simulation with three probes points.
1st probe point is at Nutube A1 input to monitor the bias. (orange waveform at 2v)
2nd probe plot is the G1 output of the Nutube. At 1Vp-p input, a 5x gain is obtained without distortion. (Blue)
3rd Probe point is at output, where output gain goes all the way up to 16v p-k, and can go into distortion also if cranked to max. (The bottom orange)