Volca Nubass mods

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Re8et
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Joined: 14 Nov 2016

Post 24 Jan 2020

I just got a second-hand Nubass this week, made a useful midi seq- out hack, and a Tube level input, althought I have not
yet understood what it does, I'm still sorting out the schematics so I'm a bit cautious about feed what to where...

I posted some pics on Muffwiggler, if interested in the PCB pics.
resized nubass.jpg
https://www.muffwiggler.com/forum/viewt ... 7&t=226750


edit: It has now the Main OSC raw square output instead of the Tube lev cv input. Very loud mono output. Pre-filter.

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EDIT: CAUTION!!!! DO NOT PATCH ANY NUTUBE PIN OTHER THAN G2 OUT!!!! FILAMENT IS VERY DELICATE!!!!! ANY WRONG PATCHING MAY DAMAGE THE TUBE!!!! ANY REVERSE OR FEEDBACK SIGNAL GOING INTO G2 MAY SNAP THE FILAMENT - DO NOT EVEN TOUCH ANY OF THE NUTUBE PINS OTHER THAN G2!!!!! :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation: :exclamation:

Things to do:

There must be the saw output, the LFO's, and the AD envelope somewhere.
LFO is modulating the MAin osc pitch, somewhere, no amount knobs, then enters Nutube OSC at F1.
The filter is lacking a mix knob.

It seems the SUB osc is something like a modulation or FM type of effect added to the Main OSC inside the Nutube.
Those patchpoints ar very sensitive however, any hack for the SUB requires some good engineering thinking.
IT's not possible to hack those patchpoints for external input without something that do not alter the modulation
or act as an antenna, maybe an octocoupler. Needs some experimentation time.
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Last edited by Re8et on 06 Feb 2020, edited 2 times in total.

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Re8et
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Post 25 Jan 2020

Snip taken from E&T magazine: https://eandt.theiet.org/content/articl ... f-reality/

One advantage of the transistor ladder filter, according to Stinchcombe is that each pole is effectively isolated from its neighbours, which greatly simplifies the mathematical analysis. “It shows the genius of Robert Moog that he had an intuitive feel for how to do filters,” he says.
The TB-303 filter is quite different. At first glance, it looks very similar. It even has the same number of ladder ‘rungs’ as the Moog, something that intrigued Stinchcombe as Roland touted the design as a three-pole, 18dB filter rather than a four-pole, 24dB circuit. In place of the transistors of the Moog structure, Roland inserted diodes.

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EnochLight
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Post 25 Jan 2020

Nice! Been thinking about picking up some Volcas at some point. I think 2020 might be the year I do it. I already own a Roland Aria TB-3 though, so I'm not sure if the Nubass will be a Volca I pick up. Still, that mod is sweet.
Win 10 | Reason 11 |  Studio One 4.5 | i7 3770k @ 3.5 Ghz | 16 GB RAM | Reactor 1TB SSD | RME Babyface Pro | Nektar Panorama P-4 | Akai MPC Live | Roland System 8 and System 1 | Roland TR-8 with 7x7 Expansion | Roland TB-3 | Roland VT-4 | Roland MX-1

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Re8et
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Post 26 Jan 2020

I just mapped a lot more patchpoints, I got pretty nasty Resonance boost, Drive Boost, Dist boost mods ready.
Today I will start experimenting with Dual-op-amp stacking.... anyway, that is the easy pony...
the tricky pony, thought, is really hard to debunk for me... electrons mean space in a vacuum... that is what is affecting the decay time I believe... IF my guessing is correct, osc trig enters at A1-A2. Everything going in there, must be exactly biased...
NUtune pins.JPG
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Re8et
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Post 26 Jan 2020

EnochLight wrote:
25 Jan 2020
Nice! Been thinking about picking up some Volcas at some point. I think 2020 might be the year I do it. I already own a Roland Aria TB-3 though, so I'm not sure if the Nubass will be a Volca I pick up. Still, that mod is sweet.
It's something rather original in some aspects, that is what I like of it. It's a bit pricey at this point, The ARIA is much more fun to play with I believe, althought I do not like the sound of it, I can hear harmonic inversions on all latter Roland products except the SE-02, which wasn't Roland engineered.

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EnochLight
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Post 26 Jan 2020

Re8et wrote:
26 Jan 2020
The ARIA is much more fun to play with I believe, although I do not like the sound of it, I can hear harmonic inversions on all latter Roland products
Strange, I don't hear that at all - but I can't hear very well in the upper frequency range these days (due to many long hours in clubs and a lovely case of permanent tinnitus). :lol: But yeah, the Aria TB-3 is very fun to play, if anything due to its simplicity and touch interface. If I do eventually pick up the Volca, I doubt I'll dig that far into it in order to mod it. Though it's very tempting - they're so cheap I don't feel like I'd be at a loss if I end up frying the PCB.
Win 10 | Reason 11 |  Studio One 4.5 | i7 3770k @ 3.5 Ghz | 16 GB RAM | Reactor 1TB SSD | RME Babyface Pro | Nektar Panorama P-4 | Akai MPC Live | Roland System 8 and System 1 | Roland TR-8 with 7x7 Expansion | Roland TB-3 | Roland VT-4 | Roland MX-1

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Re8et
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Post 26 Jan 2020

The USB audio sampling rate is fixed at 44.1 kHz on my Jp-08, it's like playing Viking 2 at 44.1 or 196Khz, it does a lot of difference even at lower freqs response. Not that it does matter when playin on a fixed 44.1 Khz laptop in a club room through the stereo aux of a 70's amp...
Some girlz came to me addressing they were hearing strange frequencies so I got myself maybe a bit too paranoied :lol:

Don't fry your gear! I fried my OP-1 once, cause of USB midi and power.... I'll never again buy anything that gets power EXCLUSIVELY through USB... (I think I was trying to get rid of usb noise, modding a cable or something...) :exclamation:

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Re8et
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Post 26 Jan 2020

EnochLight wrote:
26 Jan 2020
Re8et wrote:
26 Jan 2020
The ARIA is much more fun to play with I believe, although I do not like the sound of it, I can hear harmonic inversions on all latter Roland products
Strange, I don't hear that at all - but I can't hear very well in the upper frequency range these days (due to many long hours in clubs and a lovely case of permanent tinnitus). :lol: But yeah, the Aria TB-3 is very fun to play, if anything due to its simplicity and touch interface. If I do eventually pick up the Volca, I doubt I'll dig that far into it in order to mod it. Though it's very tempting - they're so cheap I don't feel like I'd be at a loss if I end up frying the PCB.
I have mixed feelings about it, there's a lot of fuss going on elsewhere, youtube, etc. Peoples likes it, others
not so much, and others say it's just an expensive toy; that Tat's touch is not there anymore and cost has doubled from few years ago, they're not worth the new baseline price... I played a standard Volca Bass few times, I did not like the sound, but it's three voices, then some mods came out, and now, it's possible to find them at 80$. Dirty cheap.
The Nubass on the other hand can chain all 16 patterns of 16 steps together. I would like a Panda randomizer on it, but I guess it's asking too much to Kork. Their New Logue engine I'm sure could do it... the one in the Minilogue and Nu:Teck diy Synthesizer...

edit: There is a Transpose note randomizer function ... it just lacks a hold function :P

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Re8et
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Post 29 Jan 2020

This is gonna take Waaaaaay more time than initially thought... :shock:
Nubass surgery IC11.jpg
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Re8et
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Post 06 Feb 2020

You can imagine... I had a very... very bad day.... How I did it to blow up the filament... I do not know.... for one there is hardly any current outside ratings inside the Korg.... just be mindful if you attempt to mod the unit... a spare Nutube is about 50$ plus delivery...


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Re8et
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Joined: 14 Nov 2016

Post 23 Feb 2020

Fixed, I'm not going to touch this anymore...


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