Holy Bot

Bedroom music production, gaming and random shit



A volca Confession

The first volca I got was the bass, and it was the last of the modules I sold. I’ve had three volcas – bass, keys and sample – and I’ve owned two of them for over two years.

While they had their own ecosystem they never quite fit in my particular, DAW-driven, workflow.

The three detunable VCOs of the bass, and the ring modulation of the keys, are great features, but in practice, when I wanted a bass or a lead sound for a track, I sometimes tried using a volca first, but then ended up designing those sounds on other synths. Like always. While the volcas sound fine for the money, they are not on par with my other synths, well that’s just me.

Anyway, I recently acquired the discontinued monotribe, and oh man, that timbre is golden!

Its sound might be clicky, noisy and dirty, but I do prefer this tone over the analog volcas’. To my ears, the filter is so much better on the monotribe, and the LFO is wild and really dope.

I still have to test run it in context of a full track though.

I didn’t expect much of the drumpart, but it’s cool enough it turns out.

So yeah, try to get a monotribe if you haven’t already. I got mine to 70 USD, meaning it’s the next cheapest gear I’ve got.


Tips for the monotribe

The Korg monotribe is a desktop analog monophonic synthesizer with an additional three preset drums sounds. Its sound is warm and rich but quite clicky and noisy – although I think I prefer this timbre over the newer volca series. The monotribe was released in 2011 and is now discontinued.


How to Silent the VCO When Processing External Audio

The synth has an audio in port to feed external audio into 12 dB/oct lowpass filter (which uses the same circuit as the classic MS-10/MS-20). The crux is that the synth engine must be triggered to run the filter, meaning it’s not possible to process external audio solo (without being modded). But the LFO can modulate the oscillator so that it becomes nearly inaudible. The workaround below is not exactly neat, but should do the trick. On the monotribe, do as follows:

  1. Press PLAY button and then REC.
  2. Set RANGE select switch to WIDE and press the highest key on the RIBBON keyboard during the whole sequence.
  3. Set EG to GATE.
  4. Switch TARGET to VCO.
  5. Set MODE to 1SHOT.
  7. Set LFO RATE knob to minimum speed and INT. to maximum depth.
  8. Select TRIANGLE WAVE on modulation waveform WAVE.

How to CV Control the monotribe with the Analog Keys’ Keyboard

OS version 2.11 allows the SYNC IN connection to be used as a pitch CV/gate input. This makes it possible to control the monotribe with an external keyboard or sequencer (which is great because the ribbon keyboard is almost impossible to play). There are many ways to do this, but the theory is the same: send CV and gate via a TRRS 4-pole mini jack – where gate is tip and CV the second ring.

Now I got an Elektron Analog Keys which can send both tip and ring from the same CV output, but to do that to the monotribe I’d need a special cable (sort of TRS to TRRS) and I haven’t soldered any yet. So until then, I hacked a workable cable with many different pieces I found laying around (e.g. the composite video cable was provided with a TV I acquired last year). Again, you can build this patch cable more streamlined, but here’s my solution:

  1. Connect a composite video cable to SYNC IN on the monotribe and connect a RCA connector, white male to white female and red male to yellow female. On the other end, connect a pair of adaptors, RCA female to mono 3.5 mm mini jack male and then another pair of adaptors, 3.5 mm mini jack female to 6.3 mm jack male and plug white in CV AB and red/yellow in CV CD on Analog Keys.
  2. While this setup only uses the tips, and demands both CV ports on Analog Keys, set CV A to Gate, V-Trig, 5.0 V and CV C to Pitch V/oct, C 3, 1.000 V, C 6, 4.000 V. (CV B and D are not used.)
  3. Download and install System Updater 2.11.
  4. Prepare the monotribe as described in the documentation that came with the download package. Activate CV/GATE mode, set the Pitch CV curve to V/oct and GATE polarity to high.

P.S. It’s also possible to create a feedback loop by feeding the headphone output back into the monotribe’s audio in. This will render a mild thickening, and if you have some kind of attenuator on the feedback signal path, you can dial in some overdrive too.

Small Sawtooths and Low-Pass Filters

I got a few small analog synths that I put next to each other for comparison. The test pattern is defined as follows:

  1. The raw sawtooth waveform of the synth, 100% open frequency cutoff and resonance at null.
  2. Manual filter cutoff sweep, resonance at 0%.
  3. Manual filter cutoff sweep, resonance at 50%.
  4. Manual filter cutoff sweep, resonance at 100%.

The input levels are adjusted to roughly peak at -6 dB on each audio clip (maybe that was a bad decision). All synths were connected to a Mackie 1202VLZ4 mixer before being recorded using high-grade Cirrus Logic converters. No normalizing was added in post.

First is the Korg volca keys. When resonance is added, the volume is intensely boosted. The filter section uses the circuitry of the Korg miniKORG700S (which used dual 12 dB per octave low-pass and high-pass filters that were combined). Given the 128 steps that can be controlled via MIDI, the filter sounds very steppy on high resonance (peak).

Next is the Korg volca bass with the second and third VCOs muted. I’d say it has a little buzzier tone than the volca keys. Its filter is also much smoother, especially on high resonance. It’s a fine-tuned analog filter with a bright and crisp sound, with the resonance going from a clean peak to an increasingly distorted sound. As for the volca keys, the volume jumps with resonance.

The toyish Gakken SX-150 Mark II has a quite nice thick tone, with low resonance that is. Slightly less bottom end content than the volca modules perhaps. Unfortunately the pitch slides some due to me messing up operating the stylus pen. Raising the resonance seems to lower the overall volume. With filter cutoff set to fully open and resonance at 100%, the filter is making a loud noise (hiss). I think the synth has a voltage-controlled filter, Sallen-Key low-pass type, 12 dB per octave.

As a bonus the Yamaha CS01 from 1982 is included. The oscillator (labeled VCO, but is in fact a digital tone generator) lacks of woof and weight compared to the others. The first audio clip is the sawtooth 100% open frequency cutoff and resonance set to low (this model is equipped only with two resonance settings). The high setting follows after. The filter is a 12 dB resonant voltage-controlled filter.

Not sure what conclusion could be drawn from this, if any. However, there are some discussions about which of the volca modules are the best sounding et cetera, and maybe this could help deciding. Although this is just a comparison of their isolated sound engines and filters. Interface, voicing options and such have not been regarded.

P.S. You might be interested in a low-pass filter test I made, running a SH-101 trough the filters of a MiniBrute, a Minitaur and an Analog Four,

The Final Countdown of the microKORG

I thought the microKORG was okay sounding and quite fun even to program, but it was hard to find the right sonic spot in my productions for it; it competed with major league players, like the analog Minitaur and the Juno-106, or some great softsynths like the Thor. So I sold it (and by selling it, I made room for another purchase).

Still, just because there wasn’t any obvious place for the microKORG in my personal setup, it doesn’t mean it’s a bad or redundant synth for everbody.

Anyway, before I sold it, I printed down two generic bass sound designs, very basic but still good sounding.

The FM Bass

The first sound is a FM-esque bass, though it doesn’t try to mimic the style of the classic Yamaha DX7 of the 80s (for that, choose sine waves for both oscillators, carrier and modulator, and bypass the filter section entirely).

You can use a LFO as the modulation source for the oscillator, but in this case I’m using another oscillator to achieve a fairly complex overtone structure with only two operators. So by definition, the bass is actually a Cross Modulation (X-Mod) bass type. Let’s start by breaking down the oscillators:

Osc 1: SIN, 25, 0, -, –
Osc 2: SQU, OFF, 24, 0, –

The first oscillator (carrier) is set as a fundamental sine wave with no overtones. Some depth of cross modulation is added (in the patch below, adjust this with the modulation wheel).

A square wave is used for the second oscillator (modulator), with the oscillator modulation turned off, and detuned two octaves upward for harmonic-component effects. Also, try tweaking the tuning for different sounds.

Here’s the full program (another timbre was layered to fatten the sound up a bit):

*The default factory value, just skip to next setting.

Timbre 1
Edit Select 1
Voice: SYT, LAY, MON, MLT, –
Pitch: -12, 0, 0, 2, 0
Osc 1: SIN, 25, 0, -, –
Osc 2: SQU, OFF, 24, 0, –
*Mixer: 127, 0, 0, -, –
Filter: 12.L, 37, 41, 23, 34
Filter EG:  0, 31, 0, 0, ON
Amp: 127, CNT, OFF, -16, –
*Amp EG: 0, 64, 127, 0, ON
*LFO 1: TRI, OFF, OFF, 10, –
*LFO 2: SIN, OFF, OFF, 70, –

Edit Select 2
Patch 1: MOD, 1.CT, -8, -, –
*Patch 2: LF.2, PTC, 0, -, –
*Patch 3: LF.1, CUT, 0, -, –
Patch 4: LF.2, PAN, 23, -, –
*Mod FX: FLG, 20, 0, -, –
*Delay: STR, OFF, 40, 0, –
EQ: 320, 5, 6.00, 0, –
*Arpeg. A: 120, 1.16, 80, UP, 1
*Arpeg. B: OFF, 0, OFF, 8, BTH
*Global: 40.0, 0, CRU, PRE, OFF
*MIDI: 1, ON, INT, -, –

Timbre 2
Edit Select 1
Voice: SYT, LAY, MON, MLT, –
Pitch: -12, 0, 0, 2, 0
Osc 1: SIN, 0, 0, -, –
*Osc 2: SAW, OFF, 0, 0, –
*Mixer: 127, 0, 0, -, –
Filter: 12.L, 25, 11, 29, 42
Filter EG:  0, 31, 19, 0, ON
Amp: 127, CNT, OFF, -16, –
*Amp EG: 0, 64, 127, 0, ON
*LFO 1: TRI, OFF, OFF, 10, –
*LFO 2: SIN, OFF, OFF, 70, –

Edit Select 2
*Patch 1: LF.1, PTC, 0, -, –
*Patch 2: LF.2, PTC, 0, -, –
*Patch 3: LF.1, CUT, 0, -, –
*Patch 4: LF.2, CUT, 0, -, –
*Mod FX: FLG, 20, 0, -, –
*Delay: STR, OFF, 40, 0, –
EQ: 320, 5, 6.00, 0, –
*Arpeg. A: 120, 1.16, 80, UP, 1
*Arpeg. B: OFF, 0, OFF, 8, BTH
*Global: 40.0, 0, CRU, PRE, OFF
*MIDI: 1, ON, INT, -, –

The Juno Bass

The other bass is merely a sawtooth, yet beefy, virtually analogish with emulated drift and such. It’s straight forward, yet powerful, and I think it showcases the strengths of the microKORG’s MS2000 sound engine.

There’s a number of ways to enhance this sound. For example, you can turn up the second oscillator, detune it a bit, add some chorus, and get a lead-like sound. Or you can modulate the cutoff slightly with a LFO to make subtle movements in the sound.

Anyway, here’s the program of the punchy single sawtooth bass:

*The default factory value, just skip to next setting.

Edit Select 1
Voice: SYT, SGL, MON, MLT, –
Pitch: -12, 0, 0, 2, 5
*Osc 1: SAW, 0, 0, -, –
*Osc 2: SAW, OFF, 0, 0, –
*Mixer: 127, 0, 4, -, –
Filter: 12.L, 35, 12, 50, 45
Filter EG:  0, 25, 6, 30, ON
Amp: 127, CNT, OFF, -14, –
Amp EG: 0, 33, 101, 0, ON
*LFO 1: TRI, OFF, OFF, 10, –
*LFO 2: SIN, OFF, OFF, 70, –

Edit Select 2
*Patch 1: LF.1, PTC, 0, -, –
*Patch 2: LF.2, PTC, 0, -, –
*Patch 3: LF.1, CUT, 0, -, –
*Patch 4: LF.2, CUT, 0, -, –
*Mod FX: FLG, 20, 0, -, –
Delay: STR, OFF, 40, 0, –
EQ: 320, 6, 6.00, 5, –
*Arpeg. A: 120, 1.16, 80, UP, 1
*Arpeg. B: OFF, 0, OFF, 8, –
*Global: 40.0, 0, CRU, PRE, OFF
*MIDI: 1, ON, INT, -, –

Last evening I made 16 drum sounds on the microKORG. This synth is okay and offers quite a few possibilities with up to four separate envelope generators, four noise generators layered multi timbrally, and a multi mode filter (with resonance able to self-oscillate and to be used as a sound source). Also, complex made easy with the modulation routings on the microKORG.

Some external compression and effects where added to these four drum patterns.

It is what it is. Truth be told, I don’t really remember why I bought the microKORG. They say it’s Korg’s best selling synth ever, maybe I wanted to know why.

Faux Step Recording

The volca keys lacks a real step recording such as the bass module, but it’s still possible to program keys in a similar fashion. Activate one step and record note(s) and pot movements, then turn it off and do the same thing on the next step. Here’s the workaround:

  1. Clear sequence, press FUNC + CLEAR ALL.
  2. Enter active step mode, press FUNC + ACTIVE STEP.
  3. Turn off all steps but the first.
  4. Turn on motion sequencing, press FUNC + ON/OFF
  5. Turn off flux if necessary, press FUNC + FLUX.
  6. Leave active step mode, press FUNC.
  7. Press PLAY + REC and choose note(s) for this step. You can also set the filter et cetera if you like. You might have to hit REC a couple of times to get it right.
  8. Turn off recording, press REC, and enter active step mode again, FUNC + ACTIVE STEP.
  9. Turn on the next step and turn off the step you just edited.
  10. Repeat step 6-9 for as many steps as you like the sequence to loop.
  11. When all steps are edited, turn them on, press FUNC + ACTIVE STEP + all steps.
  12. Exit active step mode, press FUNC, and then press PLAY.

Bass for Dummies

Here’s  a song I’ve made with the volca bass and keys,

The bass sound is actually programmed in Step Mode as a simple pattern in 1/16 notes, and then resampled a few times with different manually movements. There are not many effects on the bass, just a multiband compressor and a little Haas for stereo width. (Then of course side-chain, triggered by the kickdrum.)


The bass sound is made on the volca bass. First group all three VCOs together (VCO GROUP) and turn them on (VCO1, VCO2 and VCO3 lit). Leave PITCH 2 off but detune PITCH 1 (down) and PITCH 3 (up) for a thick unison effect. Have the first (VCO1) and second (VCO2) oscillators generate a sawtooth wave and the third a square wave (VCO WAVE).

On the low-pass filter section (VCF) you’ll need a little resonance to make the LFO go well into audio range, so put PEAK level on 11 o’clock.

Set CUTOFF frequency at 11 o’clock. (As for knob movement, slightly raise CUTOFF level at the same time as EG DECAY/RELEASE drops.)

Now, set the LFO RATE to max and TARGET to CUTOFF modulation. Adjust intensity (INT) to 9 o’clock or so. This little trick – modulating the filter cutoff point (or pitch) with an audio range oscillator – introduces some buzz or grit (read: distortion) to the sound. And if you turn down the intensity a bit, you will get a fat analog sound.

Turn on the envelope generator for volume (AMP EG ON). On the EG section, set ATTACK to null, DECAY/RELEASE to 1 o’clock – turn this knob to about 10 o’clock and back again – and CUTOFF EG INT to 10 o’clock.


There were two technical problems with recording the volca modules: first MIDI latency and second, mono recording.

I’ve spent an hour or two trying to solve the MIDI offset, but didn’t succeed. In the end I just ignored it. (Well, someday I will fix it, for sure.)

And about the mono recording. The volca modules (bass and keys) are each a 3 VCO strong monosynth, and both of them have a stereo audio output. I can’t make much sense of this, but I could connect the each device to (A) a mono or (B) a stereo pair input on the audio interface (Propellerhead Balance). I chose to mono to save input ports. Moreover, I’ve read somewhere that the so called stereo, is just one mono signal rendered as left and right. This might be wrong though.

A microKORG Growl Bass

Hi, here’s how to make a dupstep wobble/growl bass on the microKORG. Or at least a good starting point. The raw sound is pretty standard, still full and with some fine overtones, that you should be able to take a step further with compressors, saturation and effects outside of the microKORG. Just resample an process.

You can manually change (or automate) the wobble speed with LFO 2 > Frequency, which is tempo synced to the BPM set on Arpeg. A > Tempo. Alright, start with initializing a program on the synth and follow the money.

Edit Select 1
Voice: SYT, SGL, MON, SGL, –
Pitch: -24, 0, 0, 2, 5
Osc 1: DIG, -, 61, -, –
Osc 2: SAW, OFF, 0, 0, –
Mixer: 127, 100, 10, -, –
Filter: 12.L, 38, 53, 0, 0
Filter EG:  0, 64, 127, 0, ON
Amp: 127, CNT, ON, 0, –
Amp EG: 0, 64, 127, 8, ON
LFO 1: TRI, OFF, OFF, 10, –
LFO 2: SIN, VOC, ON, 1.3, –

Edit Select 2
Patch 1: LF.2, CUT, -40, -, –
Patch 2: LF.2, PTC, 0, -, –
Patch 3: LF.1, CUT, 0, -, –
Patch 4: LF.2, CUT, 0, -, –
Mod FX: ENS, 20, 12, -, –
Delay: STR, OFF, 40, 0, –
EQ: 60, 7, 1.00, 3, –
Arpeg. A: 140, 1.16, 80, UP, 1
Arpeg. B: OFF, 0, OFF, 8, –

Analog for the Masses


This is the Korg volca bass on top of my master keyboard. The volca bass has a true analog synthesis, with three VCOs and a nice sounding filter (that uses the circuitry of the legendary miniKORG-700S from 1974).

The volca bass is very direct, very easy to learn. It’s tactile and inviting to play. It’s also small, like a VHS cassette, and the build is sturdy enough for the price point.

True Analog

I wanted a sound source that couldn’t be imitated digitally, and I actually wanted something well-defined (limitations somehow inspire me, while a tabula rasa has always been connected with anxiety for me). So I looked for a new analog sound engine and found the volca series.

It’s my third Korg, but the microKORG uses DSP analog modeling and the Polysix for Reason, a softsynth, uses CMT (Component Modeling Technology) to replicate the sound and parameter response of the original analog hardware.

The Sound

I like the sound of the volca bass, it’s rich, beefy, punchy and unmistakably analog. It may be inspired by the classic Roland TB-303, but the volca bass sounds different – it has its own sonic signature. Well I don’t mind, and I don’t make acid house anyway.

It’s easy to produce sounds for a wide range of music genres, like electro, electronica and EDM and even detuned old school EBM basses.

First I thought I’d be sequencing the volca bass externally in a DAW, and then resample and mix it with other instruments. I didn’t think I’d need the built-in loop sequencer, but now I admit that sequencer is part of the instrument itself: I mean, one will come up with phrases and riffs (with slides, octave jumps and such) in real-time that one never would have on a timeline in a DAW. Now I can resample, comp and edit the shit out of these loops.

The Keyboard

The ribbon controller, or the multi-touch half-step chromatic keyboard, is odd and confusing to say the least; it has inverted colors fucking up your head and begins with an A, instead of a standard C. Not a big deal though, I can live and trigger notes on an external keyboard via MIDI in.

Bass or Keys

I decided to go for the volca bass, and not the volca keys, because I wanted both sawtooth and square waveforms, and independent control of the three oscillators.

Some people say volca keys is more versatile as a standalone module, but I’m more a composer and a sound designer, than a performer, so the extended loop sequencer, polyphony and voicing options of the volca keys, were less important than the waveforms to me. They also say the filter on the volca bass sounds better than the one on volca keys, but it’s supposed to be the same filter so I don’t know. The volca keys is said to be more noisy, due to the digital delay that generates background noise.

Anyway, I’m now thinking of getting the volca keys too. Even if some features overlap, the different modules have their own niche and complement each other; surly Korg and engineer Tatsuya Takahashi designed them with this in mind.

And it could be fun too, because these devices are made for synchronized chaining of multiple volca modules (and even monotribe).


Recently Korg has designed some instruments so that they are mod-friendly. The company even published a reference schematic for the predecessor, monotron, and labeled solder points on the printed circuit boards of the volca series for modding and hacking.

For example, I’ve always thought the snare sounded weak on the volca beats, but that can be modded by placing a 104 capacitor across position C78 on the PCB.

In the same mindset, Korg released a SDK (Software Development Kit) and library that encourage people to code their own applications for the volca sample.


Of course I’d like to be able to set the volume for the individual VCOs, and to level distortion and accent et cetera. And even if I don’t mind the lack of MIDI out, I wouldn’t mind it either.

But some things I’d like to change with the volca bass. As I don’t value portability as high, I’d rather drop the built-in speaker, switch the 1/8” mini jack to a balanced 1/4” jack, remove the battery slot and include an AC adapter. I guess these changes would make the volca bass less a toy and more a studio instrument.

It’s still fine, it’s great actually.

But with them features some clever modding could accomplish, the volca bass would be perfect. In theory that is, I can’t say for sure, because I haven’t yet made any music with it.

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