A few years ago Surgeon was the focus of a Resident Advisor feature. In it he described his live setup at the time which featured a Leploop. The Leploop incorporates a sequencer that can be programmed using a sample and hold to generate the pitch data. I was wondering if there are any other synths that can be used similarly, either hardware or vst? Surgeon talks about how his job during the set is to make the resulting ‘melody’ work using his sound design skills. I want to try something similar as improvising melody, rhythm, arrangement and sound design during a set is nigh on impossible for me…
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If you have a modular or modular VST you can try something like LFO, sample and hold, quantizer to vco pitch.
The Leploop is quite unique, because the sequencer uses capacitors to store values. As the stored voltage decreases, the pitch drops and eventually the stored sequence is lost.
I don’t think there’s anything like that out there, but if you’re not interested in the part of the sequencer that loses it’s stored values, you can do similar stuff.
IIRC the sequencer in the Leploop can be edited per step or you can use the S&H to record random sequences. That’s what Surgeon was doing in the RA video, so any sequencer with random capabilities would let you do that. Noise and S&H is just used to get pseudo random sequences in an analog sequencer.
IIRC Surgeon talked about how he learned to work with randomly generated sequences live. Like he would just take what the sequencer spit out.
I’ve seen a similar approach in modular jams in the past years, sequencers like the Erica Synths Pico Seq are quite popular. The Pico Seq lets you set how many octaves, which scale, how many notes etc. will be in the sequence before you generate a random sequence.
This limits the range of surprises you can get from random sequences.
The Erica Synths DB-01 also has this feature, the Bass Bot v2 has a different approach, you have different “personalities” you can choose from (busy, funky, sparse, intricate sequences etc.) and you can also set the notes that can appear in the notes.
On an Elektron you could just engage live recording mode and wiggle some knobs…
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…u can always use a lfo in and on everything u got in use, that triggers pitch in various ways and then a lfo that does sample and hold to control and keep those values in various ways again…
Yeah, on the OT you can use the lfos on a midi track to modulate note pitch and it spits out random sequences you can further modulate/mutate and record that into another sequencer or Elektron. Each of the three lfos could modulate one of the four notes or one of the lfos could modulate another lfos depth…lots of possibilities. Use the arp, locked to scale if you want, lfos in hold mode.
A4/AK with it’s 2 lfos is also capable of generating random sequences. Target osc pitch, use hold mode and play with lfo shapes, lfo speed etc.
Edit: Hold mode on Elektron lfos is sample&hold. The lfo runs freely in the background and when the sequencer encounters a trig, it samples the current value of the lfo and holds it until the next trig.
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Some sequencers can do it quite easily.
For example Squarp Hapax (probably Pyramid too).
On Hapax one of the options would be -
Random LFO->Harmonizer Note2 (with Origin OFF) -> Scaler
Fine tune as needed.
And you can use a second LFO with very slow rate to adjust Depth of the first LFO to emulate a slow “degradation” of the sequencer. Or use an automation lane.
I´ve watched the video again, yesterday and noticed Surgeon said he uses the lfo as the source for the sample and hold Click.
The way the Leploop sequencer works (as far as I understand it) is, you choose either the lfo or noise as the source for the S&H and the output signal is stored at every pulse from S&H or Env2. The signal is held until the next pulse. So, I think this means that for every step that is set for S&H or Env2 in the sequencer, the S&H will sample the source signal, output it and hold it until the next step.
The lfo has triangle, square or sine.
Is you want a sine wave on the Octatrack, use following values in the lfo designer
0, 49, 90, 117, 127 , 117, 90, 49, 0, -49, -90, -117, -127, -117, -90, -49
This is from the Leploops manual:
S\H
The selected CV signal is stored into a capacitor at every pulse from S&H (red LED) or ENV2(blue led).
The CV is stored until next pulse, it can be routed to VCO1, VCO2 and SEQ.
ANALOG SEQUENCER
The S&H input samples the
LFO or noise generator and it will store the CV value for that input and maintain it until the next time it cycles through. What this means is that the 16 capacitors that store the values for the S&H, will actually “sample” the analog value of the LFO or Noise (and what they trigger, be it an oscillator or envelope) and store it in it’s analog memory. Thusly, the LEPLOOP has a 16-step analog recorder, much like an analog delay. Over time, as the analog sequencer cycles through its pattern, the signal will degrade and the sound will change. This is because the capacitor can only store the signal for a limited amount of time. The analog sequencer is digitally controlled tempo-wise, and will work in conjunction with the digital track sequencer.
On an Elektron you could simply use an lfo on a midi track, lfo in hold mode, target “Note1” (this is the S&H track in the Leploops sequencer).
You could set up another midi track, set to the same midi channel, also lfo in hold mode and also lfo destination “Note1” ((this is the Env2 track in the Leploops sequencer).
Send that to another Elektron, engage live record mode to capture a new sequence (works very well live and on the fly). I´d have to do some tests with midi loopback first to see if it´s a feasible option, but an Octatrack or Digitakt sequencing an A4/AK or Rytm DVCO, Syntakt or Model:Cycles should work very well!
Both lfos should use the same waveform and speed to get Leploop behaviour, but of course you can go experiment with different waveforms, lfo speeds, you can swithch the arp on and use “Note2”, “Note3”, “Note4” as destination, you could modulate arp parameters, too…
Of course the natural decay of the stored sequence as the capacitors in the Leploop´s sequencer lose their stored voltage is something that might not so easy to replicate in the OT, but since this is nothing that Surgeon actually uses to obtain musical effects or anything like that, I did not adress it in my post.
Btw, I´m still mildly confused by him using a splitter cable to connect a mono output from the Leploop to two inputs on the OT. 
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