Playing back modulation CV from your DAW doesn’t have to include purchasing a special DC coupled interface or special software.

I am offering you 4 free Instrument Racks downloads that will get you modulating, triggering and syncing your synths as easy as they’d be a plugin. All you need is an audio output!

Compressors often have “side-chain” inputs which are simply another access to their level detectors. That enables users to create unusual and useful dynamics effects, however, we rarely think about level detectors outside a compressor’s context, surely not to exploit them to generate synth’s modulation CV. A few classic synths had a dedicated ENV Follower input in them including the ARP 2600, Buchla, Doepfer and loads of other Eurorack modules by many other manufacturers.

From the ENV out we can route it to any other CV destination. So unlike compressor which always effects the level of the audio routed to a VCA, with an extra ENV FLW we can also route that CV to the filter, harmony shift or any other synth parameter we’d like to inflict that shape of modulation.

You could use our S.-Chain to get that pumping effect of a compressor’s side-chain if you feed it with the right audio with amplitude shaped like whatever you want really. I will describe exactly how and even offer a free Ableton Instrument Rack patches to help you use it in your session, later in this article. When we play audio into the Side-Chain input and switch it on, we turn that audio signal (AC) into a slow (or static) voltage signal (DC). The way it’s done is running the audio into a peak detector that resets as high as the audio peak and kind of “rides” the audio wave’s peaks. But next comes the question: How fast should the engineer make the voltage fall down between the peaks? And what about at the end of short staccato notes? The hard part is deciding how fast to fix the decay time. We all love quick ENV but the quicker it is the more harmonic distortion we’ll get. That distortion gets worse the lower the frequency played. That’s because a longer time passes between audio peaks that allows the CV to fall down further before raising again at the next peak.

The ideal audio source for any ENV follower?

I heard our S. Chain with all sorts of sources but science always wins. You have to choose faster decay for quicker ENV responses and you have to play higher frequencies to minimize harmonic noise.

The ideal audio frequency for tracking dynamics in my opinion better not be too high to be able to suffer copy generations and codec degradation. 10kHz should stay safe in most digital copy and codec scenarios and if you consider analog mediums a lower frequency of 6kHz-8kHz is better as treble degradation gets worse. Then we can record and play it back from any audio device. To me that is very exciting so I made a few tools you can use and even make your own very easily in order to perform, record and playback grooving modulations from any audio playback machine.

So how can we get faster CV control with less noise?

When riding audio peaks (AKA ENV following) you have to remember that every ENV follower has a decay factor. Determining how fast or slow the ENV FLW decay is reveals a tough trade-off between harmonic distortion reduction and faster CV rates. Such distortion will be caused to the CV and any destination it modulates. The slower the decay factor of an ENV follower is, the lower such distortion will accure. It’s very easy to hear that every octave you will climb in pitch playing into the ENV follower, the harmonic distortion will lower in level by half or so. Nice thing about our ENV FLW is that the wave is fully rectified so for every audio cycle we get 2 peaks detected instead of one. The next illustration shows you what could be an extreme case of playing a slow sinewave of 50Hz into the main input’s ENV FLW.

Considering that a 50Hz cycle lasts 20ms between adjacent cycles, you will need a pretty slow decay time to smooth it out. The resulting CV is the blue lines, looks very jugged and its heard well as added even harmonics. Some people might like the way it sounds with it’s added edgy harmonics, but as harmonics are already rich you might want to minimize those harmonics by playing the highest frequency you can. That goes for both on your instrument main input but much more so into the S.-Chain. Since the S.-Chain source can be any audio we want, I can generate any sinewave from my DAW that is in the audible range.  A sampler playing a sinewave takes very little CPU cycles and can easily play 8000Hz-10kHz. Look at the next illustration in which a sinewave is played into the S.-Chain this time at 400Hz and 8000Hz. The harmonic noise is much smaller between wave peaks and almost disappears.

Sonicsmith ENV FLW illustration

The musical benefits

The benefits of generating your own modulated sinewave are plenty! You now are no longer limited to a set shape modulation like an LFO or an ENV Generator. You can shape and process your sinewave just as you want your CV with any combination of ENV, LFO’s and audio dynamics processor like compressors, gates, expanders etc. while not suffering their audio degradation. You can edit precise modulation shapes never heard before, edit a whole track’s modulation on your DAW or sampler. You can then export such “modulation audio tracks” sinewaves to a WAV or MP3 (or analog tape) and play that audio track into your S.-Chain or main input from your phone or mp3 player for a fully automated modulation track that never fails in a live situation as long as the audio playback doesn’t. You can even listen to those sinewave files. Just remember to be careful not to play them loud. By listening you can easily understand their groove and figure out what song they belong to. and finally: you can even play them back from analog mediums, taking advantage of their audio side-effects like wow, flutter and even enjoy their none-linear saturation of the loudest parts. While playing modulation back as audio, any changing of the audio speed will also change the modulation speed which is so essential but so missing from today’s synth control. We tweak our ADSR’s and LFO so carefully to fit the track’s groove and if we later change the BPM while the ENV/LFO remains at the same rate, we may lose the sweet spot of the groove. tying the modulation rate to audio makes audio track’s pitch changes much more groovy.

Enter the SideChainor Tr. and the Sequenzor Tr. (and two others!)

The first two Ableton Live Standard Instrument Racks I uploaded for you are very standard: The Clickor Tr. and the Triggor Tr. They do what they say they do, plus some cool extra’s from Ableton’s tools. The next two Instrument Racks are sinewave sample players to be played into our synths inputs or any ENV follower out in the market (the SideChainor Tr.)

I was able to save those Instrument Racks a lot like a dedicated plugin thanks to Ableton’s customization. Adding arpeggiator, glide and stuff that until today were easy to do in digital but more challenging to translate into analog CV. If you’r wondering why don’t I just use MIDI well, MIDI can’t transfer exact pitch and ENV. But now with those two Ableton Instruments, it’s time to find out if such modulation workflow is helping or is it too cumbersome? I’m also uploading the actual sinewave samples I’v used (440Hz for the Squanzor Tr. and 8kHz sine for the SideChainor Tr.) to make the Instrument Racks. So now anyone can download those little samples and make their own sinewave patches with their own native sampler/synth. They are mono 48kHz 24bit files. The 8000Hz frequency was chosen cause it’s the highest frequency a common audio interface can play if you want to include analog mediums. Any signals above 10kHz might start suffering the analog medium treble degradation and the noise is sufficiently low.  8000Hz in digital mediums make sense cause DJ’s might also be interested in quickening the pitch up or down and with the S. Chain sinewave is too high it will go beyond the frequency response and cheaper tapes. Any lower than 4000Hz would be too close to the ripple noise frequencies. Taking into account a safe margin of pitch adjustments for DJ’s. I think 8000Hz answers all the criteria’s above.

Your feedback might changes things

So now I want you to download those utility patches and and start using your audio outs into your analog gear or your own ENV follower. After you try it for a while tell me: how is it to work like that?

It can be attractive for live instrumentalists looking to modulate their instruments according to a pre-set of movements, DJ’s (who can play more than 2 audio outputs at a time), who also want to incorporate live synths in their sets but want some modulation to happen automatically, and bedroom musicians who are looking to produce electronic music with their DAW and want that CV modulation to their external analog synths. If you think this way of working is viable and it’s worth pursuing, comment here or write some feedback on this workflow to me at info@sonicsmith.com.