Forgive my wording…
I’m asking if it is possible to use ONLY a VCO and VCA module, key tracked by the CV channel, as an oscillator source for the audio in of track 1 instead of a standard DCO?
Would the trigs have to copied between sequencer tracks to get the desired effect?
… Seems like an inexpensive way to experiment with new timbre foundations. I never explored modular but it seems VCO + VCA. Would produce a line input suitable for a #fatter “more analog” flavored OSC replacement.
You would not have to copy the trigs to the CV track. The CVs can be sequenced from any track. Page 67 in the manual shows a setup example for what you describe.
I’d go for a simple eurorack level -> line level module instead of a VCA, though.
Short:
Yes.
Longer:
To get the effects of the external (modular, euro) VCA and envelope (I presume) you’d have to leave the internal one fully open. Short attack & decay full sustain and infinite release. So yes, it is possible to use an external VCA/ADSR, being gated or trigged by one of the CV tracks.
The external VCO should be controlled by the CV pitch out and as such it is indeed a VOLTAGE controlled oscillator. But since the A4/AK still handles pitch internally via digital control, it will still (in the full chain) be digitally controlled. Fatter or more analog?
That said - you could get an external oscillator with a completely different characteristic than the A4/AK’s own. That’s cool!
You’d set the CV tracks to derive pitch and gate info from whatever track (1-4) you’re using. No copies needed.
Reading again…
If you’re talking about using only an external VCA to add analog flavoring - I’d say that’s completely overkill. The A4/AK signal chain is completely analog as is.
As a starting point I’d get just one (or two!) oscillators in a minimal case. To be able to vary the sonic possibilities by combining internal and external oscillators.
I made a tutorial on such a setup. The example uses the Arturia Microbrute, but the concept is the same.
I have an A4 and a microbrute. Always thinking about adding a little rack with just some versatile oscillators like mi braids. I will watch your tutorial with the microbrute later. But sounds like a great way to get some other interestiung sounds into the A4. I think the challenge is staying with just the Oscs and not expanding the rack once started 
HO
LY
CRAP.
so I literally just need a VCO and I’ll have a totally new sonic foundation.
… I think I get what Elektron were aiming for with this box now.
Sexy.
What a fantastic and well made video!
I have to say… This simple expansion of the A4’s capabilities seems like a solution to all the “my a4 sounds dull” people’s problems…
What a huge upgrade potential this unit has…
You need to buy a 3U case as well for powering the oscillator right?
Yep. Some sort of power (and housing) is needed.
http://www.schneidersladen.de/en/erica-synths-pico-case.html
http://www.schneidersladen.de/en/pittsburgh-modular-cell-48-case.html
Small… With some possibilities of expansion. If you’d ever want or need it. 
Thanks for the links!
I’ll think about it. At the moment I try to satisfy my Eurorack lust with Reaktor Blocks and the G2 Demo Slightly cheaper
Yay GAS!
No really tho; would love to get an:
“OSC > fuzz pedal > A4” thing going in my life 
Maybe even an:
“OSC > Insert guitar effect here > A4”
kinda lyfe…
On the other hand; I suppose if one were to purchase 3 OSC modules then they would be able to expand their a4 to 3 mono synths + 1 4 voice poly available at all times huh…?
You need to run the external audio through one track. So possibly “phat mono”+three voice polyssynth would be doable.
But for the cost of a decent eurorack oscillator (and case) you could get a self contained analog monosynth (such as the Arturia Microbrute). So if you’re only after another (or several) monosynth rather than actually using it WITH the A4 - I’d say that’s a better option.
You can also use the two pairs of CV and two ins on two regular tracks to independently sequence two external synths and still have two normal tracks
As @CarlMikaelBjork says, there are wiser ways to use your resources and the microbrute is great … When i tried all this out a while back i have to say the A4 sounded near identical to a Doepfer DE1 saw in the mid range, but the A4 did seem to be a tiny bit fizzier at the lowest frequencies … I’d be inclined to look at the external oscillator route as a creative option rather than a solution to anything
Just this little thread and I find myself on modulargrid again 
If I would combine the A4 with external oscillators, I definitely would choose an Osc which offers a different sound palett than the A4, like fm, granular, wavetable etc. As I mentioned MI Braids, or Clouds or something special like that. There is so much awesome stuff out there.
I guess another “common” analog oscillator could be little redundant.
That’s my thinking. A digital oscillator to get completely different sounds than you can get from the internal ones. At the moment I have Mysteron from Make Noise and also Clouds from Mutable Instruments that are digital. Together with the analog oscillators from the AK - I can get a wide palette of sounds.
My thoughts as well. Digital or not (I have fun using the analog Pittsburgh Modular Generator/GenXpander, for instance). The three “left over” CV outs are perfect to modulate other aspects of the module than pitch, so I’d look for a module with lots of CV modulation possibilities. Being able to use p-locks, envelopes and LFOs on the A4 to affect the external VCO makes the whole setup a lot more powerful.
Would be great to add a module with lots modulation capabilities. Or something to expand the sequencing possibilites of the A4…
I’m just gonna throw this out there … it explores the routing of an ‘improved external oscillator’ as discussed above …
I have made a recording which offers three passes of different takes of the same arp phrase using more than just the A4 Saw … the tuneless nature of the phrase should focus you only to the sound which covers a fair few octaves … so it goes Take A Take B Take C then Take A Take B Take C so you can audition twice and hear each take next to another one … always One Osc and No filter, just varying the Osc source
Straight out into a zoom field recorder
How do A B & C stack up relative to each other and the ‘dull’ and ‘bassy’ commentary in your opinion … Thoughts … can you spot the A4 ?
Linked HERE on clypit
(this is likely time limited or expiring) and don’t trust the rendered waveform, it looks different in my editor in terms of volume … obvs decent speakers/headphones reqd