Yes i have the manuals. And yes it was possible to route audio into the original. You can also route audio into some software.
Arturia have audio input in Mini V, Modular V, ARP 2600 V and Buchla Easel V.
Beside that Arturia have their filter effect applications Mini-filter, M12-Filter and SEM-Filter.
Synthi have another filter and functionality. So i was just wondering how the real EMS actually sounded using audio input. And i was wondering if you had heard something speciel, that you wanted to be able to do.
I think a audio input in Synthi V would be in it's place, as it was there in the original.
I think the organ chopping in this: The Who - Won't Get Fooled Again:
https://www.youtube.com/watch?v=SHhrZgojY1Qand the voice filtering in this: KING CRIMSON - LIZARD - Happy Family:
https://www.dailymotion.com/video/x31ogfcwas made with EMS Synthi, but i'm not certain. Is that what you wan't to do? If so, then i think you can do what you wan't with the above applications.
This is just some music examples i have heard about. But i can't find any good examles showing the feature - or a tutorial. I found a very bad video once where the EMS ring modulator and filter was used, but it was very very bad, so i can't use it for anything.
And examples from the software versions there are of Synthi and VCS3 does'nt show anything very speciel. But Arturias version perhaps could because of Arturias sound. I can't tell.
EMS also builded analog vocoders like this:
http://www.vintagesynth.com/misc/ems_vocoder.php - There is a video showing a little of this on this page.
EDIT:
Found this by chance.
Pete Townshend on "that" sound from Won't Get Fooled Again :
https://www.youtube.com/watch?v=O5voNyRmvXsLook from 0:50.
So that was true.
Here is an example with the same tune using Arturias ARP 2600 V3:
https://www.youtube.com/watch?v=Pw-ZpUZ0GTELook from 1:42.
Also found the above mentioned bad movie: EMS SynthiA demo Part 2 - External processing:
https://www.youtube.com/watch?v=0Hv3ItM9mbgEDIT END