Slightly off topic on Roland VT-1

[Sean Costello]

Magnus Danielson wrote:
> 
> HI there!
> 
> One particularly visous person happend to put a Roland Inside magazine
> into my hands just a few min ago, while browsing throught it I found a
> little gizmo they have called VT-1, Voice Transformer... I thouht that
> people on this list ought to be able to give me the technical
> explanation of what is in it without getting houted "it's not analog"
> or "Roland Crapotronics at their worst d*****l nightmar" etc.
> 
> There seems to be a pitch-shifter, but there also seems to be a
> vocoder. Anyone care to give me any details worth mentioning.

I think that the VT-1 doesn't have a vocoder in the traditional sense. 
It has a special "robot" feature, for vocoder-LIKE effect, but I doubt
it is a true vocoder. Possibly some sort of delay-line feedback comb
filtering (most likely), or maybe ring modulation (less likely).  

The VT-1 does have a rather cool feature - it allows you to shift the
pitch and formants of the input signal independantly.  This allows pitch
shift without "munchkinization"; conversely, you could keep your voice
at its normal pitch while shifting the formants to sound like Jabba the
Hut or chipmunks.  Probably there are other devices that do this better
(Digitech), but it might be cool for DJs, or people who want to emulate
the vocal effects Gibby Haynes used in the Butthole Surfers (anyone else
out there like this band?).  My guesss is that LPC (Linear Predictive
Coding) is used for the analysis and resynthesis of formants.  It's hard
to tell from the literature on the product - too many manufacturers use
their own cute lingo for what their product does, without using the more
universal technical terms.

Later,

Sean Costello

P.S. Way off topic, but: Clavia (www.clavia.se) announced Version 2.0 of
their software for the Nord Modular.  It includes a 16 band vocoder,
where you can determine what input frequency band controls what output
frequency band. The new operating system also includes more x0x-like
drums, formant oscillators (perhaps similar to VOSIM/CHANT type stuff),
a phaser, and more goodies.  Plus, the case of the keyboard version is
so cool looking (almost like an old Saab Draken fighter jet, but in
synthesizer form).  All Hail Sweden!!!!! :)

Now if I can just find one of these in the US...hopefully I'll have one
on order soon...