[sdiy] 40-band vocorder

[Scott Nordlund]

If the analysis and reconstruction filters can be adjusted independently, this opens the door to all sorts of formant scaling/shifting/inversion.

Years ago I built a vocoder in Reaktor that could do this.  For convenience I also added a "high value" and "low value" where the frequency of each band would an interpolated value between the two points, and since these were independent for the analysis and reconstruction sections, the formant could be manipulated more or less arbitrarily.  These values could also be modulated by LFOs, which quickly led to very strange territory.  This was enough that I never really saw the need to for more obscure mappings.  Of course I could do so if I wanted, but the result generally didn't have any audibly logical relation to the input.

It's definitely worthwhile territory, but for obvious reasons should probably only be attempted in software.

Anyway, speaking of crazy/stupid ideas, I'd always sort of wondered if it would be possible to make a crappy vocoder using a gimmicky home stereo with a graphic EQ (filter bank) and spectrum analyzer (filter bank + envelope follower) as a starting point.  Of course it's immediately pointless as no one would actually want to search for the "right" model whose circuitry would permit such abuse...


 
----------------------------------------
> Date: Wed, 1 Apr 2009 12:06:46 +0200
> From: fanwander at mnet-online.de
> To: taciturn_unquiet at hotmail.com
> Subject: Re: [sdiy] 40-band vocorder
> CC: synth-diy at dropmix.xs4all.nl
>
> Hi Ian
>
> What about a 10 or 15 Band vocoder with tunable bands? I once made some
> tests with multitracked vocoding (physically only one band, but the
> vocoding was done on a multitrack tape).
> It is astonishing how you can improve the sound, if you adjust the band
> freequencies suitable to the vocoded voice.
>
> Florian
>
>
> Ian Smith schrieb:
>> Hey all,
>> I'm back with another insane idea. Here are the sources of my madness: A book on Vocal Coding and Formants, Paia Corporation's Vocorder, and Jurgen Haible's 40 band fixed filter bank.
>> I know some of you just twitched in terror at the thought of all that wire.
>> For those of you that didn't: 80 filters (2 sets of 40, one for the vocal input one for the instrument input) with 80 sliders, 40 envelope followers, and 40 VCAs.
>> Yup... there go the rest of you. That twitch was disturbance-in-the-force worthy...
>> But wouldn't it be awesome to be able to shape both the instrument signal AND the vocal signal?
>> In other questions... how advanced do the VCAs need to be? Do they have to be full blown log/lin VCAs or would a simple little single transistor VCA like the one in Ray Wilson's Weird Sound Generator work?
>> -Ian
>> _________________________________________________________________
>> Hotmail® is up to 70% faster. Now good news travels really fast.
>> http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_HM_70faster_032009
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at dropmix.xs4all.nl
>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy

_________________________________________________________________
Windows Live™: Keep your life in sync.
http://windowslive.com/explore?ocid=TXT_TAGLM_WL_allup_1a_explore_042009