Vocoder?

[slotbot]

Does anyone have a schematic for a vocoder of any type?

Thanks!

[Tychobrahe1979]

Ive never found one but if you real want a good one check out the Digitech Talker. It is absolutely amazing.

[Mark Hammer]

There are a few posted around.  Elektor had one several decades back in their "Formant" synthesizer series.  The schematics for that one are posted, though I forget where.  PAiA still sells Craig Anderton's budget vocoder in kit form, though I think you can simply buy the board from them if you have the parts.

One of the things I've come to understand about analog vocoders is that  you either need to put in a lot of R&D into what the crucial formants are in your own voice (or whomever the final user will be), or else be prepared to make one with a LOT of bands.  It's a bit like equalizers.  If you have no idea what the critical bands will be, you likely opt for a 31-band EQ and start monkeying around with the sliders.  If you *know* what the critical bands are, a 3-band parametric that you can tune to the problem zones is quite sufficient.

Mike Irwin (VSAT) demoed the PAiA one for me (8 bands) and it sounded okay but it was really more of an interesting timbral modulator than any obvious voice substitute.  That's not a flaw, necessarily, unless you really WANT it to sound just like a voice.  Of course the deal with the PAiA/Anderton one is that is presumes NOTHING about the users voice other than that it covers the spectrum typical of the human voice.  It completely ignores any differences between male and female, low and high voices, gravelly vs melodious ones, etc., and merely assigns fixed-width voice bands to fixed-width signal-filter bands.  If you have 30 bands of voice-filtering and 30 identical bands of signal filtering, you can get it to work great, but 8 bands is simply not enough specificity to cope with idiosyncracies of individual voices.  That being said, the PAiA unit *could* be tuned to the user's voice and optimized so that 8 bands behaves like more than 8.

If you simply want to monkey around with voice-directed tone changes and don't really care if it sounds like a voice or not, there are plenty of other options.

I've dished this one out before, and never got to building or drawing it for that matter, but I'll dish it out again.

Imagine you have a voice-mic input, 3 tunable filters, each with their own envelope follower driving an LED/LDR combo.  The LDRs are entirely nondedicated.  That means you can insert them wherever a resistor would/could go.  One LDR gets set up for overall guitar signal level.  Another gets set up for distortion amount (independent of level), and the third gets set up to retune a bandpass filter.  The first LDR depends on overall voice amplitude.  The second is tuned to one broad voice band (perhaps higher pitched vowel formants like E or I), and the thrid is tuned to lower pitched voiced formants like Oh and Oooo).  With this simple arrangement, you should be able to produce some rally interesting real-time modulation of your guitar signal with your voice.  I called it a "talked-to" pedal, rather than a "talking" pedal, because it merely responds interestingly, rather than being designed to copy your voice in any way.

[slotbot]

Yes i have seen the talker. never used one though.

I recently bought azoom studio 1204 on ebay (still waiting for it in the mail) for 50 bucks which is about 1/3 of what ive usually seen the digitech talkers go for (150+). apparently it has a pretty good vocoder in it. Alos it has other effects too (its arack unit). So ifigure for 50 bucks even if the vocoder isnt great (although ive only read good things about it) i willstill get soem other stuff to play with.

I also noticed that on PAiA there is an analog vocoder kit you can buy for 139. I  *think* it said it was designed by craig anderton but dont quote me.

In terms of a DIY one im not tooo concerned about the quality. More jsut the effect itself. ANY leads appreciated.

[Peter Snow]

Hi,

I have the Zoom 1201 rack effects (a non-midi version of the 1204 I believe).  I remember playing with the vocoder when I first bought it and was surprised at how good it was.  Mmmmm I must dig it out and play with it again.  Lots of other neat FX in that unit too - like a lo-fi filter, telephone filter, etc.  And of course those great Zoom reverbs.  $50 is a steal for the 1204 unit.

I also built the PAiA vocoder some years ago and for the cost it is quite good.  I would definitely recommend it for a starter vocoder project.  As with all PAiA stuff if is great value for money, but don't expect it to sound like a 32-band unit that costs hundreds of dollars more.  Building it taught me a great deal about vocoders generally. As with all PAiA kits, it is open to all kinds of modding if you are up to it.

If you decide to go with the PAiA kit, check out the "clarifier" mod on their web site, developed by their resident tech Scott Lee.  It is basically a whole bunch of op-amps that buffer the 16 filter inputs, reducing noise and enhancing clarity.  I have not built this mod so I cannot comment on it's effectiveness.

At the time I built it, there was some information on the web (can't remember where) indicating that it was worth hooking up a scope to the various control filter outputs to check their level. Using the given component values the output level of some bands were way below the level of others.  After tweaking those levels, much better results were claimed. Again, I never tried this.

HTH and good luck.

Peter

[Vsat]

Hi slotbot,
Unless you are really interested in  building a vocoder for the learning experience, I would highly recommend the digital multi-fx box approach - a cheap digital box will  give much better results than a high-end analog unit which costs several thousand dollars. There was  a 11-band vocoder design by N. Okita featured in a Japanese hobby magazine that is fairly buildable, but still uses a lot of parts (ten NE570 for example). It is somewhere between the PAiA and Roland SVC-350 in sound quality. I built it, it's OK... but still a digital vocoder will run circles around it.
Regards, Mike

[Paul Perry (Frostwave)]

What most vocoders (analog or digital) dont have, is !. the ability to adjust Q of the filters so you can get spiky ringing effects and 2. the ability to have a cross patching of input and output filters, so that the envelope driven by a particular input band is driving a different output band.
Plus, nobody ever runs the same signal into both inputs, but if they did, they would have a cheap noise suppressor (maybe..)
here is a good link: http://web.inter.nl.net/hcc/davies/vocpage.htm