vocoder dim

[Rene Schmitz]

>To all vocoder experts :
Sorry, I'm not an expert on that. But heres some thoughts 
about this topic.

<snip>


>Ripple suppression might get important if the analysis and
>synth section are not connected in the usual way but
>for example inverted (lowest band to highest band etc).
>In this case any control voltage ripple should give non
>masked audible am-modulation artefacts.

An idea could be to connect the VCAs in the syntheziser section
at the *input* of the filters, instead of connecting them at 
the output, as seen on so many block diags. Any am-modulation
dirt, would then mostly be filtered out anyway, right ?
(Not my idea, I believe sennheiser did it that way)

>Some EMS Vocoders have slew regulation for rising and falling
>edge of the analysis detector simultaneously with a single pot
>for all channels. Interesting feeeaaatuuuure.
>How ?
>Voltage controlled RC slew regulation with junction fet as "R" ?
>They also have a freeze feature.
>Could also be done with "RC"-fet as sample & hold.
>Does anybody know if the EMS freeze function suffers from leakage
>after some time. That would be a hint.

Smells like a slew rate limiter with an OTA to me. High current into 
the OTA would give maximum speed, low current low speed, and no current
would be hold.

OK Bye
  René