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Subject: Re: [motm] [OT] Vocoders

From: "J. Larry Hendry" <jlarryh@...>
Date: 2000-06-14

> From: Nathan Alan Hunsicker <nate@...>
> Although didn't someone write that
> when put to the test the PAIA only has 3 or so
> "actual" bands, I seem to recall reading that somewhere.
> Although this does help me to understand
> the expense and labor required. -Nate

I have seen this (rumor) too. However, there was a modification to the
original PAiA design that did more to reduce noise and even out the bands
so that more are active/open at the same time. In my opinion, these
additional op amps made for a significant improvement in the PAiA
performance. However, my VERY limited vocoder experience has taught me to
put a nice 31 band EQ on the microphone channel when dealing with an
inexpensive vocoder like the PAiA that does not have level controls for the
individual bands. You can manipulate the EQ to even out the levels to
greatly improve performance of even cheap vocoders. First and foremost is
a reduction in the bass end. It seems to me that bass frequencies of a
voice are of greater magnitude than frequencies in the upper spectrum.
Yet, bass frequencies in an inexpensive vocoder tend to really muddy up the
sound and make the speech difficult to understand. So, roll off the bass
end for added clarity.

I have built the PAiA vocoder, and like most PAiA products, cost cutting
was a primary initiative. However, I was significantly impressed with the
price / performance ratio (Especially with the Scott Lee modification). A
while back, I made several samples for John (using the PAiA vocoder) for
his web site. I sent them to him without telling his what any of them
"said." He pegged them all, which does at least say that the speak was
intelligible. Now, when he put them on his site, he ruined them by
squeezing them to 8 bit resolution and 11kHz sample rate (to save space).
I still have all the full bandwidth samples I would gladly mail to anyone
privately if they are interested. Compared to the anticipated SynthTech
vocoder, I am positive it is totally anemic. However, compared to other
under $500 choices, I think it stands up real well. I think most of the
people who can't get good sounds from it (and other vocoders) just don't
know how to "adjust" their gear.

I'm not promoting the PAiA vocoder here on the motm list -- just giving a
first-hand, objective review of its actual performance.

Stooge Larry