[sdiy] Speaking of the Elektor Vocoder (and the Korg Vocoder)

Grant Richter grichter at asapnet.net
Fri Feb 22 18:21:25 CET 2008


This helps explain why the noise comes up so fast in a Ring Modulator.

Viewed on a real time Audio Spectrum Analyzer, sine waves with high  
THD into a multiplier produce a whole series of peaks in multiple  
frequency bins (visually similar to quantization noise).

At some point, when enough frequency bins have near equal content,  
the ear classifies it as a flat line, which is the Spectrum display  
for noise.

That's my story and I'm sticking to it ~^;

On Feb 22, 2008, at 7:36 AM, Andrew Simper wrote:

> As everyone knows already, a BPF with high Q takes a while to decay  
> which is totally different from what is going on in an FFT.
>
> Just because you have a single bin in an FFT doesn't mean that this  
> bin is it's own "signal" that can be treated independently. The  
> contributions from nearby bins makes the signal (for signals that  
> aren't an exact multiple of your FFT length). Putting a window  
> around the central bin you want to solo will help.
>
> Andrew
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