[sdiy] Question for those with musical ears

Richie Burnett rburnett at richieburnett.co.uk
Fri Apr 16 11:50:24 CEST 2021


> What sort of time period are we talking about for the jitter frequency in 
> this 'trill' ?

I guess it could be anything from twice the pitch update period upwards, if 
successive pitch estimates dance between two pitch quantisation levels.  The 
worst case would seem to be a high pitch update rate but with quite coarse 
pitch quantisation, because this can make the resulting pitch estimate 
toggle between two quite radically different pitches at a high rate.  This 
is almost FSK (frequency shift keying) and would have a horrendous spectrum!

-Richie,



-----Original Message----- 
From: Mike Bryant
Sent: Friday, April 16, 2021 10:36 AM
To: Richie Burnett ; synth-diy at synth-diy.org
Subject: RE: [sdiy] Question for those with musical ears

Haven't noticed this yet but good point and I'm doing nothing to avoid it so 
obviously need to.

I do check the frequency bins as I slide the window along and if a pair of 
bins are at one frequency with the one between them off I do force it back 
to the same frequency.  But maybe I need to look at it on a wider basis, 
perhaps with a low pass filter on the bin results, although the problem then 
could be human voices are capable of remarkable continuous (i.e. not 
staccato) shifts in pitch in next to no time so need to avoid slurring it.

What sort of time period are we talking about for the jitter frequency in 
this 'trill' ?

Many Thanks

Mike


-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Richie 
Burnett
Sent: 16 April 2021 09:16
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Question for those with musical ears

I think that is an important point Gordon.  The "Trill" that results from 
sustained jitter between two pitch quantisation levels in the presence of 
noise is more noticeable than an occasional little step.  So, perhaps some 
small amount of hysteresis in Mike's pitch tracking algorithms would help 
prevent this.

-Richie,



-----Original Message-----
From: Gordonjcp
Sent: Friday, April 16, 2021 8:34 AM
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Question for those with musical ears

On Thu, Apr 15, 2021 at 08:01:38PM +0100, Tom Wiltshire wrote:
> The VCDO chip I designed only manages 6 cent steps (16 steps a
> semitone, actually = 6.25).

In my experiments with using Arduinos as VCDOs I used the internal ADC and 
5V 1V/oct CV and got 6.25 cents per step.  This sounded pretty okay.

Driving it with a Behringer TD3 it was impossible to hear any stepping 
although if you were being incredibly picky you could sometime here it 
"jitter" between steps on sustained notes.

--
Gordonjcp

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