Temperature-compensated resonance ( was Re: [sdiy] RE: [AH] Parametric EQ)

[Walker Shurlds]

That's the thing for basically every kind of engineering anyway: it's not how well humans can perceive, it's how
well the customer THINKS he can perceive.

Walker

On: Mon, 22 Feb 2010 18:02:21 +0100
cheater cheater <cheater00 at gmail.com> wrote:

> On Mon, Feb 22, 2010 at 17:51, Tom Wiltshire <tom at electricdruid.net>
> wrote:
> >
> > On 22 Feb 2010, at 14:54, cheater cheater wrote:
> >
> >> Tom,
> >>>
> >>> Aww, c'mon! Who ever bothered having a temperature-compensated
> >>> resonance control anyway? Certainly no synth I own has one.
> >>> You're lucky if you get a
> >>> tempco in the filter *cutoff*, let alone the resonance.
> >>
> >> This only shows the sad state synth designs are in. Most high
> >> quality equalizers have tempco Q.
> >
> > Can you back that up with examples? I'm curious to see some.
> > A quick search turned up this extremely expensive EQ
> > (http://www.yoursoundsource.com/mw-avalon-ad2077.html) but it
> > doesn't mention tempco Q.
> 
> Most mastering EQs have discrete settings on Q, frequency, and gain,
> made up with tempco or better yet temperature-unaffected circuits.
> 
> >>> One thing I'm really learning about synth building is that you
> >>> can often get
> >>> away with a lot less than you think you need. It's amazing, but
> >>> the human ear really isn't "hi-fi" at all. I thought I needed
> >>> 16-bit parameter values
> >>> for everything, but 12 will do, and often 8 is enough.
> >>
> >> The way I think of this is that I can't figure out all ways that
> >> people will be using my synth/eq/computer program/other invention,
> >> therefore I shouldn't compromise where *I* think that *I* don't
> >> need the accuracy. I usually go and ask experts, I'm definitely
> >> not the best expert in the use of anything I created.
> >
> > I'm not talking so much about 'possible use' as the limits of human
> > perception. Digital 'stepping' is the big evil that everyone is
> > trying to avoid, and the question is "how many steps do you need
> > before they become imperceptible?". This does depend on the
> > situation (a slow sweep of a highly resonant filter is about the
> > worst case scenario) but is a practical question that can be
> > answered by experiment. Whilst some people's ears might be more
> > sensitive than others, it's not a subjective point. A similar
> > example is the question of how small a pitch difference is audible
> > ("about 6 cents" is the accepted answer, with caveats). Obviously
> > some people have a much better ear for pitch than others, but if
> > your oscillator is producing discrete pitches every 0.01 cents, you
> > don't need to waste time and effort trying to  "improve" it to
> > 0.001 cents accuracy. For synth use "better than human hearing" is
> > a useful day-to-day definition of "good enough".
> 
> You are judging the limits of human perception by your perception?
> That's brave to say the least :-)
> 
> The limits of perception are, by definition, a subjective point. Our
> subjective opinion is dictated by perception, and our perception
> determines our subjective opinion; they are one and the same.
> 
> Pitch perception can be backed up with extensive research. Can you
> back up your hardware design decisions with a similar amount of
> research with large populations of geographically and otherwise
> statistically various individuals?
> 
> Just to give you a practical example: at 10kHz, your accuracy of 0.01
> cents can create a beat interval of 20 seconds, 9 seconds, and so on.
> A 0.001 cent accuracy will be much finer and will allow creative usage
> of the parameter at hand.
> 
> Every time you come up with a reason why you can't notice a
> difference, someone else will be able to tell you why they absolutely
> need it.
> 
> D.
> 
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