PWM on complex audio signals

[Magnus Danielson]

From: Don Tillman <don at till.com>
Subject: Re: PWM on complex audio signals
Date: Tue, 2 Jan 2001 22:01:24 -0800 (PST)

>    Date: Tue, 02 Jan 2001 22:20:39 +0100
>    From: Magnus Danielson <cfmd at swipnet.se>
> 
>    There are many reasons not to like Baxendall's tone controls, but I
>    would please ask you to elaborate some on this topic. I'd also love to
>    hear some comments on what you would use instead and why.
> 
> It's not so much Baxendall tone controls per se, it's hifi style tone
> controls in general.  Hifi style tone controls are designed for subtle
> adjustment of the balance of the highs and lows with respect to the
> mids with minimal interaction.  Which is what you want for hifi.
> 
> But on a guitar, or any electronic musical instrument for that matter,
> you want to make dramatic changes to the response.  The tone controls
> on a guitar amp (Leo Fender's originals or any of the variations)
> throw radical hills and slopes into the response curve.
> 
> Another issue is that a guitar has a limited frequency range; there
> are no subharmonics so there's nothing below 82 Hz (low E) and pickups
> don't put out anything over 4 to 6 kHz, depending on the pickup
> design.  With hifi tone controls on a guitar, when you turn up the
> bass or treble control the greatest amount of boost occurs at the
> extreme frequencies (below 82 Hz, above 6 kHz) where the instrument
> isn't putting out any signal.  So the treble control ends up operating
> as a hiss level control and the bass control ends up as a hum level
> control.  Not good.
> 
> The right thing is a tone control that makes the greatest changes to
> the instruments' midband frequencies.
> 
> (There's also the "existance proof"; it's hard to name a respected
> guitar amp with Baxendall tone controls.)
> 
> (All my opinion, of course.)

Ah, thank you Don.

Would that mean a wider range of control (+/- 24 db at peak rather
than +/- 6 dB)?
Would that mean wider (low-Q) or smaller (high-Q) peaks/valeys?
Or do we talk about shelf responces?

Curiosity killed the cat!

Cheers,
Magnus