[sdiy] Resonance control taper ?

Gordonjcp gordonjcp at gjcp.net
Mon Sep 19 22:43:20 CEST 2022

On Mon, Sep 19, 2022 at 02:09:42PM +0100, Tom Wiltshire wrote:
> > On 18 Sep 2022, at 15:18, Gordonjcp <gordonjcp at gjcp.net> wrote:
> > 
> > On Sun, Sep 18, 2022 at 02:01:21PM +0100, Tom Wiltshire wrote:
> >> This almost becomes another argument for programmability in synths. As soon as you have programmability, all the controls *do* become 10K linear because they're just a panel being scanned and having their values sent to DACs. If you need a specific reverse-log curve for a specific control, it's a look-up table away.
> > 
> > I always thought it was hilarious how the Juno 106's PWM control has a fixed resistor in series to stop it going all the way to 0% PW.
> > 
> That *is* pretty crazy, but I suppose it just goes to show that a single resistor is even cheaper than a lookup table or a few lines of code - or at least, it was back then when both memory and processor time were at a premium.

Roughly half the Juno 106 voice CPU ROM is lookup tables! All the magical sound of a Juno happens in the digital section.

I'm guessing they decided to fix that issue after the mask ROMs were made. It's possible to add a buffer and an IC socket and rejumper the 78C01 to run an external ROM but I bet adding a single resistor was cheaper ;-)

The voices actually use PWM "all up one end" to shut the squarewave off when you turn it off from the panel.


More information about the Synth-diy mailing list