[sdiy] a different kind of slide

[Tony Allgood]

>On the 303, slides always seem to arrive just a hair short of their
destination regardless of
tempo.

The time constant of the TB303's slide is fixed and constant. It makes
no difference with the speed of the sequencer. There is no premonition,
no clever circuitry, its a RC filter, thats all. There is a switch
system by which the glide is turned on and off, but this does not affect
the time to glide if it is enabled at all.

Colin> To create this type of glide you need a resistor and a capcitor.

Yes. Although, you may will want to follow it with a op-amp buffer of
some sort.

>As you know, the 303 is a bit more complicated.

No its glide circuit is simple.

>The CV is the output of a resistor network going into an op-amp.

Yes, but the output resistance of the DAC is constant irrespective of
note played. The CMOS gate that drives the resistor array is a
symmetrical output device and has more or less similar output
characteristics at high and low states.

What IS different about the TB303's glide implementation is that the
glide is always enabled for a brief moment before every note whether
glide is programmed or not. Charge injection spikes into the timing
capacitor may produce a slight blip in the VCO's pitch, as well as the
fact that the CV is lagged slightly on every new gate. This may or not
be audible.

Regards,

Tony Allgood                       Penrith, Cumbria, England

Oakley Sound Systems                     www.oakleysound.com
Modular projects            www.oakleysound.com/projects.htm