[sdiy] Roland TB-303 "square" wave variation

Bruno Afonso bafonso at gmail.com
Thu Oct 22 19:30:52 CEST 2015


Are you reading this off the VCO waveshaper or after going through the rest
of the circuit ?

b

On Thu, Oct 22, 2015 at 11:04 AM Richie Burnett <
rburnett at richieburnett.co.uk> wrote:

> How the shape of the 303's square waveform changes over the pitch range
> from
> 10Hz up to 1kHz:
>
> http://www.richieburnett.co.uk/temp/303sqr.gif
>
> The broad rounded waveform is at the lowest frequency (about 10Hz,) and the
> tall narrow pulse is at the maximum frequency (about 1kHz.)
>
> There's only a small region around 85Hz on my TB-303 where the duty ratio
> is
> 50% and the shape is practically square.  All this funkiness is a result of
> using an over-driven common-emitter amplifier to clip the VCO's sawtooth
> waveform into something that is approximately square in shape.  No wonder
> it
> has a unique sound.
>
> -Richie,
>
>
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