[sdiy] TR-909 schematic/PCB error

[Kylee Kennedy]

I use this rimshot emulator, just press the red button.

http://instantrimshot.com/

Kylee

On Mon, Nov 14, 2016 at 12:51 PM, Richie Burnett <
rburnett at richieburnett.co.uk> wrote:

> Bruno Afonso wrote:
>
> Do you mind sharing a bit about your digital modelling?
>> Are you modeling the analog circuits using spice like equations?
>>
>
> Yes, sort of.  I can;t go into the details now, but it's like a spice
> model optimised for speed (realtime calculation on DSP) and audio quality.
>
> Seems impressive your model could pick up on these details given even
>> people making clones missed out on those
>>
>
> You can easily see the difference in the rimshot waveform when it is
> high-pass filtered.  There seems to be some discussion about it here (the
> diagrams are perfect for this discussion although I haven't read the
> thread...):
>
> https://www.kvraudio.com/forum/viewtopic.php?t=383536
>
> The RS waveform looks like the very top waveform when viewed directly at
> the output of the VCA (before the HPF).  (The second thick waveform is just
> a magnification of a sketch of the RS waveform in the TR-909 service
> manual.)
>
> The RS waveform looks like the third waveform down at the output of IC50b
> (after the HPF.)  It is quite an aggressive high-pass filter at about 230
> Hz, and it's LF rolloff has the effect of introducing a "tilt" or "droop"
> on the otherwise "flat" portions of the clipped RS waveform.
>
> -Richie,
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