[sdiy] uLaw DACs in the modern era?

rsdio at audiobanshee.com rsdio at audiobanshee.com
Fri May 25 08:39:32 CEST 2018


It would certainly be possible to pre-process the hi-hat samples with an exponential compression curve while pre-processing the cymbals with a linear compression curve, all carefully coordinated so that the playback envelope restores the original envelope.

Whether they went to the trouble of doing this remains unknown, but they certainly bothered to create different envelope circuits for each one, so it stands to reason that they might have followed through and developed different compression for each category. Then again, we now have the benefit of 80-bit DSP for audio, which would have been a bit difficult in the TR-909 days.

Brian


On May 24, 2018, at 3:15 AM, rburnett at richieburnett.co.uk wrote:
> I suspect that the resulting dynamics of the sound are not exactly authentic to the original though.  The hi-hat samples in the TR-909 get exponential decaying envelopes applied to them upon playback, whereas the ride and crash cymbals get *linear* envelopes applied to them that are actually generated from the ROM address counter outputs!  Anyone who's ever used a 909 will recall how "compressed" the cymbal samples sound.  I think this is largely due to the replacement of the instruments' natural envelopes with linear ones!
> 
> -Richie




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