[sdiy] Ideal polyphonic digital reverb

[Steve Lenham]

>>> Thanks for that link. Interesting architecture: they use the same 
>>> 12-bit DAC for the a/d controller (IC 9) as for the output d/a (IC 
>>> 17). With an added SAR controller chip (IC 8).
>>
>>
>> This seemed to be “a thing” in the mid eighties - check the SMs for 
>> the Roland SDE-1000, and the Roland/Boss RDD, and RSD units, available 
>> online. There is something about the sound of these “vintage digital” 
>> units that I love…
> 
> Interesting, yes. But it might have been an economic decision. I built 
> and sold an 8-bit audio sampler for the Atari-ST way back then. I 
> remember looking at 12-bit A/D chips and they were eye-watering 
> expensive. So nice crispy 8-bit it was. :-)

Cost is certainly one good reason - the converter would have been one of 
the most expensive parts. But there is also a hidden advantage: if you 
use the same converter for ADC and DAC duties then, for delays and other 
things where you do not modify the signal much in the digital domain, 
some of the converter imperfections like offset and non-linearity cancel 
out. Any distortion caused by the transfer function of the converter on 
the way in is reversed on the way out.

Steve L.
Benden Sound Technology