[sdiy] uLaw DACs in the modern era?

[paula at synth.net]

Tom,

  Why go for a hard to find DAC? why not recreate it?

  I "recreated" the uLaw using a 12 bit DAC and an 8 bit LUT. Then I was 
able to play back the LInn samples directly.. sounded pretty nice too 
IMHO. Ok, yes I should've used 13bits, but I didn't have any 14bit DACs 
to hand, but I did have 12 bit, so I went with that.

Paula

On 2018-05-19 11:08, Tom Wiltshire wrote:
> Hi All,
> 
> Over the last couple of days I’ve been studying early drum machines,
> mostly the Linn LM-1 and the Oberheim DMX.
> 
> Both of these machines use 8-bit memory, but manage a 12-bit dynamic
> range by using a u-Law coding and outputting samples via the AM6070
> u-Law DAC. Datasheet here if you’re interested:
> 
> http://synfo.nl/datasheets/AM6070.pdf
> 
> Does anything like this exist any longer? It seems to me that the
> unusual DAC response is big part of the “thump” of these early
> machines, since it has considerable distortion, but manages to spread
> it to areas where it’s perceptually less noticeable (so higher level
> signals have less detail than lower level signals).
> Alternatively, would it be possible to build such a device? The
> combination of a 4-bit value plus some gains and offsets doesn’t seem
> impossible to manage, but I’d be interested to hear people’s ideas for
> how you’d do it.
> 
> Thanks,
> Tom
> 
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
> 
> 
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