[sdiy] uLaw DACs in the modern era?

rsdio at audiobanshee.com rsdio at audiobanshee.com
Sun May 20 09:53:27 CEST 2018


Well, sure, telecom with digital speech came before digital audio for synthesis, but it’s still a memory limitation and lack of affordable DAC chips no matter what your vantage point might be. I’m sure that digital synths repurposed telecom chips, but those chips are 8-bit because of the memory limitations of the time.

These days, communication channels easily have 32-bit words (USB-MIDI), but 8 or 9 bits was common in the early days of digital. Even by the time Compact Disc standardized on 16-bit audio, there were still a few early players with only 14-bit DAC chips.

Lots of industries, including the arcade game industry, leveraged the technology that came before, such as telecom. But in every case, 8-bit was the norm in the beginning, followed eventually by 16-bit and then 32-bit. It was a long time before 16-bit memory was available, but many synths still wired two 8-bit chips in parallel to get what was needed.

Meanwhile, it wasn’t until Rev 3 of the Prophet 5 that an affordable 16-bit DAC was available. Prior to that, the Rev 1 and Rev 2 had very limited D/A capabilities. The Prophet 5 actually came before the Compact Disc, but people were willing to spend thousands on a synth buy only hundreds on consumer players.

Brian


On May 19, 2018, at 11:25 PM, Roman <modular at go2.pl> wrote:
> Wasn't original reason for this in telecom industry?
> AFAIK u/a-laws were invented to provide better dynamic range of phone conversation, because all you have in there is 8 bits. It was better idea than stealing 2 slots for one channel, reducing throughput by half.
> 
> Roman
> 
> Dnia 19 maja 2018 23:47 Brian <rsdio at audiobanshee.com> napisał(a):
>> The original reasons for 8-bit and u-Law were the memory limitations and expense of precision DAC chips at the time. These days, memory and precision are not a challenge. So, if you still want the grunginess of variable quantization, just bake it into the samples.
>> 




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