[sdiy] Parallel 8 Bit DACS?

MTG grant at musictechnologiesgroup.com
Wed Nov 20 15:07:55 CET 2013


I think the MXR used the DAC0800.  There was one for sure, but I'd have 
to research to double check that.  I think it was called MXR drum 
computer.  If the DAC you're referring to is linear 8-bit then the 
dynamic range is limited. Most 8-bit drum machines of that era used a 
companding format from the telephone system (Linnn, etc) and a 
non-linear DAC to suit. Slightly better quality.  Some companies then 
moved to 12-bit (Emu) and eventually 16 (Alesis).

GB

On 11/20/2013 5:35 AM, Jack Jackson wrote:
> I'm investigating the world of drum machines and EPROMs. I quite like the idea of a DAC with parallel inputs and +/- output as per the DAC0800. I can't find any implementations of it though, apart from the datasheet. First question:- Is there a similar DAC that might better suit this purpose?
>
> As far I understand it, a fairly standard implementation for a drum machine would be an oscillator driving a parallel-out binary counter fed into an EPROMs address inputs with the EPROMs outputs fed into the the DACs parallel inputs. Like so:
>
> Oscillator -> Binary counter -> EPROM -> DAC
>
> Second question, in terms of EPROMs I believe it would be easier to use a Flash EPROM, which is electrically erased and programmed (as explained on this page: http://www.arlabs.com/help.htm ). Could one use a PIC style programmer to programme these? The Linn drum .bin files I found online seem to contain HEX code as you would programme a PIC IC with.
>
> Last question: Is there any magic to using this topology, and also analogue VCA and filtering, over using samples of original drum machines?
>
> Best Regards,
> Jack 		 	   		
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