[sdiy] +7 and + 2 volt supply

Adam Inglis 21pointy at tpg.com.au
Tue Jun 11 01:39:39 CEST 2019

Thanks all, yes I see, nearly all the analogue stuff is on 0-9.
Perhaps it allowed better fidelity/dynamic range?
This is the half rack version, the pedal version just uses 0-5 and 0-9. However, this unit manages to get 2000 ms max sample/delay time (double the memory), whereas other units using the same system max out at 800 ms.
The A to D is a 4066/FET/comparator. The D to A is a resistor array/op amp/4066, pretty much like all the others.

Tom said 
“"I once did something similar with a PIC. I wanted to process the PIC’s 0-5V output with an op-amp, and if you’ve got a standard op-amp on a 0-9V single supply, it clips at the lower rail. Raising the PICs voltage to 2-7V puts it in the middle of the range and avoids this problem.””

I take it one wouldn’t use this type of A/D/A system today? I believe it was thought of as pretty cheap (those economical Roland engineers at it again?)

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