Hi Florian and list,

First I'd like to explain that the "current position" CV that I proposed would not be a CV addressing (which Dieter explained is unfeasible) but be a voltage and would go to that point on the positive edge of a gate. This would, for instance, enable to sync it to the a-155 or another sequencer for loop playing. Or sync it to a VCO for wavetable kind of synthesis.

>> I'd like to have the module to record and play at the same time, so,
>> having one gate for record and another for play.
>> [...]
>> This would
>> require one extra feature: a cross fade between the old and new
>> sample-play position.
>> [...]
>> Same type of crossfade would be desirable if the record mode starts in
>> the middle of the sample (crossfade between old and new sound).
>
>Those suggestions require heavy hardcore DSP programming.

I was more concentrating on functionality than feasability :) But it might be doable. I think a 16-bit micro controller could do is (it is not that heavy...) or using an 8-bit controller by doing it in analogue domain (requiring twice the amount of DAC's). Maybe it is expensive but I think it would add a lot.

But Dieter's suggestion of using (positive) zero-crossings only might do the job too. The sample would play until its next positive zero-crossing and then jump to the first positive zero crossing after the new set point. It might add some instability for short loops (wavetables) because you change the length of the loop so you change where it ends next time giving frequency jitter.

>A simple sampler could be achieved much easier by an A/D-converter, a
>clocked counter and a SRAM chip. Dieter did this in the SSS-modules 20
>years ago.

Hmm, I know nothing about those....

>> It would be great if negative voltages would lead to the sample being
>> played backwards.
>cute idea, but assumingly not easy to achieve (at least in an exact
>reproducable way).

In the case you use an external HS-VCO I can see problems. but if there is an internal address counter that should be doable. (or am I missing something ) For one thing it means that the cv is linear and not log-scale. Maybe for wavetable kind of things you would like log scale but for delays or loops linear seems more practical.....now I think of it, you might want both with a switch to select...or log with a trick around 0V (like being linear from -.1 to .1V or so)

>
>> Why not have two outputs with independent positions Opens
>> possibilities for ping-pong delays, as well as stereo chorussing,
>> a loop playing in canon and the monitoring function.
>Very fine idea. This would require to have the same clock, but
>independant address counters. This leads again to a even more modulized
>version: separate modules for
>- highspeed VCO module,
>- VC addresscounter module,
>- A/D-RAM-D/A module

Hmm. I am all for a modular approach but I miss the added value of the separate modules. I'd say you'd need them all to be functional. It would be useful when there are small add-on modules (I could see a midi add-on could be useful for dumping the samples. I would not likely buy it though). It would also be useful if the modules are useful by themselves (which I can see for the HS-VCO but not for the others). I might just be missing it...

For a poll it would be useful if there was some price info (even if vague).

I can see why Dieter would be hesitant in developing such a module if the A-112 sales are not that great :(

Christophe






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