AW_2: programmable 16 step shift register?

[Haible Juergen]

	>Also, has anyone experimented with using BBD delays for looping
sequencer
	>CVs? 

BBDs have many delay stages, which would allow delaying
rather non-quantized (time-wise) events, but might also
produce some inaccuracy due to loss over these many
stages. So you might want a quantizer at the end of the BBD
line at least. 

	> Someone I know has done this with a serge with a tkb and a
wilson
	>analog delay.

The Serge analogue shift register (is this what you mean,
or is the wilson delay something different ?) is a small number
of S&H stages in series. Kind of short, but high-precicion
BBD device. I built a similar thing, it's at

http://www.synthfool.com/diy/jhasr.gif

This is good for delaying CVs, but the delay time is very quantized:
You can either trigger it from the changing keyboard CV (or GATE),
or by an external LFO or rhythm generator.

Another idea:
Instead of using a BBD with all its imperfections + a quantizer
(that basically consists of an ADC + DAC)to restore the 
information, put the delay line
in *between* the ADC and DAC. Then the BBD would be replaced
by a few shift registers in parallel, or a RAM with some rotating
adress pointer. Sounds familiar ? Yes, that's an ordinary 
digital (PCM) delay. So the circle closes.
But there would be some possible enhancements on an
existing cheap Digital Delay, if you want to use it for precise
CV delay. 
First, you might want to make the audio parth fully DC-coupled.
(So Delta Modulation based delays wouldn't work, for a start.)
The ADC / DACs of usual 8-bit PCM delays would cause errors.
So, use the same old trick as for a pure quantizer: Disable the
two least significant bits and turn your bad 8-bit quantisation in
a very good 6-bit quantisation (covers 10 octave range).
With the feedback potentiometer, you could even produce
chromatically shifted delays !

Just got a feeling for the possibillities while I'm writing this.
*Must* try this out. Got a lot of cheap gigital delays at home,
maybe one of them uses ordinary 8-bit ADCs. Would be fun ...

JH.

PS.: I'm very much into Looping stuff at the moment.
        Nothing beats a frequency shifter in the feedback loop
        of an audio delay. 8-) 

 (BTW, someone has an Oberheim Echoplex for sale? I want
to experiment with longer loops as well ...)