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Giles Goat

@kenshirriff So it's like 1 bit analog shift register ? I suppose as you have an analog signal on the input pin as you "shift" you also "re-sample" the input at the "clock frequency" you are using to shift the thing ? So it's a bit like a "256 bits analog sample FIFO" ?

4 comments
Ken Shirriff

@gilesgoat Yes, although it doesn't make sense to discuss bits, since it is analog. It has 256 stages, so there are 256 analog samples inside the chip. Nowadays, you'd use a digital delay instead.

Giles Goat

@kenshirriff Yeah I mis-explained I meant "it's like every analog capacitor holds 1 analog bit". What I really meant was 256 STAGES. Yeah me too I don't get "how the transfer happens" and doesn't average .. there must be "some trick" ..

int21h

@kenshirriff @gilesgoat
Analog delays are still in use.
Even some digital delays mimic analog delays sound...

craquemattic 🏳️‍🌈

@kenshirriff @gilesgoat I have several BBD delays in my Eurorack cases that would disagree. ;)

BBDs have a particular charm over digital delays, and have specific feedback characteristics to boot, which make them very popular. I think these days there are double digits of brands that make a BBD delay module.

The PT2399 chip is what is used in the lion's share of these modules. I have several in my own collection and have designed my own delay circuit with it! BBDs are also perfect for karplus-strong synthesis.

So I suppose for most purposes the BBD is not the delay of choice, and it's definitely not the cheapest. But it is alive and well in the PT2399.

@kenshirriff @gilesgoat I have several BBD delays in my Eurorack cases that would disagree. ;)

BBDs have a particular charm over digital delays, and have specific feedback characteristics to boot, which make them very popular. I think these days there are double digits of brands that make a BBD delay module.

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