Re: Analog Pitch Shifter

On May 30, 3:55 am, Nils <n.pipenbri...@xxxxxxxxx> wrote:
bharat pathak schrieb:

I do not have analog background. So i do not know what can
be achieved and what cannot. By the way are there any good
"analog signal processing" books out there?

....

In short you can do the following mathematical operations using analog
electronics:

- add
- subtract
- multiply
- tanh
- exp
- square

If you add an opamp you get:

- divide
- log
- roots

You can approximate other functions like sin or cos either using
polynomials. For sin the tanh function can be directly used for small
angles.

That's enough to do quite a bit of math. All the essential stuff is
there. Some of the functions are hard to build in practice if you need
high precision and low noise. Temperature compensation is not easy to
get right as well.

You can do delay using BBD chips or allpass/dome filters. That'll give
you some memory if you need it. Not exactly high precision but it works.

you need to do *varying* delay *and* some means to splice and
crossfade. other than the rotating tape head, i dunno how that could
be done non-digitally. also, if you don't like glitches in your pitch-
shifted output, you need to be able to analyze the input signal to
look for good splice points where there is more similarity in the
waveform. dunno how one would do that outside of a discrete-time
context.

r b-j
.