[sdiy] Pitch detector Envelope follower!

[KD KD]

2011/11/1, Harry Bissell <harrybissell at wowway.com>:

> I'm not sure I understand. Do you need to have Pitch tracking or envelope
> tracking ?

Both!

> Envelope tracking can be quite simple if the input signal is (somewhat)
> predictable.

Yes indeed it is.

> Generating a 'filter sweep' can be done with a peak detector very easily.
Just what i did with the diode+cap+ resistor. ;)

>This works well for  percussive sounds (syndrum dooooo....).  The trouble is detecting
> a sudden  drop of the input  signal, if you need to track that.
dooooo? here we say piiuuuuu.

>Often a filter sweep completing with no  input can reveal  a lot of unacceptable noise..

That's if resonance are set high and decay curve very long.

> If pitch detection ~is~ needed, how fast does it need to respond ?

No idea really, but there are trade-offs to make as we know.

>Do you need a slow response  to control (let's say) the general range of filtering,
>or  are you trying  make a VCO follow a pitch input ?

> I don't know why, but it seems in these posts that no one wants to say (in
> any detail) what their  application will be.  I'd be happy to discuss the benefits
>and shortfalls of  the various methods either on-list (preferred) or in private.

Well we have discussed pitch trackers in the past several times and come to the
conclusion there are many bad ways to do it since the whole bussiness are tricky
in analog domain. But here is the catch:

I'm not trying anything besides trying to convince a customer who's
stubborn enough
believing that analogue pitch trackers actually works 100% do not , so
better to fool the
dude with some simple stuff that works a bit and convince him that
that's how well it can
be done for the amount of money he says he's willing to pay me for my
time spent on a
hopeless endeavour. :)  I assume he's gonna use it for anything else
but accurate pitch tracking!

LM2907 with some filtering would that do? If people are happy with
MS20 pitch tracker
what else can be done similarly but with less amount of components?
Maybe i just take dsPIC and some soft and fool the dude its all
analog? :)

Reg
KD