EFM takes a break - Re: modules with different tubes?

[tomg]

ooops,  I let it sit in my out box too long......If you want to see what 
I have in mind for the new site check out the load speed of the new 
home page...

http://www.geocities.com/efm_gc/index1.html

None of the links to xavax work but it's there to see..

Tom



> I swear it says "PV-1 Pitch to Voltage Converter By Harry" or something
> like that..;-) right on the top of the page Harry, or it did which is why I'm
> writing this.
> 
> Phil says they lost the usr HD and it could be a day or two before it comes
> back up.....and then I have to re-up the files....so now we know.
> 
> We worked all weekend on the database and web-site. It's gonna be really 
> nice...but now we have to wait to upload it. Anyway it gives me a day or two 
> to reorganize things.
> 
> I still have 10meg at GC, so if I need to I can post something in the mean
> time.....the address is here...........
> 
> http://www.geocities.com/efm_gc/
> 
> 
> Tom
> 
> 
> 
> 
> 
> > Hi Scott...
> > 
> > The detector on TomG's site is the board I layed out based on Bob Moog's
> > 
> > Etherwave Pitch to Voltage Converter (with permission). It works well on
> > any
> > regular waveform, but needs to have the fundamental cleaned up a lot for
> > guitar.
> > (this depends on your expectations... I'm really fussy!)
> > 
> > I looked into the idea of using the Hilbert Transform. You need a "dome
> > filter" also
> > described in electronotes, I believe.  I got the info from JH's pitch
> > shifter (frequencies only) and did a spice model of the filter. The
> > problem is... there is enough group delay
> > in the dome filter to wipe out the advantage of getting rid of the
> > harmonics...  you will
> > end up in the same place as the LPF anyway. That seemed like a great
> > idea... and probably would work for high pitches.
> > 
> > The Gold patent assigned to New England Digital gives a workable method
> > for
> > guitar pitch extraction. It will not work well on voice at all...
> > because it uses the facts that
> > guitars are almost always decaying exponentially... and that the
> > harmonics are...
> > er.... non-harmonic.  Vocal harmonics would be much closer. Guitar
> > harmonics are
> >  very sharp!
> > 
> > H^) harry
> > 
> > Scott Bernardi wrote:
> > 
> > > You run into the same problem trying to do pitch to voltage
> > > conversion. TomG has a pitch to voltage  converter on his site that I
> > > seem to remember uses a downslope detector to detect the true
> > > fundamental (his site seems to be down right now).
> > > There's also an Electronotes article EN#136 that discusses using a
> > > Hilbert Transform: take the signal and the 90 degree phase delay
> > > network, square both of them with multipliers, then sum the squares.
> > > It supposedly removes harmonics and strengthens the fundamental,
> > > improving the multiple zero crossing problem of complex signals.  Then
> > > he runs it into a downslope detector to extract the true fundamental.
> > > I plan on playing with it (sometime - you know how it goes) because I
> > > want to build a pitch to CV I can use with voice or guitar.
> > >
> > > harry wrote:
> > >
> > >> Aahhh....
> > >>
> > >> Nice try. Probably will not work.
> > >>
> > >> Problem... How do you decide the "waveform" crossing points.  I'm
> > >> thinking of
> > >> a Guitar wave... which is a bastard !  It may cross zero more times
> > >> than you
> > >> like.
> > >> Tracking the peaks will not work either.
> > >>
> > >> DDL  pitch shifters do exactly this. If they have very short
> > >> delays... the
> > >> glitches in
> > >> the waveform are severe. If you can wait a week... you could make a
> > >> really long
> > >> delay.
> > >>
> > >> You should tape record the whole thing... then edit out every other
> > >> cycle, then
> > >> play
> > >> at 1/2 speed...
> > >>
> > >> Or just hire a Psychic to set the unit properly for the "next" note
> > >> you are
> > >> about to
> > >> play....
> > >>
> > >> H^) harry
> > >>
> > >> Magnus Danielson wrote:
> > >>
> > >>
> > >> > From: harry <harrybissell at prodigy.net>
> > >> > Subject: Re: modules with different tubes?
> > >> > Date: Sat, 13 Jan 2001 11:44:39 -0500
> > >> >
> > >> >
> > >> >>  If ANYONE gets a really good octave divider for guitar, tube or
> > >> >>  otherwise,
> > >> >>  LET ME KNOW !!!
> > >> >>
> > >> >>  I'll build it even if it is TUBES....  ;^)
> > >> >>
> > >> >>  (of course I doubt anyone will ....)
> > >> >>
> > >> > Hmm... I just came up with an obscure idea using a pair of BBDs,
> > >> > but
> > >> > I am sure you're not interested ;)
> > >> >
> > >> > Theory: Do frequency tracking, fetch an overtone to sample in a
> > >> > full
> > >> > BBD, play it out at half clock-rate. Alternate BBD so that one is
> > >> > in
> > >> > "record" and the other is in "play" mode. Since they track
> > >> > frequency
> > >> > one snaps a waveform and plays that pitched down but on the same
> > >> > boundary. Simple? Heck no! Obscure? You bet!
> > >> >
> > >> > Reason for concepti!
> > >> >  on? Annoyment and ammusement of Harry! ;)
> > >> >
> > >> > There are loads of problems with this strategy thought. Can we
> > >> > learn
> > >> > anything?
> > >> >
> > >> > Cheers,
> > >> > Magnus
> > >> >
> > > --
> > > Scott Bernardi
> > > sbernardi at home.net
> > >
> > >
> > 
>