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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

145.0. "Effects (FX): How Does A Harmonizer Work?" by EKLV00::COLLINS () Fri Sep 13 1985 13:34


	Can anyone explain to me the principals of a harmonizer ?
I know that the sounds are input to a memory at the sample rate and
played back at a faster speed . So producing a shift in pitch of the 
original sound . But would this not mean that you will run out of 
samples if you try to output them faster than you input them ??



Steve..

 
T.RTitleUserPersonal
Name
DateLines
145.1SAUTER::SAUTERFri Sep 13 1985 09:043
Something is wrong with the date/time on the base note.  Please
set your NOTES$TIMEZONE correctly.
    John Sauter
145.2SIVA::FEHSKENSFri Sep 13 1985 10:0811
I assume what they do is loop the sample.  There's an obvious problem with this
if the loop point introduces a transient.  If the harmonizer transposes by
2 octaves, you've got to loop 4 times.  It's not quite this simple, of course,
as the incoming signal's still got to be captured and buffered while the
earlier versions of it are still being scanned.  I'm just winging it, I've
never used one of these (well, a digital delay is capable of this sort of thing
but I only use mine to generate echo and chorus-like effects - which does
involve some modest pitch modification).  Obviously, transposing down is easy -
you just skip samples.

len.
145.3DONJON::CROWLEYFri Sep 13 1985 12:1810

      When a harmonizer is creating a higher interval, the unit splices
and re-splices the sample to create the illusion of hearing the full
note.  On the less expensive models such as the Ibanez HD-1500 (I have one)
you can actually hear the splicing taking place.  It gives the effect of
having a digital delay on the upper harmonic.  The better units such as
Evantide supposedly mask the splicing somehow so it is not as noticable.
But for $1000 more, I think I can live with sound of the Ibanez.  I've
actually found the sound of the spliced sample very usfull.
145.4PIPA::JANZENMon Sep 30 1985 08:4013
 PIPA::JANZEN               * Integrated Circuits *           27-SEP-1985 09:04 
 Note 47.7                      -< SAD1024 ? >-                          7 of 7 

The Reticon Analog Signal Processing Integrated Circuits data and
applications book (Spring 85) which just arrived from East REgional Office
35 Congress St., Salem, MA, 01970, (617)7457400, does not have this part,
but does have more up-to-date versions of the same function.
The application notes are about pitch transposers and reverbs and signal
processing filters.
The pitch transposer articles are in reference to tape recorders that can
play at different speeds without changing the pitch of the speaker on the
tape..
Tom
145.5EKLV00::COLLINSThu Oct 03 1985 18:4111

If an analogue delay line uses to BBD's in parallel to produce pitch shift.
Do digital delay/harmonizers/pitchshifters use parallel memory locations ?

I'm biulding a digital delay unit to my own design and would like to make
it do pitch shifting if I knew enough about it .So far I've got four
parallel twelve bit a/d converters working in unison into a sixteen bit d/a.
Sampling at 92khz .I intend adding 256k dram .

Steve..
145.6PIPA::JANZENMon Oct 07 1985 08:338
I have been thinking about this for my version of this project.
The simple approach for a processorless design for harmonizer mode is:
Have the input write to only about 30 milliseconds of RAM, and have the
output read from the same bit of RAM, and different speeds or with a
skipping-locations technique for making a higher pitch and  a
doubling-locations tchnique for making a lower pitch.  Skipping locations
threatens aliasing.
Tom
145.7EKLV00::COLLINSWed Oct 30 1985 16:1716
Can anyone help me with the following questions,

1 Are harmonizers that are built into echo units suitable for the pitch
  transposition of continuous voice signals , or just musical notes ?

2 I have heard the effect of pitch shifting a voice , on several records.
  Is this generally done using a harmonizer or a vocoder?

3 How much pitch change is needed to produce the sound on these recordings ?
  (doubling,trebling in pitch ?)

Thanks

Steve Collins...


145.8SIVA::FEHSKENSThu Oct 31 1985 16:285
re .7, q2 - I'm no expert, but the pitch shifting I've heard (like
on the new Godley and Creme thing) sounds like it was done with a
sampler or (almost the same) a digital delay.  I.e., massive munchkinization.

len.