hi-quality pitch shifter ?

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"Mad Scientist Jr"
>
> i have a whammy ii pedal that i sometimes use, but when i play chords
> through it, they sound all mechanical and warped. this pedal is 10 yrs
> old so i am sure since then something better has come out. i am
> looking for a studio quality pitch shifter for recording that i can
> plug a guitar or other instrument into and change pitch upto a whole
> step without any loss in quality. someone suggested lexicon. can
> someone recommend a specific model, or perhaps something analog?
> thanks.


** Digital pitch shifters are as common a muck these days - most floor
type multi effect units have them and there are lots of rack mount units
that include a pitch shift effect.

Why not simply go to a retail musical equipment store and try some out ???

BTW
I do not think an analogue pitch shifter exists - but there are analogue
frequency shifters so maybe you are thinking of them.




............. Phil

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In article <2nlma9F23ivfU1@uni-berlin.de> philallison@tpg.com.au writes:

> I do not think an analogue pitch shifter exists - but there are analogue
> frequency shifters so maybe you are thinking of them.

Probably not any more, but we had analog pitch changers (and speed
changers) before digital technology was advanced enough to use it for
that application. There was a mechanical tape-based system that used a
rotating head assembly. A nightmare, but it worked. It was mostly used
for changing speed and keeping a constant pitch rather than the other
way around, to shorten radio programs that were just a little too
long.

I suppose that beating the input source with a oscillator could be
considered an analog frequency shifter. They do that to record birds
and whales.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

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> I do not think an analogue pitch shifter exists - but there are analogue
> frequency shifters so maybe you are thinking of them.

what is the difference between a pitch and a freq shifter?
were the original octave pedals analog?
they could shift pitch one octave right?

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"Mad Scientist Jr"

> > I do not think an analogue pitch shifter exists - but there are
analogue
> > frequency shifters so maybe you are thinking of them.
>
>
> what is the difference between a pitch and a freq shifter?


** The first multiplies all frequencies by a number ( greater or less than
one ) while the second adds or subtracts a number from all frequencies.


> were the original octave pedals analog?
> they could shift pitch one octave right?


** They could not shift pitch a sound.

Their function was to filter out and use the fundamental frequency of a
note to trigger a simple 2:1 divider that produced a square wave output one
octave lower. This phantom note ( after some filtering ) would start and
stop with the original and could be set to any desired level with a knob.



............ Phil

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In article <7a93f3c4.0408090630.765b6a9b@posting.google.com> usenet_daughter@yahoo.com writes:

> what is the difference between a pitch and a freq shifter?

Depends on who you ask. Ask Phil and he'll tell you that the device he
designed which adds a specific number of hertz to whatever frequency
goes into it is a frequency shifter. This is a pretty unusual device
though.

If you ask me (and nobody did) I'd tell you that frequency is a
physical characteristic and pitch is a musical parameter. They're
closely related. However, listening to music that's uniformly shifted
in frequency isn't always musical. This is why the frequency-shift
based feedback reducers weren't very popular with those who had to
listen to them. I have, and it sounds a bit strange.

> were the original octave pedals analog?

The earliest "octave pedal" I remember used a flip-flop triggered from
a low-pass filtered version of the input. I guess that makes it
digital, not analog. The flip-flop's square wave output was low-pass
filtered to get rid of its harmonics, leaving something resembling a
sine wave at half the input frequency. Generally this was mixed with
the origial input signal rather than used by itself.

> they could shift pitch one octave right?

Yes, exactly one octave.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

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okay that explains it a little more.. thanks

now what about a digital pitch shifter.. hasnt anyone made a hi-res
fast enough one where you could do chords in realtime without any
noticable quality loss? 64 bit?

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Phil Allison wrote:

>** Frequency shifters that move the whole audio spectrum a few Hz up or
>down are used to suppress acoustic feedback in PA systems. I know about
>them because I designed one few years back that was later published as a
>project in Australia's leading electronics magazine.

I am very interested in that article. Please cite the name of that
magazine and the date of the issue that includes the article.

Thanks!

<snip>

--
========================================================================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mkesti@gv.net | - The Who, Bargain

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"Mad Scientist Jr"

> > > what is the difference between a pitch and a freq shifter?
>>
> > ** The first multiplies all frequencies by a number ( greater or less
than
> > one ) while the second adds or subtracts a number from all frequencies.
>
> so both work on all frequencies, and the diff is pitch shifter
> multiplies, and freq shifter adds/subtracts? so the only difference is
> in magnitude (if you think of multiplication as a series of additions,
> and division as a series of subtractions)


** That is utterly idiotic.




>
> but if you isolated the phantom note, you are left with a pitch
> shifted note, correct?


** They could not shift pitch any ** sound **.




............. Phil

Archived from groups: rec.audio.pro (More info?)

Mad Scientist Jr wrote:

> okay that explains it a little more.. thanks
>
> now what about a digital pitch shifter.. hasnt anyone made a hi-res
> fast enough one where you could do chords in realtime without any
> noticable quality loss? 64 bit?

It's a hard problem. There is no theoretical solution so
all are heuristic approximations. There are good ones but
not real time. To do it well it's very compute intensive
and introduces big latencies.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

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"Mike Diack" <
> > Phil Allison wrote:
> >
> >>** Frequency shifters that move the whole audio spectrum a few Hz up
> >>or down are used to suppress acoustic feedback in PA systems. I know
> >>about them because I designed one few years back that was later
> >>published as a project in Australia's leading electronics magazine.
> >
> > I am very interested in that article. Please cite the name of that
> > magazine and the date of the issue that includes the article.
> >
>
> The idea is as old as the hills - There was one published in "Wireless
> World"
>
> "Frequency Shifter for "Howl" Suppression" by M Hartley Jones, July
> 1973 p317.
>
> Used a pair of MC1495 4Q multipliers and a 5Hz quadrature oscillator.
> I built it and it turned feedback squeals into Vogon noises.


** The first frequency shifters used RF techniques ( crystal oscillators,
modulators etc) and date from the early 1960s. Later designs in the
early 1970s used the "outphaser" method with multiplier ICs like the
C1495 - which finally became obsolete and unobtainable in the mid 1990s.
It was this fact that prompted me to design an audio shifter for EA
magazine based on the Analog Devices AD633 multiplier which proved to be
ideal for the job.

The M. Hartley Jones 5 Hz shifter you mention is rather primitive - more
like a concept demonstration than a useable product. Electronics Today
published an improved version of this design in 1977 also using MC1495s -
it proved to be very effective at increasing the gain before feedback
threshold in speech reinforcement systems operating in reverberant rooms. I
know, because I built quite a few and sold them to PA system operators.

If, as it seems, you built a primitive frequency shifter and tested it in
in a small, non reverberant room then the results are not even worth
mentioning. You have enlightened no-one by doing so.





............... Phil

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Mike Diack wrote:

> The idea is as old as the hills - There was one published in "Wireless
> World"
>
> "Frequency Shifter for "Howl" Suppression" by M Hartley Jones, July
> 1973 p317.

I had it myself as a student around 1963 so I'm sure it goes
back even further than that. OTOH, there may not have been
a lot of reason to bring budding electrical engineers
together with one of those fairly rare things in those days,
a local rock and roll band. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Archived from groups: rec.audio.pro (More info?)

> > were the original octave pedals analog?
> The earliest "octave pedal" I remember used a flip-flop triggered from
> a low-pass filtered version of the input. I guess that makes it
> digital, not analog. The flip-flop's square wave output was low-pass
> filtered to get rid of its harmonics, leaving something resembling a
> sine wave at half the input frequency. Generally this was mixed with
> the origial input signal rather than used by itself.
> > they could shift pitch one octave right?
> Yes, exactly one octave.

So half the input frequency = one octave. Could it be modified to
lower or raise the frequency by a variable amount? And maybe using a
few of these in parallel or series, each one could operate on a
different part of the sound - i am not too familiar with audio theory,
but the difference between a single note and a chord is there are
multiple parts in the sound wave right? - so say a chord is comprised
of 6 single notes, you might have 6 of these analog variable frequency
shifters, each one acting on a single note. Just curious. Because if
analog is instantaneous, perhaps it could be the solution to
instantaneous high quality pitch shifting.

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Scott Dorsey wrote:

> In article <cfb3ii01s72@enews3.newsguy.com>,
> Bob Cain <arcane@arcanemethods.com> wrote:
>
>>
>>Mike Diack wrote:
>>
>>
>>>The idea is as old as the hills - There was one published in "Wireless
>>>World"
>>>
>>> "Frequency Shifter for "Howl" Suppression" by M Hartley Jones, July
>>>1973 p317.
>>
>>I had it myself as a student around 1963 so I'm sure it goes
>>back even further than that. OTOH, there may not have been
>>a lot of reason to bring budding electrical engineers
>>together with one of those fairly rare things in those days,
>>a local rock and roll band. :-)
>
>
> I dunno, but I don't see any reference in the RCA Radiotron Handbook so
> it can't be all _that_ old.

Well, it was a pretty stupid idea so it was likely discarded
by people not just looking for a publication. Even I, a
mere techno-tyke, realized that just shifting all
frequencies, even a little, would likely play strange on the
ears of the performers. Whan I realized that it required
frequency scaling rather than shifting I gave up because I
couldn't figure out how to do it. I wouldn't have guessed
then, however, that people would still be working on good
ways to accomplish it over 40 years later. :-)

Feedback supression is still one hell of an application
awaiting a really good, real time, low latency frequency
scaling solution.

I'm not sure it will even work, though. I fear that
feedback will turn into chirps chasing their tails up or
down the scale until they run out of bandwidth or loop gain.



Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

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"Ben Bradley"

>
> You can frequency-modulate the clock of a bucket-brigade-device
> with a sawtooth to get (moderately crude) pitch shifting (the clocking
> and charge-shifting parts are digital, but it's still "mostly
> analog" ). Isn't that (or something similar) how the earlier
> Harmonizers worked?



** The Eventide Harmoniser, released in the mid 1970s, was all digital.




............. Phil

Archived from groups: rec.audio.pro (More info?)

Bob Cain <arcane@arcanemethods.com> wrote:
>Well, it was a pretty stupid idea so it was likely discarded
>by people not just looking for a publication. Even I, a
>mere techno-tyke, realized that just shifting all
>frequencies, even a little, would likely play strange on the
>ears of the performers. Whan I realized that it required
>frequency scaling rather than shifting I gave up because I
>couldn't figure out how to do it. I wouldn't have guessed
>then, however, that people would still be working on good
>ways to accomplish it over 40 years later. :-)

It's actually a very good idea for voice applications. It makes the voice
sound a little bit weird, but it only takes a tiny little bit to make a
lav mike in a hotel conference room with a distributed system actually
work, and it does not require any actual careful setup so it can be used
by the hotel AV crowd.

It's definitely not acceptable for any musical applications, but when you
think about it, an awful lot of sound systems are never used for music
anyway.

>Feedback supression is still one hell of an application
>awaiting a really good, real time, low latency frequency
>scaling solution.

What's wrong with the Urei Little Dipper? You hear it ring, you turn
the knob, it stops ringing. Works in realtime, and the latency is as
low as the operator, which can be pretty low.

>I'm not sure it will even work, though. I fear that
>feedback will turn into chirps chasing their tails up or
>down the scale until they run out of bandwidth or loop gain.

That is what the pitch-shifting gadgets do. Instead of ringing, it sort
of gurgles.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Ben Bradley wrote:

> On 8 Aug 2004 10:53:16 -0400, mrivers@d-and-d.com (Mike Rivers) wrote:
>
> >
> >In article <2nlma9F23ivfU1@uni-berlin.de> philallison@tpg.com.au writes:
> >
> >> I do not think an analogue pitch shifter exists - but there are analogue
> >> frequency shifters so maybe you are thinking of them.
> >
> >Probably not any more, but we had analog pitch changers (and speed
> >changers) before digital technology was advanced enough to use it for
> >that application. There was a mechanical tape-based system that used a
> >rotating head assembly. A nightmare, but it worked.
>
> You can frequency-modulate the clock of a bucket-brigade-device
> with a sawtooth to get (moderately crude) pitch shifting (the clocking
> and charge-shifting parts are digital, but it's still "mostly
> analog" ). Isn't that (or something similar) how the earlier
> Harmonizers worked?

You can't use that method to frequency shift. It's an issue of samples in vs
samples out. With a fixed sampling rate in - each sample equates to a fixed time
period. If the out is clocked faster or slower then you will end up running out of
samples ( faster ) or introduce a time delay if slower ( same as slowing a tape
down for example ).

The kind of pitch shifting you refer to requires a DSP algorithm that either throws
away some samples or introduces new ones.


Graham

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<Kurt Riemann>>


** This dude is out there - he may be in YOUR neighbourhood.

Be afraid.




........... Phil

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"Pooh Bear"
> Kurt Riemann wrote:
>



** You are talking to a mental defective - Pooh.

Hard for someone you to tell - I know.




............. Phil

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<Kurt Riemann>

** This dude is out there - he may be in YOUR neighbourhood.

Be afraid.

Kurt is a serious public menace.

I do hope the police have a watch on him.





............. Phil

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In article <f03c0e77.0408101559.1af54b86@posting.google.com> thecatspjamas@aol.com writes:

> There is a big write up on frequency shifters in Bernie Hutchins
> 'Electronotes' newsletter.

Hey! I've got some of those. I'll have to look it up and see if he
mentions Phil.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

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"Phil Allison" <philallison@tpg.com.au> wrote in message news:<2nt8jnF41iitU1@uni-berlin.de>...


>
> ** That would be the same Harald Bode who's name is associated with so
> many plots ????
>

>
> ............. Phil


I had wondered the same thing in the past and never got around to
looking it up. I think I may have found some answers today.

Here is some info on Hendrik Bode of 'bode plot' fame:

http://www.geocities.com/neveyaako [...] /bode.html


There is a nice quote from Hendrik Bode on this website and some
interesting history on feedback...

http://www.geocities.com/edug2406/apuntes_hp.htm

There is a nice quote near the top of the page.

"The engineer who embarks on the design of a feedback amplifier must
be a creature of mixed emotions."
—Hendrik Bode





Further reseach found that Harald Bode also worked at Bell Labs, here
is a good link to some information on him:

http://www.obsolete.com/120_years/machines/melochord/

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"Phil Allison" <philallison@tpg.com.au> wrote in message news:<2nt8jnF41iitU1@uni-berlin.de>...

>
>
>
> ** That would be the same Harald Bode who's name is associated with so
> many plots ????
>
>
> ............. Phil



Some time ago I wondered the same thing but never got around to
finding out. Here is what I dug up on the internet today:




Hendrik Bode

'Bode Plot'


http://www.geocities.com/neveyaako [...] /bode.html


Interesting reading on feedback:

http://www.geocities.com/edug2406/apuntes_hp.htm

Quote on feedback:

The engineer who embarks on the design of a feedback amplifier must be
a creature of mixed emotions.
—Hendrik Bode



Harald Bode

'Frequency Shifter'


http://www.obsolete.com/120_years/machines/melochord/




Both happened to work at Bell Labs.



Peter