Does most modulation just try to be a Leslie?

[steadystate]

A sawtooth LFO applied a delay will give you a constant pitch shift (until you hit the end of the ramp, and it pops back to start over again ).



Can you clarify this?

By "detune chorus" I mean a pitch shifter used as a chorus; a shift of a few cents blended with the direct signal. It produces what sounds like an LFO swept comb filter similar to a conventional chorus (or any short delay), except that the sweep is unidirectional and the pitch shift is constant.

My point is, the pitch shifter sounds like it uses an LFO similar to a chorus with a sawtooth LFO, but with some extra code to eliminate the glitch. Perhaps it doesn't, but what I hear sure sounds similar. Some are stating that there is no sweep. To me, the presence of the comb sweep is irrefutable. It's just a saw shape. I also hear it with pitch shifting beyond the micro range of detune.

At the discontinuity, the sweep is far less defined. In that one respect, it is less "sweepy" than conventional chorus.

And I didn't intent to derail the thread on a tangent.

 

[Rex]

By "detune chorus" I mean a pitch shifter used as a chorus; a shift of a few cents blended with the direct signal. It produces what sounds like an LFO swept comb filter similar to a conventional chorus (or any short delay), except that the sweep is unidirectional and the pitch shift is constant.

My point is, the pitch shifter sounds like it uses an LFO similar to a chorus with a sawtooth LFO, but with some extra code to eliminate the glitch. Perhaps it doesn't, but what I hear sure sounds similar. Some are stating that there is no sweep. To me, the presence of the comb sweep is irrefutable. It's just a saw shape. I also hear it with pitch shifting beyond the micro range of detune.

At the discontinuity, the sweep is far less defined. In that one respect, it is less "sweepy" than conventional chorus.

I hear a sinusoidal amplitude modulation that varies in frequency, depending on input pitch and Detune value. Its frequency diminishes to zero at a Detune value of zero. To my ears, it sounds and behaves like the detuned signal beating against the dry signal.

 

[Rex]

I hear a sinusoidal amplitude modulation that varies in frequency, depending on input pitch and Detune value. Its frequency diminishes to zero at a Detune value of zero. To my ears, it sounds and behaves like the detuned signal beating against the dry signal.

I just tried it with white noise as the source. Now I hear what you’re talking about. It’s pretty subtle, but it’s there. It sounds a bit like a car shifting through its gears. It varies depending on Detune value. Increasing positive values give faster pitch rise times. Increasing negative values give faster pitch fall times.

 

[steadystate]

I just tried it with white noise as the source. Now I hear what you’re talking about. It’s pretty subtle, but it’s there. It sounds a bit like a car shifting through its gears. It varies depending on Detune value. Increasing positive values give faster pitch rise times. Increasing negative values give faster pitch fall times.

Yep. So, is it an LFO, or not?

 

[Bakerman]

Yep. So, is it an LFO, or not?

Probably. Fading between segments of audio so you only hear each with delay time on continuous portion of LFO. Or a time stretch/resample that gives the same result.

 

[Rex]

Yep. So, is it an LFO, or not?

All I can say for sure is that it's an artifact.

 

[clarky]

Yep. So, is it an LFO, or not?

it's not an LFO, because an LFO is an oscillator that a specific component of an effect is attached to in order to make it's value change...
this means that you have control over it in terms of it's speed and how strongly it changes the effect's component that is assigned to it..
so you can speed it up / slow it down, and / or make that amount of 'value change' greater or lesser..

creating a chorus type effect using a pitch shifter does not have an LFO
it's simply blending a copy of the dry signal that has been very slightly pitch shifted back in with the dry signal
these two signals are not exactly the same frequency so I don't think it's phasing you're hearing,
I think the term may be 'intermodulation' [need some geeky type to confirm this cos I'm not sure]
in mono it don't sound quite so pretty.. in stereo it's wonderful.. shimmery and and spacious

in my case I use two shifters set very gently, panned hard and opposite, with the dry signal up the middle
the resultant tone has a wider stereo image and a subtle chorus like shimmer
if you increase the ratio between the wet and dry, the effect becomes stronger..
personally I like it to be so gentle that it's almost not there..
the point is that you can't really hear it at all, but when you take it away you notice that a little magic has disappeared..

the killer difference is that with a chorus effect, you can always hear the rate of the LFO
with a shifter you can hear the 'swirly' effect going on, but without the sweep rate of the LFO
there are two up sides to this:
1: It's not tempo dependent because there is no LFO to set [the tempo and note value]
2: It certainly has chorus like tonal qualities, but can be used with greater subtlety [so you're adding something nice and pretty but not something 'in your face', strong or obvious]

 

[clarky]

I just tried it with white noise as the source. Now I hear what you’re talking about. It’s pretty subtle, but it’s there. It sounds a bit like a car shifting through its gears. It varies depending on Detune value. Increasing positive values give faster pitch rise times. Increasing negative values give faster pitch fall times.

however..... lol....
you don't wander up on stage and play a gig with white noise
a single note of a guitar is a composite of many frequencies...
and chords are composites or these composites...
and you play more than one note, and more than one chord in a song..
so.... lol... all sorts of 'stuff' happens that sounds really cool..

 

[steadystate]

Seems to me, basic pitch detune is fundamentally a chorus (modulated short delay) with a saw LFO and some deglitch code at the period seams. At least, that's what it sounds like to me. I don't need white noise to hear the sweep. I do prefer it to chorus in many situations. But I also like a good chorus because the delayed signal is not always sharper/flatter than the dry.

 

[mr_fender]

What you are hearing is the intermodulation distortion between the two slightly off tune signals. It's the same beating you hear when trying to tune up using harmonics or a tuning fork. The greater the difference in pitch, the faster the beating cycles. Because the pitch offset of the detune is the same for all frequencies, you hear beating at different rates for the different notes you play. Higher notes have a shorter wavelength, so the fixed offset of the detune equates to a greater mismatch between higher frequencies than it does lower ones so higher notes will beat faster in comparison. Compare the sound of each open string sustained with detune. You'll hear the beating gets faster as you move up in pitch. The beating also shifts slightly as the plucked string settles from it's initial sharp state from the pick pulling on it down to the natural note of it's tension and length.

You can recreate the same effect by double tracking a guitar part and physically tuning your guitar a handful of cents sharp or flat for one of the tracks.

 

[steadystate]

What you are hearing is the intermodulation distortion between the two slightly off tune signals. It's the same beating you hear when trying to tune up using harmonics or a tuning fork. The greater the difference in pitch, the faster the beating cycles. Because the pitch offset of the detune is the same for all frequencies, you hear beating at different rates for the different notes you play. Higher notes have a shorter wavelength, so the fixed offset of the detune equates to a greater mismatch between higher frequencies than it does lower ones so higher notes will beat faster in comparison. Compare the sound of each open string sustained with detune. You'll hear the beating gets faster as you move up in pitch. The beating also shifts slightly as the plucked string settles from it's initial sharp state from the pick pulling on it down to the natural note of it's tension and length.

You can recreate the same effect by double tracking a guitar part and physically tuning your guitar a handful of cents sharp or flat for one of the tracks.

I think I'm hearing a comb filter sweep from a sawtooth LFO, along with other code to make it smooth at the seams (and perhaps other tricks). It sounds nothing like beating. The period is independent of the input frequency.

I'm always eager to be corrected when it means learning something, but it has to be from an irrefutable source. So far, my ears are my best source of information. Pretty shaky, but that's the case.

 

[Rex]

What you are hearing is the intermodulation distortion between the two slightly off tune signals. It's the same beating you hear when trying to tune up using harmonics or a tuning fork.

That's what I picked out first. But there's more going on than that. Feed it with a broadband noise source, and you'll hear it.

 

[clarky]

That's what I picked out first. But there's more going on than that. Feed it with a broadband noise source, and you'll hear it.

I think that 'the bit more going on' is that if you have two signals sounding together of very very closely matched freqs, one will effectively 'move' with respect to the other because it has a shorter wave length [the peaks will be closer together]..
you'll see the peaks of the higher pitched one looking like it's moving backwards compared to the lower one as it is displaced in time if you plotted them on a graph..
this is a really difficult thing to describe in words... but I could draw you a plot of 2 waves of very slightly different freqs and you'd see what I mean..
the result of these two waves will be a sub-harmonic created by the intermodulation.. effectively a lower note created as a result of these two notes sounding together.. I'm guessing that it's the gradual and constantly shifting displacement that's causing the sub-harmonic to change pitch and create an effect that may sound like there is something LFO-like going on..
at some point these two wave will be momentarily in phase before the displacement starts over..
this could explain the saw-tooth like sound
my personal setting are far too gentle for this effect to be apparent..

but is there an actual LFO in the pitch-shifter doing something??
no, not at all.. no matter what it actually sounds like.. there's no oscillator in this effect

 

[steadystate]

You're guessing, as am I. I don't think you know any more than I do if there is a saw LFO in a standard pitch shifter. But I am convinced that what I am hearing is not intermodulation beating. It sounds like a clearly defined sawtooth comb filter sweep (except at the seams), and sounds nothing like beating. Speculation is fun. But recognize it for what it is. How do you know, with certainty, that there is no LFO in a standard shifter? I know for a fact that you can make a rudimentary shifter out of a delay modulated by a sawtooth wave. You can even do it with the chorus in the Axe. You just get a nasty pop every cycle. If an authority I can trust chimes in to correct me, I'll be as appreciative as I would be if I were validated.

I have little doubt better methods are available and are in use than this older approach. Many of them are described online. But I'm curious as to what I am hearing here with this sweep.

Here is some interesting information. Though I don't know how it relates to this specific artifact. They use no LFO, but also state a latency of around 30 ms. That is practically an eternity, though apparently their performance tests were not run on a DSP.

http://www.guitarpitchshifter.com/algorithm.html

I'm happy to bow out here. I was just curious about the sweep, since older algorithms used a saw LFO. I never intended to open a can of worms. I just don't see how you could get a stable, periodic upward or downward comb-like sweep from intermodulation using a random noise source as input.

 

[Rex]

I think that 'the bit more going on' is that if you have two signals sounding together of very very closely matched freqs, one will effectively 'move' with respect to the other because it has a shorter wave length [the peaks will be closer together]..
you'll see the peaks of the higher pitched one looking like it's moving backwards compared to the lower one as it is displaced in time if you plotted them on a graph..
this is a really difficult thing to describe in words... but I could draw you a plot of 2 waves of very slightly different freqs and you'd see what I mean..
the result of these two waves will be a sub-harmonic created by the intermodulation.. effectively a lower note created as a result of these two notes sounding together.. I'm guessing that it's the gradual and constantly shifting displacement that's causing the sub-harmonic to change pitch and create an effect that may sound like there is something LFO-like going on..
at some point these two wave will be momentarily in phase before the displacement starts over..
this could explain the saw-tooth like sound
my personal setting are far too gentle for this effect to be apparent..

but is there an actual LFO in the pitch-shifter doing something??
no, not at all.. no matter what it actually sounds like.. there's no oscillator in this effect

I get what you mean, but this really doesn’t sound like two frequencies beating against each other. Feed it with a Synth block set to white noise, and you’ll hear it.

White noise is a random whoosh of a signal containing all frequencies all at once. Pitch-shift up that by a few cents, and you get, in theory, the same signal, minus a few cents of low end. There should be no beat frequency. But in this case, you hear a periodic frequency artifact that sounds for all the world like a distant car running through its gears while air escapes from a nearby compressor hose.

Maybe it’s a byproduct of the Synth block’s pseudo-random algorithm beating against itself, but I’m not sure. I’m not saying it’s an LFO. But if I were trying to duplicate that sound, that’s what I’d use.