Calling all geeks now-- Modulation effects & how they work?

0utputXfmr

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So, I found a decent article online about the differences between Chorus, Flanger, and Phaser effects: https://producerhive.com/ask-the-hive/chorus-vs-flanger-vs-phaser/

I do have an electrical engineering background (though I work mostly in power systems), so I do understand the differences between Amplitude Modulation, Phase Modulation, and Frequency Modulation-- in fact, the latter two are mathematically-related.

According to the article, Flangers and Chorus effects share an LFO (and before that, bucket-brigade IC's), blending a modulated signal with the original (causing all kinds of constructive and destructive interference, as a result), which certainly explains why a lot of Flanger pedals, like the Stereo Electric Mistress and TC Electronics SCF, also have a Chorus effect onboard. The main difference appears to be delay time-- Chorus uses a longer delay time, which induces some frequency modulation. The second significant difference appears to be that flange utilizes a feedback loop, where chorus does not.

Given that Vibrato is also a frequency modulation effect, how is it related to chorus? My guess is that vibrato is distinguished from chorus in that vibrato modulates the original signal, thus no blending of original and modulated? I noticed that a lot of vibrato pedals also have a chorus on board-- does that imply there is a way to get a chorus effect utilizing the same components as the vibrato, as there is between chorus and flanger?

Next up-- Rotary Speaker effect.
 

0utputXfmr

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Rotary speaker effect

I'm guessing this utilizes the doppler effect, which would be a modulation of both volume (amplitude modulation) and pitch (frequency modulation)-- is that the basic gist?
 

0utputXfmr

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Lastly-- what the heck is a Uni-Vibe REALLY?

Every description I can find of the original Shin-Ei unit describes it as a "13 transistor circuit" and utilizes a light source and photocell. Given what sounds like an absence of bucket-brigade IC or LFO, why are the Uni-Vibe effects labeled "Chorus" and "Vibrato" when they very clearly cannot be?
 

NoTeleBob

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Rotary speaker effect

I'm guessing this utilizes the doppler effect, which would be a modulation of both volume (amplitude modulation) and pitch (frequency modulation)-- is that the basic gist?
Might help to visualize/examine how a real rotary speaker works, e.g. a Leslie. That's what the rotary speaker pedal effects are trying to mimic: https://en.wikipedia.org/wiki/Leslie_speaker

And then I will add "sort of". The guy who came up with Uni-vibe, for example, was not actually trying to imitate a Leslie. So I'm not referring to that, but to some unknown generic rotary speaker effect.
 

Swirling Snow

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Yes, you've unearthed the secret behind the curtain! All these modulation devices are like colors of light - we perceive red, blue and green as different things, but they're really all the same. It the limits of our senses that make them seem like they deserve names. Flangers and phasors et cetera, all work the same but sound different.


The Univibe was a weirdo one-off Japanese toy that would have been forgotten if Hendrix hadn't played one. Exclude it from your sample, for sanity's sake.
 

Ronzo

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I thought that Roger Mayer invented the Uni-Vibe, as well as the Octavia and other effects. Am I incorrect?
 

Swirling Snow

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He modified Hendrix's pedals, then issued his own when Univox stopped selling them. I think. I only sold the Univox pedals.
 

0utputXfmr

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Might help to visualize/examine how a real rotary speaker works, e.g. a Leslie. That's what the rotary speaker pedal effects are trying to mimic: https://en.wikipedia.org/wiki/Leslie_speaker

And then I will add "sort of". The guy who came up with Uni-vibe, for example, was not actually trying to imitate a Leslie. So I'm not referring to that, but to some unknown generic rotary speaker effect.

I was more curious about "rotary speaker effect" as a category-- like phasing, vibrato, and chorus-- not just the Uni-Vibe, which appears to be its' own thing entirely.
 

Highway Chile

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Vibrato is an old effect that goes back to the 1950s, if not earlier. I understand that it was originally created using some form of phase shifting but I don’t understand electronics. This old type of vibrato was the predecessor to the Magnatone vibrato amps and, later, the Univibe. With the Univibe, the dry signal was added to create chorus and the two effects could be separately selected using a toggle switch.

In the 1970s, analog delay with bucket brigade chips became practical and this led to the flood of delay pedals, Boss-style chorus pedals, and flangers. Over time, the popular view solidified that “real” chorus and vibrato required analog time shift rather than phase shift. This is why some folks are confused when they see that a Univibe — a device which has no delay chip — can have settings called “chorus” and “vibrato.”

The Japanese engineer who designed the Univibe now claims that he wasn’t trying to emulate the Doppler effect that was produced by the Leslie cabinets. That may be so, but who knows whether that is revisionist in view of decades of people saying that the Univibe “failed” as an accurate rotary sim.
 

WalthamMoosical

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My guess is that vibrato is distinguished from chorus in that vibrato modulates the original signal, thus no blending of original and modulated?
Yes, you can make a vibrato by means of some kind of delay line with variable delay, leading to frequency modulation. Then blending that back with the original signal gives a chorus effect. There's been a discussion at BYOC recently concerning modding their Vibrato pedal to make it into a chorus by this method.
 

nickmm

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Doppler effects. Velocity Increases pitch of a sound as it approaches and thus decrease as they depart.

A Chorus is an electrical approximation of the leslie that is a physical one.

Flanging is a Electrical simulation of time delay effects on tape machines running out of sync.

Phasers are use inverted wave forums to comb filter frequencies.
A univibe is an early attempt to recreate a Lelie using phasing principles..
Vibrato is pitch modulation.

Hendrix didn't use Univibes on the famous studio recordings.
 
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memorex

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I thought that Roger Mayer invented the Uni-Vibe, as well as the Octavia and other effects. Am I incorrect?

Incorrect. The Shin-ei Univibe was designed by an engineer named Fumio Mieda who worked for Korg. He later worked with Vox (parent company now Korg) to help in the modeling of the Univibe effect for the Tonelab series. I still have a 2005 Tonelab SE, and I believe it has, by far, the most accurate recreation of the original Univibe. The Univibe in my Boss GT-100 is so bad I never use it, but the rotary effect can be made to sound somewhat like a Univibe if you turn the depth down.
 

nickmm

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Incorrect. The Shin-ei Univibe was designed by an engineer named Fumio Mieda who worked for Korg. He later worked with Vox (parent company now Korg) to help in the modeling of the Univibe effect for the Tonelab series. I still have a 2005 Tonelab SE, and I believe it has, by far, the most accurate recreation of the original Univibe. The Univibe in my Boss GT-100 is so bad I never use it, but the rotary effect can be made to sound somewhat like a Univibe if you turn the depth down.
Roger Mayer is rumoured to have created a Leslie unit for Hendrix made from a organ unit. That developed into the virbratone. I'm not sure what the real story is.

Hendrix used a univibe on live recording at a later stage. Woodstock and Band of Gypsys.
Not on Little Wing, House Burning Down, Axis Bold as love.
 
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arlum

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Chorus, Flanger and Phaser all hold their own and are usable in multiple applications. Vibrato and Uni-Vibe are highly genre specific. Where they work they work great and are pretty much required to reproduce the tones you'll need. They just don't offer a wide variety of use and would probably only be required for tribute bands, etc. I own one of each because I'm Obsessive- Compulsive but would put them well down the list of current guitarists effects pedals to own.
 

BigDaddyLH

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Chorus, Flanger and Phaser all hold their own and are usable in multiple applications. Vibrato and Uni-Vibe are highly genre specific. Where they work they work great and are pretty much required to reproduce the tones you'll need. They just don't offer a wide variety of use and would probably only be required for tribute bands, etc. I own one of each because I'm Obsessive- Compulsive but would put them well down the list of current guitarists effects pedals to own.

I'd love to see a pedal with a toggle labelled "Obsessive/Compulsive"
 

Peegoo

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When you take a look at the circuit topologies and how they generate the effects, you quickly learn that manufacturers have mixed up the various 'labels' to describe their effects. That only makes the discussion more confusing. Just like Fender calling a vibrato bridge a "tremelo" and the tremolo effect on their amps "vibrato." They got them bass ackwards.

It's better to think about these effects from the perspective of what they attempt to electronically simulate (some better than others) as @nickmm describes above.
 

nickmm

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When you take a look at the circuit topologies and how they generate the effects, you quickly learn that manufacturers have mixed up the various 'labels' to describe their effects. That only makes the discussion more confusing. Just like Fender calling a vibrato bridge a "tremelo" and the tremolo effect on their amps "vibrato." They got them bass ackwards.

It's better to think about these effects from the perspective of what they attempt to electronically simulate (some better than others) as @nickmm describes above.
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A hard concept to explain on the interwebs. I feel old.

Back to working on the tremolo arm on my strat :)
 

SRHmusic

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So, I found a decent article online about the differences between Chorus, Flanger, and Phaser effects: https://producerhive.com/ask-the-hive/chorus-vs-flanger-vs-phaser/

I do have an electrical engineering background (though I work mostly in power systems), so I do understand the differences between Amplitude Modulation, Phase Modulation, and Frequency Modulation-- in fact, the latter two are mathematically-related.

According to the article, Flangers and Chorus effects share an LFO (and before that, bucket-brigade IC's), blending a modulated signal with the original (causing all kinds of constructive and destructive interference, as a result), which certainly explains why a lot of Flanger pedals, like the Stereo Electric Mistress and TC Electronics SCF, also have a Chorus effect onboard. The main difference appears to be delay time-- Chorus uses a longer delay time, which induces some frequency modulation. The second significant difference appears to be that flange utilizes a feedback loop, where chorus does not.

Given that Vibrato is also a frequency modulation effect, how is it related to chorus? My guess is that vibrato is distinguished from chorus in that vibrato modulates the original signal, thus no blending of original and modulated? I noticed that a lot of vibrato pedals also have a chorus on board-- does that imply there is a way to get a chorus effect utilizing the same components as the vibrato, as there is between chorus and flanger?

Next up-- Rotary Speaker effect.
Chorus and flanging are time delay based. The signal is split, one path is delayed and mixed back with the original. Vibrato is frequency variation. Two different things. And once you have an LFO and a mixer (audio summing circuit) it's easy to add in other effects in one unit, perhaps why we see more combined chorus and vibe units out there.

You might want to look at how analog synthesizers work- lots of similar concepts (LFOs, summers, swept filters, etc.)
(Edited for clarity)
 

nickmm

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Chorus and flanging are time delay based. The signal is split, one path is delayed and mixed back with the original. Vibrato is frequency variation. Two different things. Once you have an LFO and a mixer (audio summing circuit) is easy to add in other effects in one unit.

Chorus was the sound described by a Leslie speaker. (a sound of many voices)
Flanging was touching the rim of a tape to make it run out of sync with a another tape machine.
They can be recreated/approximated with time based and LFO circuits.
 




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