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Beta 4 VC 'Warble' on Clean - SOLVED

Brian Coonan

Experienced
Hi - just wondering if this would be an expected result - this is a clip with the pitch block off, then it on but set at 0, then on and dropped 1/2 step and I noticed that it almost sounds like tremolo block is on, but it isn't. My tuning is on, but my intonation is off so I'm wondering if it's just due to that, but thought I would ask anyway. I think I can hear the same thing when the Pitch block isn't so thinking that maybe it's just being amplified.


With gain/distortion and playing normally, it's much less noticeable.

Thanks for any help,
Brian
 

Attachments

Brian Coonan

Experienced
All real time pitch shifters display some degree of tremolo on certain chords. Ours is better than most. The worse your guitar's intonation the more tremolo.
Thanks a bunch - yeah - I just did some more testing and was just coming out here to say this is more than likely related to my guitar(s). Victim of changing seasons and not having things set up that well. Beta 4 ROCKS!
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
The way real time pitch shifting works is the input is split up into "granules" which are little snippets of audio. Those granules are played back either faster or slower to shift the pitch up or down respectively. An analog analogy is a tape recorder with rotating heads. As these heads rotate they eventually leave the tape and the other head enters. As this happens the heads crossfade. If the audio isn't perfectly correlated during the crossfade the amplitude will vary. This causes the tremolo. The pitch detector's job is to find the pitch so that the audio is correlated during the crossfade.

If your intonation is off the correlation will be weak during the crossfade causing more tremolo.

Pitch shifting isn't perfect, especially in real time. It's a perceptual process. It's not like solving equations or modeling amplifiers. It's about fooling the human auditory system. So any pitch shifter is going to have some level of artifacts. In my comparisons with other products I feel these latest algorithms are among the best. I compared my Eventide Eclipse, Kemper and Digitech Whammy DT.

The Eclipse is the weakest of the bunch. It tracks very slow which causes artifacts when you change the note you are playing. It does, however, track complex chords well. For example, if you are playing a harmony the harmony will change from, say, a major 3rd to a minor 3rd depending upon the note you are playing. The slow tracking causes the shifter to sound the wrong interval for a bit until the tracking catches up. So you get a pitch "blip" when you change notes. It has a pleasant characteristic sound which has an almost bell-like quality that makes it useful for certain special effects.

The Kemper has pretty good shifting and tracks much faster than the Eclipse. It exhibits the most tremolo of all the devices tested (I know why this happens but I'm not about to spill the beans :) ) It struggles, however, with chords. If you play a D/F# (the classic pitch shifter stress test chord) it goes all wonky because it can't figure out the pitch. This is because it's pitch detector window is too short. It has a "smooth chords" mode which doubles the window length but then the latency becomes much greater and the tracking much slower. It also has a formant shifting feature but in my tests it's all but useless. It only works with single notes, adds a lot of latency and doesn't really sound convincing.

The Whammy DT is an interesting device. It exhibits almost no tremolo effect regardless of the chord played. The Eclipse, Kemper and Axe-Fx all have similar sounding shifting. IOW they seem to be based around similar algorithms implemented to varying degrees of success. The Whammy has a fundamentally different sound. This is both good and bad. The lack of tremolo is good. However when playing even simple chords (i.e. an open E or A) there is an underlying grittiness and "inharmonicity" and the guitar sounds out of tune. It also exhibits a strange behavior during the pick attack. The Whammy glitches during the pick attack kind of "cuts out".

For the Axe-Fx I'm using a wavelet approach to the pitch detector which results in a multi-resolution pitch detection. This means the pitch detection window is short when you want it short or long when you want it long. This results in extremely fast tracking. There's almost no audible "blip" when the harmony changes. It also tracks complex chords pretty well but it does sometimes struggle with locking onto the pitch and will alternate between the "best guess" when there isn't a clear answer. To be fair the other products do this too.

So all the devices exhibit their idiosyncrasies and artifacts. The question becomes which artifacts are the least offensive. If I were to choose I would choose either the Whammy or the Axe-Fx. However the Whammy only supports chromatic shifting. It has a "Harmony" mode but it isn't diatonic harmony where you can set the key and scale/mode.
 

Brian Coonan

Experienced
The Whammy DT is an interesting device. It exhibits almost no tremolo effect regardless of the chord played. The Eclipse, Kemper and Axe-Fx all have similar sounding shifting. IOW they seem to be based around similar algorithms implemented to varying degrees of success. The Whammy has a fundamentally different sound. This is both good and bad. The lack of tremolo is good. However when playing even simple chords (i.e. an open E or A) there is an underlying grittiness and "inharmonicity" and the guitar sounds out of tune. It also exhibits a strange behavior during the pick attack. The Whammy glitches during the pick attack kind of "cuts out".
Thanks so much for all that info- was a great read. I think I experienced what you mentioned about the Whammy with the Pitch Fork pedal when I had the AX8. I couldn’t play with that pedal on (trying to just have one guitar and going down 1/2 step) because it just had this weird artificial sound.

i don’t find that to be the case with the III at all. Totally usable live - even down further than only 1/2 step.

So in my experience, I’d agree that the Axe Fx III is way beyond the others - so thank you for that as well.
 

bradlake

Axe-Master
I am very impressed and inspired by these pitch updates....just tried putting 2 pitch blocks in series at the front of the chain, first a VC down a fourth, then a classic whammy on FC 1 up two octaves....absolutely flawless to my damaged ears using the two together.
 

unix-guy

Legend!
The way real time pitch shifting works is the input is split up into "granules" which are little snippets of audio. Those granules are played back either faster or slower to shift the pitch up or down respectively. An analog analogy is a tape recorder with rotating heads. As these heads rotate they eventually leave the tape and the other head enters. As this happens the heads crossfade. If the audio isn't perfectly correlated during the crossfade the amplitude will vary. This causes the tremolo. The pitch detector's job is to find the pitch so that the audio is correlated during the crossfade.

If your intonation is off the correlation will be weak during the crossfade causing more tremolo.

Pitch shifting isn't perfect, especially in real time. It's a perceptual process. It's not like solving equations or modeling amplifiers. It's about fooling the human auditory system. So any pitch shifter is going to have some level of artifacts. In my comparisons with other products I feel these latest algorithms are among the best. I compared my Eventide Eclipse, Kemper and Digitech Whammy DT.

The Eclipse is the weakest of the bunch. It tracks very slow which causes artifacts when you change the note you are playing. It does, however, track complex chords well. For example, if you are playing a harmony the harmony will change from, say, a major 3rd to a minor 3rd depending upon the note you are playing. The slow tracking causes the shifter to sound the wrong interval for a bit until the tracking catches up. So you get a pitch "blip" when you change notes. It has a pleasant characteristic sound which has an almost bell-like quality that makes it useful for certain special effects.

The Kemper has pretty good shifting and tracks much faster than the Eclipse. It exhibits the most tremolo of all the devices tested (I know why this happens but I'm not about to spill the beans :) ) It struggles, however, with chords. If you play a D/F# (the classic pitch shifter stress test chord) it goes all wonky because it can't figure out the pitch. This is because it's pitch detector window is too short. It has a "smooth chords" mode which doubles the window length but then the latency becomes much greater and the tracking much slower. It also has a formant shifting feature but in my tests it's all but useless. It only works with single notes, adds a lot of latency and doesn't really sound convincing.

The Whammy DT is an interesting device. It exhibits almost no tremolo effect regardless of the chord played. The Eclipse, Kemper and Axe-Fx all have similar sounding shifting. IOW they seem to be based around similar algorithms implemented to varying degrees of success. The Whammy has a fundamentally different sound. This is both good and bad. The lack of tremolo is good. However when playing even simple chords (i.e. an open E or A) there is an underlying grittiness and "inharmonicity" and the guitar sounds out of tune. It also exhibits a strange behavior during the pick attack. The Whammy glitches during the pick attack kind of "cuts out".

For the Axe-Fx I'm using a wavelet approach to the pitch detector which results in a multi-resolution pitch detection. This means the pitch detection window is short when you want it short or long when you want it long. This results in extremely fast tracking. There's almost no audible "blip" when the harmony changes. It also tracks complex chords pretty well but it does sometimes struggle with locking onto the pitch and will alternate between the "best guess" when there isn't a clear answer. To be fair the other products do this too.

So all the devices exhibit their idiosyncrasies and artifacts. The question becomes which artifacts are the least offensive. If I were to choose I would choose either the Whammy or the Axe-Fx. However the Whammy only supports chromatic shifting. It has a "Harmony" mode but it isn't diatonic harmony where you can set the key and scale/mode.
This is probably something that should be added to the wiki, eh @yek?
 

yyz67

Experienced
EDIT: Rerecorded artifacts in another post below with defaults (FAST, tracking = 0.5).

This may be expected (given Cliff's explanation above), but I'm finding that playing a single note can create a rapid stacatto / ringmod artifact using VC (at -12, but present to varying degrees at all negative settings). This occurs with FAST and SMOOTH settings and any tracking dial setting. I could find different notes on different spots on the guitar that does this to varying degrees. As it mostly only occurs with certain notes on certain strings, it could be the harmonics of my guitar on those notes (ESP EC-1000 w/ SDs). But if I'm experiencing it, I imagine others will.

Attached preset and recording. First clip is with VC only, second is with VC panned right and dry guitar left. I don't hear anything strange with the original dry signal.

 
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FractalAudio

Administrator
Fractal Audio Systems
Moderator
This may be expected (given Cliff's explanation above), but I'm finding that playing a single note can create a rapid stacatto / ringmod artifact using VC (at -12, but present to varying degrees at all negative settings). This occurs with FAST and SMOOTH settings and any tracking dial setting. I could find different notes on different spots on the guitar that does this to varying degrees. As it mostly only occurs with certain notes on certain strings, it could be the harmonics of my guitar on those notes (ESP EC-1000 w/ SDs). But if I'm experiencing it, I imagine others will.

Attached preset and recording. First clip is with VC only, second is with VC panned right and dry guitar left. I don't hear anything strange with the original dry signal.

Your tracking value is set too low.
 

AZG

Inspired
The way real time pitch shifting works is the input is split up into "granules" which are little snippets of audio. Those granules are played back either faster or slower to shift the pitch up or down respectively. An analog analogy is a tape recorder with rotating heads. As these heads rotate they eventually leave the tape and the other head enters. As this happens the heads crossfade. If the audio isn't perfectly correlated during the crossfade the amplitude will vary. This causes the tremolo. The pitch detector's job is to find the pitch so that the audio is correlated during the crossfade.

If your intonation is off the correlation will be weak during the crossfade causing more tremolo.

Pitch shifting isn't perfect, especially in real time. It's a perceptual process. It's not like solving equations or modeling amplifiers. It's about fooling the human auditory system. So any pitch shifter is going to have some level of artifacts. In my comparisons with other products I feel these latest algorithms are among the best. I compared my Eventide Eclipse, Kemper and Digitech Whammy DT.

The Eclipse is the weakest of the bunch. It tracks very slow which causes artifacts when you change the note you are playing. It does, however, track complex chords well. For example, if you are playing a harmony the harmony will change from, say, a major 3rd to a minor 3rd depending upon the note you are playing. The slow tracking causes the shifter to sound the wrong interval for a bit until the tracking catches up. So you get a pitch "blip" when you change notes. It has a pleasant characteristic sound which has an almost bell-like quality that makes it useful for certain special effects.

The Kemper has pretty good shifting and tracks much faster than the Eclipse. It exhibits the most tremolo of all the devices tested (I know why this happens but I'm not about to spill the beans :) ) It struggles, however, with chords. If you play a D/F# (the classic pitch shifter stress test chord) it goes all wonky because it can't figure out the pitch. This is because it's pitch detector window is too short. It has a "smooth chords" mode which doubles the window length but then the latency becomes much greater and the tracking much slower. It also has a formant shifting feature but in my tests it's all but useless. It only works with single notes, adds a lot of latency and doesn't really sound convincing.

The Whammy DT is an interesting device. It exhibits almost no tremolo effect regardless of the chord played. The Eclipse, Kemper and Axe-Fx all have similar sounding shifting. IOW they seem to be based around similar algorithms implemented to varying degrees of success. The Whammy has a fundamentally different sound. This is both good and bad. The lack of tremolo is good. However when playing even simple chords (i.e. an open E or A) there is an underlying grittiness and "inharmonicity" and the guitar sounds out of tune. It also exhibits a strange behavior during the pick attack. The Whammy glitches during the pick attack kind of "cuts out".

For the Axe-Fx I'm using a wavelet approach to the pitch detector which results in a multi-resolution pitch detection. This means the pitch detection window is short when you want it short or long when you want it long. This results in extremely fast tracking. There's almost no audible "blip" when the harmony changes. It also tracks complex chords pretty well but it does sometimes struggle with locking onto the pitch and will alternate between the "best guess" when there isn't a clear answer. To be fair the other products do this too.

So all the devices exhibit their idiosyncrasies and artifacts. The question becomes which artifacts are the least offensive. If I were to choose I would choose either the Whammy or the Axe-Fx. However the Whammy only supports chromatic shifting. It has a "Harmony" mode but it isn't diatonic harmony where you can set the key and scale/mode.
I’m finding that using the same guitar, Suhr Modern, that b4 glitches a lot more than b3. I’m sure it’s because the guitar needs new strings and intonation, probably been 6 months to a year since either have been done. But it might be nice to have the option for either the b3 or b4 algorithm In the III since b3 seems slower but more tolerant of poor setups.

I will need to pull out a guitar without a Floyd Rose, that’s easier to setup if needed, and give it another go.
 

yyz67

Experienced
Rerecorded after resetting the pitch block and selecting VC to -12 with INPUT 1. Tracking at default of 5.0. Occurs with FAST (default) or SMOOTH. Also independent of Tracking parameter value.

First clip is with VC -12 only, second is with VC panned right and dry guitar left. I don't hear anything strange with the original dry signal.

 

Attachments

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AZG

Inspired
Do we need adjustments or algorithm choices here?
Good question. I’m guessing based on Cliff’s comments that different solutions have different pros and cons. B3 had more noticeable latency to me, but seemed to have little issue with my guitar that needs new strings and intonation. B4 has lower latency, but seems more particular about setup. Both were at default settings so some settings changes might help. And of course using a better setup guitar probably does wonders. But maybe both algorithms have value in different situations?
 

DLC86

Fractal Fanatic
It also has a formant shifting feature but in my tests it's all but useless. It only works with single notes, adds a lot of latency and doesn't really sound convincing.
Regarding this I have a tc helicon device for vocal FX and it has a really great formant shifting (called gender bender), no noticeable latency or artifacts whatsoever.
But maybe it's just a lot easier to do it on voice than on a guitar.
 
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