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Shepards Tone


gritzildino

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I am trying to Create a shepards tone effect in logic.

I want to pitch bend a sound up an octave smoothly. And have other sounds shifting down octaves and ect. The onl;y way I know that works smoothly in logic is to use the pitch bend automation under midi piano roll. But what are these units of measurement they have listed? It starts at 1 and goes up to, or down to, +/- 63. Are these units semi-tones?

 

And. Is there a way to smoothly automate pitch using an audio file. I wass using the pitch shifter plug, but this does not transition smooth between semi tones. I also loaded the audio sample into ESX and used a pitch bend, but this changed the length of the audio sample and as i inresed the pitch the sample ended before I wanted it to.

 

Also. Making a shepards tone effect also involves fading the volume in/out of sounds. Ive noticed that working with audio the fade tool works perfectly. Audio can be faded in/out very smoothly. When I tried this with MIDI I used Volume automation to create the fades..., it was not so smooth... Going from 0db to -infinite with the same slope as the fade tool left the start and the end levels correct but everything inbetween way too low in volume.

I know I am asking a lot. But this website is the only plkace I know of to ask 'dumb question' .. I have no producer friends.

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But what are these units of measurement they have listed? It starts at 1 and goes up to, or down to, +/- 63. Are these units semi-tones?

 

Pitch bend data doesn't have any relation to pitch ranges (like semi-tones) other than what the instrument receiving that data makes of it. The units displayed represent MIDI CC values from 0 to 127, or, in the case of centered values (pan, pitch, etc..), -63 to +63 (or something like that).

 

If your instrument's pitch bend range is set to +/- 2 semitones (usually the default), then +63 is +2 semitones. If your instrument's pitch bend range is set to +/- 12 semitones, then +63 represents +12 semitones, or one octave up. I'll pass on pitch being actually a 14 byte event which the Hyper Draw does not display.

 

Is there a way to smoothly automate pitch using an audio file. I wass using the pitch shifter plug, but this does not transition smooth between semi tones.

 

More or less smooth I guess. You could try automating the AUPitch plug-in.

 

Making a shepards tone effect also involves fading the volume in/out of sounds. Ive noticed that working with audio the fade tool works perfectly. Audio can be faded in/out very smoothly. When I tried this with MIDI I used Volume automation to create the fades..., it was not so smooth... Going from 0db to -infinite with the same slope as the fade tool left the start and the end levels correct but everything inbetween way too low in volume.

 

Change the slope (Control-Shift-drag the segment up/down or left/right for S curves), or bounce to audio and use the fade tool?

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Yes, pitch bend data has zero relation to pitch bend amount, and is totally normal. The pitch bend amount is entirely up to how the synth/sampler/plugin is programmed. The reason for this is that you can set the full travel of the pitch wheel (in either direction) to be whatever you need it to be. Furthermore, many instruments allow you to program them so that the + bend range is different from the - bend range.

 

To create a Shepard Tone (not plural) you'll need at least 4 sound sources. It cannot be accomplished with just one. The pitch of each sound source has to rise as the volume fades in and out, and the pitch and volume modulation have for each sound source have to be offset by 90º from one another (called "quadrature").

 

Start with one sound source (whatever you're using) and using hyperdraw, have the pitch ramp up over 8 measures starting at bar 1 and ending at bar 9. Then create volume modulation starting at zero at bar 1, peaking at bar 5, and fading down to zero again at bar 9. Finally, you're going to need a single note that plays for 8 measures.

 

Now duplicate your sound source track three more times. Copy your regions (notes & plug modulations) to the second track and shift the whole thing 2 measures (starting on bar 3).

 

Copy that to the next track and shift it to start on bar 5.

 

Copy it again to the fourth track and shift it to start on bar 7.

 

That will get you started, but it may sound a bit "thin". The best results come from using a minimum of 8 sound sources. But hopefully that will get you started.

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And. Is there a way to smoothly automate pitch using an audio file.

Are you needing to do this with an audio file? It's a lot easier to do with a synth where you have better control of oscillator parameters within the synth itself, ie using EG's instead of automation.

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Ya I didnt want to buy any new plug ins.. I thiught it would be possible with all logic stuff... Although I've had problems using logic flanger and phaser .. Which I'm not sure are necassary plugs for this technique.. But every1 says you should use them.. Any one have luck using logic flanger with this effect?
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And. Is there a way to smoothly automate pitch using an audio file.

Are you needing to do this with an audio file? It's a lot easier to do with a synth where you have better control of oscillator parameters within the synth itself, ie using EG's instead of automation.

Yes I am trying both ways. But Ive seen a videos with a white noise sample that this individual pitched with a flanger... Whicfh worked well.. and got the sound i was after...

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The best / easiest way to go is def. Definetly using synths..

Since Logics pitch shifting is NOT GREAT. I created 4 layers by using 1 synth which is much easier... Just got a LONG RISE peferably 32 bars (from an LFO mostlikely). I actually used only 16 bars. Then bounced the whole thing cut it into 4 different sections of four bars then layered, then looped... Then it is all about automating fades nicely.

This works most def.

Only thing is I used The ES1 first. I now want to do it with the ES2 because u can get some wierd funky sound with it but.... How do u turn off the effects?? I am getting way too many crazy phase issues with those effects.

Cheers

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Also. Using the technique which I described above, I used the ES1. When I select the Inverted Saw LFO and Modulate Pitch using that to get rise. The ES1 consistently gets it wrong. The Rise will stop short of completing the 32 bars and the LFO will reset to the lower tone... Just to make sure I used the ES2. The ES2 gets it right. The rise will continue all the way through the 32 bars and at Bar 33 it will reset... The ES1 consistently resets short somewhere around 32.5 bars... I was wondering whats going on here.. Bug?
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  • 8 months later...

sorry to drag up an old thread but i've had a play with this and can't really get it to work -

 

i've got 4 massive synths running - each set to sine wave - each one has 1 region programmed on the arrange page - lowest is A1 - then A2 - A3 - A4....

 

I've set the lfo's so that there's a saw one modulating the pitch an octave upwards over 8 bars, and theres another triangle Lfo modulating the amp of the Osc so that its amp starts on zero and ends on zero ( with the loudest point at the end of bar 4 / start of bar 5)

 

ive then staggered the regions in the arrange window so that the lowest sine starts on bar one, then the next bar 3, bar 5 and then bar 7

 

ive looped all the regions across the arrange page

 

 

But it still doesn't sound anything like a shepard tone.... the pitchs are all rising and the amp's are fading in / out but it's all quite followable, unlike the proper one which are a bit of a head trip!

 

i was just wondering where i'd been going wrong, ?

 

cheers

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hey ski.... so all four tones have to be on the same note, ? (eg A1)

 

ive done that and i think it sound's a bit better, although it still doesn't have that great a consistency.....

 

im not sure how to go about layering more tones though - i tried using 8 with them starting on each bar instead of every two bar's - but it still sounds a bit transparent, doesn't seem to have the continuous effect of tone's such as

 

cheers ski, would love to get this !

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.... so all four tones have to be on the same note, ? (eg A1)

No, the unison is 4 notes in contiguous octaves, eg A1-A2-A3_A4. The trick is in their relative levels to each other. For each glissando the lowest note and the highest note should be barely audible with the middle notes being loudest. The tough part is tweaking that power curve! Easiest to do this in the hyper editor where you can see them. Make 1 region and 3 aliases of it for the other tracks. Then you only need to edit one of them!

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OK - so i don't think i understood what ski was saying about them needing to be in the same octave... ?

 

ive done it again, with 4 synths, sine wave's, edited the volume in the hypereditor so that it starts at zero - peaks half way through and returns to zero - made three aliases - each one an octave up in pitch from the previous one and with an LFO modulating the pitch through an octave...

 

but it still sounds pretty off...

 

ive attached a short clip of what i did as maybe this will be more obvious as to what im doing wrong....

 

cheers though!

tone test.mp3.zip

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OK - so i don't think i understood what ski was saying about them needing to be in the same octave... ?

It means that your regions need to be identical. Each gliss starts on the same pitch.

- made three aliases - each one an octave up in pitch from the previous one and with an LFO modulating the pitch through an octave...

LFO? I got the impression you were doing discrete notes. OK, you don't want to transpose the other tracks. Everything is playing the same thing, just offset in time. When track 1 climbs one octave, track 2 is starting, etc. You always have a 4 note unison, always an octave apart.

 

I'll post a little project example. Give me a minute.

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ah ok... i kind of get the concept but's it's not really working (for me... well, im not working... the concept obv works....)

 

would be ace of you could post an example!

 

apparently you can use the method for drum's as well, ? although i haven't heard that yet.

 

cheers fader!

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Gads! Snowing here....

 

Here's the basic idea done with 5ths just to keep it simple, and following your thinking for transposing each track which is fine since your using a sweep. This just shows how the volume has to interact between the tracks. Tough to get it perfect. This comes close.

 

If I recall correctly, to do octave intervals and be convincing, you need 7 or 8 voices going. I'll have to play with that sometime.

f8_ShepScale_2.logic.zip

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ace, cheers for that fader!

 

does the volume automation work better as a curve,? i don't understand why that would be...

 

and would you count this as 4 layer's or 12, ? (as each es2 has 3 osc set to different pitch's.... although i guess a few would over lap)

 

i don't really want to be too much of a bore but im struggling to find a decent PDF or anything that covers this topic..... so if anyone knows somewhere i can read the theory properly that'd be great

 

nice one

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The theory is pretty simple actually, just tricky to implement well. In a nutshell, your brain thinks the first harmonic of a higher tone is some higher harmonic of the lower tone as they are crossing over. Getting the levels right is the tricky part. So using sounds with complex harmonics already, just makes it a bit easier. More harmonic fodder, you might say.
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