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Avoiding Phase Issues when Layering Guitars (2 Amps or more One Take)

Discussion in 'F.O.H.' started by EachHit, May 17, 2015.

  1. EachHit

    EachHit ScytheBeast

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    Hi,

    I am curious how some of you handle latency when you reamp.

    For Example: I have some Guitar DI's which I am reamping with my Kemper. Sometimes I like to layer 2 different Profiles (of cause from the same take so the DI is absolut identical).
    Problem is that I always have Latency due to the Delay the signal needs to be converted from the Interface, the Kemper etc.
    My recorded Signal cam in Pro Tools exactly 349 Samples late.
    So how would you make sure to get not latency when you try to find another Profile which fits best.
    Normally I would just let the first Track untouched without nudging it 349 Samples to the start of the Track.

    I guess that there are a lot of ways to do it but I would really like to know how the more advanced guys in here handle that kind of Stuff.

    Heavy Greetz
     
  2. He's Dead, Jim

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    Before anything else, go into the Kemper system settings and set it to constant latency. The default is varying latencies based on # of effects, stomps, etc., but constant latency sacrifices a small number of ms for being reamping-compatible by setting all the DIs to one constant latency.
     
  3. EachHit

    EachHit ScytheBeast

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    I dit that already. But still it seems that there is a problem when I do it my old way.
    Normally I put a click right before the DI Signal which is dead on the Grid. So later I can just realign the reamped track to the Grid with the Waveform from the Click and have it all back "in time" with the Drums and Bass.
    But when I reamp the same DI with another Profile (or real Amp) this won't be in phase with the already recorded first Track.
    So do you first reamp all tracks before aligning it back to it's orginal place?

    I also thought about realigning the first recorded Track to it's original position and then put a Time Delay with the exact Samples (Latency) on the Master Bus. Should this work? Or will that also delay my DI Track which is send to the Kemper via the Sends in Pro Tools. From Pro Tools to an Output of my Audient ID22 and then from the Kemper back to the Preamps from the Audient.

    I will definetly see if the Delay is always 348 Samples or if it's different from Project to Project or from Profile to Profile.

    Heavy Greetz
    Heavy Greetz
     
  4. bryan_kilco

    bryan_kilco Member

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    Why can't you just keep doing the click thing to all the tracks?
     
  5. Jormyn

    Jormyn Member

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    When you record normally, does the recording end up on time or is your playing 349 samples late? If it is, then Pro Tools isn't compensating for your interface's latency.
     
  6. EachHit

    EachHit ScytheBeast

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    I normally always put a click on the beginning of everything I reamp.

    Made a quick test and the constant Latency with the Kemper seems to be always about 345 Samples. Of course the first Dip in the Waveform from the Click doesn't always look the same due to the different Profiles.

    My Concern is that my Perception is different when the already recorded tracks are not 100% in time with the one I am monitoring while reamping.

    For example:
    I reamped a DI with a 5150 Profile with the Click in Front. Then I aligned the reamped track so that the click is on the grid again which is mostly about the 345 Samples.
    Now everything is back in time I think.

    But when I want to layer another Profile with the same Take (for example a Rectifier) over the 5150 then I hear all Instrument in Time but the Reamped Signal which I am hearing (live) should be 345 Samples late.
    Of course I could just record a few seconds and align and decide if I like it or not. But somehow I feel that I need to judge everything "on the fly" so I can make smalle adjustments in the Kemper.

    Maybe I am totally overthinking the 345 Samples. So just tell me when you think I am an Idiot and I shouldn't worry about that ;)

    Heavy Greetz
     
  7. bryan_kilco

    bryan_kilco Member

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    I understand you now. But yeah, PT should be taking care of the latency for you. I had some issues when running outboard gear in Reaper and I actually had to put a plugin in my chain that would correct latency for me.
     
  8. EachHit

    EachHit ScytheBeast

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    Yeah pro Tools is doing some Latency correction after Recording. I am not sure how the Program calculates it but I see it happen quite a lot.
    Especially when I am recording Drum Samples on my Kit.
    When I look at the screen I am very often ahead of the Grid. But after the Recording is stopped I can see how Pro Tools shifts the Recorded Tracks slightly to the right.

    Your post bringed back some memory. I think there was a kind of Delay Compensation for Outboard Gear Is think.
    Guess I have to read something about that and try to find something which I understand.

    Heavy Greetz
     
  9. SoundsLikeFog

    SoundsLikeFog Member

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    If the different profiles use different mic positions from each other, and you use the same take, how could they line up perfectly in phase, even if you aligned the tracks to a grid?
     
  10. egan.

    egan. daylightdies.com

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    Is the timing and phase of kemper profiles accurate to the rigs they capture (independent of processing latency)? If so if a mic was 2cm further away in one profile vs another they're going to be off by 28 samples. Anyway, dragging them to the same starting point may or may not sound the best. I always just throw time adjuster on the secondary tone and play with it until I'm happy.
     
  11. TRUIE

    TRUIE Member

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  12. EachHit

    EachHit ScytheBeast

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    I am not sure how the Kemper handles it when Profiles have different Mic Positions. I think when Constant Latency is checked they may all start at the same point when I reamp the same Signal.
    That's a good point cause I never really thought about that.
    I should do some test Profiles with different Mic Positions when I do some profiles in the Future.

    For now I think I will do it the way I did it before with the Click in Front of the DI and do some test recordings to judge if I like the blend of Profiles.

    Guess I have to check out the Forums at Kemper and see what process they recommend when I want to layer different Profiles.

    Would be interesting how people who mic real amps handle that Kind of Problems. I guess they just trust their ears.

    Heavy Greetz
     
  13. TRUIE

    TRUIE Member

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    Yeah, there isn't a "correct" way to do this kind of things.
    Multiple amps (or profiles) layering is all about phase cancellation anyway, so just play around with a delay plugin or something automatic like the one I mentionned, until you find the best alignement (= the one that sounds better/like you want).
     

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