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Absolute Phase

Discussion in 'Recording' started by CFS, Oct 10, 2001.

  1. CFS

    CFS Guest

    So I get the concept of absolute Phase and why its important but can anyone describe what a mix without absolute phase would have the one with it would have. I am concerned cause I realised half way through a record the other day that my Kick trigger was out of phase when it was hitting the console due to faulty wiring. since it wasnt a miced signal with the drum set it wasnt the end of the world but it did make me add a ton of EQ i didnt need to intially.
     
  2. pan

    pan Guest

    Absolute Phase is about hitting the Snaredrum in your face or ot of it...

    I think, absolute Phase is something, you cannot really distinguish-in your case it's about relative phase, wich is important in Drumsets or doubled Strings.

    You always have to care about the relative phase! Absolute Phase is about "is the Woofer coming OUT or IN?"


    Anyone cares about "absolute phase"?
     
  3. Originally posted by pan:

    I think, absolute Phase is something, you cannot really distinguish-in your case it's about relative phase, wich is important in Drumsets or doubled Strings.


    Hmmm, well I can distigush absolute polarity differences in many instruments. One way seems to sound better than the other in many cases and I will adjust it accordingly.

    Of course the phase relationship between microphones in a multi-miced situation, such as a drum kit has a much more drastic effect on the sound and should be carefully adjusted. Always listen in mono to determine the best positioning of multiple microphones.
     
  4. ironsheik

    ironsheik Guest

    I'm still having trouble plowing my mind through phase relationships. Are you saying for instance that with a stereo setup of overheads, you should check the summed signal in one speaker? What exactly do you hear that is evidence of a problem other than it just not being *right*? I suppose this is a good idea before tracking any stereo tracks? Thanks
     
  5. anonymous

    anonymous Guests

    Lack of bass, it's the phase setting that sounds 'light' that is incorrect - for drum recording anyhow...

    :)
     
  6. pan

    pan Guest

    posted by mp:

    Hmmm, well I can distigush absolute polarity differences in many instruments. One way seems to sound better than the
    other in many cases and I will adjust it accordingly.


    I sometimes got the feeling, that when inverting the phase of a Vocal in a mix, the Vocal might appear kind of closer - is this imagination? (I don't talk about relative phase to the delays/reverb - no, I could blindtest and would pick the inverted....or imagination, though :confused:
     
  7. Opal Ent

    Opal Ent Guest

    In reply to Josh.
    You want to mono sum during the mix to see if thing disappear. If you through the mix in mono and a keyboard disappears, than means that the keys are out of phase. That's not an intirely bad thing though. Alot of mixers are throwing keys and backup vocals out of phase to give the mix more depth. It makes it sound like they are in back of you. It's a cool trick. I wouldn't do it with drums though! Hope that helps.

    Marty
     
  8. e-cue

    e-cue Active Member

    Originally posted by pan:



    I sometimes got the feeling, that when inverting the phase of a Vocal in a mix, the Vocal might appear kind of closer - is this imagination? (I don't talk about relative phase to the delays/reverb - no, I could blindtest and would pick the inverted....or imagination, though :confused:


    I've sometimes noticed this too. I always seem to check it. I got into this when I began to notice that sometimes it helped get rid of headphone bleed (and sometimes made it worse) I've even gone so far to flip all the phase buttons on my board while tracking vocals back in the day (and then sending a phase flipped cuemix, etc...). Eventually, I was just splitting hairs.
     
  9. miketholen

    miketholen Member

    why is there no phase switch on a PT channel?...DUH...Digi!!! :p :p :roll:
     
  10. anonymous

    anonymous Guests

    Hey, Mike - I confess I adore your rants, even though I am but a mere slovenly ProStoolie, (and I happen to like EveAnna as well...). And I have tremendous respect for your knowledge of vintage gear. But in this case, perhaps you speaketh too quickly. In vs. 5.1 there is a trim insert that takes up zero DSP. It allows -INF to +6db gain adjustment, as well as polarity flip and mute. Very useful little item, and admittedly long overdue. Love ya!
     
  11. anonymous

    anonymous Guests

    P.S. - Now, on the other hand, if you'd like to discuss why Greg Mackie has never seen fit to put a polarity switch on any of his mixers ever...

    For a really fun time, try asking the Mackie reps at trade shows that question. Usually you will get something about it was considered non-essential because:

    a) You can always wire up a cable to flip the polarity.

    b) Many Mackie users have outboard pres with polarity reverse. (This usually comes while they are standing under a poster which brags about how their $50/channel pres sound as good as the "big boys")
     
  12. Scott Gould

    Scott Gould Active Member

    Um, Littledog, I gotta take issue with you there - my D8B has a polarity (phase) switch on all 72 channels...
     
  13. anonymous

    anonymous Guests

    (red face) mea culpa! I confess, I never really looked at the D8B that closely after I saw a prototype at AES a few years back - and I swear - that unit had no polarity switches! Honest!

    Greg, I apologize. And I actually do use one of your 1604 VLZ's for my band PA set-up. (And I'm sure there's no polarity switches on those babies).

    Then again, there's the annoying phantom power only in banks of eight (or global, depending on mixer)...
     
  14. Scott Gould

    Scott Gould Active Member

    Well, Greg did kind of "cheat" on the D8B 'cause the polarity switches are in software, not physically mounted on the surface. (the phantom power switches ARE physical...and 1 per mic-pre)
    Scott
     
  15. Dave McNair

    Dave McNair Active Member

    The reason that absolute phase is sometimes audible is because different speakers and to a certain degree gain stages, will sound better one way or the other. Some speakers are less sensitive, some are very sensitive. It has to do with the design of the speaker system and whether it has the same response moving in or out with a positive voltage applied. Gain stages' audible behavior amplifying a signal with pin 2 or 3 hot is another design related topic. I can tell you that Amek 9098 preamps are VERY sensitive is this regard. The polarity of the final signal is the result of which pins are hot on every piece of gear that the itsy bitsy signal passes through on its way to your monitor speakers. Some gear even have an odd number of phase inverting stages and will reverse phase of any signal passing through em, even if all your connections are wired the same. The good news is, I've never thought this to be a major issue, certainly not as important as the relative phase between a sound source recorded with multiple mics. YMMV
     
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