Stereo overdubbing, phase issues and acoustic mono...

Discussion in 'Microphones (live or studio)' started by Plec, Feb 14, 2005.

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  1. Plec

    Plec Guest

    Hey everyone!

    I have some issues with a mix that has been bothering my noodle for the last two days. After this, I will be more in line to use the audio analyzers a little more often though :lol:

    I have a dense metal production consisting of drums, bass, guitars and vocals. Nothing strange going on production wise, just the usual guitar overdub stuff panned left-right. Now, after tracking everything and I sit down to mix this thing, I find the horrible situation that just about EVERY sound is clashing with another, but it's not that the bass and guitars occupy the same range and stuff, it's a bit more complicated...


    The problem here is that the combined guitar tracks has three slight resonances at about 1.3K, 2.6K and 3.9K that you don't really notice until you pull out an analyzer and take a closer look at it. This comb filter-style problem is not evident when listening to each overdub individually. When listening to it combined and panned in stereo it sounds ok, but if you take a stroll and listen to it in acoustic mono, these frequencies are pretty much all you hear.


    Much of the kit is triggered, so it's the overheads thats causing the problem here. There's a spaced pair being used for overheads and the nice thing is that there are certain phase problems that make some frequencies jump out at you. Basically 650Hz, 1.3K, 1.0K, 2.7K and 4.4K.


    There's amp distorsion on here that has a very dynamic 3.3K-4.7K string sound area that's a problem.


    Sounds perfect!

    Now... the joy of it all is that all these phase issues combine to wipe out the entire mix. So let's look at the score...

    Guitars: 1.3K, 2.6K, 3.9K
    Drums: 1.3K, 2.7K, 4.4K, 650Hz, 1.0K
    Bass: .......... 3.3K-------4.7K

    As you see... almost all of these interact perfectly. I'm beating mysealf senseless 'cause I can't figure out how the f___ I could've missed such a thing when tracking. There's no separation anywhere 'cause ALL the instruments have almost the same problem frequencies and of course interact like crazy when combined and all you hear is pretty much "schhhhhhh, hwooooooo, iiiiiiiiiiiiiiiisch" and sinse it's dense metal.. it's just like mixing a number of noises that all need their definite place anyway, so this isn't helping much at this point.

    What I've done in an attempt to remedy this is actually notching out all of these problems.. about -4db/frequency. This separates everything perfectly, but now the problem is that it all sounds like a slight comb filter over the mix :cool: When you bypass the notches it all goes from nice to brutal irritating noise :roll:

    Now, after this totalt mishap of the year I was wondering, can you actually get this perfectly right from the very beginning?? I mean, drums... spaced pair. The whole principle is out of phase, so would this not always result in some comb filtering of this sort? Guitars... this was very strange, cause the day after, I did a guitar session using the exact same setup, a different player and a different guitar though, but same amp, settings, miking, preamp..... We only did one single take though, and no overdubs but there wasn't the slightest sign of this combing filtering taking place on that one guitar.

    I'm totally lost here... anyone who could explain this to me?
  2. anonymous

    anonymous Guests

    Feb 10, 2001
    I can't explain what happened... but I might have an alternative solution you may want to explore... which could be only notching a couple of tracks at those frequencies, and possibly sliding the bass a couple milliseconds ahead or behind the guitars and drums [usually behind works best, but you never know until you try both].

    This should minimize some of your buildup issues.

    If I were to guess what happened I would guess that in the recording process you used a couple of like Chinese condenser mics in the recording of the guitars [the frequencies you outlined seem to be the 'hot spot' for many of the cheap condensers I've heard]... you also probably used the same mics and pre's for a most of the overdubs which led to a "buildup" of a specific sound characteristic on each subsequent overdub.

    My advice would be that in the future you try a different mic and pre, or at least mic for every overdub... a different guitar is equally [if not more!!] useful... and if you really want to get crazy with it, try some open tunings on additional backing tracks that are playing like whole notes through a lot of the passages [except if there is staccato stuff... in which case those tracks do that right along with the other tracks].

    Best of luck weeding it out...
  3. Plec

    Plec Guest

    Thanks for the tip Fletcher!

    The setup was pretty standard though. SM57 to an AMEK 9098 preamp/EQ to Apogee AD8000 converters. This usually works for me, but I don't now if this time was just bad luck or something :)

    I've been notching and playing around with it pretty much.. take a listen and see what you think?
  • AT5047

    The New AT5047 Premier Studio Microphone Purity Transformed

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