kick drum out of phase in one of oh's

[christiannokes]

So i have been trying to practice checking for phase issues between drum mics. today i checked the kick drum with the oh's and the left was ok but the right was phasing lower frequencies out.

Obviously I should make sure that things are cool before I record but because I am a newbie I act like a newbie.

What are some ways that you deal with this?

[christiannokes]

the kick is in phase with the left and 180 degrees out with right.

[christiannokes]

and the kick drum sounds in phase when it reaches the two oh's.

[Randy]

So i have been trying to practice checking for phase issues between drum mics. today i checked the kick drum with the oh's and the left was ok but the right was phasing lower frequencies out.

Obviously I should make sure that things are cool before I record but because I am a newbie I act like a newbie.

What are some ways that you deal with this?

What type of OH configuration do you have? Is it a spaced pair? If so, there are a lot of things to watch out for, especially distances of the mics to the drums and to each other. For instance, if you have the OHs placed so they are the same distance away from the snare, you shouldn't have problems with the snare, but you may have a problem with the kick.

The trick is finding a place where the two OH mics are equal in distance from both the snare and the kick. All the other drums and cymbals will be out of phase, obviously, because that's what causes the stereo effect.

When you start adding in the close mics, things can get dodgey, and all I can say is listen to playback if you can make the musicians keep quiet long enough to do so. If you have a dual trace oscilloscope, you can connect a stereo signal off the board and put the scope in x-y mode and see if there are any signals that create a slope from top left to lower right. That would indicate out of phase. (in-phase is a slope lower left to upper right) I do that while I am dialing in the levels while the drummer is warming up. I just compare mics to each other by panning them left and right in solo on the board and seeing how they compare to each other. The overheads in this case should look like a fuzzy oval that tilts with the top going to the right.

After saying all that, if I have phase problems with the overheads in a room, I quickly change the OH mics to be a coincident pair at least three times the distance from the drums that any of the drums are from each other. That tends to make for a less wide stereo field, but it sounds a lot more real if that's what you are going for.


Good luck!

[christiannokes]

Randy- yeah they are spaced pair, but in a funky way. The oh r mic was actually mostly to capture the ride (down lower then the oh l mic).

[kakumei47]

i am assuming if you just invert phase on the ride overhead the two overheads have other phase problems, right?
since most of the problems will be in the low end, try listening to just the ride track and hi passing (cut the lows) as high as you can while still getting the body of the ride sound. you should be able to get reasonably high into the low mids while not f-ing with the ride sound in the mix too much. Then it won't mess with the low of the kick so much.

[???????]

you could try inverting just the lower bit of the offending OH track using the free "phase tone" plugin from tri tone digital.

[???????]

ha! I just saw your other thread and realized you beat me to it.

Be aware that using the sliders to adjust phase, the effect will be subtle.

I recommend reading the manual that downloads with teh plug and putting the two tracks in solo to listen to what you are doing. Where the "Q" is set makes a lot of difference.

You can also just click on "90 degrees" down at the bottom to hear what that sounds like.

Make sure you have the "blend" fader all the way up. Realize that with a higher "Q" you will have a wider band of frequencies affected, but there will be less phase shift (like 90 or so degrees)

[twangdillio]

Does anyone have suggestions on how to get an oscilloscope in the signal path, i.e. at what point should it be connected and how best to connect it? The one I have has BNC-style inputs.

[drumsound]

Listen to the 2 overheads in mono and make sure they are phase coherent. Then listen to the pair in connection to the BD. I check my OHs and if one needs to have the polarity flipped, when I check to the BD I flip both the OH mics, so they stay the same in relation to themselves, but change in relation to the BD. Also there can be a preferred difference between changing the polarity of the BD and changing the polarity of the OHs.

Also If the right OH is more for the ride, maybe you should try a coincident pair AND a ride mic (if it needed).

[@?,*???&?]

Coicident x/y

Near-coincident x/y

Blumlein

ORTF

Spaced pair

These are all terms you should know before you begin destroying someone elses music with your recording.

Now, it is possible you could destroy music with any of the above techniques, but I am guessing with some research, you could suss out the right way to go with this.

My own advice for novice recording engineers is ALWAYS use coincident x/y overhead mic'ing. It alleviates your described headache 100% of the time.

[Nick Sevilla]

Coicident x/y

Near-coincident x/y

Blumlein

ORTF

Spaced pair

These are all terms you should know before you begin destroying someone elses music with your recording.

Now, it is possible you could destroy music with any of the above techniques, but I am guessing with some research, you could suss out the right way to go with this.

My own advice for novice recording engineers is ALWAYS use coincident x/y overhead mic'ing. It alleviates your described headache 100% of the time.

+1

[Professor]

Coicident x/y

Near-coincident x/y

Blumlein

ORTF

Spaced pair

These are all terms you should know before you begin destroying someone elses music with your recording.

Now, it is possible you could destroy music with any of the above techniques, but I am guessing with some research, you could suss out the right way to go with this.

My own advice for novice recording engineers is ALWAYS use coincident x/y overhead mic'ing. It alleviates your described headache 100% of the time.

Make that +2 on this guilt trip!
And especially on, "These are all terms you should know before you begin destroying someone elses music with your recording."
I know lots of folks like to believe in the notion that all we really do is stick mics in front of things according to some formula of 'this mic for this source' and 'that mic for that source', but sometimes it helps to know what is going on.

Now as far as what you're running into, you actually have a couple of problems that you're up against. It's important to understand that phase relationships are a function of time - specifically the speed of sound and the distance from the source to all of the mics that might be hearing it.
Consider the 'source' here to be the point of impact of the BD beater on the drum head, and the distances to be the distance from that point to the BD mic, the snare-side OH, and the ride-side OH. The out-of-phase arrival that you are seeing is because at the particular frequency of the bass drum, the distance difference is about 1/2 of a wavelength.
But simply flipping the phases on that particular channel aren't going to cure the problem because that could potentially send other sources out of phase that were previously in-phase. How is the snare drum in the track?
What you can do is apply a delay to the bass drum track and the ride-side OH, and the snare drum mic, and move all those mics 'through time' to align with the furthest mic from all the sources which is presumably the snare-side OH. Now when you do that, you'll find that some of the tracks are actually naturally backwards or polarity-reversed (the only time that one s really an accurate phrase). In particular, the bass drum mic is probably on the other side of the drum head from the pedal, so the initial impact "pushes" air towards the microphone while the OH mics are on the beater side of the head, and the air pulled away at that impact. A lot of folks invert the BD mic for the sake of ease, but personally I invert everything else so the initial impact is still a push of air as nature intended - a subtle distinction, but it's not that hard to do in a DAW, so why not?

Anyway, it's important to be aware that the problem you're running into is a function of time & distance. The whole 180? out-of-phase, or 90? or whatever is completely meaningless because that is a function of one particular frequency not of the full-spectrum audio signal. It's used in high-voltage electrical power because they deal only with a 60-Hz A/C voltage, and actually do send three phases of the power down three lines each set 120? (at 60Hz) off from one another, or about 6.2ms from wave-front to wave-front. But they aren't multiple copies of the same spread-spectrum wave as in audio, they are constant 60Hz sine waves (ideally) and happen to be aligned with those delays on purpose.
For our purposes, balanced audio signals output two 'phases' of the signal, one that is polarity-correct to nature (positive air movement equals positive voltage) and another that is directly inverted, not 180? unless you mean 180? at 0-Hz (which is meaningless), but polarity-incorrect to nature. The phase issues we have in recording and mixing are not usually related to those two phases used in the balanced signal, but are a function of time, and the delay I mentioned previously. So for us, it's solved by planning, awareness, and good use of short delays to get all the wavefronts to line up.
My method these days is to go into the live room after the end of tracking each song or different drum setup, and record a take of me playing soft, medium, & loud hits on each drum and cymbal in the kit. Then I can take a clear measure of the delay from each close mic to the OHs, and delay and reverse phases as needed so everything lines up. The side benefit is that I also then have a bunch of samples of the drums & cymbals if I need to replace any off-target hits, or cover up edits with crashes, or whatever.


If none of that works for sorting out your particular problem on this recording, then try this:
Use the snare-side OH as a mono OH, maybe panned slightly off-center, but not much.
Put a gentle low roll-off on the ride-side OH, maybe like 100-120Hz at 6dB/octave.
Keep the ride-side OH about 3dB or more lower in the mix than the other.
Pan the ride OH out a bit, maybe not hard but a good halfway or so.

All that together will drop the signal level of the out-of-phase BD in that mic relative to the BD mic & other OH. You'll still cancel a little bit, but not completely. +1 plus -1 may indeed equal 0, but +1 plus -0.3 equals +0.7, right? You can think of the same sort of thing happening with the lower level, especially at that frequency, on the ride-side OH mic.


Happy mixing.

-Jeremy

[dynomike]

People are +2ing the "before you destroy someone else's music..." ? Wow.

Apart from the nasty tone I'd agree that you should look into XY. I've never had much luck with it though. Its handy in that you can just move around the pair until they represent the balance you're looking for. I find XY often gives me more of the drums than I actually want in the overheads, and the stereo image of the cymbals can be kind of wacky. Try for yourself..

For this time I'd just roll off some low end from the overheads and try not to worry about it.

-Mike

[drumsound]

Coicident x/y

Near-coincident x/y

Blumlein

ORTF

Spaced pair

These are all terms you should know before you begin destroying someone elses music with your recording.

Now, it is possible you could destroy music with any of the above techniques, but I am guessing with some research, you could suss out the right way to go with this.

My own advice for novice recording engineers is ALWAYS use coincident x/y overhead mic'ing. It alleviates your described headache 100% of the time.

Are you trying to be helpful or trying to be a dick? It's so hard to tell.