Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

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eggCota
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Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by eggCota » Tue Nov 03, 2020 5:20 am

Here's something that I've been pondering for a long time. In multi-mic sessions, tracking engineers spend a long time perfecting mic choice and mic placement not only for the best tone, for isolation and capturing the right kind of bleed, but also for maximum phase coherence. We want the bleed we do get to be phase coherent with other mics in a way where the sum of the mics tone is greater than its parts.

This is another long winded, but hopefully entertaining and educational post fostering solid talk.

I was fortunate enough to assist for a 13+ time Grammy winning engineer, and he gave me a gem of advice about not focusing entirely on cutting and gating and removing bleed, but to let bleed work for you. If you're setting up a band in a big live room, you want to position your instruments and players not only for isolation, but to also consider line of sight and good bleed as well. "Good bleed?" I thought. He said that he knows he wants the piano track to have a little distant room mic'ing, so he positions a horn player playing away from the piano, but chose a condenser, U87 I think, and faced the horn player (trombone) so that the piano was also being picked up in the mic from about 15ft away. His thinking was that it's always possible to gate out ugly bleed, but why not try to get the room to work with you. He would also do things like setup groups of low fundamental instruments in the arrangement closer to high range instruments, like flutes next to bassoons (for example). The idea there being that you will filter out the lows from the flutes anyway, so you will naturally cut out a lot of bleed coming from the bassoon just by the natural moves you were going to make anyway. Position players thinking about arrangement. These ideas seemed so simple yet blew my mind.

Granted, this is the kind of session where you aren't editing tiny edits, mostly huge chunks like this chorus from that take and this verse from that one. not modern editing where you're grid mapping live takes.

Anyway, Most of us don't work on large big band type of music, the rock types, we close mic drums and guitars, run bass DI or amped etc. But I started thinking,

When I put 2 or 3 mics on a kick drum (including a subkick) , rather than sit and play with the distances until I've reached total phase coherence (sometimes I'll record a quick second and see where the wave forms are and move the mics that way) but still, I will nudge the close mics to get all the major transients phase friendly.


My question is, is there a difference between physically moving the mics in the room, and nudging the tracks in the daw? Will it sound the same?

I knew another engineer who would take drum room mics, and he would nudge those tracks forward until the larger kick waveform transient was phase aligned with the overheads and he would nudge the overheads less but still to get them right above the kick. He claimed it was the way to get the most punch from the drums, and my science brain figured there's something to it, but it's not natural. There's supposed to be a few milliseconds of delay between the room and the close mics. Almost like a slap back. If you nudge the room mics forward, you are still getting a room distant sound from the mics, but it's unnatural right? It sounded punchy tho. it sounded like the best plugin reverb on the kit with no predelay set. I was very confused... and still am.

In the case of the kick mics, or overheads, maybe there are reflections in the room that one position gets that nudging doesn't get.

So what's the difference? is it the same when considering the close mics on the single source? has anyone done the room mic nudge? is there any value to it? if your mic is in a room node place in the room where bass is reduced, don't you record that node? so nudging it won't fix that you were in a poor node spot right?

Anyway, yes I'm long winded and sometimes I'm not sure what I'm asking, but any engineer who is climbing the challenging world of tracking and mixing, any engineer who looses sleep wondering if it's better to use the same mic for top and bottom of the snare because flipping the phase of the bottom mic will cancel more consistently if it's the same mic / frequency response... for all those people, let's talk this out.

For everyone who says just setup a mic and get to work making music, or just try what sounds best and move on... that's cool too, theory discussion is not for everyone. For everyone else... what are your thoughts on the subject.

Thank you.

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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by A.David.MacKinnon » Tue Nov 03, 2020 6:20 am

eggCota wrote:
Tue Nov 03, 2020 5:20 am
My question is, is there a difference between physically moving the mics in the room, and nudging the tracks in the daw? Will it sound the same?

Thank you.
I'm sure some people can do it but I've never had an experience where nudging elements of the drum kit results in anything other than a giant fucking mess. Move the mics til it's right. It takes more time and more work but if you are an engineer it's your job. Do it right so you don't have to fix it later.
Tony laid out a perfect method in another thread -
drumsound wrote:
Sun Nov 01, 2020 11:34 am
You're method of looking at the waveform is a bit misguided. What we're trying to do is make a cohesive sound where big parts of the frequency spectrum aren't canceling and making the sound thin or hollow. Most of what has already been said in the thread is true. The more mics, the more possibilities of issues. The other really important thing is that when using multiple mics, and especially with the various distances for the different, close together sounds with different pitches, there WILL be phase anomalies. That isn't a bad thing, because those are the things that help us perceive distance and space.

We must also remember that phase coherency is is most critical and perceptible in MONO. To that end, its best to check for phase coherency in MONO.
Someone mentioned Fletcher, and one thing I picked up from him many years ago was to check of mono compatibility using ONE SPEAKER. I believe the reason being that, even using the mono button on a console, hearing mono from two speakers would interact differently with the room, and also, if you weren't in the perfect triangular sweet spot, the signal from each speaker would hit your ears at different times. AND...phase issues are 100% time related.

So, when you are checking for mono compatibility and phase coherency it is simpler and more accurate to listen to just one speaker. When I had Mackie monitors I'd hit the mono button on the console and just power one off. Now that I have moved on to passive Truth Audio monitors, I hard pan the mics to one side with doing my drum record ritual. (oddly enough, when I'm working with a drummer in the room playing I use the left speaker, because its in front of the drum input channels, but if I'm recording myself, I use the right, because the computer in on the right in my control room)

So, here is how I go about it. With all mics panned to one side, I start with both overheads. I reverse the polarity* on one mic. Hopefully the sound gets really thin and shitty. That tells me they are right. This is of course generally the case with a coincident pair, but it will tell you if there's possible a cable issue in the sound gets bigger with a coincident pair. Spaced pairs are more prone to coherency issues, even if you've carefully measured, it's just their nature. Next added will be the bass drum. [if using 2 or more bass drum mics I will mute the overheads and compare the mics to one another before comparing to the overheads] I'll reverse the polarity of the bass drum mic in relation to the overheads. Often the low end gets bigger, clearer and more defined. If that's the case I leave it reversed, if it get thinner, I go back to the original polarity. I add the snare next then each tom individually, using the same process. Each mic that I add to the mix remains ON as the next is added. If there are stunt mics (knee, cheapo, super high overhead etc..) those are added after the close mics. There are ALWAYS stunt mic(s).

Now comes the room mics. Usually its a stereo pair, and often spaced. I'll actually check those alone first. I want to make sure their relationship to one another is good before comparing to the rest of the drumset. So, just like the overheads, I listen to the pair and reverse the polarity on one mic to see if the low end gets bigger or smaller. There are times when that is the case, so I end up with one room mic's polarity reversed from the other. Then I open the overheads back up and listen to rooms in relation to the overs. I switch BOTH room mics in relation to the overs, so if the left room is reversed and the right isn't I change to the opposite to see how it works with the overheads. Again if the bass gets bigger, that's how they stay, if it gets thinner, it goes back to where it was.

Then I add all the other mics back in and spend a little time on balance, so that the general drum mix sounds right with the playback faders at 0, as a good place to start tracking and mixing.

* Polarity refers to the positive and negative of a balanced signal. It is a binary situation. Reversing the polarity switches positive and negative. Phase, however is more intense than + or - and is time based. There are times when reversing the polarity isn't enough of a fix and that's when its time to move microphones.

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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by digitaldrummer » Tue Nov 03, 2020 7:24 am

I concur that nudging drum tracks to align perfectly is a mess and unnecessary. They are not all aligned for your ears when you are standing in the room with the kit. they arrive at different (microscopic) times due to distance and reflections (unless you play a single drum, but even then you get reflections). just check phase and move a mic if you need to.
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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by eggCota » Tue Nov 03, 2020 8:07 am

Thanks for the great replies. The methodical approach is exactly what I wish I could do in sessions if I had the time. When I was working in the more expensive studios as an employee engineer, everything was rush rush rush. 3hrs to get a track done, please!

So that's why I asked because I wish I could take my time like that.

But now I know what to do when I'm in control of the pacing.
I could spend 3 days moving mics tho lol.
I have a small setup at home with a kit, so you know I'm about to perfect it.

Thanks again.

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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by MoreSpaceEcho » Tue Nov 03, 2020 8:31 am

Just want to agree, nudging tracks on a drumkit doesn't work IME. It DOES sound punchy, but it also sounds really unnatural.

The only time I've found nudging tracks to work is with close mics on a guitar amp. Or bass di and an amp.

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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by A.David.MacKinnon » Tue Nov 03, 2020 8:53 am

The more you do it the faster and easier it will get (like everything in life). There's a huge advantage of you are in a good studio with a control room and you are not also the drummer. Put up all your mics then start auditioning each against the over head. Note what works and what doesn't. Move the mics that don't work. Audition again.

If you are able to be in the studio before the band arrives and it's a house kit you can at least get the mics roughed in before the session starts. If you cant, then keep it simple. More mics, more problems.

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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by drumsound » Tue Nov 03, 2020 9:22 am

My quoted method doesn't take all that long. Especially if you aren't trying to reinvent the wheel of mic positioning. That coupled with the fact that it yields better tracks makes it worth the time. If you don't do it in tracking, someone will need to do it in mixing...

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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by floid » Tue Nov 03, 2020 11:31 am

Alignment of one drum's peak in every mic means most every other part of the kit is now not time aligned.
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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by Recycled_Brains » Tue Nov 03, 2020 12:50 pm

drumsound wrote:
Tue Nov 03, 2020 9:22 am
My quoted method doesn't take all that long. Especially if you aren't trying to reinvent the wheel of mic positioning. That coupled with the fact that it yields better tracks makes it worth the time. If you don't do it in tracking, someone will need to do it in mixing...
I've always done it this way. It's great. It takes less time than trying to do it in stereo, in my experience, because you hear the weird shit right away in mono. It either plays nicely together or it sounds terrible. I definitely will double check to make sure my decisions translate once I start panning the drums again, but they almost always do.
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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by chrisinthewest » Thu Nov 05, 2020 11:55 am

I never time align because I absolutely love how drums always sounded.

However if you do want that not so enjoyable punchy sound, I think of it like ‘overhead mic up close’. Get your overheads in phase. Then you line up the close mics ITB, and gate them/edit them so they have zero bleed and simply support the overheads. I would low pass too, just so that you are getting that solid low punch and not also a gated high end phase canceling thing. That way you can set the gate to release a little longer and get a real long low waveform though. After this, totally optional and time wasting: you can try another mult of the close mics with super tight gates, high pass and boost the high mids and highs, you’ll likely have to reverse polarity. Add compression/ limiting/ distortion or whatever, and with fader all the way down, gently bring up the fader until some “stick” is barely audible and punching through. It works but its annoying to me when I hear it because there’s no human art to it, and to me it detracts from the soul of the song and performance, the space it was created in, and stunts the imagination. It’s great for impact, if the goal is impressing people for 20-30 seconds.

Also, I was watching those Eric Valentine videos and he will often use a single overhead and duplicate the wav to separate tracks to be ‘different mics’ by sliding the waves in the time domain and process to sound like a different mic and placement. I’ve tried it, doesn’t work for me.

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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by Nick Sevilla » Thu Nov 05, 2020 1:36 pm

My question is, is there a difference between physically moving the mics in the room, and nudging the tracks in the daw? Will it sound the same?
The best method will ALWAYS be getting the sound BEFORE pressing the record button.

If you ever work with tape, well, you'll know why this is crucial, why we can take as much as a whole day (sometimes two) to get the perfect drum sound.

I took two days to get this drum sound to 2" tape:

https://www.amazon.com/Time-Lines-Chris ... B00000I04F

We did a number of test recordings, until it was as good as we could get it.

The album was recorded live, with a minimal set of fixes, if that. We did two "master takes" of each song, mixed them all, and then the group decided which performance was "the one." It came down to artistic preference, and not anything technical.

Aligning drums on a DAW is not the same thing at all.

Why?

Because you ALREADY recorded the phase differences inside each mic, and phase it both a TIME and SPACE thing. The DAW can only align the time (forward / back in time) but it cannot properly adjust degrees of phase, as this is truly a 3 dimensional measurement.

Imagine the sound of the snare, BURSTING from the origin point and filling the ENTIRE room with sound waves.

When all the microphones on the drumkit capture ALL the drum components AT ONCE, you cannot then move it after the fact.

I have had to nudge the overheads, or other components of a badly recorded drumkit before. I can only move them a tiny bit, but can never get the true sound as it was in that room, live. For that, I would have to re record it.

DAW = 2 dimensions (forward / backward in time).

Real World = 4 dimensions (X Y Z Axes plus time).
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Re: Two parter: Getting mic bleed to work for you, and the phase differences between nudging tracks and moving mics.

Post by vernier » Sun Nov 08, 2020 4:51 pm

To a certain extent nudging can do a similar thing, but there's so many variables with mics and placement. That said, I think lots of records from 1970s onward are full of multi-mic phase cancelations, which became part of the sound ..The sound of a wall of skinny sounding tracks.

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