Recording drums - delays due to mic positioning

ZV Yoda

Hi folks,

I'm slowly making progress recording acoustic drums in my home studio. I'm a novice to all of this stuff & have learned most of what I know from this very forum and the drumming Ireland forum (so thanks everybody!)

I'm running Protools 7.4 via an 003 rack with a Behringer ADA8000.

I've noticed that I'm getting slight delay on certain signals, depending on which mic is picking up the signal. It's causing a "wolly" sound on some drums ("wolly" is my technical term by the way).

E.g. I have an SM57 inside the bass drum (for the "click" sound) and a D112 about 6" in front of the resonance hole (for the "thump"). I'm happy enough with the individual sounds, but when I play them back, there is an audible delay from the D112. Since the SM57 is only about 4-5" from the beater, and the D112 is 2-3 feet from the beater, the SM57 picks up the signal first. How do I get around this problem?

I have a similar problem with the snare. I have it close mic'd with 2 SM57s top & bottom, but the NT5 overheads are picking up the snare a few milliseconds later. I have positioned the overheads so they are equidistant from the snare, so they're fine relative to each other – each just vs. the close mics on the snare.

I have tried to address this by zooming in on the waveforms in PT & manually moving the individual tracks until they are in synch. I’m not sure if this is the best approach – it doesn’t fee very technical to me?

Also, a 2nd question – how do I address phase in PT. The bottom snare mic is out of phase with the top one (since they point in opposite directions). Although I kid of understand of the theory of phase, I’m not actually sure how to change it.

Thanks in advance!

PaulBrewer

ZV Yoda wrote: »

Hi folks,

I'm slowly making progress recording acoustic drums in my home studio. I'm a novice to all of this stuff & have learned most of what I know from this very forum and the drumming Ireland forum (so thanks everybody!)

I'm running Protools 7.4 via an 003 rack with a Behringer ADA8000.

I've noticed that I'm getting slight delay on certain signals, depending on which mic is picking up the signal. It's causing a "wolly" sound on some drums ("wolly" is my technical term by the way).

E.g. I have an SM57 inside the bass drum (for the "click" sound) and a D112 about 6" in front of the resonance hole (for the "thump"). I'm happy enough with the individual sounds, but when I play them back, there is an audible delay from the D112. Since the SM57 is only about 4-5" from the beater, and the D112 is 2-3 feet from the beater, the SM57 picks up the signal first. How do I get around this problem?

I have a similar problem with the snare. I have it close mic'd with 2 SM57s top & bottom, but the NT5 overheads are picking up the snare a few milliseconds later. I have positioned the overheads so they are equidistant from the snare, so they're fine relative to each other – each just vs. the close mics on the snare.

I have tried to address this by zooming in on the waveforms in PT & manually moving the individual tracks until they are in synch. I’m not sure if this is the best approach – it doesn’t fee very technical to me?

Also, a 2nd question – how do I address phase in PT. The bottom snare mic is out of phase with the top one (since they point in opposite directions). Although I kid of understand of the theory of phase, I’m not actually sure how to change it.

Thanks in advance!

It's an area I've been exploring recently ...... I'll post a bit later on.

ZV Yoda

Cheers Paul

ogy

phase coherence is pretty important when recording drums.
The best thing to do is to get it right at the start, rather then fixing it later in the box, although there will be an element of this too.

The important thing is, you don't have to compensate for the entire distance, you just have to make sure the crests and and troughs align at the points they hit the microphones. You can get phase testing plug-ins or just zoom in on the waves as you mentioned. First of all start with your overheads. Make a short test recording, 10 seconds or whatever. Have a listen and try and hear if theres obvious phasing, and zoom in to see if the waveforms from the two mics line up. If they don't, move one mic a little, and retest. Eventually you'll get them lined up. Small movements make a difference, so it won't interfere with the approx position you want the mic to be to get the sound you want.

When the overheads are in phase with each other, add the main kick mic, position where required, then check that it is in phase with the overheads. Add the second mic and make sure its in phase with the first/overheads. then check the snare is in phase with the overheads. Then check the tom mics are in phase with the overheads (under skin mics on snare and toms should be 180 degrees out of phase as you said).

With a bit of work your mics should be phase aligned at this point. When you do your recording flip the phase on all the under skin mics. On cubase theres a button on each channel in the mixer to do this. Looks like a null sign, like a 0 with a line through it.

Ideally you should be listening for phase differences rather than just zooming in on them. Because frequencies all have different wavelengths, what you see on the screen when you zoom won't neccesarily be an accurate representation of the phase of every single wave making up a sound, just the overall waveform. So basically, there will always be a phase issue, but its up to you train your ear to position your mics so that it is minimal. But speaking as someone whos definitely not quite there yet, the zooming in is a handy starting point at least.

Moving waveforms after recording them can help, but again it will only align the phase of certain waves, and as usual your better off getting it right at the source, using meters and the ear. I doubt whether 100% phase coherency is possible, and i don't think its worth it or natural spending hours lining up waveforms and stuff. All the great pre-DAW recordings are testament to this.

I had some links to free phase coherency tester plug-ins, i'll try and dig them out. Expensive desks like SSls and stuff have them built in i think.

Obviously, it applies to all multi-mic situations, not just drums.

I think its a good idea to solo instruments of a similar frequency range in a final mix and flip the phase on one of the two to check your not getting phasing between them, e.g. kick drum and bass guitar

hope that helps!

ogy

Theres a plug-in protools to flip the phase, its not built into the channel like on cubase.

Another thing to watch out for that can cause problems when mixing in protools LE is the lack of plug-in delay compensation. if you use any 3rd party plug-ins they delay the track theyre on by a certain number of samples. You can do something to make the total number of delayed samples appear on the little window at the bottom of each channel, then you have to send all the other channels to a stereo bus to delay them by the amount of channels so that everything is kept in phase. Think i saw a new plug-in that saves this hassle somewhere but not a Protools user so didn't look into it.

i57dwun4yb1pt8

forgot to mention this to you yoda - when we met.


this is my policy - may not be perfect but it works well enough :



a/ i measure both overheads and adjust until both are exactly same distance from snare top center.

1/ I leave the phase of the kick alone ( its under head )
as the forward transient pushes the speaker out which is what you want.

2/ any mic pointing down gets reversed phased ( tom mics and overheads )
as i want to make it a positive transient - to give more snap and body- its sublte but it is noticeable
( by again pushing the speaker out )

snare i place across the drum so usually leave alone

when im finished - if it sounds ok i leave it -





but alot of times - i actually go in and move the waves around until they all meet up this way :

1/ since the track is to click then i use the snare as the master reference for timing.

2/ I move both overheads in line with the snare by zooming right in and draggin them in line with
any loud snare strike i find.
( you may have to remove a tiny section of the overhead track peaks window
so make a project copy to do this )

3/ I move all tom tracks in line with the overhead tom strikes

4/ hi hat i may or may not move depends on how much spill is in it.

4/ if there is two kicks , i move the outside one in line with the inside one.

its tricky and takes practise , but it get rid of the wooly ness and focuses the drums alot better.


i dont have room mics as the room is dead ,
so it doesnt affect any ambience -
if you use a room sound you need to experiment to see what the best policy is.


its best to experiment and see what approach works for your room / style.

PaulBrewer

The lads above have saved me a heap o typing!



I find the 'Zero' point i.e. the point where the wave crosses between positive to negative a good definite spot to line up as peaks can be ill defined.

What I've started doing is putting up a mic thats only job is a 'phase' centre - all tracks get pulled to that.

We have been putting that close to the drummer's head - we have also experimented with the Phase Centre mic out in front of the kit but I'm not sure about that.

I pan my phase reference to the left and the track I'm checking to the right and listen. We go for what sounds better even if the wave says otherwise.

We also have a Phase meter on the console.

The phase meter can be ambiguous too, though - if you have a short transient sound, like perhaps a well damped snare, the length of that (compared say to a distant ambient room mic) could put you astray insofar as the snare signal will effectively be gone whilst the room mic clatters on leaving the room mic alone feeding the phase meter.

Digi do a Phase Meter bundle called Signal Tools

http://www.digidesign.com/index.cfm?navid=115&itemid=4951

It's all a bit witchcrafty but really does seem to work.

ZV Yoda

Thanks folks - as usual, lots of good advice. I'll tweak the mic positions this week based on your suggestions. Likewise with the waveforms.

Tish, you did previously mention ensuring the o/h mics are equal distance from the snare, so I was doing that already. I hadn't even thought about all of the closed mics being out of synch.

It's all a learning experience!

teamdresch

Now this is just me, and I'm full of ****, but...
**** the waveforms.
Use your ears.

1. Get overheads right. Move those suckers until they're in phase and you're capturing the parts of the kit that you want them to hit.
2. Get kick drum mic(s) right. I use this as my phase "ground zero". Once I get the kick mic in the right spot vis a vis the overheads (as in sounding good and in phase) then it becomes the phase reference for all the rest of the spot mics. Each mic I add will be referenced back to this and the overheads and will get moved or phase flipped until it works with them.
3. Check each subsequent mic you add against the OHs and Kick. Keep moving them suckers and flipping phase until it's right.

The problem with lining up waveforms in an editor is as Ogy mentioned above - that it doesn't and cannot represent phase across the whole useful frequency range. Your ears will serve you better with a little training.

Also, it's easier to hear phase problems in mono, so keep everything panned to the centre (or all to one side) until your phase is all correct.

trackmixstudio

This is a can of worms!
when you are moving waveforms to phase align the kit, be very careful not to time align the whole kit or you will loose all the depth and space. It may initially sound fuller and clearer but it is hits arriving to your mics at different times that gives depth to the sound.
The only time I would time align is for an inside/outside kick mic or the snare in metal.
The best way (for me) to get phase correct (if its not right while tracking) is to zoom into the attack of each element of the kit and check phase with the overheads then nudge the track a couple of samples to get the best balance of phase with the overheads AND the other close mics on the kit. You could have a rack tom in phase with the overheads but out of phase with the snare!
Phase on a kit is very complicated and requires experience to get almost right.
The current trend of layering a sample with the shells takes phase out of the equation to a large extent and if you are trying to match the drum sound of a modern production by getting the kit in phase you will not get close as there are almost definitely samples mixed with the live shells.
One trick I use all the time is to move the room mics a couple of cycles later. Once you keep the phase correct by lining up a zero crossing with the overheads you get the sound of a bigger room by giving the impression the room mics are further from the kit. Works a treat!

i57dwun4yb1pt8

thats what i said - if you use room mics or are in a good room then you need to be very careful in time aligning .

but if you are in dead room like myself ( and yoda - id say ) you are better off gating the toms and time aligning the overheads to the snare and the toms to the overheads and snare - then using artificial room sound / reverb to liven it up later

must of us project studio guys have crap rooms , so are better off recording dead and focussed - then using illusion later.

i dont move my kit about and the room is tiny and dead- so i leave the mics always up in the same ( best ) spots i can find for that mics / drums tone .

sometimes this is not always the best spot for combined phase - so need to time align.

just my observations - im no master at this .

ZV Yoda

Thanks folks... great discusson. I'm very much learning as I go here!

As Tish mentioned, I'm in the same boat as he is. I have a dead room (about 12ft x 12ft x 8ft high... not only used for tracking, but also mixing - since I'm a one man band when it comes to playing/recording).

What I'm taking from all of the above is that as a minimum, I should keep:
- kick mics in phase with each other (by looking at waveform & nudging in Protools?)
- snare mics in phase with each other (by looking at waveform & nudging in Protools?)
- then keep kick, snare & o/h in phase with each other as much as possible (listen for phase by ear & nudge in Protools as appropriate?)

Another dumb question on phase (which will really highlight how little I know about this stuff).

Most of the mics (overheads, snare top & toms) point down towards the batter heads on the drums. So when I hit a drum, the waveform initially travels away from the mics. If I look at this waveform, the overheads, snare top & tom mics show a trough - however, there are visible (although granted, very slight) time differences between the start of the trough on each mic... so a snare hit is a very big trough on the snare track, a smaller one on the tom track, & smaller again on the kick track. The time delay is a factor of how far each mic is from the sound source. So in theory, the snare mic picks up the snare first, followed by the tom mics etc... finally to the o/hs which are furthest away). So I get that.

However, some of the mics (kick mics & snare bottom) are situated behind the batter heads. As such, when I hit/kick a drum, the waveform initially moves towards the mic. When I look at the waveform, there are also time delays as above, but in addition, a hit that shows as a peak on the kick/snare bottom mic is actually a trough on all of the other mics.

So, I see 2 issues:
1 Peak = peak but with time delay... can be fixed by nudging as outlined in all the posts above.. or gating some fo the closed mics to minimise spill/phase
2 Peak = trough but with time delay

Are both of these phenomenon (time delay vs. peak = trough) called phase or are they something different? How do I deal with peak = trough (I assume these are cancelling each other out somehow)

Reading back over this post, it's really badly written, but am I making sense?

tweeky

Stop moving waveforms around!!!!!!!

Make sure all mic leads are wired correctly!!!! ie. the same pin hot on all
leads.

USE YOUR EARS!!!!!!!!!!


If you don't know what "out of phase" sounds like flip your phase button on one channel of a mono source brought up on two faders.

ogy

yeh i think i know what you mean.

if each close mic is in phase with the overheads than your okay i think. the level of the target drum for each close mic should be far louder than the others, by gating the close mics the spill from other drums should be minimal and they won't cancel the overheads/close mic to any great degree.

and yes thats phase too:)

PaulBrewer

tweeky wrote: »

Stop moving waveforms around!!!!!!!

Nah! It's the future!! A button can only shift 180 , a nudged waveform can skip across by what you need.
It's very fashionable on the Continent I believe ...

Something for the geeks to be at too .....:cool:

studiorat

From the discussions on this I've read it seems people are about 50/50 on this technique. So while people are quite happy to use phase eq recording guitars etc, we seem to be going to getting rid of this when it comes to drums. The difference in phase between the different mic's on a kit are as important to the sound of the drums as the room they are in.

My take on this is people are using too many microphones on the kit in the first place. I might cover the kit in microphones but I'll only use as many as I need.

I've a few issues with technique though, unless you are using a waterfall display how the hell are you going to know if the waveforms you have aligned are in phase? What may be in phase at 1kHz may not be in phase at 10kHz or 100kHz. Anyone who actually examines the way a drum skin vibrates and how the sound radiates will tell you that it doesn't move as one simple in and out motion but has harmonics all over the surface of the skin.

And what about the hi hat for instance? Do you align the snare spill to the snare mic? Probably 6ms delay, so where does the hat end up phase wise? Nevermind that the close miked snare is now in the same place time wise as the sound of the snare on the overhead.


Apart from this. this is a technique that can only be performed after recording so what do you aim for when actually tracking? It's starting to sound like a fix it in the mix gig...

If you look at the likes of Butch Vig for instance he'll spend ages getting the phase right before recording, moving microphones, listening, repeating...

Record it properly in the first place lads, jaysus, John Bohnam must be rolling in his grave...

ZV Yoda

As somebody said above, it sounds like this is a can of worms! My preference is def to fix it at source... the less I have to play around with the mix after tracking, the better for me.

I just want to get a good sound from my drums. I don't know the best way to do this, so I'm hoping the collective wisdom here will help me.

It was much easier when we used to jam in Temple Bar back in the 80s... we'd just bring in one the lads Topaz twin tape decks & press record. There was no phase back in those days!

i57dwun4yb1pt8

err,

i think you are missing the point - we are talking about in a dead tiny room - the room is not in the equation , and in most cases needs to be removed from the equation

phase aligning in a good room is better fixed at source with mics

thats agreed - I totally agree and prefer this sound / method.

bonham recorded in great rooms with minimal mics - all pahsed properly
this is just not possible in a dead tiny room .

so its better to get the kit sounding as dry and locked in as possbile , then re create a room around it.

studiorat

I still don't know, for a bass drum fundamental say 60Hz you have to move about 22 samples for each degree of phase at 44.1K . More than 10 degrees and you are going to hear phasing...

PaulBrewer

DaDumTish wrote: »

err,



phase aligning in a good room is better fixed at source with mics

Everyone seems to be in agreement with that.... but how do YOU do it?

I'm not looking for a 'Use your ears' smartarse reply, that's what Gearslutz is for....

We're much more civilised...;)

PaulBrewer

Surely Brettzy has opinions on this?

PaulBrewer

Niall - Dahlia wrote: »

I've always just gone with what sounds best, if it's good enough for the past 50 years of music it's good enough for me...but this sounds interesting, gonna try it some time. Cheers Paul!

It's only a variation on an old idea, nothing new really...

i57dwun4yb1pt8

at the moment all i do is put the master in mono and find the best spot for each mic roughly ( all in phones ) until they pick up everything except the hi hat well

( as i have a hat mic - again to isolate each drum part as much as possible )

then measure and tweak until both mics are same distance from snare center .

I flip the phase of the overheads and leave the other mics phases alone
( dont use an under snare as the c42 pic up enough wire )

I only time align if the sound is still a bit hazy - this happend more with the oktava than the c42 - so i dont do it as much as i used to .

also the c42 appears to pick up feck all kick drum so thats easier to use .


id love to see how its done in a good room though - checking phase .

its hard to do it on your own when you have to drum and record at the same time.

if6was9

What I've been doing for tracking drums is taking my time to get 2 overheads in phase with each other then working on the snare mic so that it sounds good with the overheads, same with the kick mics and add the mics so that they sound good and full. I only really zoom in when I get to the mix stage to check how they came out looking.
I experiment with time aligning when mixing but i time align eveything to the overheads which I make sure are in phase at tracking. The only drum I've really had a problem with sounding out of phase is the kick and then I fix that with time aligning.

the idea of moving the room mic off by a few more samples is a good one i've not heard before- next time I track drums i'll give it a go!

i57dwun4yb1pt8

but if you time align to the overheads - your snare and kick will be out with the click track

as the sound from the drummer hits the oh later than the snare

the drummer is going to be closer on the snare to the click than the overheads will be .

PaulBrewer

DaDumTish wrote: »

but if you time align to the overheads - your snare and kick will be out with the click track

as the sound from the drummer hits the oh later than the snare

the drummer is going to be closer on the snare to the click than the overheads will be .

That was how I came up with the Drummer's Head 'Phase' Centre mic.... not even the drummer himself hears the snare when he hits it ......

studiorat

Right, I had a go at this and for me it dried out the kit too much. It hid all the extra stuff in the kit like the extra colour from the floor tom ringing in sympathy with the kik, the decay of the snare on the overheads etc. I also noticed that although I moved the spill from the kik to match the actual kik drum mic on the tom mic the kik spill was out of phase with the kik while the tom was in phase with the overheads. I couldnt get a position where the timing and phase were right on all the mics (spill was out of phase while the actual main signal was in phase) I used a PZM on the floor equidistant from kik and snare as my guide.

tweeky

DaDumTish wrote: »

but if you time align to the overheads - your snare and kick will be out with the click track

That's if they were ever in!

PaulBrewer

studiorat wrote: »

Right, I had a go at this and for me it dried out the kit too much. It hid all the extra stuff in the kit like the extra colour from the floor tom ringing in sympathy with the kik, the decay of the snare on the overheads etc. I also noticed that although I moved the spill from the kik to match the actual kik drum mic on the tom mic the kik spill was out of phase with the kik while the tom was in phase with the overheads. I couldnt get a position where the timing and phase were right on all the mics (spill was out of phase while the actual main signal was in phase) I used a PZM on the floor equidistant from kik and snare as my guide.

StudioRate! Ah, you're not doing it right then....

PaulBrewer

DaDumTish wrote: »

but if you time align to the overheads - your snare and kick will be out with the click track

I remember when click tracks started to come into fashion shortly after the Boer War ....

I did a session with a drummer and the conversation got to drum machines and click tracks.
Yer man says ' Yea, drum machines are great and all that, but there's no 'give' in them,is there? '

'No' I said 'there isn't' .............. and erased his tracks.

i57dwun4yb1pt8

lol- "no give" he he


seriously though - you nearly need to be superhuman to cut a good feeling drum track to a click with every hit perfect sounding in level etc - very few people can do it well ( and no guitarists can ;-) )

im still working on it ;-)

actually im gonna start a thread on it .

PaulBrewer

DaDumTish wrote: »

lol- "no give" he he


seriously though - you nearly need to be superhuman to cut a good feeling drum track to a click with every hit perfect sounding in level etc - very few people can do it well ( and no guitarists can ;-) )

im still working on it ;-)

actually im gonna start a thread on it .

I know Lads!

PaulBrewer

http://recordproduction.com/ken-scott-drum-recording.html

This might be of interest - perhaps Tweeky might comment on the mics, some of which I'm not familiar with?

It looks like this is going to be a series, so whilst this video is limited info wise hopefully the ones to follow won't be.

PaulBrewer

http://www.recordproduction.com/recording-engineer-tips.htm

Another few ... if there's nothing better on telly ...

i57dwun4yb1pt8

thats greeat ! thx

studiorat

Funny I was shown that mic facing the floor thing by a New Zealand dude too. He used it to pick up really low bass frequencies from Double bass in a orchestral score and use it to feed the subs in a surround mix. "TLM-170 mic'c taped to the floor facing down.

Bass frequencies "stick" to or travel close to surfaces like walls and floors. Not sure what the effect is called. I reckon theres a proximity thing going on there too.

Re-amping drums is a real fave of mine, always very big on the combo in the stairwell vibe.

like the trick with the auratone on the snare drum too...

PaulBrewer

Another couple of small vids with drummers at

http://recordproduction.com/ken-scott-drum-recording.html

studiorat

PaulBrewer wrote: »

Another couple of small vids with drummers at

http://recordproduction.com/ken-scott-drum-recording.html

Very good!
I learned a few things there.
Can't wait to get back at a drum kit.

Actually, interesting that he was using so many condensor mics on the kit. Particularly snare, I'm wondering how relevant this is these days since that set up would have been going to tape which would have softened the transients of the hits.

I remember some discussion about old KM-84's being too bright now and that they were good for analog but too bright for digital recordings. The sony c-38 is a very bright mic too, I always use try use one for a room mic.