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Hey Danny -
Speaking of videos.......
You still working on that one about HeadCase?

:)

Nah, it's done. :) Not sure when it will be released, but ABG has it. It's a bit long as well...near 2 gigs and 3 parts but really cool and in depth. ABG said they liked it and would let it roll. It's raw and un-edited, not very professional and well...me just being me in my basement showing results without trying to bombard anyone with false intelligence nor am I trying to be something that I'm not. It's just really human but maybe a bit too human for a company looking for sales. We'll see. :)
 
-Danny

Beepster
There is however a lot of great info on EQ settings, performing certain procedures in Sonar I was not aware of and probably the most beneficial to me is the fact he is using the method of mixing the drums to the overheads and room mics and using the very minimal close mics (just snare and kick) as helper tracks. I've always approached it from the opposite direction (close mics first then overheads for the cymbals). This will be very useful if I end up in a situation where I have minimal mics/channels to work with and I know this is more like how things were done in the past.

 
The thing to keep in mind with drums is, it depends on your situation. Room mics and all the stuff that goes with them are super important. However, in today's sounds...it's not a common practice for most things. When was the last time you heard a Bonham type drum sound? Or, how about a "strictly room mic" kit or a mid side mic'd kit on a professional mix released to the masses?
 
All that stuff is good to know...it truly is. But you being a rocker/metal head, you're not going to encounter it much because the sounds you need are in your face and direct.close mic'd sounding. See that's the key, all these people brag about these roomy things and mid side mic tecnhiques...don't they realize it sounds like @ss when they compare it to something professionally done? I mean seriously....how can they kid themselves. Yeah, the technique is cool and I like it and have used it....but it sounds like a cheap drum kit in a room because there are no distinct instruments taking over when you compare it to a properly mic'd close kit.
 
Don't get me wrong, I'd prefer less close mic'ing for a live jazz band, live jazz record, live blues band.....but for a rock band, metal band, power pop band, gospal group with power instruments, I'd not waste 5 seconds on a room sound being much of a factor other than adding a slight ambience and stereo spread to the entire kit as an entity very lightly.
 
I work the opposite Beeps. I'll handle the room stuff after I have the drums themselves sounding the way I want. That to me, is the impact. The room, is the ambience and though it needs to be cared for, the dominant instruments in a room are cymbals with the drums that bleed through adding only slightly into the scheme of things. Of course if you kill the room you lose something on the drums, but more room and less drums isn't the answer for impact in MY world. We have such incredible impulses these days and powerful computers, there's just about nothing we can't pull off in a non-destructive world with close mic techniques. But, that's just my thoughts brother. There is no right or wrong....as long as something works for a person, they are right where they need to be.
 
-Danny

Beeps the two mics on the snare drum top and bottom is also a good example. Same thing applies here too. Just bring up the top mic and get that snare sound good then bring in the bottom mic. If you feel the sound is starting to go a bit astray then try inverting the polarity of say the bottom mic. Something will happen to the sound. Could get worse or better or may not change at all. The 3 to 1 rule is still being satisfied to a certain extent with the two snare mics. (I am not a big fan of the bottom snare mic, I know some guys love it. The snare does not sound that great underneath. It is more of a horrible crack type sound. Sonor snare drums are just SOOOOOO good that the sound is already there on the top head. No other mic required, period!)

The 3 to 1 rule states that if you have two mics on one source the second mic should be at least three times the distance from the first mic for phase issues to not occur. 

So if you had the top snare mic 1" from the top head and the bottom snare mic 1" from the bottom head but the snare is say 6" deep then the bottom mic is in effect 8" away from the top mic so phasing wont be such an issue. Still OK to try reversing the polarity of one of them though because you will get a sound change as a result and it might be nice. (or not)

That plugin that Danny is using is fantastic and the reason is that the phase angle can be adjusted or it is variable. The problem with inverting the polarity is that you are introducing a 180 phase shift but what if the phase problem is some other phase angle than that eg 90 deg out of phase. What is so good about that plug is that you can try altering the phase angle while you are listening to the two sources and you might find the best sound is at some other setting than 180 degrees.

A good trick that Mike Stavrou suggests is when recording a guitar cab set up two mics. One a fixed distance form the speaker and the other on a boom stand and organise the boom horizontally so that second mic can be swung in a large arc and in the middle of the arc the second mic is next to the first but it can come in closer or be moved further away to the speaker. While the guitarist plays you should be in the control room listening to both mics blended while a friend slowly moves the second mic on the boom arm through the arc. You will hear many many many different guitar sounds and don't forget you can also flip the phase of one of those mics for another set of sounds too! What you will hear when you do this is way more tone controlled sounds that you could ever get out of the guitar and amp themselves. The idea is when you hear an amazing guitar sound you tell you friend to stop and make a note of where the swinging mic is and leave it there. In this mode you are using the phase differences to effect. (this is a bit fiddly but fun to do and very revealing!)

I tend to agree with what Danny is saying too above re using digital room ambience in close miced sounds. I have just finished a jingle where I played the drums but close miked them. I used Reverberate to deliver a fantastic sounding drum room. Small and tight but it just sounds so real and convincing. The great thing though is you can determine what parts of the kit are going to go into the room. Not so much kick for example and more of this and that. Very controlled room sound. Something that is hard to do with a normal drum room.  

Because I like doing this (adding digital drum rooms) I tend to favour the O'heads being picked up with a smaller condensers with HPF's in. That way they interfere very little phase wise with the rest of the sound. They do the cymbal thing and bring them into the picture without effecting anything else too much. 

Voxengo makes a plugin PHA -979 that does the same thing and runs as VST.

SONAR has a hot key nudge function that can be used as well.



best regards,
mike

What hasn't been mentioned yet is that the reason there's no objective method specified for checking and mitigating phase cancellation is that such a method does not exist. 

No matter where your microphones are or how far apart, comb filtering will always occur at some frequencies. Changing the mic position does not eliminate it, it just changes which frequencies are affected. The idea is to judge - by ear - which set of frequencies enhance the tone, or at least minimize the degradation. 
 
Of course, if your room mic is far enough away and the room is reverberant, the density of room reflections will mask the effects of comb filtering like an artist smudging a charcoal drawing with his thumb. The comb filtering is always there, though.

Would that be true with a single sound source and two microphones in an anechoic chamber? (allowing for discussion, the fact that a true single point source doesn't really exist outside of theory)



Does that realization describe a circumstance where you have multiple sound sources at different locations?

and/or

Does that realization describe a circumstance where the early reflections are some significant potion of the sound pressure level at at least one of the mics?


Your statement got me to thinking. :-)

Picture it this way...imagine 2 microphones at different distances from a source. They are positioned such that a 1KHz tone will reach them 180 degrees out of phase. That means 1KHz will be attenuated, along with all of its harmonics; IOW, comb filtering.

Now imagine you move one of the mics such that 1KHz arrives at some other phase angle. Now 1KHz is no longer as attenuated, but maybe now 900Hz is. The comb filtering is still there, but affecting a different series of frequencies.

Reverberation masks this, because copies of the same frequencies will also be arriving as delayed reflections, at different times and different phase relationships. Most will not be comb-filtered to the same extent or manner as the direct sound.

Of course, in an anechoic environment you don't get this masking effect, which is why speakers and microphones and acoustic materials are tested in anechoic chambers. Fortunately, nobody records drums in anechoic rooms (although I'm sure in the 80's they probably would have if it had been an option!)

I think you are very right Dave. The best anyone can do is to listen while making any sort of adjustments to phase on one of the mics and just go for the sound you want to hear. The fact that phase angles are going to be different for different parts of the spectrum could be used to advantage.

That plugin that Mike refers to is very interesting and you can alter the phase angles of various parts of the spectrum. You could use your ears to get the bottom end of say a kick drum happening. Then turn your attention to the mid range and change the phase angle of the centre part of the spectrum. It could be a good way to alter the sound of the kick before any EQ is applied. An advanced type of tone control.

That approach would work with guitar sounds too using two mics. 

Tweaking phase angles on close mics when distant mics are present is still not the preferred way. I was in a hurry (what happens under severe time pressure and wanted a quick 5 channel drum sound) did an interesting drum recording recently where I use two figure 8 mics to capture 3 toms by putting them in between the toms (one between hi tom and mid tom and the other between mid tom and floor tom) and facing their null points around the snare and kick. They piked up the cymbals nicely as well. Amazingly low snare and kick spill on those tracks resulted. The other three did kick snare and hats. I pulled a great drum sound fast. Being such a lovely player I balanced cymbal and tom levels in my playing. Less time needed later to sort out. The two figure 8 mics panned rather nice too. 

What happens under pressure is you can suddenly devise quick and very time saving ways of doing things eg to capture a good drum sound and spend little time on it later in the mix. It always turns out well usually. There is a situation where you would NOT be spending an hour tweaking the phase angles of mics to get the drum sound right. 

I don't get into too much phasing problems because often I am composing with and work with synths and things and I am dealing a lot with independent samples and outputs etc. And when I do record drums (and anything acoustic)  I often use the approach I mentioned above of recording the bass filtered O'Head sound. (or the complete O'Head sound with all the bass in but not use the close mics much, love that sound too) 

Interesting how under pressure one can alter their approach and get good results in a simpler manner. It is also very interesting to see how your DAW performs under real pressure too especially when the user gets into a serious power usage mode. (eg non stop and fast!) That is another story but I can say Studio One excels in this mode. 

Hiya, bit. Thanks for popping in. I hope your back is feeling better.

This is all awesome stuff guys and I really appreciate the time you've taken to explain it all to me. A little later in the vids I was watching he actually did come across a doubled bass part that was phasing and showed how to fix it but it was EXTREMELY simplistic compared to the info and methods provided here.

What would I do without you guys?

I'd blather some more about all the stuff I learned today working through more of those vids (and things I think were pretty weird/potentially wrong) but my brain is fried. Probably just be boring for you guys anyway so I'll just thank you all again. 

Thanks! ;-)

bitflipper


Picture it this way...imagine 2 microphones at different distances from a source. They are positioned such that a 1KHz tone will reach them 180 degrees out of phase. That means 1KHz will be attenuated, along with all of its harmonics; IOW, comb filtering.

Now imagine you move one of the mics such that 1KHz arrives at some other phase angle. Now 1KHz is no longer as attenuated, but maybe now 900Hz is. The comb filtering is still there, but affecting a different series of frequencies.

Reverberation masks this, because copies of the same frequencies will also be arriving as delayed reflections, at different times and different phase relationships. Most will not be comb-filtered to the same extent or manner as the direct sound.

Of course, in an anechoic environment you don't get this masking effect, which is why speakers and microphones and acoustic materials are tested in anechoic chambers. Fortunately, nobody records drums in anechoic rooms (although I'm sure in the 80's they probably would have if it had been an option!)

Hi Bit,


 I was looking at it from a different perspective.


 Let's say you have a sound source in an anechoic chamber and two mics spaced at different distance to the source.


 If you slide the tracks into alignment in post... and it was truly an anechoic chamber... will they not just sync up? That's the question that I was left thinking about when I asked.


 I guess I'm thinking about how your statement suggests, and I agree, that simply sliding 2 tracks, that were recorded in a reflective environment, into alignment will never completely eliminate comb filtering... it will just minimalize the effect.


 I thought it was useful to define a circumstance that is free of comb filtering so that we could discuss where/why/what is getting comb filtered when it does happen.


 If you are sliding tracks into alignment, the comb filtering you can not practically avoid is the extra content coming from reflections and or multiple locations of sound sources. 




 Stuff like that. :-)




best regards,
mike