mixing complex recording.... ? need yes or no answer

[a2n3d7y]

Ok I'll TRY and keep this simple.
I have been a home recordist for about 16 years now and I'm always trying new techniques. I actually don't really like sharing my techniques with strangers unless they share theirs with me but in this case I have a crucial (I think) technical question and can't find it spacifically adressed anywhere on the www.

My question is regarding mixing stereo room mics with their close mic'd source subject.

For example:
(what I've done in the studio for this may seem like overkill but so far the results sound amazing for what I'm trying to do...which is make my bands demo sound like it was performed live in the same room so that the listener may enjoy a more realistic listening expierience.

What I did was record an extra stereo room track for every instrument that was individually tracked.

I used Cubase SX 2.01 and have 2 Echo Mia sound cards installed which gives me 4ins and 4outs. Obviously not enough inputs to record a full band and still have controll over everything in the mix. My SR2404 Mackie has the inputs but Im pretty poor so have limited mics. 1 CAD condenser, 2 SM57's (which I used for stereo room), and an AKG D112 (Im the drummer with all the equipment but I mostly make electronic computer music you know? So I don't spend the good money on good mics really.) SO everything was tracked sepperately 1 take after another.

Anyways....the question!

If I tracked each instrument seperately (guitars and bass) with the exact same mic placement (left the room mics where they were for all basic tracks and put each amp in the same place facing the same direction for each take) how should I set the POLARITY of the stereo room tracks?

I still have controll over this since I recorded digital and can easily reverse the polarity of the specified recorded tracks.
The amp roughly 2ft away from and facing into a corner of the room (2 conrete walls, the other 2 walls behind are drywall) with the stereo room mics directly behind and above the amp (about 7ft back) facing the back of the amp and concrete walls (90 degree directional offset). The front of the amp is also close mic'd. The close up mic is generally mixed higher using the room as a subtle ambience. The true beauty in this is that the room we recorded in is the same room we always reherse in...so its the room we're used to.
The Problem I have is that while viewing the audio tracks on screen the room mics and their close mic'd conterpart are 100% out of phaze. If this is true I can easily flip the polarity of the room tracks and its fixed. But while listening to both options I hear no major difference in the sound at all. And also while doing some simple phaze testing (mono the main mix and if the signal level reduces drastically then you're out of phaze) I found nothing wrong.

So should I flip the polarity of the stereo room tracks?
Or mabey even simpler...
If you recorded the front and back of an amp would you reverse the polarity of the mic behind the amp?
But my case IS different because the mics behind the amp are also recording the reflection of the front of the amp off of the concrete walls.

Thoughts? Sugestions? Criticizm? Anything PLEASE?

There might not even be a problem.

 

[Blue Bear Sound]

A couple of things.........

Sound travels about 1 foot per millisecond, so a room mic placed 20 ft away from the close mic on the source will have a time difference of about 20 mS if you compare the waveforms from the same point of origin. You can use this to judge distances and if comb-filtering becomes an issue between the close mic and room mic tracks, you can compensate by lining them up manually.

Second, you mention you have a waveform that is fully 100% out-of-phase with the other mic... this is impossible due simply to placement - you'd never get 100% polarity inversion in this situation - what's more likely is that you have a cable whose polarity is flipped (ie, wired incorrectly)...

The key is to listen to the 2 tracks together, summed to mono -- comb filtering is very obvious as the sound will flange in and out cyclically and it will vary from sounding thin & hollow to more normal (although in certain cases might make for a cool effect!)

If you don't hear any obvious artifacts when playing the 2 tracks together, then you got off easy and don't have a problem. If there are artifacts, you can shift the room track's waveform to line-up as I described above.

 

[a2n3d7y]

Thanks for the quick reply.

Sorry I exaggerated. Not exactly 100% out of phase but you can see visualy that the 2 waveforms kind of react in an opposite fashion from one another.

Ill reply after some more investigation.

But ya no loss in volume when mono-ing and no real difference in the way it sounds after flipping the polarity.

Thanks again.

 

[A Reel Person]

Yeah,... what HE said.

If there were major phasing issues, you would hear it. So, if you don't hear a problem, then there is no problem,... despite what it looks like on the screen.

Interesting technique & question, though.

Please, maybe post the final mixdown recording, when you're ready. It would be interesting to hear, and many of the trained ears around this board could tell you if you have a phasing problem.

 

[a2n3d7y]

Yes of course. I'll post a high quality mp3 atleast.

I just spent the last few hours grouping and mono-ing and fliping around the phaze of the stereo-room track for each instrument. There is no problem.

Further details and questions about mixing...

If I hadn't added the stereo-rooms the basic tracks would have only taken 7 tracks...
1: drums - stereo over-head
2: kick
3: snare
4: bass guitar
5: guitar
6: synth - juno106 woohooo!
7: main vocal
8: backup vocal
...but then add a stereo-room track for the bass, guitar, synth, and both vocal tracks (yes even the vocals wich were tracked in the bathroom of my bands apartment).
Im really at a loss on how to get a good DIRECT bass sound. She has a killer bass amp so I just stick the D112 up close on axis. The room-mics really add a filling space of bass. It was loud in there, like shaking the walls loud. Its my favorite bass tone I ever got.
The juno when played live for shows and rehersal is routed thru the MONITOR section of the bands PA. (The PA has 2 output sections. One is for MAIN outs and the other for on-stage monitoring. But we just use it as a 2nd out connected to an old Bassman cabinent with 2 12s. So ya that thing sounds real nice and dirty! We got used to it sounding like that but at first naturally I tried recording it direct in stereo. That sounded great of course on its own but that punky-overdriven sound was gone. So we mic'd it up instead and now sounds as it should.

So anyways... All of this was recorded 48000Hz/32bit float. Whats the best way of converting the final final final final stereo master into a 44100Hz/16bit CD-burnable wav. file? I've been making electronic music for the past 8 years and I'm just now attempting my first stabs at recording a REAL band on a computer. I always used Tape before. I will never use Tape again for a project like this. So far this sounds great.