3:1 rule and Haas effect?

[FALKEN]

hi, I want to revisit an old topic but a good one. Lately I have been recording the whole band live in one room. The results have been good but not great. I am thinking that to make this really work I must observe the 3:1 rule better. which means that if the overhead is 3' away from the furthest drum head (for example), then the next closest mic, the vocal mic, should be at least 9' away. right?? I think this is the first problem.

I think in addition, all of these mics are very close together in the room and that there is some smearing going on in the time domain because the "reflections" are appearing closer in time to the "original" close-miked sound which is making it sound like a blurry single sound. whearas if the mics were further apart the time between arrivals would be greater and the mind would perceive them as a separate distinct sound. But this would necessitate a specific distance, which I'm not sure how to calculate, and wouldn't have much to do with the 3:1 rule, as it would be a constant distance, although might be dependent on frequency.

any thoughts?

 

[mixsit]

Recording in those conditions does make for an interesting mix of those two ideas. I simply go with the assumption (because I've not seen this particular notion shown exactly elseware), that the short reflections that fall under the Haas effect must combine with the source. Ie, under about 20ms add blur, to whatever depth their sig. to noise makes it, >20ish = nice clean (expensive ) room effect.
So part of our job particularly in smaller rooms and mixed paths like that would be to consider how, or to what extent we want them 'stuck on to our raw sounds and attenuate them where we can.

As to 3:1, that number I believe is based on two sources (for example) of similar volume, with two mics at similar sensitivities and distances, mixed at similar volumes. The trick is you're describing conditions where almost none of these 'rules' (assumptions) are true.
Where to go from there?

 

[flatfinger]

I'm no expert but I thought the 3:1 thing was pertaining to phase cancelation wit more than 1 mic and Haas was about thickening or stereo effects. ( turns into echo at about 40 ms)

 

[mixsit]

I'm no expert but I thought the 3:1 thing was pertaining to phase cancelation...

Yes, but it's about using whatever amount of distance it takes to attenuate unwanted phase rffects. Once it's a multi-path-multi-time mix, there is no getting back to 'coincedent' -in phase.

and Haas was about thickening or stereo effects. ( turns into echo at about 40 ms)

Pretty close. Also known as the precedence effect. It just says that if it's a tight echo' it can sound connected to the original, or for paning (0- to about 1 or 2 ms), or 'thickening if it's intentional, but maybe a screwing with the picture if it's not.

http://www.rane.com/par-h.html

 

[ecktronic]

You could always DI the bass, and place the amps so they are facing away from the drums and pretty quiet. Then use monitor headphonesand set up a mix so you can hear each other. The drums should be loud enough wihtout having to put them throught the mix, so all you will need is the amps and vocals n anything else.

Eck

 

[NYMorningstar]

I'd say to fix your problem you need more room treatment.

For the 3:1 rule; if you have a source 3' away from a mic then yes your other mic needs to be 9' from that mic but also needs to be 3' from it's own source. That makes it almost impossible with the two sources you mentioned.

 

[jabulani jonny]

Ouch, having drums in the same room as vocal mic, that sounds like a recipe for a tough mixdown. Are there no other alternatives for isolating some of the instruments in other rooms as has been suggested? I'd definitely try to get amps in closets or bathrooms, DI bass, and then I'd look at getting the vocalist away from the Drums. Hell, lay a scratch vocal and come back and overdub if that's a possibility.

I know you know this Falken so I know I'm preaching to the choir. Just my thoughts.

Jonathan

 

[ecktronic]

When I record live I would tend to set up a headphone monitor mix with the vox rather than using PA speakers to hear the vox.
Then even re-track the vox after the live recording.

Eck

 

[mixsit]

..For the 3:1 rule; if you have a source 3' away from a mic then yes your other mic needs to be 9' from that mic but also needs to be 3' from it's own source. That makes it almost impossible with the two sources you mentioned.

Why would you want that second mic to be the same distance from the source as the first (unless it just happened to sound better there)? Any time you can get closer it cuts back bleed from the other things in the room.

 

[ofajen]

hi, I want to revisit an old topic but a good one. Lately I have been recording the whole band live in one room. The results have been good but not great. I am thinking that to make this really work I must observe the 3:1 rule better. which means that if the overhead is 3' away from the furthest drum head (for example), then the next closest mic, the vocal mic, should be at least 9' away. right?? I think this is the first problem.

I think in addition, all of these mics are very close together in the room and that there is some smearing going on in the time domain because the "reflections" are appearing closer in time to the "original" close-miked sound which is making it sound like a blurry single sound. whearas if the mics were further apart the time between arrivals would be greater and the mind would perceive them as a separate distinct sound. But this would necessitate a specific distance, which I'm not sure how to calculate, and wouldn't have much to do with the 3:1 rule, as it would be a constant distance, although might be dependent on frequency.

any thoughts?

The 3:1 "rule" assumes you have normal volume fall off with distance, but in a small room like that, sound falls off with distance only for so many feet before the reflected sound volume equals the direct sound and then, of course, the volume stays about the same. Your falloff may well stop before 9 feet.

Cheers,

Otto

 

[NYMorningstar]

Why would you want that second mic to be the same distance from the source as the first (unless it just happened to sound better there)? Any time you can get closer it cuts back bleed from the other things in the room.

You use the 3:1 rule to reduce comb filtering but I'm not saying it's a solution for this problem.

 

[mixsit]

You use the 3:1 rule to reduce comb filtering but I'm not saying it's a solution for this problem.

Ah yes, agreed.
Just wondering why you'd care to have the two mics have the same distances.
(Were you thinking a stereo pair on one source?)

 

[NYMorningstar]

(Were you thinking a stereo pair on one source?)

No, he said he had two sources, drums and vocals.

 

[FALKEN]

so if sound travels at like 1100 ft/s and the haas effect cutoff is 40ms then sound will have to travel 44 feet to be outside of the haas effect. probably not going to happen in a home studio anyway. I might be able to get half that.

I was wondering that about the 3:1 rule. I didn't remember anything about pattern or volume differences. I would think that a drumset next to a vocal mic might skew the numbers. and the directionality of the mic because course it wouldn't be an omni mic its a directional mic but there's another problem. the vocal mic is picking up predominantly reflected sound of the kit. so the kit ends up sounding very uhh....roomy. especially after compressing the vocal. (another potential kink in the 3:1 "rule")

I could overdub the vocals I guess that is what I have usually done in the past. But lately my vocals have been sounding really good and I've never been able to think that before. I really just want to capture this stuff live but have it sound close miked.

 

[mixsit]

No, he said he had two sources, drums and vocals.

Then it doesn't apply then does it.

 

[Mc'guyversen]

the vocal mic is picking up predominantly reflected sound of the kit. so the kit ends up sounding very uhh....roomy.

Have you tried using different vocal mics?
Ive been fighting this same problem in my (one room) live band recordings.

Over the last few sessions I've tried using lots of different vocal mics to try and reduce this problem.

My best results came with using a Senheiser MD-441, with the vocalist facing the kit, about 10 feet back.
My EV. RE-16 also did a really nice job of reducing the "uhh roomy" drum bleed sound.

 

[NYMorningstar]

Then it doesn't apply then does it.

I'd say it doesn't apply because it is a small room with alot of reflections and also because of the volume differences. If it were a large room and a quiet jazz drummer I'd say it would be a consideration.

Are you saying the 3:1 rule applies to a single source?

 

[mixsit]

I'd say it doesn't apply because it is a small room with alot of reflections and also because of the volume differences. If it were a large room and a quiet jazz drummer I'd say it would be a consideration.

Are you saying the 3:1 rule applies to a single source?

First of all please allow me to withdraw that crappy way of turning a question into a point. Poor etiquette on my part.
What I guess I'm focusing on is the idea that I'd consider equal distance important to stay phase coherent on a picture of anything. I don't see where equal distance is a concern on separate sources. IOTW, in this context put the mics as close to sources and as far from each other as you can get away with.

 

[FALKEN]

but really is 40ms a pure cutoff line? beyond this point is separate and before it is same? or is this more of a gradual thing? if you were blindfolded and placed in a room with people talking in it, you might be able to guess its size roughly. and I don't think your guess would be "not really sure but definitely smaller than 44 feet". your brain would be able to perceive much smaller spaces than that and probably make a good guess on the ceiling height as well. so I still postulate that distance of the mics in the room from various sound sources would cause the brain to perceive the music differently based on how close each instrument is. that the timing differences of each instrument to each other's mics and also from the walls surrounding would all have a huge impact on the perceived "sound" as a whole. that it is the timing in conjunction with the volume which causes the "sound" to take on certain spatial characteristics such as "open" or "boxy".

 

[mixsit]

...I would think that a drumset next to a vocal mic might skew the numbers.

Definitely. Again, unless I'm mistaken, the 3:1 number gives sort of a minimum amount of attenuation when you're dealing with things of the same volume and sensitivity cross pollinating. If the 'two are radically different everything shifts.

.. the vocal mic is picking up predominantly reflected sound of the kit. so the kit ends up sounding very uhh....roomy. especially after compressing the vocal. (another potential kink in the 3:1 "rule")

I had decent luck with a band several years ago -R'& B/soul with two live vocals in my front room. We were lucky in that the bleed worked ok but I remember at one point thinking 'I need to shorten the drum verb'. Then rediscovering it was the vocal verb.

So you might try zero inches to the vocal. That's as good as it gets for s/n if it sounds ok. (Let's see, what's three times zero? Nevermind.

Got some gobos up?

I could overdub the vocals I guess that is what I have usually done in the past. But lately my vocals have been sounding really good and I've never been able to think that before. I really just want to capture this stuff live but have it sound close miked.

On the up side, performance always trumps sound.