Jun 26, 2005 12:07 pm I don't....i mean....understand....well, if....what are....you....talking...about.....i'm lost...please....calm...down....and tell...us...what...you...are...asking.....i...am...con...con...fus..fused.
Phase Cancellation...Cardioid
Posted on Jun 26, 2005 11:50 am
wontdieinPA
Member Since: Apr 27, 2002
well...we've all heard of it...some have even experienced it...but you see....I HAVENT...and i kinda wish i had so i knew exactly what it was...what it sounds like...i understand it in a technical aspect...sometimes when i mic the underside of a snare as well as the top...i check the waveforms to see if there are in phase with one another...and like...as far as i can see and hear, they are,...which to me...is odd...but not like it matters...i have no way of switching the phase anyways...nowhere in my signal chain does it give me that option...so i dont know...
also...everyone knows that Shure SM-57s are dynamic cardioid...and this technically means that at some spot in its pickup pattern,...there is a bit of natural rejection? correct? there is a spot that naturally rejects sound...correct? where is that and how do i find it?
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Jun 26, 2005 12:07 pm I don't....i mean....understand....well, if....what are....you....talking...about.....i'm lost...please....calm...down....and tell...us...what...you...are...asking.....i...am...con...con...fus..fused.
Jun 26, 2005 12:44 pm Check your Delta control panel, on the "hardware settings" tab. At the bottom, there are check boxes for each of your inputs to invert them 180 degrees.
As for the SM57 and its pickup pattern, I'm not so sure that it like actively rejects sound. It's just inherent in the cardioid pickup pattern. Look on the microphone itself, on the plastic head. Between the words "Lo Z" and "Shure", there's a little rounded upside-down heart shape. that's the cardioid pickup pattern. Imagine a larger version of that shape, in that same orientation, with the little notch right at the head of the microphone. That's the pickup pattern for the microphone. It'll pickup sound within that pattern, and sounds outside that pattern are greatly attenuated.
Jun 26, 2005 03:10 pm vdale, i don't quite get what it is exactly you are getting at. As far as the phase thing is concerned; it seems that i just cant quite tell when i would even need to use the phase reverse. And also, if i need to switch the phase and i go into my M-Audio control panel while Nuendo is open and i make this switch will the effects be instantaneous in Nuendo or will i have to close and re-open the program?
Also, about the pickup pattern on the SM-57, i understand the concept of the different microphone patterns, cardioid, hyper-cardioid, omni..etc. I also understand that there is a particular spot in the cardioid pattern that is less sensitive to say. And i was just wondering how i could find which part is because i read that some engineers sometimes use this to help reduce leakage to some degree, not dramatically, but to some degree.
Jun 26, 2005 03:11 pm ...................................................................................................................................................
-thats for all the ones i forgot in my post...
Jun 26, 2005 05:46 pm The phasing problems <I think> your talking about are when the sound reaches one microphone before the other such as mic'ing a guitar cab with 2 mics. When the mic's are out of phase with each other you will normally get a thin sound, as you move one of the mic's while monitoring the sound will become full and normal once the mic's are in phase with each other.
As for the SM-57, go to Shures site and you can look up the spec's on the mic which will tell you what the different dB levels are around the mic. From experience the SM57 picks up very little from directly behind so if you keep other sound sources directly behind it you will minimize the sound leakage.
Dan
Jun 26, 2005 07:07 pm Reducing spillage with cardiod mics, close micing is easy.... just make sure the front of the mic isnt pointing at any other sound source!
A 57, is a cardiod, yes you are correct in saying that. It has the greater of its sensitivity, on axis , and the greater rejection of sound, off axis (ie. to the side, and back)
Its as sim ple as that. More sound from front. Less sound from back and sides.
Sound engineers use this this to their advantage by positioning other instruments where there will be the least bleed from mics. To the sides and backs of the microphones.
Thats the best i can explain it on an empty stomach.
The "natural rejection" you talk about, is actually not that natural. A 57, belive it or not, is actually omni directional!Wow, didnt see that one coming!
The 57 has phase ports just below the 'grill' of the mic. This makes sounds with shorter wavelengths (High F), coming from the back, reach the phase port at a different time then the head of the mic, resulting in phase cancelations. This does not happen with bass F as the the friggin wave lenghts are to friggin long. (the wavelenght of a 20 Hz. wave is the size of a bus!). so therefore the bass F reach the back and front in the same wave.
BTW PHASE IS THE TIME DIFFERENCE BETWEEN TWO SOURCES.
CHEERS
C_S
Jun 26, 2005 07:13 pm A quick note to everybody:
By blocking the phase ports on ANY CARDIOD MICROPHONE (with gaffa or even your hand(remember when you were just a kid, doing your first live gig and you would hold the microphone by putting you hand all over the grill, then the sound system feedback like a mofo, and you thought it was cool?))
YOU TURN THE MIC INTO AN OMNIDIRECTIONAL MIC!(picking up sound from behind, casueing the mofo feedback *nudge)
And my theory is , that therefore it will also flatte the F response. Can someboy smart prove my theory?
Jun 30, 2005 02:59 pm i dont get it at all...not that i dont want to understand it...i simply just dont...i wish i was smarter
Jun 30, 2005 04:45 pm I'm not sure what points you're not understanding...there are several questions all mixed into the thread here.
- any cardioid mic will pick up sounds directly in front of it the strongest. It will pick up sounds from the sides of it quite a bit less, and it will hardly pick up sounds from behind it at all. I don't think that there is anything more complicated to rejection than that.
- you can use the phase invert switch whenever you are micing the same sound source and you have microphones facing each other in your micing scheme. Like the over/under snare drum setup. Flip the phase of one mic or the other.
What other specific questions do you have?
Jun 30, 2005 05:33 pm Oh...oh..oh <hand raised in the air> I have a question.
Am I correct to understand that viewing the reverse phase WAV file in Audition will display it "upside down"? And if so, can this (same thing as selecting reverse phase) be acheived after the fact, by flipping the WAV in Audition?
Jun 30, 2005 05:46 pm As far as I know, the answer to your questions is yes.
Jun 30, 2005 10:02 pm no...im not talking about any of that Tadpui...im talking about blocking the sides of the microphone of a cardioid mic and having it turn into an omnidirectional mic
Jul 01, 2005 11:42 am yeah i wasn't sure about that one either...
back to beer's question, that and the ability to nudge tracks over very accurately pretty much negates the need to have your mics, direct signals, and all that time aligned!
hehe my guitar mics were defanetly outta phase, but it was an easy fix.
Jul 01, 2005 12:05 pm yeah i need to ditch Kristal audio as my multitracker. You can't zoom in very closely and nudge tracks to correct phase. I'm using a phase correction plugin, but it introduces latency into the signal,so you have to use the plugin on all of the signals you're trying to sync up so the latency is the same, then start futzing with phase...it sucks. I need Cubase SE so bad I can taste it.
But it does make a huge difference when things are in phase! At very least you can flip the phase of one signal and keep whichever inversion is closest to being in phase.
Jul 01, 2005 12:17 pm you do get comb filtering when things are out of phase, which can lead to a futile persuit of an eq fix, which mean many hours wasted.
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