Silly question about the SM57

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philbagg

philbagg

Just Killing Time
I'm going to go ahead and assume that the 57 is cardioid the same way almost
any other mic is. Because of the vents at the side of the mic right?

I just gotta ask, I'm holding one here and I can't see em.

Where are they?? :confused:
 
I have that page open on a separate tab already, but it doesn't show me where
the ports are.
 
Manslick said:
Maybe this shows it.

http://www.shure.com/stellent/group...g/documents/web_resource/us_pro_rk244g_ug.pdf
Click to expand...

Thanks Manslick, you are a hero.

Now, I'm not 100% sure but I think I'd be right in saying that the rear vent is
where "Screen and Grille Assembly" is pointing in the top left diagram of that
PDF?

Looking at my own 57 here, there seems to be a ring around the top of that
part, and then just under it is like a foamy kind of material? I'm assuming that
the sound from the rear would pass through that and cancel with the same
signal arriving at the front, creating cardioid?

I hate sounding like a newb but the ports aren't really obvious on this mic.
 
Manslick said:
Not sure how the pattern is created. Mine looks like it has slots or vents all the way round, so something inside must be at work.

Here's another thread on the topic

https://homerecording.com/bbs/showthread.php?t=206880&page=1
Click to expand...

Thanks manslick, I was just reading the guys telling him to get rid of the tape
on the "swivelling" part because it blocks the vents. So that must be where the
vents are.

Thanks for all your help!
 
Had to take a nap

Yeah I read that too. Who knew?
The vents are on the side but how they create a cardioid pattern is beyond me.

I did find an article on the Sound on Sound web site about how the vents work to create the patterns but it’s too much for my pea brain to comprehend.

Back to your OP. Yes the SM57 is a dynamic cardioid microphone with vents on the side and the best thing I have found to illustrate it is this - check the image at the top.
http://www.google.com/imgres?imgurl=http://www.whitepark-acoustics.co.uk/knowledge/cardioid%2520pattern.gif&imgrefurl=http://www.whitepark-acoustics.co.uk/microphones.htm&h=136&w=192&sz=2&tbnid=7X4JcigKRceIwM:&tbnh=73&tbnw=103&prev=/images%3Fq%3Dcardioid%2Bpattern&hl=en&usg=__lliKz0FeL3lc_9uRMgkdmLYexdE=&ei=NCtDS9rKI8WEnQeA07CCCQ&sa=X&oi=image_result&resnum=7&ct=image&ved=0CBsQ9QEwBg

Man, I’ve used this mics for decades and never even thought about this.
 
Manslick said:
The vents are on the side but how they create a cardioid pattern is beyond me.

I did find an article on the Sound on Sound web site about how the vents work to create the patterns but it’s too much for my pea brain to comprehend.
Click to expand...

I assume you understand phase?

Basically, the sounds arriving from the back travel through the vents and hit
the diaphragm from the back. But they also travel around and hit the diaphragm
from the front.

Therefore, the same signal hits the diaphragm on both sides at almost-equal
energy resulting in 20 to 30dB of phase cancellation. This is how it rejects sounds
from the rear but not the front.

It should also be noted: the more vents a mic has, the more directional it is
(usually).

Here is a shotgun mic, the most directional type of microphone. Check out
the amount of ports.
image.php


Whereas this would be omnidirectional. No ports at the side, nothing to allow
the sound to hit the back of the diaphragm. Sound from all angles is picked up
at equal energy.
20899_l.jpg


Hope this helps.
 
Helps? Not really. But you certainly don’t sound like a newb now.

I remember reading some stuff about grill patterns and how they diffuse sound to create mic patterns, went in one eye and out the other.

Few months back I was thinking about measuring my room for standing waves and all that, from some home theatre site I joined.
They have this procedure where you needed an omni mic.
I figured hell with that and forgot it. But now, if all I have to do it tape up the SM57 I’m good.
 
Manslick said:
Helps? Not really. But you certainly don’t sound like a newb now.

I remember reading some stuff about grill patterns and how they diffuse sound to create mic patterns, went in one eye and out the other.

Few months back I was thinking about measuring my room for standing waves and all that, from some home theatre site I joined.
They have this procedure where you needed an omni mic.
I figured hell with that and forgot it. But now, if all I have to do it tape up the SM57 I’m good.
Click to expand...

Think of it this way, two people of equal strength are trying to push a table in
opposite directions. It's not going to move anywhere.

In the mic's case, the two people are the sound waves from the front and
the back, and the diaphragm is the table. The diaphragm won't move, and
thus rejects the sound from the rear.

Oh, and I wouldn't just tape up a 57 to check your room acoustics. They're
not flat at all and would give you some pretty inaccurate results, not to mention
the tape wouldn't be a great solution either.

We got a talk from a guy who does a lot of room acoustics stuff, and he has
an omni mic he uses. It looks very similar to that omni mic I pictured above.
He picked it up for about 20 or 30 euro. Flat frequency response, accurate
results, great for room treatment.

Apparently, it sounds like shit though :p But I wouldn't worry about that if
you're just using it to test your room. Take a look around google and ebay
and see if you can pick one of those up, might be just what you're looking
for.

PS: glad to see I've picked myself up from n00b status again :D
 
just point it at your face and sing into it or at your sound source and play.
 
ez_willis said:
just point it at your face and sing into it or at your sound source and play.
Click to expand...

Don't see how that helps reporting on it's construction to alter the polar pattern,
but yes, that is an idea.
 
The SM57 is not well suited for this sort of measurement the response curve is no very flat and even with the ports blocked with tape the SM57 well not be equally responsive from all directions. The Behringer ECM8000 is available from most of the usual sources on the Internet for under $50. It is omni-directional and has a very flat response curve. It is well suited for room correction applications. The only drawback I see is that the ECM8000 does require phantom power (15 to 48 V). I have been using one for a couple years with excellent results.
 
Ok, new question. Didn't want to start a new thread.

I'm researching the U87 now.

Does anyone have any information on how the two capsules (dual diaphragm)
work together to switch the polar pattern between omni, cardioid, and figure of
8?

I read something about the 2nd capsule reversing phase against the first to
cancel sound from the rear. I'm guessing that's how it makes cardioid? Really
not sure.

For omni, does the mic only use the 1st capsule?

This is confusing the hell outta me :confused::confused::confused:

I'd really appreciate some help, thanks guys.
 
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