newbie: how do you measure the pattern?

[cordura21]

Hi, and sorry about this basic question but I hope I can get some help from you guys.

I read Harvey's thread and of course I think it's great. In life I am always searching for those teachers that makes a click inside your head and that was one of the few cases. I hope I could find a thread like that about stock investing, so I can retire in a couple of months and put a studio near a beach.

Anyway, maybe I didn't get it or I missed it in one of the pages but: how do you measure the pattern, parallel to the mic or perpendicular?

I mean, an sm-57 catches more on the fron an less on the back, right? What about the sides ( if you put the mic standing up like a broadcast one, is it the same any side)?

And what about standing mics, like condensers in position to record voice? From what I think I learned, the pattern is perpendicular to the mic. Is that right? And if so, is it because the capsule is not aligned with the mic's body, but perpendicular?

Maybe I am not making myself clear, but my english is not the best thing in life. But maybe some of you guys can help me with this one.

(I was going to ask about the 3d effect of the pattern, but my ignorance is huge so I'll start with small steps).

Cheers, and thanks in advance to all.

Andrés

 

[Harvey Gerst]

OK, let's keep it simple. Imagine a perfectly round, big balloon (about 6 feet across). Now imagine an omni mic inside the exact center of the balloon. Now imagine that the only rule in this "imagine" game is this: If your lips aren't touching the balloon, the mic won't hear you. So with our omni mic completely inside the balloon, we can stand just about anywhere in relation to the mic, and as long as we're touching the balloon, the mic will record us.

OK, new conditions, the balloon is now only one foot across. We now have a Shure 57 on a mic stand, pointed at the singer and the balloon is in front of the mic, and we gently push the balloon forward, so that the head of the mic pushes into the balloon about 1/3 of the way. The same rule applies: If your lips aren't touching the balloon, the mic won't hear you.

BUT, we add a new "imagine" rule: The closer your lips get to the actual mic, the lower the output. So, as you move around towards the backside, and your lips get closer to the mic, the output drops, and of course once your lips touch the actual mic (because you're now directly behind it, no sound at all. That's a cardioid polar pattern.

In real life, the balloon is kinda invisible, and it's not perfectly round at all frequencies, and it extends out a lot further, getting softer as you move further back, but that's kinda how polar patterns work and a good way to remember them.

Does that help?

 

[cordura21]

yes, that helps a lot. Thanks very much.

What I think was confusing me is the shape of mics. If you think of the "direction" of the mic as the long size, then when you put a mic on stand for a singer a la Frank Sinatra, it looked to me that the mic was pointing up. Maybe is because I was thinking of the 57s, which have the diaphragm perpendicular to that "direction".
I suppose that singers' mics are either omni or have their diaphragms/s paralell to the mics, so the balloons are 90° from that "direction".

The balloon image was nice, thanks. I have to read the links that you gave about sound propagation on the big thread. That's my homework.

Thanks again. I always remember words from the CEO of Cisco networks, who said "the business is in the complexity". I am glad that there are guys there who don't believe it and keep it simple , clear and accesible to anybody.

Cheers, Andrés

 

[Harvey Gerst]

yes, that helps a lot. Thanks very much.

What I think was confusing me is the shape of mics. If you think of the "direction" of the mic as the long size, then when you put a mic on stand for a singer a la Frank Sinatra, it looked to me that the mic was pointing up. Maybe is because I was thinking of the 57s, which have the diaphragm perpendicular to that "direction".
I suppose that singers' mics are either omni or have their diaphragms/s paralell to the mics, so the balloons are 90° from that "direction".
Cheers, Andrés

Frank Sinatra's mic was usually a long body Neumann U47, and the capsule is parallel to the mic body. It's called a "side address" mic, and yes, you sing into the side of it. The balloon would be 90 degrees from the front.