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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Audio Measurement and Testing => Topic started by: Al Rettich on December 10, 2016, 02:37:35 pm

Title: Where to point the mic.....
Post by: Al Rettich on December 10, 2016, 02:37:35 pm
I've seen many of guys use their Smaart rigs.  I keep seeing the same 3-4 ways they put their reference mics. 

1. On a stand pointed towards the PA.
2. On a super tall stand with the boom extended all the way out. Pointed towards the Pa
3. Pointed down towards the floor.
4. On a straight stand full extended, with the mic pointed straight up.

So the question is which is right,  which is wrong, is one better than the other?
Title: Re: Where to point the mic.....
Post by: Ivan Beaver on December 10, 2016, 03:51:48 pm
I've seen many of guys use their Smaart rigs.  I keep seeing the same 3-4 ways they put their reference mics. 

1. On a stand pointed towards the PA.
2. On a super tall stand with the boom extended all the way out. Pointed towards the Pa
3. Pointed down towards the floor.
4. On a straight stand full extended, with the mic pointed straight up.

So the question is which is right,  which is wrong, is one better than the other?
As usual-it depends.

When you say "pointed at the floor"-are you talking about a PZM mode (with the mic next to the floor) or on a stand pointed at the floor.

If the later-that is NOT a good way.

When doing the PZM, it depends on how high you are trying to measure.  For very high, it should be pointed  straight down-with about a business card space between it and the floor.

When on a stand-if you are trying to measure up high (above 10K or so), then you MUST point the mic towards the speaker.

Even the best omni mics will become a little directional that high up.

You should generally get the mic as far away from any boundary as possible-BUT still be representative of a listening position.  Sometimes that means placing it in a different place than where you actually want the response to be-in order for the mic to be away from boundaries.
Title: Re: Where to point the mic.....
Post by: Luke Geis on December 10, 2016, 05:08:31 pm
The mic on and pointed at the floor is used to eliminate issues when measuring in highly reverberate spaces. Since the bounce of the signal off the floor is so close in time to the direct sound, there is less phase issues and the software can more easily determine what it is measuring. Since you gain some SPL with the floor boundary it can also help in a situation where you can't blast pink noise through the PA at performance level.

Getting the mic up and away from the floor is to eliminate the boundaries and ensure that the PA is the first thing that the mic hears.

The mic is omni directional so it should not matter what direction it is pointed per se, but I do think it makes sense to point the business end at the intended target. I have gone as far as PFL'ing the measurement mic to hear what it is actually getting and moving it to suit what I think best represents the current state of the room. It would make sense that if the mic doesn't hear the correct information, your measurement would also be off. A quick listen and movement of the mic to different spots can help sort that out.
Title: Re: Where to point the mic.....
Post by: Mark Wilkinson on December 12, 2016, 05:29:22 pm
Measurement mics often have calibration files for both 'pointed at' and perpendicular orientation, so that may be a factor in what you're seeing.
Title: Re: Where to point the mic.....
Post by: Jerome Malsack on December 16, 2016, 12:07:40 pm
Don't forget to turn off any ceiling fans in the venue when close to the measurement mic also.
Title: Re: Where to point the mic.....
Post by: Dan Richardson on February 20, 2017, 04:59:24 pm
A theatre full of seats presents a puzzle. I've attempted to solve this by finding something large and flat, like a folding table, a sheet of plywood, or even a big piece of cardboard, and laying it across the seats. Then I PZM the mic on that. Seems to get me reasonable results.
Title: Re: Where to point the mic.....
Post by: Ivan Beaver on February 20, 2017, 07:44:26 pm
A theatre full of seats presents a puzzle. I've attempted to solve this by finding something large and flat, like a folding table, a sheet of plywood, or even a big piece of cardboard, and laying it across the seats. Then I PZM the mic on that. Seems to get me reasonable results.
I used to carry 2 pieces of plywood that were hinged and had carpet on the underside.

That way I could lay them across pews or theater seats and not damage them.

I would PZM the mic also.

I got tired of carrying it around and just started looking at the phase trace to see if any notching in the response was caused by the bounce to the mic
Title: Re: Where to point the mic.....
Post by: Mark McFarlane on March 02, 2017, 11:52:41 pm
...
I would PZM the mic also.
...


I've never seen PZM used as a verb.  Are you saying you put an omni mic against a temporary boundary to turn it into a boundary mic?  Capsule almost touching the boundary at some angle to get the business end down to the boundary ?
Title: Re: Where to point the mic.....
Post by: Ivan Beaver on March 03, 2017, 08:00:42 am

I've never seen PZM used as a verb.  Are you saying you put an omni mic against a temporary boundary to turn it into a boundary mic?  Capsule almost touching the boundary at some angle to get the business end down to the boundary ?
Yes, I guess I should have said "put the mic in PZM position"