RTA outdoor setup for speaker response corrections with PEQs

quaizywabbit

anyone got some pictures showing proper mic placement, orientaton, etc...

I want to establish a fairly accurate baseline response outdoors to set the PEQs against so the speaker is putting out whats going in.

Should the RTA mic point towards the speaker or straight up/down? Would I need to do the nearfield indoors method? (except outdoors?)

Also, are there any good tips/rules of thumb to setting the RTA mic up for use wth SMAART(placement, orientation, etc...)

any help is appreciated.......

Gadget

The indoor method is quicker and easier... It's pretty much predicated upon the tops only... Outside it's about 6 feet aimed at the space between the horn and the mid/lo mid, one stack only... and it has to be LOUD... concert volume If you intend to do SMAART you will find that you will need to take samples at multiple locations. ANY indoor SMAART or RTA will be affected by reflected energies that are in the 180 degrees out of phase area...

Gadget

quaizywabbit

I understand the nearfield method compensates for the floor bounce effect( saw a illustration somewhere that made that pretty clear)


Any tips on mic orientaton/placement(Smaart)?
I ask because Ive gotten conflicting advise elsewhere( some say point the mic straight up or straight down, on the floor, etc..) The mic is omni directional, so does it really matter? Should all my samples be taken at the same height above the floor?

Just wondering if there is a defacto standard...

Thanks for the tip on taking multiple samples...

Gadget

Inside... I'd suggest the floor...or better yet like the indoor method ...PZM fashion.. something like that to eliminate reflected cancellations. I have my \"monitor the system\" mike on the ceiling so it doesn't get stepped on...I'll see if I can get Mikey to weigh in here... he's the expert on SMAART...
G

Mikey

Short answer on mic placement-depends on what you want to measure.

First, let me interject a quick comment. At high frequencies, even an omnidirectional microphone is directional. I have to do a measurement on my system next week and will collect some data with the mic normal to the face of the speaker and again at 90 and 180 degrees to show the effect.

What Smaart will show you are the reflections in the time domain (impulse response) so you can predict where the dips are going to occur in the frequency domain (transfer function). Additionally, coherence is low where reflections are a significant part of the frequency response.

That said, I generally measure systems with three microphones. They make an \"L\" shape so I can see what is coming from the front/rear and the sides by comparing the response from each mic location. Very often, I will use chairs with blankets draped over them to get rid of ground or even side reflections.

Another way to do it is to place your mixer cover or a large flat surface on top of some chairs/sawhorse and place the mic head close to the large flat surface thingy but generally aimed in the direction of the speakers. Ground reflections are then eliminated by the large flat thingy. I think this is somewhat like Gary's method for indoor measurements.

My preferred method, advised by Robert Scovill, is to place the mic at standing head height and take your measurements there. Take into account the reflections as show in the Smaart data and all is good.

Mic positioning is an art and a science. You really have to know what you want to measure and think like a soundwave.

Mikey