Installation of the measuring microphone

Posted on

Member Since: Dec 25, 2011

I want to use pink noise and measuring microphone to set up a room in the club.

Where and how should I put the measuring microphone (ECM8000)?

Should I send pink noise to the two speakers at the same time or one by one? (phase incoherence can affect frequency response?)

Must the microphone look upward or forward (on stage)? It is omni-directional microphone, I know)))

I apologize for my English (if it seems bad) ...

[ Back to Top ]


The Czar of BS
Member
Since: Dec 31, 2007


Dec 25, 2011 07:17 pm

Typically you place the mic in front of the a set of speakers about 3 feet away. This is where you are setting the delay for all of the drivers in your system. So, subs to low mids, low mids to highs.

Set both sides so that all frequencies are running at the same time. Again, lows, mids, and highs.

Form there, I usually move the mic to where the two sets of speakers (Left and Right) cross in the room. Set your delay first. Then EQ the room. Once you have the room set close to where you want it at, I usually move the mic back to the FOH board. And leave it there for the show. And make any corrections that are needed for FOH listening.

Hope this helps. If you need move information, please do not hesitate to ask.

Member
Since: Dec 25, 2011


Dec 26, 2011 05:36 am

Thank you!

[quote]....... This is where you are setting the delay for all of the drivers in your system. So, subs to low mids, low mids to highs .....
...... Form there, I usually move the mic to where the two sets of speakers (Left and Right) cross in the room. Set your delay first ..........[/quote]

You mean, make subs, mids, highs phased with each other?

How can I do that?
How does the measuring microphone will help me with this?

The Czar of BS
Member
Since: Dec 31, 2007


Dec 26, 2011 04:19 pm

Well, phase does come along for the ride. But, sorry. What I mean by this, is the delay of each of the speakers to one another. This is where you move the delay on your crossover so that each driver is moving at the same time.

In the air, high frequencies will move faster then low end will. So, you need to find the slowest moving frequency in your room. This will be the low end. You take a measurement with Smaartlive 7. (If you don't have a copy, here is a link to the 30 day demo version. www.rationalacoustics.com/pages/Smaart_Download) In the IR (Impulse Response) You turn on just your subs. And remember, this is with the mic only 3 feet in front of your speaker stacks. Once you see where your subs are in time, then you turn off the subs, and turn on the top boxes. Take another measurement. Now, look at the difference in time. If you have a crossover that allows you to set delay, you just enter that difference in time between the two. If you do not have a crossover that allows you to set delay time, then you must physically move the top boxes, or subs to get them to line up.

This will put the phase, and spectrum in better alignment. And will give you a better starting point for EQ.

Now, why does time alignment effect phase? Remember that phase is where you are getting cancellation between groups of frequencies. Where on frequency is going up, and the same frequency is going down from another driver, you get 180 degrees of phase cancellation. You can correct this by moving a driver forward or backwards. So that the frequency is moving up and down at the same time. This way there is no phase cancellation.

We can find out how large a wave is, by dividing 1130 by the frequency. So, 1K works out to be 1.13 feet. So roughly one foot. This really means that 1000 hz's is really one foot long. This also means that 100hz is 11.3 feet long. And that 10,000hz is .113 inches long.

By moving a driver (And I use the term driver to mean a speaker that is for a group of frequencies.) just a little in space, will align the spectrum for better phasing, and EQ.

www.TheLondonProject.ca
Member
Since: Feb 07, 2005


Dec 26, 2011 08:12 pm

Rob I always absorb your info. I have learned more from your posts that any others I have read. ANYWHERE. Thank you very much for this. I hope to return it someday.

The Czar of BS
Member
Since: Dec 31, 2007


Dec 26, 2011 08:46 pm

Thanks BeerHunter.

When I first started out to learn sound engineering, I found extremely difficult to find anyone that would take the time, and explain things to me. Everyone loved to use as many .50 cent and 50 dollar words that they could. Which drive me nuts!

I try to explain things without getting overly simplified, or overtly complex. And I'm glad that you found my ramblings useful. :)

Related Forum Topics:



If you would like to participate in the forum discussions, feel free to register for your free membership.