# what direction should have the mic facing using a SPL meter with a tri pod



## acousticignorant (Oct 29, 2011)

I have recently bought a Radio Shack digital SPL meter and I'm about to buy a tri pod for it. One thing I'm not really sure about is which direction do I have the mic facing when using REW? Towards the speakers or the ceiling? Any info would be great.


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## SAC (Dec 3, 2009)

Per the manual the meter should be pointed at the source.

Also, yu will ideally want to use a mic stand or threaded (as provided for on the meter's bottom) and you want to move away from the meter lest you become a source of reflected energy.


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## robbo266317 (Sep 22, 2008)

For most omnidirectional microphones you would face it up towards the ceiling at ear height at the listening position. 
Although you may not find any discernible difference in the graphs from facing it forwards. Try it and see for yourself.

Cheers,
Bill.


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## Alex2507 (May 10, 2008)

The manual does say that the meter works best when pointed at the sound source and I think that would be important if you were checking a speaker's output from 1 meter away. Using the meter to check room response or to level match a surround system I would point it up at the ceiling. At my seating position of about 10' from my front sound stage I didn't notice any differences with the direction the meter was pointed in while calibrating my gains.


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## aackthpt (Jan 24, 2011)

> Just really unclear what you folks are doing with the SLM? If you are using it for raw spl at a single location and have speakers all around you then point it straight up and get out of the way. If you are using it as a measurement mic for spectral analysis, don't.


Yes, many use the RS SPL meter as a measurement mic for spectral analysis. Its accuracy and limitations have been discussed in the home audio community nearly ad nauseum, so it is generally only used for leveling and equalizing subwoofers - no one would use it for purposes such as aligning crossovers for mains (tops as you may call them). Yes, it's technically not a great mic for that, but it is better than nothing and since many already own one it makes acoustical measurement available for many enthusiasts at the very pleasant price of free. I personally applaud any effort that gets a wider cross section of the audio enthusiast community to make measurements rather than relying on the pure subjectivism, salesmanship, and pseudoscience that I have seen in the "audiophile" community. I nonetheless tend to encourage people to buy a measurement mic, but I suspect that there is a cross section of the community for whom the research time is an issue when they can just run with what they have on hand (typically an RS SPL meter... I have the old analog one, as does everyone interested in audio who is over 35 I think - but no I don't use it for any measurements).

As for the time vampires, you have no idea. My time wastage here and at avsforum is growing, but in the last year I have spent countless hours on gearslutz.... however it's not really all wasted as I have certainly learned much from the folks who hang out in their acoustics section.


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## acousticignorant (Oct 29, 2011)

I went to Guitar Center today to ask if they had the ECM8000 Measurement mic from Behringer.The employee told me he'd sell me his for 30$ after he gets out of work. Sounds like a deal, what great costumer service. Now I just have to download the cal. file and wait till 8pm to pick it up. Ready to start measuring my room. Thanks for all the helpful advice!


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## aackthpt (Jan 24, 2011)

Sounds like a decent deal; you'll have to use the generic cal file but it's probably close enough. Better than the RS mic.

Right now the EMM-6 direct from Dayton is $39, presumably plus a bit of shipping. That is a good choice too.


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## Wayne A. Pflughaupt (Apr 13, 2006)

robbo266317 said:


> For most omnidirectional microphones you would face it up towards the ceiling at ear height at the listening position.


Even omnidirectional mics exhibit directionality at the upper frequencies, so it’s imperative to use the correct calibration for either vertical or horizontal orientation.










*Common Off-Axis High Frequency Response of a Measurement Mic*​

That said, it’s a pretty much a moot issue since the topic at hand is the Radio Shack meter, and it’s only suitable for low freq measurements. For low frequency measurements, orientation doesn’t matter.

Regards,
Wayne


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## acousticignorant (Oct 29, 2011)

I just bought an EMC8000 the other day and also had it sent off the get the cal files for a 90° and 45° angles. I keep reading that its better to use a measurement mic than an SPL meter.


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