Measuring the SPL of loudspeaker at home.

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Recently, I have bought a Dayton Audio UMM-6 USB Measurement Microphone to measure my loudspeaker's SPL (vs freq). I am quite new to this thing.


I have read somewhere that measuring the SPL vs frequency of a loudspeker or a driver fairly acurately is possible at home using a laptop and some software. The software is supposed to measure the effect of the room first and take that into consideration while measuring the SPL of the loudspeaker.

Is such a task possible with True-RTA? How?
Is there a tutorial link somewhere?

How am I supposed to connect the laptop to the speaker? I have a Moon 220i integrated amplifier at home.


I would greatly appreciate any help and info.

Thanks.
 
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HOLMImpulse is a good software to use, and it's free. You can get a lot of help here using it. HOLM should see your USB mic as an input.

You'll need something linear as an output to your speakers. The soundcard line out of your computer may be good enough.
 
The frequency response of your amplifier should be wide enough and flat enough for your measurements. Just make sure that you bypass all of the audio effects in your laptop before running the tests. You won't need much amplifier power either. Follow the directions from the HOLM website.
 
Disclaimer: I am only faintly familiar with True-RTA. But generally, Real-Time Analyzers are NOT set up to window reflections out of a measurement, and so cannot get you the response of only the speaker. You'd also miss narrow notches or peaks in response.

Having said that, you could try it with the speakers outside on top of a high ladder, far from any buildings, and it will give you a decent rough idea of what is going on
 
Many of us find RoomEQWizard (REW) to be the easiest program for home use. It has many features that help you to understand what is going on in the room too. It's Help files are really informative. You must register to the website to download, free!

For signal output, buy some USB-DAC or use any DAC with USB-in and RCA-out. Laptops's Phones-outs are not linear enough but Line-out or SPDIF-out are.

There are also many tutorial videos of REW https://www.google.fi/#q=rew
 
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I tried to do some measurements! Here is the pic of what I did...

374856d1380945729-measuring-spl-loudspeaker-home-spl2.png


(diferrent plots are for different L-pads adjustments.)

Did I do everything right?

How is the response?

Also, can anyone kindly give me recommendations about mic's placement with regards to the speaker?
 

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What I usually do is use a dual channel setup and measure the loudspeaker at 96cm or 1 meter.

Mostly I use Arta's measurement box for dual channel setup, and take the dB value at 1khz as the SPL.

Another method is to get a 8ohms resistor, crank up the volume till you measure 2.838Vrms across the 8ohms resistor. Then measure the loudspeaker at 1meter.
 
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I would say yes, you did it right. ;up: The measurements look good. Do you have a calibration file for your mic? (I think you said you did).

You can also ungate the measurements you took and use some smoothing, like 1/6 octave, to get a general idea of what you'll hear. Raw response or 1/12 octave will show you nasty peaks that you might need to take care of.
 
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I would say yes, you did it right. ;up: The measurements look good. Do you have a calibration file for your mic? (I think you said you did).

You can also ungate the measurements you took and use some smoothing, like 1/6 octave, to get a general idea of what you'll hear. Raw response or 1/12 octave will show you nasty peaks that you might need to take care of.

Yes, the mic is calibrated, but I use the RegaDAC and I don't know how to calibrated that yet.

How can I ungate the measurement and the smoothing? Can you give me a hint?
 
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