Audio and Video Talk > Acoustics and Room treatment

Room EQ Measuring Equipment

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alanB:
It seems my questions were starting to hijack the sub-woofer discussion below.  :P

As suggested I've started a separate thread on the subject although I've only just learnt about the subject.

My requirement is that I would like to be able to quantify improvements to my listening room (and maybe others) after adding sound treatments such as absorbers etc.  Clearly I dont want to spend a lot of cash on this, because that would make the project a non starter.

I understand that to do this I need:
1) Freeware Room EQ software, which I have now downloaded http://www.hometheatershack.com/roomeq/
2) A USB Sound card (bit worried about the cost of this)
3) An SPL meter (it seems the Radio Sahck meter is relatively inexpensive.

Once I have this I understand that I would get the software to generate a sweep signal, which I play through my system via the sound card and RCA intelinks connected to my amp.
The SPL meter records the response at my listening position and I can then compare before and after plots to evaluate any changes made to the room.

Any other tips and hints would be appreciated.

Timber_MG:
Often times the frequency response of cheap electret mics below 50Hz is unpredictable (and some have significant production variations). A calibration is the best answer to this question, but that is a problem here in South Africa where the only calibration facilities cater for mega-buck externally polarized microphones (and those generally only require a measurement point per octave or so and thus one doesn't get the calibration curve one needs for consumer type mics)

A couple of  forum members use the Behringer ECM-8000 with various software packages, but even there we have problems and we will likely go for a calibration exercise in the near future as both sub and HF are in doubt.

GearSlave:
OK, I have elaboratd about my setup in fragmented fashion all over the place, but I'll outline it here for completeness.

My main goal was having a platform that can be used to measure various things, not just room modes. So, I did go all out when purchasing hardware, so it'll maybe exlude it from your list Alan, but may be of use to others. Anyway, I wanted the ability to measure speakers, amplifiers and other bits of audio hardware. So, this setup needed to be quite universal and semi-portable as well.

Hardware:
- M-Audi Firewire 410 Audio Interface. This can also supply phantom power to the mic
- ECM8000 measurement Mic
- Breakout box for speaker measurement with all the loopback capabilities for the measurement reference
- Breakout box for audio hardware measurements with attenuators

Software:
- Sound Easy V14 - Measuring speakers and Rooms
- RMAA Pro for doing distortion measurements

With the rig above I'm pretty much set to measure anything audio related and with the software/hardware I'm pretty much guaranteed of making distortion measurements down to around -110dB.

Just a note on measurement software. I understand that a lot of the freebie stuff uses swept sinewaves to perform measurements. This is the easy way, but is prone to contamination from adjacent signal sources. A better way is to use MLS based systems. This limits contamination of other signal sources affecting the measurements.

Like I said before, this configuration may not apply to you Alan, as it is pretty expensive. But, I noted it here for reference. Also, If you just want to make casual measurements on your room, you welcome to borrow it and this offer stands for anybody else in the JHB are.

Cheers

Gert

alanB:
Thanks guys

As I understand it I would be looking for two types of improvements in the graphs:

1) A "flattening" of the peaks and valleys
2) A decrease in reverberation times

Do I need a highly calibrated mike/spl meter for that? 

Also as an aside what does EQ stand for?  I've worked SPL stands for Sound Pressure Level.  If I'm going to throwing these terms around I better know what they mean  :D

Vaughan:

--- Quote from: alanB ---Also as an aside what does EQ stand for?  I've worked SPL stands for Sound Pressure Level.  If I'm going to throwing these terms around I better know what they mean
--- End quote ---

EQ stands or equalization. In simple terms equalization is the process of boosting or cutting the level of certain audio frequencies or tones compared to other frequencies.

Regards,

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