I used a Radio Shack Digital SPL meter, Room EQ Wizard (free software), an external sound card with LINE IN and a bunch of cables.tammojsmit wrote:Please excuse my ignorancebut how can, or did you really, measure down to 2 hz? This is a first for me!
Here are the quick guide instructions. http://www.hometheatershack.com has an entire section devoted to Room EQ Wizard if you're further interested:
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Wayne A. Pflughaupt's REW Quick Instructions from http://www.hometheatershack.com
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REW quick instructions
Here's a bit of a rough step by step of the setup once the soundcard.cal and meter.cal are loaded and the cables are all hooked up and ready to go..
To go through these steps only takes a second......
1. Run the Check Levels routine (Settings icon, Soundcard tab) selecting Check/Set Levels with Subwoofer in the Levels pull down box, with the SPL meter at the listening position and the dial of the meter at 80dB position (or whatever scale allows 75dB to be measured).
Ensure the REW output VU meter is at -12db and the Sweep Level at -12dB.
Set the Wave Volume at 1.000 and the Output Volume about ~0.500. (If those fields are blank, change Input Device Input and Output Device Output from Default to USB Audio, or the name of the soundcard, if that options available, and Speaker for output, and Line In for input. Change).
Adjust your receivers volume control so the actual standalone Radio Shack SPL meter reads ~75db at the listening position.
Then adjust REW Input Volume to end up with -12dB on the REW input VU meter (i.e., matches the Output meter).
2. Still in the Settings section, run the Calibrate SPL routine (in the Meter Tab) to match REW's SPL meter to the real SPL meter to ~75dBSPL. Make sure the “C Weighted SPL meter is checked.
3. Close Settings window. Run the Set Target Level routine (Target Settings icon to left of screen), which will set the target to ~75dB. Also, set the Cutoff, which is the crossover frequency you’re using
4. Run the Measure routine and set the End Frequency to 200Hz for subwoofers.
5. Measure.................... (use a larger number of sweeps and longer length for more accuracy and less noise)
6. Using the Graph Axis Limits icon, set the vertical scale to 45dB to 105dB and the horizontal scale for subs to 15Hz to 200Hz.
7. Select Filters icon at top of page, to call up windows to tweak EQ filters.
To get a waterfall graph, select the LF Waterfall tab at the top. Then press Generate LF Waterfall icon at the bottom of the screen.
8. To save graph, select Graph from Menu Bar, then Save Graph as JPG. Use 800 size setting.
Talk into the mic 
