My experience in two partial days of testing:
Equipment: Laptop: MacBook Pro, 2.16GHz Core2Duo, MacOSX 10.5.4 Leopard.
Mic/preamp: Behringer ECM8000 into Behringer UB1202 mini-mixer. Radio Shack digital SPL meter.
Amplifiers: Eden WTX260, Eden WT500B, Stewart PA200B (tried 'em all)
Setup & calibration: Yesterday, I spent almost two hours trying to get the program to create a calibration sweep for my MOTU 828MkII FireWire audio interface. Turns out the program has some problems between its Java code and the Mac, which makes many external devices fail. The Mac's internal line-in/line-out are within about 0.5dB across the spectrum, so I used this interface, and created a calibration file. One less thing to carry. This problem is only on the Mac; the program apparently works fine on Windows systems.
SPL meter: The program generates pink noise; you tell it what your standalone SPL meter shows, so its reading matches. The RS meter showed 110dB; I couldn't enter numbers >100 into the program, so I used 90dB and manually remembered it was 20dB shy. (I've reported that to the author.)
RTA: The RTA is easy to use. You get to set start/end frequencies, output level, sweep speed and number of sweeps. Trace smoothing ranges from none to 1/24 octave. A single click option separates all traces by a few dB for readability. You can enter an offset for any curve; if you wish, REW will even add that offset to all the data points. REW can export an entire curve as a list of freq/dB numbers in a .txt file.
In my garage, I ran several sweeps of the Eden D112XLT and Omni15 cabs at 1w/1m. My cheap multimeter only has 0.1 resolution, so 2.8v was the closest I could get. (I just ordered a Fluke 115 DVM.)
Amplifiers: I tried three: The Eden WTX260, the Eden WT550B, and the Stewart PA200B. Surprisingly, the five-pound Stewart was flatter below 35Hz than either of the Edens. They were almost identical and dropped of several dB below 35Hz. I didn't try getting 28.3v (100w) out of any of the amps; the Eden 550 is probably the only amp I have that'll do so into 8 ohms.
Documentation: The program automatically displays its dozens of pages of documentation; there's also the online forum. A copy of the documentation is here: http://www.hometheatershack.com/roomeq/ ... index.html.
Mac Usability Annoyances: I don't like CTRL for keyboard shortcuts, since the Mac uses its CMD key. Vertical scrolling of the RTA curve is reversed from conventional scrolling. The aforementioned problems with outboard sound I/O devices should be fixed. SPL calibration >100dB needs to be fixed.
Conclusions: For a free program, REW looks very good. I still have to fiddle around with the SPL calibration, and I have to double-check that I ran the RTA sweep at the same level as the SPL calibration. There'll be more fooling around and learning before I lug everything out into the wild for outdoor testing.
Attached: Red trace is Omni15 (3015LF+mid, no tweeter); green is Eden D112XLT. Amp is the Stewart PA200B. 2.8x volts at 1m. Smoothing 1/3oct. Caveats: It's an indoor test with room interactions; this probably explains dips at 32Hz, 128, and 256Hz. Absolute SPL numbers may not have been properly calibrated.
