No, you can simply set up a reasonable level during the Check Levels routine (that asks you to set the listening position to 75dB with an SPL meter). Once the Check Levels routine is complete, then run the Calibrate SPL routine and cheat by setting the value in the thumbwheel to 75dB. This now sets the internal REW SPL meter to match the level you set at the listening position (whether it was 70dB or 80dB doesn't matter). The graph will then place its traces at 75dB for you. Rerun Calibrate SPL every time you change a system level.Do I really REALLY need an SPL meter in order to measure my room?
No problem. Just create a text file using Windows Notepad and save the file with a .cal extension. The files data is a list from low to high frequencies of the mics response you take from the graph. The interval spacing is not important as REW will fill in the blanks between readings. Download a calibration file of any mic from our download page and drop it into Notepad to get the feel for the layout. Once your file is created, load it into REW and take a look at the trace and see if it is a reasonable facsimile of the graph you have for the mic.a manually created calibration file for the Mic (I would want to punch in values based on the mics freq response chart)
You can use Response, Waterfall and ETC to great advantage in your setup.