Rational Acoustics

May 13th, 2014, 02:36 AM
I've read several posts on the forums saying that the less expensive RTA-420 or the dbx microphone are usually good enough for most theatre system tuning, as compared to going to an Earthworks or DPA reference mic. My question is how much do you gain by spending the extra money for the calibration file, specifically for the RTA-420? Is the calibration file worth it? I also see the rational store doesn't have any calibrated mics in stock, which also is a consideration. Thanks for the help!

Arthur Skudra
May 13th, 2014, 10:52 PM
Most of the "cheapie" test mics show most of their deviation starting around 3-4,000 Hz and upwards, the mic calibration file compensates for this variance on axis, thus giving you a bit more confidence in what you see in the HF on the computer screen. You need to determine whether that extra cost is worth the extra confidence you have in making measurements at such high frequencies. In live sound situations, you will probably be making judgements on what is happening at those high frequencies more "by ear" than staring at a trace on a computer screen, considering air loss due to listening distance as well as the type of HF drivers used. In a recording studio, you definitely want the spend the $$$ on microphones because those frequencies are critical to the process, and listening distance so short. I see theatres as being an application that sits between live sound and recording studios, accurate playback of the HF is rather important.

June 12th, 2014, 03:07 AM
The calibrated EMM-6 Dayton by Cross Spectrum, has a pretty flat 20-20K response compared to Earthworks M30 Measurement mic (http://www.hifizine.com/2012/09/dayton-emm-6-measurement-microphone-calibrated-by-cross-spectrum-labs/). Impressive… and cheaper then the calibrated RTA420.