Figure 2 shows the simulated and measured responses. I also measured just the woofer in the vented box.
#True audio truerta pro
I measured the box dimensions and then used Harris Technologies’s BassBox 6 Pro simulation software to model it as an unfilled, vented enclosure. I measured Vas with the added-mass method. I used Dayton Audio’s WT3 woofer tester (which was recently replaced by the Dayton Audio Test System) to measure its Thiele-Small values with Dayton Audio’s WT3.
#True audio truerta free
I disassembled one of the units and removed the 5.25″ woofer, which I suspended in free air. I wasn’t content to just examine the overall frequency response, so I decided to dig deeper.
My test determined that the reviewers were right about the MTX 5i’s weakness in the midrange frequencies (see Figure 1). (I used a Tenma 72-7260 sound-level calibrator to achieve absolute calibration at 1,000 Hz.) I used TDL Technology’s Model 411 measurement microphone amplifier as a microphone preamplifier.
With groups of three, you can self-calibrate by comparing microphone pairs. The microphone was one of a group of three Behringer ECM8000 electret condenser microphones or one of a group of three Dayton Audio EMM-6 electret condenser microphones. The graveled ground scattered the noise and minimized direct sound reflections. I mounted the measurement microphone on a plastic tripod, which I could place up to 30’ from the speaker. I placed the test speaker on a wooden platform about 4’ off the ground. I used a speaker cable and a microphone cable that run through the wall outside my computer room to measure the loudspeaker performance. So try to minimize sound reflections into the measurement microphone.) (Quick Sweep is not gated, which means the measurement time is longer than the signal duration. I used True Audio’s TrueRTA Quick Sweep Version 4.0 spectrum analysis software and pink noise to conduct a listening test and make an outdoor measurement. Except for the 150-Hz peak, the curves are not similar. I used TrueRTA Quick Sweep software for the measured response (green circles). Figure 2: The frequency response of the original MTX 5i woofer in a vented box (green circles) is compared with a simulated response (blue triangles) using BassBox 6 Pro software.