Sub response and measurement in room

[BradJudy]

So, I'm sitting at home thinking 'I have a nice quite Sunday and nothing NEEDS to get done, so why not do some measurement?' A few weeks ago we had rearranged our family room (basically rotated it 90 degrees) and I hadn't done any measurements since. For reference, here was a measurement I made before rearranging the room:



I whip out my trust ETF/ECM8000 combo and get to work. At first things are a bit odd because I had the receiver configured wrong for the front panel input. I can only set my crossover to 40 or 60Hz when using stereo mode on the analog inputs on my H/K, leaving me with some response issues (80Hz is best for my speakers). I switched to DPL II to get a 80 Hz crossover and measured this:



Ouch, that isn't pretty, but looks like at least a partially easy fix. Those who have spent time around crossovers (or out-of-phase drivers) will recognize the reverse null. So, I switched the phase on the sub from 0 to 180 and measured again:



Ding, my toast is done!! Forget the R-DES and/or room treatments I was considering before. Wrap up the measurement HW and kick back and enjoy.

Feel free to debate the impact that using DPLII had while taking these measurements. I'm going to enjoy the rest of the day.

(Cross-posted to AV123 forum - forgot to mention this is using a Hsu VTF-2 MkI).

[bikeman]

Because I have a BFD, I'd have to tweak it. Without the BFD, I'd be real happy with your results. Congrats.

David

[curtis]

I still want to mess around with my BFD some more, but finding time has been tough, and I have been lazy.

Brad....looking at your last graph....geez, some guys have all the luck!

[BradJudy]

Even if I have a BFD or R-DES in hand, I wouldn't tweak it. It would probably be hours of tweaks and measurements just to go from +/-2.5db to +/- 2db (maybe 1.5). Either way, a lot of work for what would likely be an inaudible improvement.

[bikeman]

Even if I have a BFD or R-DES in hand, I wouldn't tweak it. It would probably be hours of tweaks and measurements just to go from +/-2.5db to +/- 2db (maybe 1.5). Either way, a lot of work for what would likely be an inaudible improvement.

Brad, you're forgetting all the fun you'd have along the way. It's the journey, not the destination.

David

[CraigT]

What equipment was used for those measurements? I did a search and found that the ECM8000 is a mic but not sure what an ETF is.

[BradJudy]

ETF is the measurement software by Acoustisoft. I'm also using an M-Audio MobilePre as the soundcard/mic pre-amp. With this setup, noise is minimized since everything is using my notebook's battery.

I'm also using a RadioShack SPL meter for the SPL calibration - it isn't terribly accurate, but only relative values matter in this measurement, not absolute SPL numbers.