Rotary Subwoofer Install Blog

September 30, 2006

Hard Numbers are in…

Filed under: Uncategorized — bassment @ 12:00 pm

OK, here are the results of the installation of the dual TRW’s seen here in this blog.
First let me say that Bruce wants to convey this data to show what the distortion is at given frequencies vs SPL.
Actually the 120dB here is more like 125dB, but he wanted to be conservative, but do understand that the distortion figures hold more or less for another 3 to 5dB. The charts below are all SPLs and distortion measured at the golden seating position.
Distortion for 1Hz at 120dB SPL
tzucc install 1Hz 120dB.jpg

Distortion for 7Hz at 120dB SPL
tzucc install 7Hz 120dB.jpg

Distortion for 9Hz at 120dB SPL
tzucc install 9Hz 110dB.jpg

Distortion for 12Hz at 120dB SPL
tzucc install 12Hz 120dB.jpg

Frequency response of TRW solution, at seating position, about 1/2W of amplifier power:
tzucc install freq resp.jpg

We are going to tweak up the crossover to get closer to 20Hz on the upside, so as to blend with the Watchdogs better.
Note that this curve can be shifted all the way to 125dB SPL or more without compression. The point is you can see how flat the response is from 1Hz to 20Hz. Probably from 0 to 20Hz, but the mic probably doesn’t respond well to less than 1Hz:)

There you go… this establishes the TRW as a solution for previously unknown SPL levels at sub 20Hz frequencies, AND with low distortion. You can find reviews on the web for various 15″ and 18″ subs with phenomenally high distortion at levels like 95dB at 12Hz. Of course, this isn’t really fair, since most of these subs aren’t tuned for performance below 20Hz, but just to make the comparison for funs sake, it would take fifty dual 18″ subs to equal the current TRW install at 12Hz.
How’s that for a figure of merit? Again, it’s not a fair comparison, because these other subs aren’t tuned or designed to even try for 12Hz.

Next up is to get some graphs of SPL’s reached during various movie clips… check back tomorrow AM for that.

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