Rotary Subwoofer Install Blog

October 10, 2006

TRW impact on movies… here are numbers

Filed under: Uncategorized — bassment @ 11:14 pm

I’ve taken some spectral analysis during some movie sequences suspected to have low bass content.
These snaps are of a peak hold FFT during the scene… so you are seeing the maximum SPL levels reached between 0 and 90 Hz for the 2-3 minute clips of interest. I believe Bruce and I calibrated this mic when he was here, so the SPLs should be somewhat accurate, but I’ll do the cal again soon, just to make sure.


HHGTTG Earth Demo w TRW.GIF

this is HHGTTG (dts5.1), when the earth is demo’d. Notice that we’ve almost reached 115dB at 10Hz. Cool.

I need to post another snap of what happens without the TRW’s.


m and c cannon scene dts5.1 w TRW.GIF

this is Master and Commander (dts5.1), with all 5 subs woofing away. Pretty cool to listen to.

Nearly 110dB SPL across 1-5Hz.


m and c cannon scene dts5.1 no TRW.GIF

Now for the same scene in M and C without the TRW’s. The crossovers are set so that the XS is responsible for the performance around 20Hz.
You can see that it does pretty respectably down to 18Hz at 100dB or so… not bad at all!
My sentiments at this moment are to first calibrate the mic once again, and endeavor to make sure that these SPL readings are in fact accurate. Because if they are, I want to see 110-120dB SPL peaks being reached instead of 100-110.
I think. I am not sure… 120dB might just rattle the room apart as I’ve noted before… but 115 seems doable without drywall crumbling to dust.

I have put some fiberglass just behind the grill covering the TRW’s manifold … this has reduced fan self noise, but perhaps whacked a few dB off output. I have the following courses of action, again, assuming the mic is calibrated:
1) increase amplifier output… right now I am at 12 o’clock on the dial.
2) I could try opening the garage door or window up above… that provides more venting back space
3) I could try opening the media room office door…that would provide ultimate venting.
4) combination of 1 and 2or3.

I’ll check with Bruce as well… he got a clean 120dB out of the system with pure tones…I need to acquire that software and see if I can duplicate our earlier outputs.

Tomorrow I will post some pics of the finished install areas. I am no finish carpenter, but I did a decent job on the grills for which I copied Winstons original design.


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