After reading last night about modding the Sony 12" 120W SAWM 40 subwoofer, I thought I would give it a shot. My first mod dontcha know.
All it involves is taking some polyfil and stuffing the insides of the casing with it. Prior to it, the only internal insulation the thing had was a 1/4" thick piece of polyfil on the wall opposite the woofer. Not much at all. I took probably a 1/4 pound of the stuff and stuffed it in so that the two sides and top walls had another 3-4" of polyfil in them. The bottom of the housing was left alone so that the port would not be plugged.
The results were worth the $5 and 15 minutes of time. I did no testing with an SPL meter. I still need to get one. :) Anyways, all results are subjective, but thats what really counts. I did a before and after using my HT demo DVD that I am still in the process of finalizing. Tracks reviewed were:
Matrix lobby scene
LOTR FOTR battle scene were Sauran get his hand chopped off, ring falls and body explodes. (I find this scene to be a good measure of a sub's capability as it goes deep and has a distinct tone that reveals quality in the sub as well.)
Antz picnic scene
Finding Nemo with Darla
U-571 depth charge scene
Equipment and settings:
DVD player: Pioneer DV 434
Speakers: Polk R40 (front) set to small
Polk CSi20 (center) set to small
Monster Cable subwoofer cable
AVR: Onkyo TX-SR 600 (crossover set to 80Hz) Volume set at 70
Subwoofer: crossover set to ~110Hz and gain at the 1:00 position.
The two words that come to mind after the mod are clean and tight. Clean in that before hand it felt as if the sub would let out, in addition to the intended bass, noticable amounts of bass in the surrounding frequencies. Now it really feels that the correct tones are delivered without competion. Clean.
Tight in that it hits the note and its over with. This has really been a problem when listening to music. Classical, rock, jazz and even rap. It was easy to tell the bass was just dragging on too long. I have yet to evaluate this with music, but the bass was much tighter after the polyfil.
Some reviews have argued that the quality of the tone/timbre was improved post-mod. I didn't really notice this, but it may be. Of the above scenes, Sauran's explosion was the most dramatically improved one. Again, I have no SPL meter to evaluate, but it felt as though the bass extended deeper. I have heard all the scenes on an SVS 20-39, for reference. After the mod, the bass extension was closer to matching the SVS than before (and still very far away). Any extension lower is minimal and debatable.
Bottom line: a fun, easy, cheap and effective mod that has injected some fun back into my little hobby. The results were small but significant. I am looking forward to getting some time with music on the rig now and evaluating the mod further.