Friday, December 2, 2011

Asymmetric Port Tuning

At the very close new sweet spot (VCNSS) listening position, the image is very transparent and 3D, and the bass seems about right on Bass E (see earlier post about this recording).  Elsewhere in room, the bass is very boomy.  I thinking of getting an active bass trap for that.  I now think Living Room sounds better than Bedroom on Bass E.

Right now I have one subwoofer tuned with 1 port plug (15Hz) and the other tuned with 2 port plugs (10Hz).  I'm thinking of changing 10Hz to 15Hz, because that is the tuning most recommended by Ilkka from his distortion tests, and even SVS themselves no longer recommends the 10Hz tuning on the newest edition.

Adding these plugs has seriously improved my bass in Living Room.

But now I'm also wondering if there isn't an advantage of having the Subwoofers tuned differently.  One problem with stereo subs is that most bass material is actually mono, and therefore if played back through two speakers there can be comb filtering.  If the subs are tuned differently, there is a small amount of random phase between the two subs which could suppress the comb filtering effects.

So when I remove the second plug from the right sub, I should test not only that sub, but the whole system, looking particularly for evidence of comb filtering effects.

I've ordered a tiny amount of Auralex open cell foam.  Just to get started.  I was going to get a pair of Auralex 12" cubes, which are in an inexpensive $80 two cube kit, but decided to get 4" cornerfill (4x4x24) instead.  It seems like nobody actually stocks the cubes, they're drop shipped often with no explanation of what shipping will cost, but Sweetwater had the 4"cornerfill, which I'll call sticks, at a nice discount price with free shipping.

The sticks can be placed in the corner behind the left subwoofer.  The bass in that corner is so intense the wall and windows rattle,  and it would be great if that could be ameliorated somewhat.   I'll arrange the 4" sticks similar to a triangular LENRD in the corner.  A real LENRD would probably be slightly too large, and LENRD's are not available except in $300 sets of 8.

Auralex foam is auralex foam.  There is nothing special about the shaping on the surface of a LENRD, a flat surface would work just as well (or better) for bass.  What really counts is the total volume and where you can squeeze it into your room layout, and the more the better, stuffing all corners would be nice.

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