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Discussion Starter · #1 · (Edited)
Hi all.

I am working on solutions to anemic bass in my home theater. . . Well, not entirely anemic. I think it's the "slam," room pressure aspect that is missing. The bass quality is actually great (music) and scenes such as the opening of Edge of Tomorrow are earth shattering. But, that's low extension.


This room is somewhat oddly shaped, kind of like a plus. 120X220 (inches) X8 (feet). The right wall length is 220. The left wall length is 236. The room is sloped. At its highest point it is 8 feet. That point spans about 5 feet across and then it slopes sharply to the wall. There is 106 inch screen in the front of the room. I have a 5.1 setup. Front left and right speakers are toed inward toward the listening position and fairly close to the side wall and a couple of feet in from of the front wall. There are two windows in the room, both covered by wooden blinds. One is sloped, almost like a skylight. The other is small. Both are within the plus portion of the room (two alcoves that are in the middle of the room to the left and right of the sitting area). The floors are wood. I have a 9X12 area rug in the room that is thick and on a furniture pad. The room initially was extremely reverby. I consulted with Gik and got a bunch of room treatments. This made a massive difference in sound quality in the room. Just massive.

B&W 603s3 fronts
600 series center
685 rears

Subwoofer: initially SVS 10 inch ported sub. now, PSA s3000i. Moved the SVS downstairs to an open and large living room (much bigger room). The SVS slams harder than the bass in my theater in some frequencies. This is obviously not the fault of the s3000i.

receiver - denon x4100 . . . calibrated with Audyssey x32

I really need to do some measurements, but I need a mic. I've done the subwoofer crawl. Seems the left front corner works best. Sub is placed in between the left and center front speakers. My questions:

- Does orientation of the subwoofer matter? Since I've had it (January or so), I had it oriented so the drivers pointed at the left and right speaker (perpendicular to listening position). This morning before heading to work, I turned it so that one driver is facing the listening position.

- Should I be concerned about interference with my left front speaker if it is too close? I moved the sub closer to the left speaker, about an inch away from it, slightly behind it. This gets the sub much closer to the corner.

My immediate impression was that these two changes improved bass output. But, I need to do more testing. I think I am probably fighting a bass null zone.

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This is pretty much the go-to measurement mic:
It is USA-lab calibrated for 5hz-24khz +-3db (often times +-1db).

The version directly from China is only rated to 20hz (from an unknown lab in china), that's why it's $20 cheaper.

I use this USB extender so that I can walk the mic around the room with the subwoofer at the seat to find the best spot (much better than crawling on hands and knees and "guessing".)

As for the subs. Yes orientation can make a difference.
Often times the best location for a subwoofer is either nearfield (within 2ft of your head/ears) or at the closest wall/corner junction with the cone facing and placed within 5 inches of that nearest wall.

That gives max SPL with minimum nulls.
It doesn't always work, but it works more often than it doesn't... try it.

The only downside is that you might lose some SPL above 60hz.

When people complain that they lack 'slam' it is often because they have a null somewhere between 40 to 300hz, or they aren't using a pro-subwoofer with a +100db/watt efficiency.

Such as a JTR OSP:

Or on the cheap-end a Behringer B1800HP:

Or for the DIY crowd, a PA-460 in a 35hz ported box:

My B&W's are fine for music, but they aren't very good for loud action/horror movies.
I went the PA-460 route, and eventually phased the B&W's out of my system entirely by adding better and better drivers to my DIY mains until the B&W's were out-classed.

Adding the super-tweeters and extra subs closed the gap, the B&W's could no longer compete or keep up.

Just a matter of effort and will power. :)
My DIY mains are cheaper than your B&W 6 series, or about the same price.

My mains and center are flat from 4Hz to 40kHz as they are 4-way's (and 100db/watt and rated for 2000watts RMS per.)

The downside is that they are a quad 8-ohm load per speaker. Which means lots of amplifier channels to push them since they are active speakers (digital XO's).
[Can't power these with an AVR! insufficient channel count and power, missing onboard multi-way XO's too.]
Similar to the B&W Nautilus snails: 4-way and external XO's... (fairly optimal, but not very practical or common.)

You should really hear an action movie with them though, it is straight up nuclear! (Just the way action is meant to be played IMO! ;))
It literally feels like being bombed.

From anemic-bass to too-much-bass, guaranteed! ;)


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75" Samsung Q80R QLED, 2x Amazon Echoes, Echo "Sub", Amazon 4K Firestick. Yep, I'm high end baby.
8,908 Posts
Here is the solution, short and simple:

1) Get a Umik-1 mic and REW or Dayton Omni mic.
2) Get a matching S3000i and place the two subs properly via measurement.
3) Enjoy.
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Reactions: Madmax67

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Two things to try that helped me get more "slam" out of my system:

  • Turn off DynEQ and add 5 or 6dB to the sub trim
  • Turn the crossover up to 120hz
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Reactions: Madmax67

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Discussion Starter · #5 ·
Thanks for the responses. I will order a mic and do some tests. Turning the speaker seems to have a made a difference. One speaker is now firing rear (s3000i has two speakers) and the other toward the listening position. I haven't tried and movie sequences yet nor anything at volume, thus I'm not sure about "slam" yet.

The room is small (around 1500 cubic feet), so two s3000is seems like overkill. But, maybe. . . I've thought about it.

The DIY route would yield cabinets too big for my space, I think. But, nice work!

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The DIY route would yield cabinets too big for my space, I think. But, nice work!
My room is 3000cuft. Your's is only about half that volume. It is still possible to fit all my subs in a room that small.
You would have to use a 5.1 system instead of 7.1, and you wouldn't be able to build huge horned subs, but you'd have room for 2 big ported subs and the rest being sealed.
You would be limited to about 3 seats plus 4 bean bags for kids. Definitely a step smaller, but still do-able.

My left and right only takes up 3sqft each. The center takes up a bit more: 7sqft. The 16 subs takes up 20sqft. That leaves you with lots of sqft for seats, side speakers, and a wall mounted screen (which takes up no floor space).

The reason why they use so little floor space is that they are all stacked 4-7ft tall, and I jam them right up to the front wall and corner to maximize the appearance of even more floor space.

DIY has no fixed size. It is possible to mount 5 UM-10's in a 20x20x20 box (or maybe even 6 with rubber feet) or 2 in a 12x12x12 box, or maybe 4 UM-15's in a 20x20x20 or 2 UM-18's etc etc etc
At least the mounting depth seems valid (I haven't double-checked the cross-sectional area.)
That's a lot of bass in a very small box.

Not that you'd want to DIY. Just saying that: it is possible.
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