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Discussion Starter · #1 ·
I'm writing to see if I can get some feedback for my ACI Force subwoofer setup. I ordered and received the sub recently and diligently went to work setting it up; reading the guide, playing with positioning, and measuring the in-room response. My findings were that the subwoofer sounds best nearer to a corner, with the bottom plate off, aiming down at a medium thickness carpeted floor. I ran measurements from my primary listening position, twice just to be sure, with an radio shack analog spl meter according to ACI's instructions w/ their test CD. My crossover is at 100Hz, the signal is line level left in, phase is 0, crossover A and B dials on the sub both near 100 mark, and gain on max on the subwoofer with a 1 setting from the receiver (out of 0-20). One interesting thing I saw (and this is perhaps quite normal) is that the subwoofer driver still resonates when frequencies are played that are above 100 well through 150 with the 100Hz crossover. I am enjoying the sub and the bottom end it is filling in but as is usual would like to get the best performance possible. My compensated measurements are listed below. Room size is ~ 12'Hx16'Wx16'L with carpet and one large entry way, of which the audio system is pointed away from, and the room having no other paths for sound to escape.


Atm, i'm considering an EQ system to even out the response(RDES, SMS, or RoomEQ w/ soundcard). Bass traps will be hard to pull off because of WAF but willing to look into it. Thanks for any help.


20 -> 70.2

22.5 -> 70.4

25 -> 68.4

27.5 -> 68.7

30 -> 66.4

35 -> 61.5

40 ->64

45 -> 62.7

50 -> 60.3

55 -> 65

60 -> 70.9

65 -> 72.8

70 -> 737

75 -> 72.6

80 -> 69.5

90 -> 62.4

100 -> 69.3

110 -> 60.25

125 -> 74.2

140 -> 75.15

160 -> 75.1
 

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You can expect a declining sound level above the Xover, but you show an increasing level above 110. Very strange. I assume you are measuring just the sub. Have you tried the Theater setup?


If you leave it connected as is, I would turn the gain down on the sub and up on the AVR. I would also set the Low Pass filters to 250 and let the AVR handle bass management.
 

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It is strange that you SPL increases above your crossover. I'm assuming that your measurements are without the speaker.


Your frequency response is relatively uneven. If you have already optimized placement, any of the equalizers you mentioned should help out some.


As far as bass traps are concerned, you might want to look at GIK Acoustic's corner traps. They have a little more WAF, IMHO.


BTW- you have a mighty fine subwoofer!
 

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Discussion Starter · #6 ·
i went ahead and recalibrated with the subwoofer gain at halfway. this time my receiver subwoofer setting is at 10/20 and i am running it about ~4db hotter then my LCR speakers according to radioshack meter.


i'm running measurements with subwoofer and speakers hooked up with the test cd tones. i'll try setting the low pass filters to 250 and see how it changes the sound... and run some more measurements

i'll look into eq and room traps, since placement is restricted. thank you, it is a great subwoofer, i just really would love it to sound as good as i know it can/should.
 

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Congrats on your sub!


The Force is a nice sub (i had the Titan, and now have the Maestro XL). The crossover is about 24db/octave if you use the subwoofer's crossovers together at the same frequency. That roughly means that if you crossover at 110hz, then you will have appreciable output into the mid 100 hz frequencies. By 220hz, the subwoofer should be minimally impacting the sound.


The Force is small enough such that you can place it at your listening position, and crawl around your floor to find where the bass is most even. This process may take some time, but I have found that it is worth it. You simply play the test tracks and keep the RS meter in your hand and take down notes of "problem" frequncies. The location with the least "problem" frequencies is the place your sub would sound the best at when you sit at the listening position.


Typically, I wouldn't consider putting the subwoofer amp's gain beyond the 40% mark. Also, if you use the theater input, the subwoofer's gain and crossovers may be bypassed such that changing the setting on the subwoofer will not change its performance. This will allow you, if you have a good receiver, to assign all the settings that you want for your speakers and subwoofer in the receiver.
 

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Discussion Starter · #8 ·
i spent some time today trying to place the sub. there are only about 3 places where it can go, and 2 of them block some of my av components. in one spot the bass sounds like it's almost gone, very disappointing, and that spot would have been the best for it (near a sidewall). the second and third spots are both more near the front and sides and work better but not great. when i go stand in the corner of my room the bass sounds full and great. to imagine this is all with just one listening position in mind, and the frustration of measuring and adjusting for many positions, makes it worth considering that putting a subwoofer in a room with subpar-average response is not worth it at all. there should be more warning and attention paid to in-room response instead of manufacturer specs and promises/hype.
 

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Quote:
Originally Posted by dano1122 /forum/post/0


i spent some time today trying to place the sub. there are only about 3 places where it can go, and 2 of them block some of my av components. in one spot the bass sounds like it's almost gone, very disappointing, and that spot would have been the best for it (near a sidewall). the second and third spots are both more near the front and sides and work better but not great. when i go stand in the corner of my room the bass sounds full and great. to imagine this is all with just one listening position in mind, and the frustration of measuring and adjusting for many positions, makes it worth considering that putting a subwoofer in a room with subpar-average response is not worth it at all. there should be more warning and attention paid to in-room response instead of manufacturer specs and promises/hype.

The corners are bound to have deep nulls and sharp peaks... this is one of the highest excitation of room modes locations. How does the sub sound in between your Left and Right speakers? How does it sound near the front wall around your speakers? How does it sound right next to you? Is your listening position in the center of the room, or on even fractions of a room dimension -- if so, you should consider moving the listening position as you will have trouble some nulls that are only somewhat mitigated by room treatments.
 

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Mike and the rest of the tech staff at ACI will help you with setting up your force.

Don't be too frustrated, enjoy playing around. Don't forget that it is ok to just set it up by ear, your ears are very sensitive and effective tools.

I was lucky, I just plopped my Titan where I wanted it and adjusted it by ear. Just a little room bump at aaround 30 Hz, other wise a very smooth musical sub.
 

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Looking at your original #s . . . you're flat to 20Hz and probably below . . . excellent!

You've got a null from around 35-50Hz, very common.

You've got a peak at 65-75, again, very common.


The rising response above 100 might be your mains or their placement. You might be able to reduce that by lowering the subwoofer cutoff on one or both filters.


Even with the peaks and nulls, you only +- around 6 db under 100Hz . Not bad for an untreated domestic room. I've seen (lots of us have) FAR worse.


Standing in a corner or moving the listening position against the back wall will yield gobs of bass, but there are problems of course.


An EQ like RDES can tame the peaks but won't do much for the valleys, but they won't be nearly as obvious once the peaks are cut down. Room treatment will help with both and offer other subjective improvements as well.


And most important, I wouldn't get too hung up on the #s . . . they can be pretty intimidating at first. It's all about enjoying music and movies, not #s
 
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