4 manifold infinite baffle setup - AVS Forum
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post #1 of 12 Old 07-08-2012, 01:18 AM - Thread Starter
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Hi Guys,

I have built a 4 manifold IB system with 2x 18" FI IB3 drivers in each manifold, each (ceiling mounted) manifold is in the corners of a virtual room of my room size shrunken by 25% (width and length). The actual room size is 7'7" high by 22'6" long by 13'1"wide.

Both the front manifolds are powered by an Behringer EP4000 with each manifold on a separate channel and the same with the rear. The receiver is an Onkyo 5009 and each EP4000 is on a separate sub output from it.

I have been running the drivers in with the pretty loud bass tones from a bass test CD and using REWs sine wave function for the past few days. Its pretty powerful;)

Now its time to set it all up. I have had advice to set up each manifold in turn by running the 5009s sub calibration noise through the manifolds in turn and setting the EP4000s channel gain settings so that there is a 72db SPL at the main seating position.

Then i ran a sweep on REW (I am using a 2nd generation Radio Shack spl metre) with the associated .cal file imported into REW and have calibrated the sound card with a loop as instructed.

Here is the sweep with all manifolds on-
1stsweep1.jpg

As you can see its fab below 50hz but then massive dips. I then did some sweeps with just the fronts and then just the backs running-
frontmanifoldsonlysweep.jpg
rearmanifoldsonlysweep.jpg

And then finally I ran Audyssey and did another sweep-
after1staudysseyeqtdlspeakers.jpg

Much better, but still work to do. Any suggestions? Next step is to run a sweep on each manifold on its own.

Thanks in advance!biggrin.gif

Steve
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post #2 of 12 Old 07-08-2012, 09:56 AM
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did you try the manifold crawl test ?

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post #3 of 12 Old 07-08-2012, 10:24 AM
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Quote:
Originally Posted by bighairybloke View Post

Hi Guys,
I have built a 4 manifold IB system with 2x 18" FI IB3 drivers in each manifold, each (ceiling mounted) manifold is in the corners of a virtual room of my room size shrunken by 25% (width and length). The actual room size is 7'7" high by 22'6" long by 13'1"wide.
Both the front manifolds are powered by an Behringer EP4000 with each manifold on a separate channel and the same with the rear. The receiver is an Onkyo 5009 and each EP4000 is on a separate sub output from it.
I have been running the drivers in with the pretty loud bass tones from a bass test CD and using REWs sine wave function for the past few days. Its pretty powerful;)
Now its time to set it all up. I have had advice to set up each manifold in turn by running the 5009s sub calibration noise through the manifolds in turn and setting the EP4000s channel gain settings so that there is a 72db SPL at the main seating position.
Then i ran a sweep on REW (I am using a 2nd generation Radio Shack spl metre) with the associated .cal file imported into REW and have calibrated the sound card with a loop as instructed.
Here is the sweep with all manifolds on-
1stsweep1.jpg
As you can see its fab below 50hz but then massive dips. I then did some sweeps with just the fronts and then just the backs running-
frontmanifoldsonlysweep.jpg
rearmanifoldsonlysweep.jpg
And then finally I ran Audyssey and did another sweep-
after1staudysseyeqtdlspeakers.jpg
Much better, but still work to do. Any suggestions? Next step is to run a sweep on each manifold on its own.
Thanks in advance!biggrin.gif
Steve

Looks like a pretty sweet house curve. Do these measurements have any mains running?
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post #4 of 12 Old 07-08-2012, 11:14 AM - Thread Starter
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Hi both,

Otk, I didn't do the subwoofer crawl i followed the advice from here http://www.onhometheater.com/features/20040801.htm on placement of 4 subs.

I did have some old small floor standers i use in the workshop so i used those, my proper mains will hopefully come this week.

Steve
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post #5 of 12 Old 07-09-2012, 07:20 AM
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Looking good! I don't see ANYTHING to mess with on that last FR graph. One thought, you'll get more SPL capability by gain matching rather than level matching. I know you're not likely to be pushing the limits but depending on the disparity between levels on the 4 channels being used you could run into issues (one channel could be clipping while the others are coasting). Ideally all the drivers would be running off the same power source, since you're running two EP4000's that isn't an option though. You could get it down from 4 to 2 though by wiring the two front manifolds together and running them bridged mono on their EP4000 then doing the same on the rear manifolds then try to set both EP4000's the same. It could be difficult to set the levels across the 2 EP4000's accurately though as there's no guarantee the knobs correlate to the same power. It's probably not necessary but you could calibrate them by running a test tone with the subs disconnected and measuring the output with a multimeter biggrin.gif

You mentioned measuring each manifold separately. I don't think there's much value in that exercise as you aren't concerned with what each is producing - just the summation. Rather than measure each manifold measure more seating positions and try to optimize for the best average smile.gif
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post #6 of 12 Old 07-09-2012, 12:58 PM
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Quote:
Originally Posted by bighairybloke View Post

Any suggestions?
Steve

I have a suggestion. Dont change anything. The 2D plot is close to perfect. Now, get us a 3D one (amplitud. frequency, time) to see if there are any ringing going on.
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post #7 of 12 Old 07-10-2012, 05:32 AM - Thread Starter
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Thanks guys, i agree all looks good with Audyssey doing its thing, but was wondering if its possible to do something to help the eq have an easier life...however audyssey is doing its job fine so likely just leave it alone!

Will post a waterfall shortly...

Steve
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post #8 of 12 Old 07-10-2012, 11:10 AM
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Is your 4 manifold placement based on Floyd Tool's multi-subwoofer placement research? I have a single manifold setup in my rented house. There was already a perfect HVAC vent hole in the floor that I re purposed for a dual 18-inch IB manifold. I now have house shaking bass but if I move a few feet to another seat the bass is completely different. I'd love to cut a 2nd hole on the wall opposite the first manifold to smooth seat to seat response, but as a renter that's just not possible.
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post #9 of 12 Old 07-10-2012, 11:37 AM
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Quote:
Originally Posted by bighairybloke View Post

Hi Guys,

I have built a 4 manifold IB system with 2x 18" FI IB3 drivers in each manifold, each (ceiling mounted) manifold is in the corners of a virtual room of my room size shrunken by 25% (width and length). The actual room size is 7'7" high by 22'6" long by 13'1"wide.

Both the front manifolds are powered by an Behringer EP4000 with each manifold on a separate channel and the same with the rear. The receiver is an Onkyo 5009 and each EP4000 is on a separate sub output from it.

I have been running the drivers in with the pretty loud bass tones from a bass test CD and using REWs sine wave function for the past few days. Its pretty powerful;)

Now its time to set it all up. I have had advice to set up each manifold in turn by running the 5009s sub calibration noise through the manifolds in turn and setting the EP4000s channel gain settings so that there is a 72db SPL at the main seating position.

Then i ran a sweep on REW (I am using a 2nd generation Radio Shack spl metre) with the associated .cal file imported into REW and have calibrated the sound card with a loop as instructed.

Here is the sweep with all manifolds on-
1stsweep1.jpg

As you can see its fab below 50hz but then massive dips. I then did some sweeps with just the fronts and then just the backs running-
frontmanifoldsonlysweep.jpg
rearmanifoldsonlysweep.jpg

And then finally I ran Audyssey and did another sweep-
after1staudysseyeqtdlspeakers.jpg

Much better, but still work to do. Any suggestions? Next step is to run a sweep on each manifold on its own.

Thanks in advance!biggrin.gif

Steve

Edit: Nevermind just saw you were @60db those graphs look big threw me off. smile.gif

Maybe add a graph of each discrete sub channel independently to see what they are all doing under that total graph.

Dont forget to read and apply the Tips in audyssey thread about tweaking sub distance/phase.

Looks pretty stout on output. Nice Job!

Don't waste time reading signatures.....
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post #10 of 12 Old 07-10-2012, 11:48 AM
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Nick,
Wow lots of potential with this setup!!!
Looks like it should did down to about 8hz (or less)?

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post #11 of 12 Old 07-11-2012, 12:21 AM - Thread Starter
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607d5d80.jpg

The only treatment at the mo are commercial foam type 12" bass traps in four corners and some 3" acoustic wedges on the ceiling.

Yep, she goes down lowwwww!

And yes manifold placement is based on Tod Welti and Floyd Tools research, ie shrink room by 25% and place subs in the corners of the shrunken room.

Steve
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post #12 of 12 Old 07-12-2012, 11:20 AM - Thread Starter
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So guys what do you recon? Any good?

I was thinking of making a couple of poufes to rest our feet on but also double up as substantial bass traps if i cover them with acoustic fabric.

Had the speakers come yesterday- Klipsch RF-7II and the matching 4 surounds and centre----WOW!!! I am in audio heaven and it can only get better still with the further room treatments i will be adding!

Steve
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