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I've been doing some alterations and re-calibrations to the new speaker set up and I have to say the results were very surprising!
For the first time I've been really able to hear the benefits of the baffle wall..:T

I first of all mounted the centre speaker on some of that rubbery mat material..It was thin enough to just fit under the speaker and still be able to slide the speaker in and out of the baffle..
Doing this took out most of the hollowness I was hearing..and gave the centre more projection..
I also moved the speakers back a little so they were absolutely flush with the baffle wall..They had previously been protruding slightly..

I then placed some of the car carpet under the subwoofer..I had previously been using a rubber backed carpet tile..It had been quite affective but I thought I would try the baffle wall carpet..

I re-calibrated the whole system..including room reverberations and standing waves using MCACC..and re-set the levels with the SPL meter..

I put on "2012" and the end result quite blew me away!!
The projection of sound forward from the sides of the screen was very strong and the overall sound stage was very good..
But what really got me was that for the first time the whole room was full of sound!! It really felt like I was there in the middle of all that chaos..
The sound projection was that good that the fronts and the surrounds just blended together so there was sound all along the walls, overhead and in the middle of the room!
That movie never sounded Sooo..good!..

The lower bass also sounded more defined as well, with a very smooth transition between the fronts and the sub..So the car carpet works well under a sub..

As you might have guessed, I'm very impressed with this baffle wall!! :D

My next test will be the stuffing of the ports with cotton wool balls..I can't imagine how there could be any further improvement!
 

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Discussion Starter #144
Prof,

Sorry if I missed it. Is your screen up?

You wait until your actually watching a film and hearing the sound actually come from the picture.
 

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Prof,

Sorry if I missed it. Is your screen up?

You wait until your actually watching a film and hearing the sound actually come from the picture.
Oh yes!..It's been up since before working on the baffle wall!
The point location of voices across the screen is very realistic..:T

Prof, I'm glad to hear it. It will surely bring enjoyment for years to come.

Dan
Yes thanks Dan..Watching movies won't be quite the same again..:D
 

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My next test will be the stuffing of the ports with cotton wool balls..I can't imagine how there could be any further improvement!
Well I was wrong!..There does seem to be some further improvement with the ports stuffed..:T

I put on "Poseidon" last night and I could here a distinct difference in certain frequencies..

Starting from the very low bass, I couldn't hear much difference there, but in the mid to upper bass it sounded more defined with more of a musical quality to the bass notes..

Voices took on a richer and fuller sound, with very good projection..In that movie there is lot of combined sounds with voices, explosions, surround sounds all about..and music playing all at the same time..and the voices would sometimes tend to blend in to the rest of the sounds with my previous set up..This time I was able to almost distinguish every word!

What I did notice was how well defined mass orchestral strings sounded..With this particular movie it's always sounded a bit gritty with some distortion coming through..This time there was more clarity to the strings with a more mellow sound to them..
I have to say though that I haven't played that movie since I put up the baffle wall, so that also may have something to do with it..

I'll have to play a few more of my later movies to get a better feel of where there has been some real improvement, but I have to say that stuffing the ports may have made an improvement overall..
 

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What you are describing would be pretty much how I would describe the change. However, your THX wall should be a bigger improvement overall compared to just the cotton I would think. You may want to try stuffing them and placing some masking tape over the whole side(covering the ports). With your Baffles, trying to reduce the edge effect is not necessary. That's part of what I was trying to do with the cotton. Does that make sense? I'm tired as can be so my thoughts may not come out straight.

Dan
 

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So I take it that you're suggesting to block the ports off completely? That being the case, then I wouldn't need to stuff the ports, would I ?

one thing I've wondering about is if there is any interaction between the ports and the tweeter!, with the ports being in that position?
Have any of your tests shown any affect in this area?
 

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The only reason I'd say go ahead and stuff some cotton in those ports prior to duct taping them would be to hopefully minimize the vibration of the tape. I'd bet you could come up with something that would work even better.

The interaction with the tweeter is precisely what my graphs show and the reason I wanted to stuff the ports to start with. Minimizing the effects of those should really improve the MR/Treble. With your THX wall, the baffle edge won't be a diffraction source. All that's left is the ports. The reason I was leaving the cotton hanging off the front of mine was to absorb the wave getting to the edge. IOW, to reduce the effect of that diffraction by having less available to diffract. The THX wall does a much better job of this.

Dan
 

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One idea I've been tossing around is something I saw used by M&K speakers some years ago..
They had thick strips of a foam type material placed around the perimeter of the the tweeter..
The purpose of this was to reduce the diffraction affect..

My thinking is that if I put strips like this between the tweeter and the ports, that it might tend to help to reduce any interaction between the two..
What do you think?
 

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Sure sounds like it would work. I tried it over at a friends house though and it did have an effect, just not the desired one. I can't answer why, but it may be d/t the narrow directivity of his tweeter. You shouldn't have that issue.

Dan
 

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Discussion Starter #153
The foam used on the THX 150 M&K speakers was because of the three close spaced vertically aligned tweeters to control the vertical directivity. The foam helps make them a little more "musical" as they released a cheaper version without the foam.
 

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Rummaging through my box of bits and pieces, I found some foam stripping..It's some sort of semi-rigid foam 1/2" thick and 1" wide with sealed faces and it's grey!
I have no idea what it is or even where it came from, but it looks like it might be ideal for putting strips between the tweeter and the port..

I'll try that idea first and then maybe use it to cover the ports completely..
it looks to be quite a porous material so I might be able to use that instead of the cotton balls!
 

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Well I tried a few different set ups on the Behringers last night, with a variety of end results..
These are the test I did..

Test 1..
Ports stuffed with cotton wool and the foam strips placed between the tweeter and ports..

Not good..The overall sound felt closed and flat, with voices sounding withdrawn..

Test 2..
Ports stuffed with cotton wool and foam strips placed over the ports..

This was a little better and started to sound like it did previously with just the cotton wool, but it still sounded flat and lacked openness..

Test 3..
Cotton wool removed and just the foam strips stuffed into the ports..

This set up sounded very similar to the ports stuffed with cotton wool..Overall the sound was very smooth and I could hear more timbre to the instruments.The highs sounded really sweet with no sign of edginess..Voice projection was good, but it still lacked a bit of openness and the low to mid bass didn't have that clarity that I had heard previously..

Test 4..

This time I stuffed the bottom half of the ports only with the foam and left the top half open..

That did it for me!..I retained all the benefits of test 3 but now the openness had returned and the low to mid bass sounded much clearer..
Voice and instrument projection was very good..and it was very easy to pin point and track sounds across the screen and beyond!
It also showed me just how affective the THX Baffle Wall really is..:T
 

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This is a cool thread guys!

The one doubt I have is regarding installing typical monitor speakers in this configuration. Most have baffle step compensation built into the crossover to account for their own baffle width. Isn't this installation going to screw up the polar response? A baffle step compensation isn't going to work properly in an infinite baffle.

I can see it working if the speaker was designed for IB or if you are eliminating the factory crossover but I don't think those Berhingers are designed that way...
 

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It won't screw up the polar response(should actually fix some problems there), and his automatic EQ should fix the bass. That is what the baffle will screw up in a sense. So actually it's a win-win. Additional free bass from acoustics, means a cut from the electronics which frees up headroom and reduces energy consumption.

a happier planet,

Dan
 

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The one doubt I have is regarding installing typical monitor speakers in this configuration. Most have baffle step compensation built into the crossover to account for their own baffle width. Isn't this installation going to screw up the polar response?
Polar response it quite good actually..Certainly better than my previous set up..

A baffle step compensation isn't going to work properly in an infinite baffle.
I'm not sure what you're referring to here..The baffle wall isn't an infinite baffle!

It won't screw up the polar response(should actually fix some problems there), and his automatic EQ should fix the bass. That is what the baffle will screw up in a sense. So actually it's a win-win. Additional free bass from acoustics, means a cut from the electronics which frees up headroom and reduces energy consumption.
That is something I've noticed also..At times I think that it's lacking a bit in bass, but then when it's there in the movie it really comes through in bags!!


Yes mine boosted the mid bass.
Likewise!
 
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