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Senior Shackster , Platinum Supporter
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Yes, that is exactly why i ignore the on and off...and pay strict attention to where the DIP switches need to be...the on and off make things extremely confusing lol.
 

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Discussion Starter #43
Rodny's arrays were/are arranged in a very stiff box. Had they been built into a flexible wall (like mine) he would have lost transient ability, output and detail in the bass.

As the driver cones in an array move one way the wall always tries to move in the opposite direction. It doesn't matter whether the cones move in or out. If the wall flexes the opposite way then the drivers can no longer follow the electrical signal.

Opposed drivers in a manifold help to cancel out mechanical reaction forces. The wall is no longer the handicap that it might otherwise be. Most walls are incredibly stiff along the plane of the surface but inherently weak to pressure applied perpendicularly to the surface. A manifold uses the longitudinal strength of the wall rather than testing its ability to bow like an array does.
 

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I believe the Rodny box was an add on once he decided that the whole attic was being insonified. I think he had his IB mounted in wall like you and I before the box was built.
 

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Discussion Starter #45
I can't believe how much bass I have now! The weight and quality are superb!

I've had to turn the EP2500 down to 20 (from 34 max) as well as reducing the active crossover gain by 6dB.

I hit a peak of 109dB on WOTW (machine rising) using the Galaxy on Max-Fast-C. There was only very slight cone movement visible for a couple of moments. I can easily see two of the drivers in the side of the 4 feet high manifold through my french windows. Plenty in reserve then if I choose to increase the gain again. It's the first time I've seen a full set of yellow lights on the BFD. (no sign of the clipping lights though)
 

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I believe the Rodny box was an add on once he decided that the whole attic was being insonified. I think he had his IB mounted in wall like you and I before the box was built.
YEP!!

My wall is only 52" tall everybody else is at least 8', this is one of the reasons my wall didn't flex, the other thing I have two 3/4" MDF 49x 32 screw to the back of the wall, the front has two 1/2" pieces, total of 2" 1/2, most everybody else used a piece off wood 3/4" thick and 16" or 18" wide and I have one 2x4 from the wall to the 2x6 of the roof.

htnut12 is right!!.. the box was build after I decided to go with the SLLT.

HT 040.jpg

HT 043.jpg

HT 044.jpg

IB panel 042.jpg

After..........
IMG_3540.JPG
 

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Discussion Starter #47
A good solid job before and after, Rodny. :T

My new IB manifold is big enough to sit in but I can't find anybody brave enough to take a photo! :D
 

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Discussion Starter #48
My new manifold is full of surprises. Not least the incredible output power compared to the old array.

What surprised me most is the BFD suddenly showing a full set of light bars. I used to see perhaps two bars with the array if I was very lucky.

Now I'm seeing the BFD lights right up to the red clipping bars. (but red only on rare occasions)

Does this indication of clipping hold any terrors for the EP2500 or the drivers themselves?

Any thoughts on the best way to reduce input to the EP2500? I can use the active crossover to quickly reduce the gain by as much as -6dB in emergencies.

Or I can turn back the attenuator knobs on the EP2500. Is this a preferred way to limit input to the power amp?

The active crossover is within easy arm's reach which is handy when the house is close to collapse.

I have to open the door to get at the power amp's controls which isn't always easy while simultaneously donning an industrial safety helmet, goggles and approved ear defenders.
 

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Discussion Starter #54
I thought I'd better post these here just for Steve Callas to enjoy. ;)

4 x 15" manifold IB measured with Galaxy 140.

LISTENING POSITION:



NEARFIELD:

 

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Discussion Starter #56
So what exactly did you do... change to a manifold setup?
Yes. As simple as that, Sonnie. It was just like supercharging the array and giving it a dash of nitro. Check my signature for some pics of the new "box". Not only did I gain at least 10dB but sound quality is even better. Organ music is simply breathtaking in its depth and power. The subtlest of detail is effortlessly portrayed. On films it feels as if it can bring the house down. :)
 

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Discussion Starter #58
Your array must have been leaky if you gained 10db and all that low end.
Rather oddly the converse is true.

The array was well sealed with thick adhesive foam draught sealer all round the edges which was compressed by lots of baffle fixing screws to the surrounding woodwork. I went to a lot of trouble in sealing it well.

I can still see daylight around my manifold because I haven't got round to finishing it off properly. The manifold was just pushed between two studs and a couple of screws hold it in place flush with the front wall surface.

The driver polarity was double checked with a battery on both the array and the manifold. In fact the array was checked repeatedly with a battery as I struggled to improve its bottom end performance. Deliberately reversing the polarity killed the bass output as one would expect.

The BFD filters remained unchanged with the manifold's installation as did the cabling. No other changes took place anywhere in the system. When I first fired up the manifold I had to rush over to turn down the volume from my normal preamp setting. It was deafening!

I have since produced another simpler BFD filter set to better match the new performance curve. This cost me about 12dB over the previous filter set but I have so much power in reserve it hardly matters. The IB is still 6dB hotter than the array with the same gain settings.

I really have no explanation for the massive increase in overall output other than the almost total reduction in mechanical vibration. The baffle wall and double doors are now almost completely free of vibration. With the array I would lean on the doors for fun while they moved about an inch in and out with ruthless power. My full weight had no effect whatsoever.

The sound quality is also much better. Particularly on organ music. I was impressed by the array but now I am constantly surprised at the subtlety of tonal colour of the great pipes and the shocking dynamic range.

The tank gunfire in "Children of Men" was terrifying as is "WOTW: machine rising".
 
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