An LLT with two AE IB15s? - Page 4 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #31 of 58 Old 04-12-07, 01:25 AM Thread Starter
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Chrisbee
 
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Re: An LLT with two AE IB15s?

Woops. All drivers measure 3.4-3.5 Ohms DC. That makes them 4 Ohms impedance.

The specs I posted from the old AE website were obviously for the 8 Ohms model.

Series pairs make 8 Ohms per channel. A safe load and keeps the power level within bounds for these drivers in IB configuration.

I'm going to try a 2 x 2 opposed driver manifold next to take the flexible stud wall out of the equation.

I pray my wife doesn't take me out of the equation.

Thanks for all the great suggestions and driver modelling.
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post #32 of 58 Old 04-12-07, 07:50 AM
Jerry
 
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Re: An LLT with two AE IB15s?

I don't know how to say this any more clearly.

WIRE THEM IN PARALLEL two per amp side. If you don't try this you are ignoring the current flow required to get amp turns working for you.
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post #33 of 58 Old 04-12-07, 10:10 AM Thread Starter
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Chrisbee
 
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Re: An LLT with two AE IB15s?

I'm not ignoring you "nut".

I tried bridging and I tried parallel when I first built the IB and found it made little difference to performance.

I have just finished the sides of my manifold and routed out the driver openings.

Just need to fit the top, bottom and back and I'll have finished the box. Fitting the drivers won't take long.

I decided to go with a 2 x 2 with drivers nested like Jeffery F's in the Cult gallery P4. but mine is much bigger and sitting on the floor. (I have to fill the space between the existing studs anyway)

If the manifold doesn't make any difference I'll only have wasted a couple of hours and a nice sheet of 3/4" plywood.

It will be interesting to see if mechanical cancellation cures my VLF output problem. This way I won't need to guess and it might prove something useful.

Last edited by Chrisbee; 04-12-07 at 10:16 AM.
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post #34 of 58 Old 04-14-07, 11:39 PM
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Re: An LLT with two AE IB15s?

Not sure if this has already been covered...but have you checked the DIP switches? Is it possible that the either of the highpass options are enabled?

If you don't have a BFD for your sub, get one fast!
If you don't have REW, get it now!
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post #35 of 58 Old 04-15-07, 02:51 AM Thread Starter
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Chrisbee
 
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Re: An LLT with two AE IB15s?

Quote:
Exocer wrote: View Post
Not sure if this has already been covered...but have you checked the DIP switches? Is it possible that the either of the highpass options are enabled?
Thanks for the suggestion but this has been double checked every time I became paranoid about my missing bass.

The manifold is finished despite long trips out in the car to enjoy the fine weather. No attempts to seal it yet so there is just thin polythene covering the hole above the box where the array baffle once reached the ceiling. Lengthy discussion regarding fitting a window above the manifold now has been resolved. No window. So now I can get on with sealing it properly.

The difference between the array and manifold is quite dramatic. The double doors beside the IB leading out to the enclosure have virtually stopped vibrating. The wall has almost stopped vibrating. The bass output has increased with a crisper, harder-edged quality. Despite the loss of the very low bass I can still hear beating and superb detail on organ music.

This is a very satisfying result considering the unfinished details. (like a 24" x 16" open hole right above the manifold!)

Bypassing the BFD instantly produces massive amounts of bass without the usual rattles and vibration in the room. Bass guitar on rock music is a riot with the BFD bypassed! Crisp and dry without any boom and incredibly loud.

Here's a first comparison with and without the BFD at the listening position:

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post #36 of 58 Old 04-15-07, 08:57 AM
Jerry
 
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Re: An LLT with two AE IB15s?

That is good to know. I will certainly manifold my IBs when the IXLs get here.
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post #37 of 58 Old 04-15-07, 12:58 PM Thread Starter
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Re: An LLT with two AE IB15s?

Quote:
htnut12 wrote: View Post
That is good to know. I will certainly manifold my IBs when the IXLs get here.
While it is always dangerous to make blanket recommendations I am amazed at the output I have gained from changing to a manifold.

I have closed off the hole above the manifold with multiple layers of chipboard with a little acrylic sealer all around to close any remaining gaps.

I must have gained at least 6dB overall because for the first time I have backed off the crossover gain on the IB by 6dB to match the speakers at 0dB.

I have even turned down the controls on my EP2500 from max to 28. I think I still have far too much bass for organ music! Though it is very satisfying to hear such detail and superb power in the deep bass.

I have spent several hours walking back and forth between my computer and my BFD trying dozens of filters and endlessly sweeping the IB manifold with REW. This graph doesn't look very exciting but it sounds simply incredible compared with my old vertical array. Needless to say I am delighted even if I didn't end up with a giant port like Rodny's.

It's heavy, man!

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post #38 of 58 Old 04-15-07, 03:07 PM
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Re: An LLT with two AE IB15s?

Woah, who woulda thunkit?

Very nice improvement there. Enjoy!

If you don't have a BFD for your sub, get one fast!
If you don't have REW, get it now!
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post #39 of 58 Old 04-15-07, 04:58 PM Thread Starter
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Re: An LLT with two AE IB15s?

Thanks.

Perhaps I should start a new thread on how to reduce bass output from a subwoofer?
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post #40 of 58 Old 04-15-07, 05:58 PM
Jerry
 
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Re: An LLT with two AE IB15s?

IIRC Rodney had an array too, as do I if you can call two drivers an array.
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