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semi-Infinite baffle for Lowther DX45?
semi-Infinite baffle for Lowther DX45?
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Old 11th April 2014, 03:16 AM   #1
audiocats is offline audiocats  United States
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Default semi-Infinite baffle for Lowther DX45?

I recently bought a pair of Lowther Dx45's and want to build a low spl system for a small room.
The listening room is about 16'x20', ~8' ceiling. I normally listen at around 60~70dB (apartment, so....), so the 100w power handling of DX45 is probably over-kill. I want the Lowther to handle down to around 120~150Hz, anything lower will be done/augmented by a sealed woofer.

Here is my question: instead of doing a more common BLH or Voigt pipe which are capable of doing high SPL and lower bass (I need neither of these two), can I just use a relatively large sealed enclosure as a semi-infinite-baffle? Say, 4 times Vas which is about 18 liters.

again, the listening volume is only 60~70db.

If it is a go, what will the bass roll-off look like? still 12db/oct ? starting at what point?

I don't want to do an open-baffle at this point.

Thanks for any input.

Last edited by audiocats; 11th April 2014 at 04:00 AM.
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Old 11th April 2014, 10:34 PM   #2
tuxedocivic is offline tuxedocivic  Canada
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Great idea. Could you build it into your wall or do inwalls?

The roll off will be shallower than 12db/oct. I'm not exactly sure what the final Q would be as that depends on how big you actually make the box. But could be more like 9db/oct. Normally I'd warn you about excursion going way up, but if you're not listening loud... I'd still recommend a high pass if using subs, then the midrange and treble will not compete with the bass output.

Sounds great!
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Old 12th April 2014, 05:28 PM   #3
Inductor is offline Inductor  Portugal
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Quote:
Originally Posted by audiocats View Post
I want the Lowther to handle down to around 120~150Hz, anything lower will be done/augmented by a sealed woofer.
Impossible, you would need to bring the LF to upper 200Hz.
The reflex is possible for the Lowther DX45, F3 112 Hz:

VB ~ 2 L (make the space for extra driver and port inside the cabinet) net.
Port 4.4 cm/22.10 cm (D/L)
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Old 13th April 2014, 03:16 AM   #4
audiocats is offline audiocats  United States
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I see, so 18 liter is still too small, I need something more like 40L. That will be too big.
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Old 13th April 2014, 09:25 AM   #5
Inductor is offline Inductor  Portugal
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Quote:
Originally Posted by audiocats View Post
I see, so 18 liter is still too small, I need something more like 40L. That will be too big.
How did you come to that conclusion?
You are missing something here, or me...
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Old 13th April 2014, 05:00 PM   #6
audiocats is offline audiocats  United States
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I plugged in the parameters to a sealed box calculator and got something like 33L and 175hz...
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Old 13th April 2014, 05:45 PM   #7
xrk971 is offline xrk971  United States
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semi-Infinite baffle for Lowther DX45?
A very good semi IB is the Nautaloss sealed spiral TL. It has zero coloration due to back reflections as it acts like an acoustic black hole. Size it so that the total internal volume is at least equal to the optimal sealed alignment is based on Vas. Make the channel about 3 ft long and the width about 2 inches wider than the bezel. The curved channels can be made from foam core for easy bending and exterior out of plywood.

The Nautaloss Ref Monitor
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Old 13th April 2014, 07:48 PM   #8
Inductor is offline Inductor  Portugal
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Quote:
Originally Posted by audiocats View Post
I plugged in the parameters to a sealed box calculator and got something like 33L and 175hz...
Yes. That is with crossover frequency close to 200Hz.
You will have to bring up your crossover frequency as I said.
Then you will have to match the 2 woofers (output, phase and all) with the mains one for each channel/"satellite"/Lowther DX45.

I don't understand what you are using for your set-up for LFs.

Maybe you will explain, but in this case, I don't know what's up with the reflex?! Is it bad? You might have some aversion to it. I want to see how you are going to solve this problem. You have something (resolution?) up your sleeve.
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Old 13th April 2014, 07:59 PM   #9
audiocats is offline audiocats  United States
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what I want is easy construction (so spiral tunnels are out) and less coloration (reflex design more or less has that).

Maybe I should just do a folded voigt pipe and call it good....
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Old 13th April 2014, 08:03 PM   #10
Inductor is offline Inductor  Portugal
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You get perfect roll-off to match with the reflex above.
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