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Old 20th May 2009, 04:48 AM   #3381
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Default Re: Eight subwoofers

Quote:
Originally posted by j.michael droke
Hi there Patrick: Your system must sound great with distributed bass. I'm contmplating a multiple sub system and have a few questions: What connection scheme di you use? Wire (lots of wire)? Wireless? How many bass amps? Is there phase control in use? I recently read the Harman Int. study by Todd Welti, which studied the placement of multiple subs: what placement did you use? Baybe this subject should be in a diferent thread? ....... regards, Michael
It's basically an 8' x 8' platform that's about 8" tall. My couch rests on it. If you've seen the blueprints for the th-spud, it's basically the same idea.

It's not a tapped horn though; there are five subwoofers built into the platform.

In addition to that I have two bandpass subs and a tapped horn in the room.

I use a single plate amp. The power is weighted so that the platform gets a third, the TH gets a third, and the bandpass sub gets a third.

Believe it or not, the five subs run out of excursion before the tapped horn does. That's why they get the least power.
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Old 20th May 2009, 04:55 AM   #3382
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Has anyone created an Akabak model for dual woofers?

I threw one together this evening. It's quite an eye opener! The dual woofer design increased efficiency by almost double over the passband, and reduces third order distortion.

It's no wonder that Danley has released two tapped horns with dual woofers, and is about to release a TH with *eight* woofers. Multiple woofers work a heck of a lot better than one.

I posted the plans here:

The Smallest Tapped Horn

It might be worth creating a model with three or four woofers too.

Since modeling these is complex, this is what I do:

#1 - I create a design in horn response.
#2 - I transfer the design to Xara (a 2d design program. You can use whatever you prefer.)
#3 - Once I have a 2d model that works, I go back to horn response and change the parameters so that they agree with the 2D drawing from Xara.
#4 - Re-simulate in Horn Response, to be sure that it still looks alright.

Now the tricky part...

You have to put the segments into Excel, so that you can figure out where the taps go. It's a simple spreadsheet really.

Once you have the new segment lenghts and volumes from Excel, put them into Akabak, and check out your new Tapped Horn!

If these measure half as good as they model, I think we're going to see a lot of people using multiple wooofers...
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Old 20th May 2009, 05:49 PM   #3383
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Quote:
Originally posted by Patrick Bateman
Has anyone created an Akabak model for dual woofers?

I threw one together this evening. It's quite an eye opener! The dual woofer design increased efficiency by almost double over the passband, and reduces third order distortion.
I created a model for a tapped horn with four woofers. Like the dual woofer version, it seems to flatten out response at the low end and reduce sensitivity at the high end. It should be a real distortion killer. The severity of the peaks and dips is reduced also. Here's a pic from Akabak. The image at the top is a single woofer TH, the one at the bottom uses four of the same woofer. The excursion plot is at the left, and it's a bit wonky (since the minimums occur at various frequencies.)

Click the image to open in full size.
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Old 20th May 2009, 08:15 PM   #3384
Frode is offline Frode  Norway
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I have a pair of Aura 10000RPM subwoofers , is it possible to make use of them in a TH? They will be used in a small room(16sq.m/~172sq.ft) so I don't need much output. I would like to use them below 60-80Hz.

Frode
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Old 20th May 2009, 09:23 PM   #3385
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Quote:
Originally posted by Frode
I have a pair of Aura 10000RPM subwoofers , is it possible to make use of them in a TH? They will be used in a small room(16sq.m/~172sq.ft) so I don't need much output. I would like to use them below 60-80Hz.

Frode
Prosound woofers and carsound woofers have worked better than your typical home audio woofer in tapped horns. They tend to have a higher FS. The specs on the Aura looks good. I'd get a copy of horn resp and start messing around with it...
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Old 20th May 2009, 09:56 PM   #3386
Frode is offline Frode  Norway
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Quote:
Originally posted by Patrick Bateman


Prosound woofers and carsound woofers have worked better than your typical home audio woofer in tapped horns. They tend to have a higher FS. The specs on the Aura looks good. I'd get a copy of horn resp and start messing around with it...

I have Hornresp, but I have to admit that I struggle a bit with the TH-simulations. I guess I just have to read the whole thread properly.

Anyways, I've made a simulation(probably stole it somewhere in the thread):

Click the image to open in full size.
Click the image to open in full size.

It seems like it should be possible to get a decent result, so I'll just have to play around with Hornresp. I'm open to any suggestions.

Frode
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Old 20th May 2009, 10:18 PM   #3387
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A reverse taper seems to work well with that driver.
Not sure how it would work in reality though.

450 to 100 seems impressive. But then I'd be worried about "port" noise.
A total of 3m length.
Construction might be a problem.

Juggle it a little more and you might find a compromise you are happy with.
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Old 20th May 2009, 10:37 PM   #3388
Frode is offline Frode  Norway
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Quote:
Originally posted by David_Web
A reverse taper seems to work well with that driver.
Not sure how it would work in reality though.

450 to 100 seems impressive. But then I'd be worried about "port" noise.
A total of 3m length.
Construction might be a problem.

Juggle it a little more and you might find a compromise you are happy with.

Is this possible to sim in Hornresp?

Frode
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Old 21st May 2009, 12:09 AM   #3389
GM is offline GM  United States
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Quote:
Originally posted by Frode
They will be used in a small room(16sq.m/~172sq.ft) so I don't need much output. I would like to use them below 60-80Hz.
This driver wants a big cab, but considering the room size and the desire for two THs:

GM
Attached Images
File Type: gif aura 10000 rpm 14.57-132.45 hz conic th (reduced size).gif (15.6 KB, 848 views)
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Old 21st May 2009, 12:23 AM   #3390
GM is offline GM  United States
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Quote:
Originally posted by Frode

Is this possible to sim in Hornresp?
Sure, though DW's specs seem way too small to me (don't forget to use the combined response tool):

GM
Attached Images
File Type: gif aura 10000 rpm 20 hz tqwt.gif (15.0 KB, 837 views)
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