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Old 12th February 2012, 04:00 PM   #1
Einric is offline Einric  United States
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Default Acoustic Cross Helper Woofer

So...Here is my thought.
I have a 2 way RS100-8 w/ DC28F on a 5000hz first order.
I really like the way they sound but obviously the bass is a little lacking.
My idea is to take a DA175 that I have on hand and put it in a 4th order bandpass enclosure to create an acoustic crossed helper woofer.
The RS100-8 will be enclosed in a 6" PVC pipe cap to create a .06 cuft enclosure behind it.
This models to make an acoustic crossover at about 110hz which is great for this little woofer.
The only question is should I connect the DA175 in Series or Parallel?
I'm thinking parallel since I have a 4Ω stable amplifier.
Any thoughts or recommendations?
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Old 12th February 2012, 05:35 PM   #2
godfrey is offline godfrey  South Africa
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Definitely parallel. If you connect them in series, the frequency response of both will be a mess due to variations of the speaker's impedance with frequency.
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Old 5th April 2012, 01:37 PM   #3
Einric is offline Einric  United States
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OK, here is the physical design.
I am currently building the cabinet and will post more pictures.
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Old 5th April 2012, 02:01 PM   #4
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Quote:
Originally Posted by Einric View Post
OK, here is the physical design.
I am currently building the cabinet and will post more pictures.
Nice! Can't wait to see more.
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Old 5th April 2012, 06:02 PM   #5
Bill F. is offline Bill F.  United States
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Cool. Might work well.

One thing: are you sure the DA175 is an SPL match for the rest? I'm only asking because in the screenshot of WinISD, you're not viewing the system in absolute SPL...

If it's not an SPL match, an L-pad could fix it up.
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Old 5th April 2012, 07:21 PM   #6
tinitus is offline tinitus  Europe
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yes, its been done before
even commercially
from what I know there will be a port ressonance higher up
could be dealt with by a smallish inductor
dont know if its 1khz, below or above ?
but I think it will be there
or can it be avoided completely, I dont know
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Old 5th April 2012, 07:26 PM   #7
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Einric View Post
I really like the way they sound but obviously the bass is a little lacking.
My idea is to take a DA175 that I have on hand and put it in a 4th order bandpass enclosure to create an acoustic crossed helper woofer.
just remember, your woofer should not have very low Qts
I think from minimum 0.3 and up to maybe just above 0.35
if lower it might work better in 6th. order

ach, Dayton Da175 with Qts of 0.58
big magnet, and still weak motor
not too good

put it in a BIG closed box
probably cant be too big
you will then need xo, ofcourse
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Old 6th April 2012, 12:00 AM   #8
Einric is offline Einric  United States
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I will probably be running a pair of LM4780's for 4 channels with two volume controls.
This will allow me to "Gain Match" the 3db lower DA175 to the RS100.
Also it will keep my LM4780's running a nice safe 8Ωish load.
An L-Pad will handle the higher sensitivity DC28F to match the RS100.

Worst case I will just turn the thing into a .95 cuft 2-Way with the 2500 LR2, the ports would be replaced for a 31hz tuning.
The rear of this cabinet will be removable.
I am currently gluing the cleats on to support the flush rear panel.

Last edited by Einric; 6th April 2012 at 12:05 AM.
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Old 6th April 2012, 09:06 PM   #9
Einric is offline Einric  United States
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Default Speaker Porn

Here are pictures of the rear of the chassis & the LR2 Crossover parts.
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File Type: jpg Rear Chassis.JPG (637.4 KB, 84 views)
File Type: jpg Tweeter XO.JPG (608.6 KB, 84 views)
File Type: jpg Woofer XO.JPG (610.5 KB, 80 views)
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Old 7th April 2012, 01:58 AM   #10
Einric is offline Einric  United States
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Default Woofer and Brace In

Here I have the woofer and it's brace installed.
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