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Old 14th July 2013, 01:27 PM   #211
jhutka is offline jhutka  United States
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Thank you for your info and time. You've helped a lot. If nothing else, I need to get AkAbak running. Also, I don't have the knowledge to tweak things. Where I am right now, I cannot see data on a graph and know which dimensions to change to make it better. My linux system is in a room we are currently using for storage as we change the flooring in other rooms. So, no advancement on the AkAbak front.

Thanks again for the effort. What I love about this forum is very knowledgeable people who are willing to help.

JHutka
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Old 14th July 2013, 03:14 PM   #212
xrk971 is offline xrk971  United States
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You are welcome. The tweak I would make is to reduce the depth of your design from 6 in to 3.5 in and shorten the vent to 4.5 in. That should help a lot.
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Old 14th July 2013, 09:43 PM   #213
jhutka is offline jhutka  United States
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Will do. Will have the sketches done tonight.
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Old 15th July 2013, 03:25 AM   #214
GM is offline GM  United States
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Quote:
Originally Posted by jhutka View Post
Vent - 1.5in X 5in X 8.25in
FYI, there’s an elbow in the vent, so its considerably longer than 8.25”.

FWIW, I checked this driver out when ya'll started showing some interest awhile back and since it has a similar path-length, I adapted it to your’s o.d. dims, driver/floor distance and it came out something like this:

GM
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Old 15th July 2013, 09:12 AM   #215
xrk971 is offline xrk971  United States
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Yes, I modeled the 'elbow' in AkAbak - as a contraction in CSA from main area then as a duct with dimensions of 1.5 x 8.25 in. But it does add some equivalent length beyond the nominal 40 in TL length. When going to the shorter 4.5 in vent, the elbow is removed.
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Old 16th July 2013, 12:01 AM   #216
GM is offline GM  United States
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??? I haven't yet done any AkAbak designing, but if I understand you correctly, the vent is somewhat longer acoustically than you indicate and as you can see from my adaptation, don't see any point in having such a large, long vent for even two of this driver since the TL is already long enough.

GM
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Old 16th July 2013, 07:06 AM   #217
xrk971 is offline xrk971  United States
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I just meant that in my sim of design 'as drawn' I included the effect of that extended lip formed by the top edge of the shelf vent, which I thought you referred to as an elbow. Yes, the vent is way too long hence the spikey bass peak followed by a sag in response was there in the sim (when modeled without damping). That is why the optimized model ended up with a vent only almost half as long.
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Old 16th July 2013, 05:03 PM   #218
jhutka is offline jhutka  United States
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Took your suggestions.
Changed to 1/2" material. Everything seemed to fit better.


Here are the plans.

Thanks XRK.
JH
Attached Files
File Type: pdf MLTL Vifa TC9FD18-08HFIN.pdf (41.2 KB, 57 views)

Last edited by jhutka; 16th July 2013 at 05:07 PM.
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Old 16th July 2013, 05:45 PM   #219
xrk971 is offline xrk971  United States
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JHutka,
Plans look great! I look forward to seeing the build and hearing from you how it sounds. By the way, it looks like you are a fan of the Vifa driver so you may be interested in the mini Karlsonator that I built with dual TC9FD's - it's in the Foam Core thread (Foam Core Board Speaker Enclosures?) - awesome sounding speaker that is 8 wide x 8.5 deep x 15 in tall.
Click the image to open in full size.

Last edited by xrk971; 16th July 2013 at 06:09 PM.
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Old 28th August 2013, 03:27 PM   #220
xrk971 is offline xrk971  United States
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Default Big 12 in coaxial driver AMLTL

Is this a reasonable frequency response for a 12 in driver? I used AMLTL method to size the vents. This design is for an off-spec Eminence Beta 12CX with a higher Qts 0f 0.63 - which makes the cabinet huge. The design ended up as a 22.5 in wide x 22.5 in deep x 56.5 in tall tower. Using 3/4 in ply should make this a 2x2 ft x 5 ft tall tower - almost a refrigerator size .
The driver is at 14 in from the top and the qnty 4, 4 in dia x 4.0 in long vents are located at 8 in from the bottom and one on each wall.
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File Type: png AMLTL-Beta12CX-Freq-1m.png (22.7 KB, 429 views)
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