Bjorno has designed a great T-TQWP for my Maelstrom X 18" subwoofer to cover from 13 to 50 Hz. I planned to rum 4 sealed Eminence LAB-12 boxes from 40 to 100 Hz.
However, today I started thinking about putting the LAB-12's in a T-TQWP or straight pipe enclosure. I would like to keep the enclosure under 36" tall so they are not taller than my main speakers (4 Pi speakers designed by Wayne Parham) on their stands.
Unfortunately my laptop with horn response software died recently, coupled with my ineptitude with the program, makes it impossible for me to try to develop a design. The driver is commonly used in tapped horn builds so it should be fine for this application. I only need the design to go down into the mid 30's and am willing to trade bottom end for size and upper bass impact.
Usage is about 80% music and 20% home theater.
I would greatly appreciate any assistance from the forum members.
However, today I started thinking about putting the LAB-12's in a T-TQWP or straight pipe enclosure. I would like to keep the enclosure under 36" tall so they are not taller than my main speakers (4 Pi speakers designed by Wayne Parham) on their stands.
Unfortunately my laptop with horn response software died recently, coupled with my ineptitude with the program, makes it impossible for me to try to develop a design. The driver is commonly used in tapped horn builds so it should be fine for this application. I only need the design to go down into the mid 30's and am willing to trade bottom end for size and upper bass impact.
Usage is about 80% music and 20% home theater.
I would greatly appreciate any assistance from the forum members.
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I was looking through old posts yesterday, and I re-read justint's build thread (http://www.diyaudio.com/forums/subwoofers/185836-3015lf-th-35-40hz-but-only-20-deep-help.html) . This straight-pipe build was 44" tall.
Seems like by substituting the LAB-12 driver an even smaller enclosure could be designed.
I am attaching info from justint's build and the Thiele & Small Parameters for the LAB-12.
Seems like by substituting the LAB-12 driver an even smaller enclosure could be designed.
I am attaching info from justint's build and the Thiele & Small Parameters for the LAB-12.
Attachments
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Hi,
Submitting an OD-ML-TL that can be XO:d at 145Hz using a LR4 LPF (250 Hz= -20 dB down)= max Rec. frequency for to not fall
into localization problems.b
Attachments
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Hi,
Submitting an OD-ML-TL that can be XO:d at 145Hz using a LR4 LPF (250 Hz= -20 dB down)= max Rec. frequency for to not fall
b
Bjorno,
What is an OD-ML-TL? The data looks perfect for what I want. I cannot believe it extends down to nearly 20 Hz flat. Wayne Parham (Pi speakers) recommended running flanking subs up to 120 Hz, seems like this would not a problem for this design.
Thanks once again for your assistance! I was really hoping you would weigh in.
Best Regards,
Steve
Bjorno,
What is an OD-ML-TL? The data looks perfect for what I want. I cannot believe it extends down to nearly 20 Hz flat. Wayne Parham (Pi speakers) recommended running flanking subs up to 120 Hz, seems like this would not a problem for this design.
Thanks once again for your assistance! I was really hoping you would weigh in.
Best Regards,
Steve
Hi Steve,
An OD-ML-TL is an Offset Driver M(a)(ss)*-Loaded Transmission-Line that you actually can build like an folded T-TQWT(T-QWP) but with the latter always necessary driver access lid removed(detached).
ML stands for a port-system that is loading a quarter-wave enclosure stuffed or not.
b
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The room is approximately 5000 cubic feet.
I plan to have 2 lab-12's just outside and behind my 4 Pi speakers (flanking subs crossed over at 120 Hz). The Maelstrom-X will be in a corner towards to front of the room (crossed over at 50 Hz, 4th order Butterworth). The remaining 2 lab-12's may go behind the listening position. Their location is flexible, so I will move and measure to minimize nulls.
Should be plenty of bass! I will use REW to set the subs so they are +3 dB.
Hi Steve,
An OD-ML-TL is an Offset Driver M(a)(ss)*-Loaded Transmission-Line that you actually can build like an folded T-TQWT(T-QWP) but with the latter always necessary driver access lid removed(detached).
ML stands for a port-system that is loading a quarter-wave enclosure stuffed or not.
b
Sounds interesting, I did a google search and did not really find info that allowed me to visualize your design. I am not very good at the design stage of speaker building, I enjoy the woodworking and final results.
In HR the CSA:s are labeled PAR= Parabolic CSA:s but when building an OD-ML-TL enclosure:Just flatten the CSA:s with the driver frame width, here= Divide the CSA:s with 31.34 cm used in the HR export function:
b
In HR the CSA:s are labeled PAR= Parabolic CSA:s but when building an OD-ML-TL enclosure:Just flatten the CSA:s with the driver frame width, here= Divide the CSA:s with 31.34 cm used in the HR export function:
b
Bjorno, I am not sure what the information actually means. From the schematic diagram it appears the enclosure consists of 4 segments:
Segment 1: 50.479 liters
Driver Diaphram/Throat Chamber: 0.913 L
Segment 2: 55.712 L
Segment 4: 10.799 L
How do I calculate the enclosure from this infomation. From the schematic for the MAL-X I could somewhat see where the shape comes from, but with this design I am completely lost.
I was able to download hornresp on my new laptop, entered your values and played around for awhile - but I am way over my head.
Bjorno, I am not sure what the information actually means. From the schematic diagram it appears the enclosure consists of 4 segments:
Segment 1: 50.479 liters
Driver Diaphram/Throat Chamber: 0.913 L
Segment 2: 55.712 L
Segment 4: 10.799 L
How do I calculate the enclosure from this infomation. From the schematic for the MAL-X I could somewhat see where the shape comes from, but with this design I am completely lost.
I was able to download hornresp on my new laptop, entered your values and played around for awhile - but I am way over my head.
Its nice to know the volumes but pretty useless when calculating the practical CSA:s:
Start with S1(the closed end) and divide with 31.4 cm= driver frame width + a very small baffle clearance, i.e. 513/31.4= ~16.34 cm
As long as the CSA is 513cm^2 the depth width would be ~16.34 cm...
Then divide S3=S4 with 31.4===> depth width =~5.38 cm
Now fold the enclosure while preserving the sum of L12+L23+L34+L45...
Its DIY
Your Job! and is best done with a paper and pen + hours(weeks for some DIY:rs ) ,if it takes. b
Hi Oliver,
Thats a very nice folding tb46 is an
and 
when it comes to fold quarter-wave boxes!b
Ps: I will try another day to run this box in MJK to find out the optimal stuffing...and post to this thread,of course.
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I feel your pain on the chemical burns...in organic chemistry class I set my hand in a puddle of concentrated phenol - the skin was sagging 3" on the side of my hand when I first felt the burn (still have the scar today, 20+ years later).
Thank you for the folding of the design, now that I see it I can make sence of the data presented by Bjorno. Very nice compact enclosure, looks relatively simple to build.
To my untrained eye, it looks a lot like a slot-ported enclosure, how does the performace differ (I am sure that it does)? If you raise the driver does it change performance (not that I want to, I am just curious)?
I like the looks of this build!!!
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I will try another day to run this box in MJK to find out the optimal stuffing...and post to this thread,of course.
Thanks Bjorno, does the stuffing go in S1 between the driver and S5?
Hi NWCgrad,
Post #15: "... it looks a lot like a slot-ported enclosure, how does the performace differ (I am sure that it does)? If you raise the driver does it change performance..."
I think the slot is high enough @ 2.119" to give you a very similar performance to the model; but, with any folded port with a wide aspect ratio it might take a little experimenting. One way to change this would be to run a center divider (e.g.: a 2x4) down the middle of the slot/duct and raise the duct height to make up for the lost cross-sectional area.
If you raise the driver you shorten L12 and lengthen L23, this will change the performance from the model. You could raise the driver, reroute the L12 path (straight up to the top of the enclosure, then back, then down) and the L23 path (lower the horizontal divider, and shorten the vertical divider to make up for the length gained by raising the driver), and arrive at the model dimensions; the "room for amp" would now be in the middle of the back of the enclosure (I think).
This is thought as a starting point, you can add corner reflectors, braces, cleats, widen the box, add midrange and tweeter in the front.....
Regards,
Post #15: "... it looks a lot like a slot-ported enclosure, how does the performace differ (I am sure that it does)? If you raise the driver does it change performance..."
I think the slot is high enough @ 2.119" to give you a very similar performance to the model; but, with any folded port with a wide aspect ratio it might take a little experimenting. One way to change this would be to run a center divider (e.g.: a 2x4) down the middle of the slot/duct and raise the duct height to make up for the lost cross-sectional area.
If you raise the driver you shorten L12 and lengthen L23, this will change the performance from the model. You could raise the driver, reroute the L12 path (straight up to the top of the enclosure, then back, then down) and the L23 path (lower the horizontal divider, and shorten the vertical divider to make up for the length gained by raising the driver), and arrive at the model dimensions; the "room for amp" would now be in the middle of the back of the enclosure (I think)
.This is thought as a starting point, you can add corner reflectors, braces, cleats, widen the box, add midrange and tweeter in the front.....
Regards,
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