Transmission line subs with 15" Dayton drivers - diyAudio
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Old 9th July 2013, 08:49 PM   #1
haraldo is offline haraldo  Norway
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Default Transmission line subs with 15" Dayton drivers

hello all

I am thinking of a conceptual sketch of a TL sub with twin 15" Dayton sub drivers in each cabinet, we are probably speaking about a 4.5 meter line length, which can make for 1.5 meter tall cabinets =:-o

Maybe one of the following two drivers, with a line tuned at the driver's Fs

Dayton Audio UM15-22 15" Ultimax DVC Subwoofer 2 ohms Per Co 295-514

Dayton Audio RSS390HF-4 15" Reference HF Subwoofer 4 Ohm 295-468

Conceptually I was thinking of a line like the PMC TLE-1, but much larger in size....
Click the image to open in full size.

So these things are bears to design, incredibly difficult to tune, and maybe even failure rate quite good.... but I'm still writing this :-)

So from here, is there any good ideas about concept, where to go to get a good sketch, can't really find any good design programs....

Any feedback would be helpful .-)
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Old 9th July 2013, 10:33 PM   #2
Zero D is offline Zero D  United Kingdom
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Hi, nice sketch 4.5M ! That'll get down Very low

Quote:
Originally Posted by haraldo

can't really find any good design programs....
Where & how much did you look ? There are several Excellent programs, & FREE too Here's 3

Horn Response Hornresp

Transmission Line Modelling Software Transmission Line Modelling Software

TL modeling software Quarter Wavelength Loudspeaker Design

Experiment & post back
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Old 10th July 2013, 01:16 PM   #3
haraldo is offline haraldo  Norway
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Quote:
Originally Posted by Zero D View Post
Hi, nice sketch 4.5M ! That'll get down Very low
Thx, somehow I disregarded Hornresp before ..... but good tips about leonardaudio, and of course I came across Martin J. King before so I will look more into his work.

Thx
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Old 10th July 2013, 10:21 PM   #4
Zero D is offline Zero D  United Kingdom
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Keep us posted
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Old 11th July 2013, 02:20 AM   #5
badman is offline badman  United States
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One obvious choice would be how you mount them- if you put the two drivers on opposed panels, and mount one with one cone-side and one magnet-side firing into the room in-phase (wired out-of-phase), you'll cancel even order distortions and benefit from force cancellation- that would put them on the sides of the enclosure most likely.
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Old 11th July 2013, 03:04 AM   #6
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Quote:
Originally Posted by haraldo View Post
Any feedback would be helpful .-)
How about continuing that fold down to the bottom of the box and have the vent exit on the same side as the drivers?
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Old 11th July 2013, 03:11 AM   #7
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Quote:
Originally Posted by Brian Steele View Post
How about continuing that fold down to the bottom of the box and have the vent exit on the same side as the drivers?
Perhaps he was thinking of backing them into a corner to continue loading?
Distance, orientation, frequencies et. al. would be difficult if not impossible to calculate............maybe "by ear" or using microphones to measure??

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Old 11th July 2013, 06:02 AM   #8
GM is offline GM  United States
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Quote:
Originally Posted by haraldo View Post
Conceptually I was thinking of a line like the PMC TLE-1, but much larger in size....

So these things are bears to design, incredibly difficult to tune, and maybe even failure rate quite good....
Greets!

They are very easy to design once you understand WL pipe resonance theory, especially one like this where its ~ end loaded with no taper, though with HRs Loudspeaker Wizard all one need do is slide their way to a good to excellent alignment.

Anyway, the UM15 seems like its specs were designed for it with a ~ 172.25 path-length/14.4 ft^3 net Vb for two drivers. Amount, type of damping material will determine frequency, impulse, etc. response.

GM
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Old 11th July 2013, 09:46 AM   #9
haraldo is offline haraldo  Norway
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Thx Guys!

I'm not sure if I want to have the exit in the back or the front, also I'm not really sure about strategy with stuffing... it seems to be some different ideas and thoughts onto this....

If you go back to pat Mc Ginty of Meadowlark Audio he was very clear on not putting too much stuffing as in his opinion it kills the dynamics of the speakers and make them more laid-back... very difficult of course then to control resonances then, and if you look at measurements of some of his designs there are clear traces of resonances that may be more distinct than what you really would like in an ideal world..... although I'm attracted to this ideas....

Any good ideas though on the area at start of the line vs the area at the end of the line?

I'm gonna have to read-up on the theories of Mr. King

Well I do own the Meadowlark Kestrel2, which is a TL designed by Pat Mc Ginty...
Click the image to open in full size.

Click the image to open in full size.

Last edited by haraldo; 11th July 2013 at 09:52 AM.
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Old 11th July 2013, 03:44 PM   #10
GM is offline GM  United States
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You're welcome!

This is true when using wide BW drivers, especially in the mids-up BW, but below this BW, SQ is pretty much all about transient response, flat frequency response in room, so in theory, a 0.5 Qtb[c][p] is the goal, which in a TL alignment dictates using a driver + any series resistance with a somewhat higher effective Qts to keep it from becoming over-damped once stuffed.

Your drawing depicts a constant taper TL, which is easy to design, but the exposed speaker appears to be a filter chamber connected to an inverse tapered TL terminated by an expanding vent, so will require MJKs software to sim if you want to get some idea how stuffing will alter its response. For sure, for a given path-length this type of alignment will be tuned lower than a simple constant taper TL, so simple WL + end correction calculations will result in a lower tuning, sometimes an octave or more.

GM
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