Is this ¼ WL & fs loow Transmission Line realistic?

rick57 · 12th May 2007, 12:08 PM

Hi,

I’ve looked at t-linespeakers.org and see reference to Martin King's & Auspurger's computer models, am happy to learn one, before I do - is this ¼ WL goal realistic or in the ballpark ?

A 6 m 20 foot (running along the ceiling) line of Sonotube or equivalent, ie a TL with no taper, with ¼ WL = 14 Hz

- used with a driver of fs = 18 Hz (Peerless XLS 12”)

should with …….. EQ be able get flat down to between the ¼ WL & fs, ie 14 – 18 Hz?

Thanks

rick57 · 12th May 2007, 12:35 PM

I should have said, rather than dB, the goals are "tightness" & depth

MJL21193 · 12th May 2007, 11:38 PM

Hi.
Need the divers other specs for accurate modeling. If you post them I'd be willing to simulate (as I am intrigued by your idea). The thought of the line extending across the ceiling is different, that's for sure.
TL bass re-enforcement is an excellent way to increase response below Fs.

Edit: Sorry, read after I posted, driver is Peerless XLS. This driver is purpose built for passive radiator allingment, and will give inferior TL results. You should consider another driver for your idea.

rick57 · 13th May 2007, 01:10 AM

Martin,

The ceiling - I just looked around and thought - do a kind of el-pipo but using the longest room dimension. Higher ceilings make it less visually intrusive.

I’ve heard that the XLS is built for passive radiators; and also with it’s very low Q for small boxes in cars.
You may know Linkwitz chose it for it’s very low distortion at < 100 Hz, always EQed, in both dipoles (Phoenix & Orion) and sealed boxes (Thor).
Also GM suggests http://www.diyaudio.com/forums/showt...ht=#post772802 what sounds to me like a TL using XLS.

I thought in that case . . here are the TS, with a higher distortion but still lowish fs opion

What parameters are good for TL, and what are bad?

Thanks

MJL21193 · 13th May 2007, 02:11 AM

Quote:

Originally posted by rick57

I’ve heard that the XLS is built for passive radiators; and also with it’s very low Q for small boxes in cars.
You may know Linkwitz chose it for it’s very low distortion at < 100 Hz, always EQed, in both dipoles (Phoenix & Orion) and sealed boxes (Thor).
Also GM suggests http://www.diyaudio.com/forums/showt...ht=#post772802 what sounds to me like a TL using XLS.

What parameters are good for TL, and what are bad?

To be honet I've not tried this sub in a pipe this long. The resuts are different than they would be for a shorter, tapered line.
Below are the results for a line cross section 3 x Sd. First is the phase relationship between TL and infiite baffle the second is expected frequency response. Though there is a massive drop after 40Hz, there is clearly a 5dB gain over IB below this. If you can tolerate the poor step response (.02 second delay), it may not be a bad option.

rick57 · 13th May 2007, 02:27 AM

Martin,

Thanks for the info, then what parameters might be best for good step response with long or non tapered lines?

Thanks

GM · 13th May 2007, 02:39 AM

Greets!

My referenced alignments are MLTLs, big difference! An end loaded TL this long isn't a good plan, but an off-set driver (L*0.2541) one with a 12" effective diameter (113.1"^2) looks good with modest stuffing (0.3 lbs/ft^3) with no audible timing errors if XO'd around 70 - 80 Hz.

GM

MJL21193 · 13th May 2007, 02:55 AM

Quote:

Originally posted by rick57
Martin,

Thanks for the info,

Rick, not sure why you are calling me Martin. My name is John...

Quote:

Originally posted by GM
Greets!

My referenced alignments are MLTLs, big difference! An end loaded TL this long isn't a good plan, but an off-set driver (L*0.2541) one with a 12" effective diameter (113.1"^2) looks good with modest stuffing (0.3 lbs/ft^3) with no audible timing errors if XO'd around 70 - 80 Hz.

GM

GM, I agree it's not a good plan, just interesting to get that much gain below 40 Hz. Of course, 3 x Sd is quite a large pipe.

rick57 · 13th May 2007, 03:06 AM

GM,

XO'd around 70 - 80 Hz is fine

“but an off-set driver (L*0.2541) one with a 12" effective diameter (113.1"^2)”

What is L, and is that a triangular or round cross section?

Thanks

rick57 · 13th May 2007, 03:08 AM

John
"not sure why you are calling me Martin. My name is..."
oops, thought you were Martin King . .

Your thoughts on TS?

Cheers

12th May 2007, 12:08 PM	#1
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	Is this ¼ WL & fs loow Transmission Line realistic? Hi, I’ve looked at t-linespeakers.org and see reference to Martin King's & Auspurger's computer models, am happy to learn one, before I do - is this ¼ WL goal realistic or in the ballpark ? A 6 m 20 foot (running along the ceiling) line of Sonotube or equivalent, ie a TL with no taper, with ¼ WL = 14 Hz - used with a driver of fs = 18 Hz (Peerless XLS 12”) should with …….. EQ be able get flat down to between the ¼ WL & fs, ie 14 – 18 Hz? Thanks

13th May 2007, 02:39 AM	#7
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Greets! My referenced alignments are MLTLs, big difference! An end loaded TL this long isn't a good plan, but an off-set driver (L*0.2541) one with a 12" effective diameter (113.1"^2) looks good with modest stuffing (0.3 lbs/ft^3) with no audible timing errors if XO'd around 70 - 80 Hz. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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12th May 2007, 12:35 PM	#2
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	I should have said, rather than dB, the goals are "tightness" & depth

12th May 2007, 11:38 PM	#3
MJL21193 Account disabled at member's request Join Date: Mar 2007	Hi. Need the divers other specs for accurate modeling. If you post them I'd be willing to simulate (as I am intrigued by your idea). The thought of the line extending across the ceiling is different, that's for sure. TL bass re-enforcement is an excellent way to increase response below Fs. Edit: Sorry, read after I posted, driver is Peerless XLS. This driver is purpose built for passive radiator allingment, and will give inferior TL results. You should consider another driver for your idea.

13th May 2007, 02:27 AM	#6
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	Martin, Thanks for the info, then what parameters might be best for good step response with long or non tapered lines? Thanks

13th May 2007, 03:06 AM	#9
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	GM, XO'd around 70 - 80 Hz is fine “but an off-set driver (L*0.2541) one with a 12" effective diameter (113.1"^2)” What is L, and is that a triangular or round cross section? Thanks

13th May 2007, 03:08 AM	#10
rick57 diyAudio Member Join Date: Dec 2002 Location: dry ol Melbourne Australia	John "not sure why you are calling me Martin. My name is..." oops, thought you were Martin King . . Your thoughts on TS? Cheers

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