TL sub design - Qs for gurus?

Ap · 9th August 2006, 03:02 AM

I have built a few TL subs with pretty good results, all using a basic formula, relating to Sd & Fs.
For my next project I am trying to make a really small TL sub and was wondering what the most important factors are.
For example line cross sectional area as a ratio to SD - can it go below SD? If so by how much?
Can the length of the line be reduced & stuffing increased to compensate - again by how much - for example is an 1/8 of Fs feasible?
Thanks all.

GM · 9th August 2006, 05:50 AM

Greets!

You can do whatever you want, but when it comes to moving mass quantities of air, 'small is as small does'

and no amount of stuffing is going to offset it much. As you drop below Sd in CSA, the motor's strength needs to increase (lower Qes) with increasing compression ratio, raising the mass corner, F3, so corner loading is mandatory. I don't recommend >2:1, though if you load the front of the driver to make it a bandpass ala the B*** Cannon, then 3:1 if the desired HF corner frequency is low enough. To get an 1/8 WL pipe to work OK will require reverse tapering (TQWT), making it a mass loaded pipe, so a MLTL may be a better solution depending on the driver.

GM

Ap · 9th August 2006, 06:05 AM

Thanks for the reply - I was thinking of reducing Sd down to about 0.8 at exit, not quite as severe as 2:1 or 3:1.
I understand an MLTL is basically a lot of stuffing behind driver then open volume with a port - any ideas on where to get equations for modelling them?
Also, can you clarify reverse tapering in referrence to the 1/8 TL.
Thanks.

GM · 9th August 2006, 01:08 PM

Greets!

You're welcome!

Hmm, since you've been a member for so long and have prior TL experience I just assumed you were familiar with MJK's work: http://www.quarter-wave.com/ Anyway, a well designed MLTL will only need minimal stuffing (none for a LF/sub app) and his various tutorial docs will cover TL theory/design pretty much from A-Z, including reverse tapered, or line CSA at the closed end being >at the terminus. His Classic TL Alignment Tables yields good first approximations and 'good enough' for most folk's apps.

GM

Ap · 9th August 2006, 11:03 PM

Yeah I was going through his site the other day & all the info I need is there, its just that the docs are over 40 pages each and I was looking for a quick answer (just being lazy!)
Guess I'll bite the bullet and sit down & read them all, at least then I will be one step closer to being a guru!
Thanks.

Bjohannesen · 10th August 2006, 10:29 AM

Hi Ap, I can reccomend Martin J. King for DUMMIES on
http://www.t-linespeakers.org/
Guess, who wrote it

Hi from Bjorn
Wonderfull Copenhagen

GM · 10th August 2006, 05:06 PM

Greets!

Quote:

Originally posted by Ap
.........I was looking for a quick answer.

Yeah, well, AFAIK there's no 'quick' answer's to your Qs other than what I gave.

Quote:

Originally posted by Bjohannesen
.......I can reccomend Martin J. King for DUMMIES........

Nice write-up, thanks for the effort! Anyway, the salient points are that with his alignment tables and the adjustable BSC doc, you can skip the rest of his work for most apps.

GM

9th August 2006, 03:02 AM	#1
Ap diyAudio Member Join Date: May 2002 Location: Sydney, Australia	TL sub design - Qs for gurus? I have built a few TL subs with pretty good results, all using a basic formula, relating to Sd & Fs. For my next project I am trying to make a really small TL sub and was wondering what the most important factors are. For example line cross sectional area as a ratio to SD - can it go below SD? If so by how much? Can the length of the line be reduced & stuffing increased to compensate - again by how much - for example is an 1/8 of Fs feasible? Thanks all.

9th August 2006, 05:50 AM	#2
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Re: TL sub design - Qs for gurus? Greets! You can do whatever you want, but when it comes to moving mass quantities of air, 'small is as small does' and no amount of stuffing is going to offset it much. As you drop below Sd in CSA, the motor's strength needs to increase (lower Qes) with increasing compression ratio, raising the mass corner, F3, so corner loading is mandatory. I don't recommend >2:1, though if you load the front of the driver to make it a bandpass ala the B*** Cannon, then 3:1 if the desired HF corner frequency is low enough. To get an 1/8 WL pipe to work OK will require reverse tapering (TQWT), making it a mass loaded pipe, so a MLTL may be a better solution depending on the driver. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

9th August 2006, 01:08 PM	#4
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Re: TL sub design - Qs for gurus? Greets! You're welcome! Hmm, since you've been a member for so long and have prior TL experience I just assumed you were familiar with MJK's work: http://www.quarter-wave.com/ Anyway, a well designed MLTL will only need minimal stuffing (none for a LF/sub app) and his various tutorial docs will cover TL theory/design pretty much from A-Z, including reverse tapered, or line CSA at the closed end being >at the terminus. His Classic TL Alignment Tables yields good first approximations and 'good enough' for most folk's apps. GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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9th August 2006, 06:05 AM	#3
Ap diyAudio Member Join Date: May 2002 Location: Sydney, Australia	Thanks for the reply - I was thinking of reducing Sd down to about 0.8 at exit, not quite as severe as 2:1 or 3:1. I understand an MLTL is basically a lot of stuffing behind driver then open volume with a port - any ideas on where to get equations for modelling them? Also, can you clarify reverse tapering in referrence to the 1/8 TL. Thanks.

9th August 2006, 11:03 PM	#5
Ap diyAudio Member Join Date: May 2002 Location: Sydney, Australia	Yeah I was going through his site the other day & all the info I need is there, its just that the docs are over 40 pages each and I was looking for a quick answer (just being lazy!) Guess I'll bite the bullet and sit down & read them all, at least then I will be one step closer to being a guru! Thanks.

10th August 2006, 10:29 AM	#6
Bjohannesen diyAudio Member Join Date: Jan 2005 Location: Copenhagen	Hi Ap, I can reccomend Martin J. King for DUMMIES on http://www.t-linespeakers.org/ Guess, who wrote it Hi from Bjorn Wonderfull Copenhagen

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