i'm working on a TL design for:
DAYTON DC160S-8 6-1/2" CLASSIC SHIELDED WOOFER
http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=295-306&DID=7
with:
TANG BAND 28-847SA SHIELDED NEODYMIUM DOME TWEETER
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-822
in anycase, my box dimensions are:
48" inside height, 6.5" inside width, 8.5" inside depth.
there will be one devider located at a bottom corner and moving to the cented of the depth, and at a height about 6" below the top of the box. this is a voight pipe IIRC.
this seems like a length of approximately 85". this should be long enough, but i fear it may be too long. i have heard that making the opening larger i can increase the tuned frequency. right now i've calculated the opening to be 4" x 6.5".
any tips. also should i make the opening larger?
DAYTON DC160S-8 6-1/2" CLASSIC SHIELDED WOOFER
http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=295-306&DID=7
with:
TANG BAND 28-847SA SHIELDED NEODYMIUM DOME TWEETER
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=264-822
in anycase, my box dimensions are:
48" inside height, 6.5" inside width, 8.5" inside depth.
there will be one devider located at a bottom corner and moving to the cented of the depth, and at a height about 6" below the top of the box. this is a voight pipe IIRC.
this seems like a length of approximately 85". this should be long enough, but i fear it may be too long. i have heard that making the opening larger i can increase the tuned frequency. right now i've calculated the opening to be 4" x 6.5".
any tips. also should i make the opening larger?
l can understand someone wanting to do their own thing, but why go to all the trouble when there is a similardesign in parts express diy speaker section very similar to what you propose to do...... sorry cant give you a link, just do a search...... cheers TC 
Greets!
Just plugging in all the details and calcing the actual acoustic vent length and using Weems formula for calcing the driver position (~39.96" down from pointed end), I get a 60Hz Fp with lots of gain/broadband 'ripple' to beyond 1 kHz. Typical Voigt pipe performance and no need for any BSC.
Shifting the driver position to ~21.25" lowers Fp to ~45Hz, but increases the 3rd harmonic notch and shifts it down into the ~110-200Hz BW, so probably not a good plan.
Shifting the driver to ~51" and reducing the vent to 2.5" dia. x 2" long yields a flat, smooth enough response to a ~45Hz Fp. To go lower requires a rethink of the design, with much reduced efficiency and the need for BSC if not up against a wall.
GM
Just plugging in all the details and calcing the actual acoustic vent length and using Weems formula for calcing the driver position (~39.96" down from pointed end), I get a 60Hz Fp with lots of gain/broadband 'ripple' to beyond 1 kHz. Typical Voigt pipe performance and no need for any BSC.
Shifting the driver position to ~21.25" lowers Fp to ~45Hz, but increases the 3rd harmonic notch and shifts it down into the ~110-200Hz BW, so probably not a good plan.
Shifting the driver to ~51" and reducing the vent to 2.5" dia. x 2" long yields a flat, smooth enough response to a ~45Hz Fp. To go lower requires a rethink of the design, with much reduced efficiency and the need for BSC if not up against a wall.
GM
Here's the link to what your intending to build;
http://www.d-web.com/dbrown/db616tl2/db616tl2.htm
http://www.d-web.com/dbrown/db616tl2/db616tl2.htm
Two of the better programs for modelling subs;
http://www.pvconsultants.com/audio/eq/boxcircuit.htm
http://www.diysubwoofers.org/prt/
Two more programs that'll give you a quick model;
http://www.pvconsultants.com/audio/boxmodel/unibox.htm
http://www.linearteam.dk/default.aspx?pageid=winisd
http://www.pvconsultants.com/audio/eq/boxcircuit.htm
http://www.diysubwoofers.org/prt/
Two more programs that'll give you a quick model;
http://www.pvconsultants.com/audio/boxmodel/unibox.htm
http://www.linearteam.dk/default.aspx?pageid=winisd
"Took me awhile to figure out the sheets. But it's very much worth it. You can do it. Building speakers about physics/math, so if you work with the sheets you a lot better off."
Jimmy 154 if you could help us newbies out it will be greatly appreciated.
Here are two of the answers I got from cjd that had me stumped.
Driver position ratio - line length. How far from the closed end of the line as a percentage of the total line. So, take a 100 inch line length. 30% means the driver is 30 inches from the closed end (70 inches from the open end).
Port radius is exactly what it says - the radius of the port. (r) Half the diameter. Use a 3" port and you enter 1.5 for the port radius.
Now from reading this post I also have no idea what n_open, n_closed is.
I've played with the numbers to see what the effect was and still can't figure it out.
Maybe we could pool our resources and build a commentary on building a T-Line speaker so everybody can get in on it???
This site comes close to helping out newbies but he stops short at certain places to let us fully understand the cocept of building a T-Line from scratch. I understand he's running a business but it seems anybody who finally understands T-Lines cloaks their knowledge.
http://geocities.com/rbrines1/
Jimmy 154 if you could help us newbies out it will be greatly appreciated.
Here are two of the answers I got from cjd that had me stumped.
Driver position ratio - line length. How far from the closed end of the line as a percentage of the total line. So, take a 100 inch line length. 30% means the driver is 30 inches from the closed end (70 inches from the open end).
Port radius is exactly what it says - the radius of the port. (r) Half the diameter. Use a 3" port and you enter 1.5 for the port radius.
Now from reading this post I also have no idea what n_open, n_closed is.
I've played with the numbers to see what the effect was and still can't figure it out.
Maybe we could pool our resources and build a commentary on building a T-Line speaker so everybody can get in on it???
This site comes close to helping out newbies but he stops short at certain places to let us fully understand the cocept of building a T-Line from scratch. I understand he's running a business but it seems anybody who finally understands T-Lines cloaks their knowledge.
http://geocities.com/rbrines1/
Greets!
>Jimmy 154 if you could help us newbies out it will be greatly appreciated.
====
Hmm, I had no MathCad experience (nor any higher math skills for that matter!) and didn't have any problem finding all the info required to use his WSs by just reading his documentation and playing with them a little bit.
====
>Now from reading this post I also have no idea what n_open, n_closed is. I've played with the numbers to see what the effect was and still can't figure it out.
====
Since it's not in the 'user input section', why do you care unless you plan on modifying the WS's default programming?
====
>Maybe we could pool our resources and build a commentary on building a T-Line speaker so everybody can get in on it???
====
Why? MJK's most excellent documentation/selection charts are all you need.
====
>This site comes close to helping out newbies but he stops short at certain places to let us fully understand the cocept of building a T-Line from scratch. I understand he's running a business but it seems anybody who finally understands T-Lines cloaks their knowledge.
http://geocities.com/rbrines1/
====
Well, pardon us for being so selfish! I can't speak for the others, but Hell's going to freeze over before I give away ALL that I've learned through spending God knows how much of my quality time and disposable income researching, building/measuring proof-of-concepts over the past several decades, and no doubt it's just a 'drop in the bucket' compared to the 'investment' of a Ken Kantor, Earl Geddes, Nelson Pass, etc., that generously share some of their vast knowledge on the various forums.
Respond if you like, but you've been added to my twit list so I won't have to suffer through any more of your unmitigated gall.
GM
>Jimmy 154 if you could help us newbies out it will be greatly appreciated.
====
Hmm, I had no MathCad experience (nor any higher math skills for that matter!) and didn't have any problem finding all the info required to use his WSs by just reading his documentation and playing with them a little bit.
====
>Now from reading this post I also have no idea what n_open, n_closed is. I've played with the numbers to see what the effect was and still can't figure it out.
====
Since it's not in the 'user input section', why do you care unless you plan on modifying the WS's default programming?
====
>Maybe we could pool our resources and build a commentary on building a T-Line speaker so everybody can get in on it???
====
Why? MJK's most excellent documentation/selection charts are all you need.
====
>This site comes close to helping out newbies but he stops short at certain places to let us fully understand the cocept of building a T-Line from scratch. I understand he's running a business but it seems anybody who finally understands T-Lines cloaks their knowledge.
http://geocities.com/rbrines1/
====
Well, pardon us for being so selfish! I can't speak for the others, but Hell's going to freeze over before I give away ALL that I've learned through spending God knows how much of my quality time and disposable income researching, building/measuring proof-of-concepts over the past several decades, and no doubt it's just a 'drop in the bucket' compared to the 'investment' of a Ken Kantor, Earl Geddes, Nelson Pass, etc., that generously share some of their vast knowledge on the various forums.
Respond if you like, but you've been added to my twit list so I won't have to suffer through any more of your unmitigated gall.
GM
f you look at the TL Application Note and the worksheet TL_Sections I'll try and give a brief explanation.
n_closed - the number of sections used to model the closed end
n_open - the number of sections used to model the open end
These are basically the number of elements defined below where each line represents one element (note the counter starts at 0). So for n_closed = 4 requires 5 lines of input to model the closed end of the TL, the maximum subscript number should equal n_closed. For n_open = 9 means that 10 sections are used to model the open end of the TL and again the maximum subscript number should equal n_open. Looking at the application note, the closed end is not shown in detail but the open end shows 10 sections defined by the dashed lines. The dotted line traces the path and the dashed lines show the initial and final areas of each section. You should understand everything in this worksheet and Application note before you attempt to modify TL_Sections.
You can use any number of sections that you want as long as n_closed and n_open are greater than 1 (two lines of input) If you look at the back loaded horn worksheets you can see another example ot TL_Sections.
You can input step changes in area by setting the final area of a section not equal to the initial area of the next section. You can accurately model corners but at low frequencies this is really not critical or needed.
If you really are struggling understanding TL-Sections, I recommend sticking with the other preformatted worksheets. TL_Sections will solve any problem that you input, even if it is not the correct model for your enclosure.
From Martin King's answer in another thread:
http://www.diyaudio.com/forums/showthread/t-24920.html
Getting There!!!
n_closed - the number of sections used to model the closed end
n_open - the number of sections used to model the open end
These are basically the number of elements defined below where each line represents one element (note the counter starts at 0). So for n_closed = 4 requires 5 lines of input to model the closed end of the TL, the maximum subscript number should equal n_closed. For n_open = 9 means that 10 sections are used to model the open end of the TL and again the maximum subscript number should equal n_open. Looking at the application note, the closed end is not shown in detail but the open end shows 10 sections defined by the dashed lines. The dotted line traces the path and the dashed lines show the initial and final areas of each section. You should understand everything in this worksheet and Application note before you attempt to modify TL_Sections.
You can use any number of sections that you want as long as n_closed and n_open are greater than 1 (two lines of input) If you look at the back loaded horn worksheets you can see another example ot TL_Sections.
You can input step changes in area by setting the final area of a section not equal to the initial area of the next section. You can accurately model corners but at low frequencies this is really not critical or needed.
If you really are struggling understanding TL-Sections, I recommend sticking with the other preformatted worksheets. TL_Sections will solve any problem that you input, even if it is not the correct model for your enclosure.
From Martin King's answer in another thread:
http://www.diyaudio.com/forums/showthread/t-24920.html
Getting There!!!
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