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....
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 .-)
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....
An externally hosted image should be here but it was not working when we last tested it.
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 .-)
Hi, nice sketch 4.5M ! That'll get down Very low
Where & how much did you look ? There are several Excellent programs, & FREE too Here's 3
Horn Response http://www.diyaudio.com/forums/subwoofers/119854-hornresp.html
Transmission Line Modelling Software http://www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software.html
TL modeling software Quarter Wavelength Loudspeaker Design
Experiment & post back
4.5M ! That'll get down Very low Where & how much did you look ? There are several Excellent programs, & FREE too
Here's 3Horn Response http://www.diyaudio.com/forums/subwoofers/119854-hornresp.html
Transmission Line Modelling Software http://www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software.html
TL modeling software Quarter Wavelength Loudspeaker Design
Experiment & post back
Hi, nice sketch
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
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.
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??
_____________________________________________________Rick.........
Greets!
They are very easy to design once you understand ¼ WL pipe resonance theory, especially one like this where it’s ~ end loaded with no taper, though with HR’s 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
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...
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...
An externally hosted image should be here but it was not working when we last tested it.
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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 MJK’s 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 ¼ WL + end correction calculations will result in a lower tuning, sometimes an octave or more.
GM
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 MJK’s 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 ¼ WL + end correction calculations will result in a lower tuning, sometimes an octave or more.
GM
This probably should have been stated in the first post...
Some of the main properties:
Designed for corner placement
I will bring with me the room gain that I can get by corner placing the sub, another reason is that for practical reasons it's too invasive to have such a sub in any other place than in the corner. I also do have a wife and will keep it that way
This probably means a a Q = 0.5 is a good target, at least it's my understanding
PEQ in the digital domain is something acceptable to make fine tuning
Tapered line
This is not a user requirement per se, but I always had the understanding that a "proper" TL is tapered, so contrary to what's in the above sketch I believe an opening area of 1/2 of the start area of the TL is a starting point, not sure yet what I would benefit from having more or less tapering.
Also believe both drivers will be front-firing....
Passband range
There will be two subs' symmetrically placed
I will have to be able to cross them as high as 125 - 150Hz as I do have some Duntech PCL-15 bookshelf speakers that may have to be crossed quite high with a high-pass filter as they just don't manage the low bass.... they're sensational but -3dB is around 75Hz and they really need to be freed from the low bass to be able to breathe properly, midrange breaks up when I push them due to high-excursion of the mid/woofer...
One good reason to make the subs is that I really want to hear what the Duntech's are good for
ohhhh, then I have to upgrade the front-end too as I don't have proper sub x-over
End of line opening
Still not decided if I should have end of line at the back or front, I can see both things even from same producer of TL subs, maybe it's best with opening to the front if I design for corner loading
Inside must be accessible
I will have to make it so that I somehow can remove top or bottom and then secure it again safely and air-tight, just so that I can adjust the amount of stuffing... as this for sure will have to be some sort of research project for me too I have to find a way to bolt the top plate securely to the cabinet (Probably top plate if I lead the end of the line to the front at the bottom)
Size
I will probably be thinking much about downsizing a bit to 10" or 12" driver with a tuning around 25 Hz, it's probably way too difficult to manage the sheer size of a 15" based 4.5 meter long line ... especially if I have to build cabinets in two or more iterations
Maybe then the bigger ones will come later when I'm more confident.....
go/no-go
The go/no-go for the building part will be when I do have some confidence that modelling seems to be at a good enough level that I do have some belief that they will at least perform more or less good, not sure what that means yet... LOL
So for now I'm reading and reading MJK's papers and references and findings, as I will try to understand as much as possible before I take any further steps.
I always considered myself competent in Math (grades underline this fact) but I don't understand anything about MJK's formulas yet, or maybe it's just too long time since I was in college...
At the moment, the S/W from leonardaudio.co.uk is my #1 choice for modelling
so there's a long thread to read about this too...
So far this keeps me quite busy
Some of the main properties:
Designed for corner placement
I will bring with me the room gain that I can get by corner placing the sub, another reason is that for practical reasons it's too invasive to have such a sub in any other place than in the corner. I also do have a wife and will keep it that way
This probably means a a Q = 0.5 is a good target, at least it's my understanding
PEQ in the digital domain is something acceptable to make fine tuning
Tapered line
This is not a user requirement per se, but I always had the understanding that a "proper" TL is tapered, so contrary to what's in the above sketch I believe an opening area of 1/2 of the start area of the TL is a starting point, not sure yet what I would benefit from having more or less tapering.
Also believe both drivers will be front-firing....
Passband range
There will be two subs' symmetrically placed
I will have to be able to cross them as high as 125 - 150Hz as I do have some Duntech PCL-15 bookshelf speakers that may have to be crossed quite high with a high-pass filter as they just don't manage the low bass.... they're sensational but -3dB is around 75Hz and they really need to be freed from the low bass to be able to breathe properly, midrange breaks up when I push them due to high-excursion of the mid/woofer...
One good reason to make the subs is that I really want to hear what the Duntech's are good for
ohhhh, then I have to upgrade the front-end too as I don't have proper sub x-over
End of line opening
Still not decided if I should have end of line at the back or front, I can see both things even from same producer of TL subs, maybe it's best with opening to the front if I design for corner loading
Inside must be accessible
I will have to make it so that I somehow can remove top or bottom and then secure it again safely and air-tight, just so that I can adjust the amount of stuffing... as this for sure will have to be some sort of research project for me too I have to find a way to bolt the top plate securely to the cabinet (Probably top plate if I lead the end of the line to the front at the bottom)
Size
I will probably be thinking much about downsizing a bit to 10" or 12" driver with a tuning around 25 Hz, it's probably way too difficult to manage the sheer size of a 15" based 4.5 meter long line ... especially if I have to build cabinets in two or more iterations
Maybe then the bigger ones will come later when I'm more confident.....
go/no-go
The go/no-go for the building part will be when I do have some confidence that modelling seems to be at a good enough level that I do have some belief that they will at least perform more or less good, not sure what that means yet... LOL
So for now I'm reading and reading MJK's papers and references and findings, as I will try to understand as much as possible before I take any further steps.
I always considered myself competent in Math (grades underline this fact) but I don't understand anything about MJK's formulas yet, or maybe it's just too long time since I was in college...
At the moment, the S/W from leonardaudio.co.uk is my #1 choice for modelling
so there's a long thread to read about this too...
So far this keeps me quite busy
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Hi haraldo,
Just in case you don't have enough to look at yet : search this forum for contributions by bjorno on offset driver mass-loaded transmission lines, and tapped tapered quarter wave tubes/pipes (OD-ML-TL, OD MLTL, T-TQWT, T-TQWP and so on). bjorno has used MJK's spreadsheets and papers, and developed a whole family of designs (he is also very helpful when it comes to designing internal acoustic treatments); and they can be modelled in Hornresp too (with the exception of the acoustic treatments, filling/stuffing/lining); e.g.: http://www.diyaudio.com/forums/subw...band-w8q-1071f-8-x-12-box-reccomendation.html . Also, 15" driver TLs don't have to be huge: http://www.diyaudio.com/forums/subwoofers/223358-lab-15-design-suggestions-ht-use.html , that's the advantage of MJK's mass-loaded designs.
These are quite interesting, and with the speaker and filter Wizards in Hornresp, they are now relatively easy to design. Hornresp also allows you to export an AkAbak script, which then gives you even more design freedom (but the easy part is gone).
Regards,
Just in case you don't have enough to look at yet
: search this forum for contributions by bjorno on offset driver mass-loaded transmission lines, and tapped tapered quarter wave tubes/pipes (OD-ML-TL, OD MLTL, T-TQWT, T-TQWP and so on). bjorno has used MJK's spreadsheets and papers, and developed a whole family of designs (he is also very helpful when it comes to designing internal acoustic treatments); and they can be modelled in Hornresp too (with the exception of the acoustic treatments, filling/stuffing/lining); e.g.: http://www.diyaudio.com/forums/subw...band-w8q-1071f-8-x-12-box-reccomendation.html . Also, 15" driver TLs don't have to be huge: http://www.diyaudio.com/forums/subwoofers/223358-lab-15-design-suggestions-ht-use.html , that's the advantage of MJK's mass-loaded designs.These are quite interesting, and with the speaker and filter Wizards in Hornresp, they are now relatively easy to design. Hornresp also allows you to export an AkAbak script, which then gives you even more design freedom (but the easy part is gone).
Regards,
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Managed to go through some of Martin J. Kings papers and realize it's been a while since my college days and differential equations, I just don't understand reasoning behind all the equations, so it seems to be time to buy some of his references too (more background material)
Realize that a tapered line it must be.. as it seemingly generally is more well behaved according to MJK's experiments
Well so far I understand that the length of the line depends on tapering
Process is continuing
Realize that a tapered line it must be.. as it seemingly generally is more well behaved according to MJK's experiments
Well so far I understand that the length of the line depends on tapering
Process is continuing
Pearls from Martin J. King Quarter Wave Design
In addition to Martin J. King's papers, there's a good read hare:
Pearls from Martin J King Quarter Wave Design
In addition to Martin J. King's papers, there's a good read hare:
Pearls from Martin J King Quarter Wave Design
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