I just started doing the initial designs for a bass TL box for the dayton 8". This will be matched with a CSS WR125 for a mid and an Aurum Cantus G2si for treble. The G2's and the WR125's should be at my doorstep any day now, the Daytons haven't been ordered yet, just have to stop being lazy. I haven't worked out crossover points yet, so I'm not worried too much about that. Likely the mid crossover will be around 250hz, and the entire system will be actively crossed.
My question doesn't really have to do with the Dayton specifically I suppose, but more about mounting. Is it too much of a compromise to mount the midbass at the bottom of the enclosure, near the ground? I would like for the line to have a single bend and exit at the bottom in the rear. I suppose I could put two turns in and mount it at the top, but I just don't know how long the line is going to be. I'm planning on a tapered line so it should keep length to a minimum.
Also on a side note, I can't seem to find and appropriate Sd measurement for the Dayton driver. Where can I find this.
So anyways, I'm probably just looking for design tips in general as I go through this. This is my first T-line box that I've designed so I'm trying to get everything just right. I also can't seem to find a copy of Mathcad that I can use. If someone wants to plug in the Dayton to the MJK sheets and lemme know what it comes up with, I would be eternally greatful.
Thanks very much
-Steve
My question doesn't really have to do with the Dayton specifically I suppose, but more about mounting. Is it too much of a compromise to mount the midbass at the bottom of the enclosure, near the ground? I would like for the line to have a single bend and exit at the bottom in the rear. I suppose I could put two turns in and mount it at the top, but I just don't know how long the line is going to be. I'm planning on a tapered line so it should keep length to a minimum.
Also on a side note, I can't seem to find and appropriate Sd measurement for the Dayton driver. Where can I find this.
So anyways, I'm probably just looking for design tips in general as I go through this. This is my first T-line box that I've designed so I'm trying to get everything just right. I also can't seem to find a copy of Mathcad that I can use. If someone wants to plug in the Dayton to the MJK sheets and lemme know what it comes up with, I would be eternally greatful.
Thanks very much
-Steve
>My question doesn't really have to do with the Dayton specifically I suppose, but more about mounting. Is it too much of a compromise to mount the midbass at the bottom of the enclosure, near the ground?
====
Depends on high up the XO point/slope is, ergo how close the mid must be for good summation, ergo where is it in relation to the listening position vertically. That, or how much slope the baffle has.
====
>Also on a side note, I can't seem to find and appropriate Sd measurement for the Dayton driver. Where can I find this.
====
Look at the measured specs, it lists the effective diameter, which you can calc it from using (d^2*pi)/4.
====
>So anyways, I'm probably just looking for design tips in general as I go through this. This is my first T-line box that I've designed so I'm trying to get everything just right. I also can't seem to find a copy of Mathcad that I can use.
====
??? Do you mean you have an Apple?
====
>If someone wants to plug in the Dayton to the MJK sheets and lemme know what it comes up with, I would be eternally greatful.
====
Traditional, ML-TL, or somewhere in-between?
BTW, folks tend to be more helpful if provided with enough info that they don't have to search for it, so posting any pertinent links, etc. is encouraged.
GM
====
Depends on high up the XO point/slope is, ergo how close the mid must be for good summation, ergo where is it in relation to the listening position vertically. That, or how much slope the baffle has.
====
>Also on a side note, I can't seem to find and appropriate Sd measurement for the Dayton driver. Where can I find this.
====
Look at the measured specs, it lists the effective diameter, which you can calc it from using (d^2*pi)/4.
====
>So anyways, I'm probably just looking for design tips in general as I go through this. This is my first T-line box that I've designed so I'm trying to get everything just right. I also can't seem to find a copy of Mathcad that I can use.
====
??? Do you mean you have an Apple?
====
>If someone wants to plug in the Dayton to the MJK sheets and lemme know what it comes up with, I would be eternally greatful.
====
Traditional, ML-TL, or somewhere in-between?
BTW, folks tend to be more helpful if provided with enough info that they don't have to search for it, so posting any pertinent links, etc. is encouraged.
GM
What kind of bass response do you want? I messed with modeling a TL for a pair of RS225's and it got pretty big pretty fast as I moved the low frequency target down (22Hz is realistic if you have the room IIRC). Also, I believe that the drivers weren't mounted at the end of the line, but partway along it. Which would mean they could be up off the floor some.
I'm not sure where you can get the free version of MathCad any more - I know the link on MJKing's website doesn't work any more.
Also, remember to remove the area of the phase plug from the cone area when calculating based on the diameter.
C
I'm not sure where you can get the free version of MathCad any more - I know the link on MJKing's website doesn't work any more.
Also, remember to remove the area of the phase plug from the cone area when calculating based on the diameter.
C
Alright. I had a few minutes and Mathcad already open and the RS225 specs handy...
Single RS225.
Line length 84-88 inches long.
Driver can be placed as far as 24" from the line end without significant ill effects, though it starts to introduce broader ripples at 200Hz up.
Line taper at 5Sd to 1.5Sd (with 1.55Sd being the open end) looks good. Err on the side of a little big. 7:2 looks great still, but a smidge under 5:1.5 starts to raise F3 quickly.
Stuff with 3-4oz per cubic foot (or, .2lb/ft^3)
This gives you an F3 at 30Hz.
Lengthen the line up to 120 inches, still 5:1.5 up to 7:2 taper ratio, same stuffing ratio. This gives you an F6 at 24Hz which, in-room, will often end up being flat.
Need smaller? Drop the taper ratio, shorten the line, and add stuffing. For example, 2.5:.75 taper, .5lb/ft^3, 66" length = F6 at 42Hz. You also need to move the driver closer to the closed end to reduce higher frequency ripple. 2.5:.71 taper stuffed .2lb/ft^3 at 84" gives you an F3 at 40Hz, F6 at 33Hz.
It's all about picking your compromises.
Have fun! And let us know how it turns out.
C
Single RS225.
Line length 84-88 inches long.
Driver can be placed as far as 24" from the line end without significant ill effects, though it starts to introduce broader ripples at 200Hz up.
Line taper at 5Sd to 1.5Sd (with 1.55Sd being the open end) looks good. Err on the side of a little big. 7:2 looks great still, but a smidge under 5:1.5 starts to raise F3 quickly.
Stuff with 3-4oz per cubic foot (or, .2lb/ft^3)
This gives you an F3 at 30Hz.
Lengthen the line up to 120 inches, still 5:1.5 up to 7:2 taper ratio, same stuffing ratio. This gives you an F6 at 24Hz which, in-room, will often end up being flat.
Need smaller? Drop the taper ratio, shorten the line, and add stuffing. For example, 2.5:.75 taper, .5lb/ft^3, 66" length = F6 at 42Hz. You also need to move the driver closer to the closed end to reduce higher frequency ripple. 2.5:.71 taper stuffed .2lb/ft^3 at 84" gives you an F3 at 40Hz, F6 at 33Hz.
It's all about picking your compromises.
Have fun! And let us know how it turns out.
C
I knew you guys would come through. Thanks so much for your effort so far.
On the mathcad note. I have a PC, and a linux box, but I can't find a demo for anything. I'm sure we have it on Campus somewhere here at OSU, I just have to find it.
I'm thinking that 90" or so would be about a max for the line. I figure that gives me a 50" tall box. That means my mid would be mounted about 55" high, which is getting pretty tall.
While I'd love a pair of speakers that would be give me good response down to 20hz in room, I don't need it. I'll give up ultra low response for a smaller cabinet. My living room is sloped ceiling with 8 foot on one side and 20ft on the other. I'm thinking that a nice straight line in one corner with a 15" driver will fill in the bottom octaves nicely. So I'm going to look into something with an f6 in the high 30's.
I'm at school right now and late for Microcontroller system design, but when I get home I'll draw up an initial box design and see what everybody thinks.
Thanks again
On the mathcad note. I have a PC, and a linux box, but I can't find a demo for anything. I'm sure we have it on Campus somewhere here at OSU, I just have to find it.
I'm thinking that 90" or so would be about a max for the line. I figure that gives me a 50" tall box. That means my mid would be mounted about 55" high, which is getting pretty tall.
While I'd love a pair of speakers that would be give me good response down to 20hz in room, I don't need it. I'll give up ultra low response for a smaller cabinet. My living room is sloped ceiling with 8 foot on one side and 20ft on the other. I'm thinking that a nice straight line in one corner with a 15" driver will fill in the bottom octaves nicely. So I'm going to look into something with an f6 in the high 30's.
I'm at school right now and late for Microcontroller system design, but when I get home I'll draw up an initial box design and see what everybody thinks.
Thanks again
>I'm not sure where you can get the free version of MathCad any more - I know the link on MJKing's website doesn't work any more.
====
Oh really?! It just worked for me.
====
>Also, remember to remove the area of the phase plug from the cone area when calculating based on the diameter.
====
Technically correct, but has no real bearing on a cab's design, assuming you use CSA instead of Sd to define SO/SL. Even then, a little too big is better than too small. Still, I didn't know it had one or would have said the same thing.
GM
====
Oh really?! It just worked for me.
====
>Also, remember to remove the area of the phase plug from the cone area when calculating based on the diameter.
====
Technically correct, but has no real bearing on a cab's design, assuming you use CSA instead of Sd to define SO/SL. Even then, a little too big is better than too small. Still, I didn't know it had one or would have said the same thing.
GM
dunderhead:
I would go with an 84" line and the 2.5 to .75 Sd taper, driver ~18" from the closed (large) end, stuffed with about a quarter pound per cubic foot. That's actually a very reasonable box size. If you build an angled division in the box from front to back to separate the TL from the mid enclosure (so the mid/tweet gets mounted into a triangular shaped box, looking at it from the side) you can get the tweeter in at ~40" off the floor or so even, I think.
GM: Haven't tried that link in a couple weeks. It wasn't working last I tried it. Guess I should've checked. And Sd/Bl relate in such a way that it can tweak the design some. Not hyper critical in this case, but not unimportant either. Try adding 5-10cm to Sd on a model. It's interesting. In the case of M King's stuff, since it uses Sd to base the rest of the numbers it's not unimportant either I think. Probably not much more than interesting once all is said and done.
FWIW, I did this modeling with M. King's "Offset Driver" worksheet. Fine tune with the "Sections" worksheet.
C
I would go with an 84" line and the 2.5 to .75 Sd taper, driver ~18" from the closed (large) end, stuffed with about a quarter pound per cubic foot. That's actually a very reasonable box size. If you build an angled division in the box from front to back to separate the TL from the mid enclosure (so the mid/tweet gets mounted into a triangular shaped box, looking at it from the side) you can get the tweeter in at ~40" off the floor or so even, I think.
GM: Haven't tried that link in a couple weeks. It wasn't working last I tried it. Guess I should've checked. And Sd/Bl relate in such a way that it can tweak the design some. Not hyper critical in this case, but not unimportant either. Try adding 5-10cm to Sd on a model. It's interesting. In the case of M King's stuff, since it uses Sd to base the rest of the numbers it's not unimportant either I think. Probably not much more than interesting once all is said and done.
FWIW, I did this modeling with M. King's "Offset Driver" worksheet. Fine tune with the "Sections" worksheet.
C
I don't really have a suggestion on the TL, but here are the specs from PE:
Dayton RS225s
Specifications: *Power handling: 80 watts RMS/120 watts max *VCdia: 1.5" *Le: 1.0 mH *Znom: 8 ohms *Re: 6.4 ohms *Frequency range: 27-2,000 Hz *Fs: 27 Hz *SPL: 88.1 dB 2.83V/1m *Vas: 2.75 cu. ft. *Qms: 1.60 *Qes: .47 *Qts: .37 *Xmax: 7 mm *Dimensions: A: 8-3/4", B: 7-3/8", C: 4".
PARAMETERS
Re 6.40 [ê ]
Fs 26.35 [Hz]
F1 14.13 [Hz]
F2 47.32 [Hz]
Zm 26.01 [ê]
D 162.00 [mm]
Qms 1.55
Qes 0.50
Qts 0.38
Bl 7.60 [N/A]
L1K 0.79 [mH]
L10K 0.26 [mH]
Ms 27.52 [g]
Vas 78.64 [l]
dBSpl 87.48 [dB]
Cms 1.33 [mm/N]
Ma 84.00 [g]
FsMa 13.09 [Hz]
GB
Dayton RS225s
Specifications: *Power handling: 80 watts RMS/120 watts max *VCdia: 1.5" *Le: 1.0 mH *Znom: 8 ohms *Re: 6.4 ohms *Frequency range: 27-2,000 Hz *Fs: 27 Hz *SPL: 88.1 dB 2.83V/1m *Vas: 2.75 cu. ft. *Qms: 1.60 *Qes: .47 *Qts: .37 *Xmax: 7 mm *Dimensions: A: 8-3/4", B: 7-3/8", C: 4".
PARAMETERS
Re 6.40 [ê ]
Fs 26.35 [Hz]
F1 14.13 [Hz]
F2 47.32 [Hz]
Zm 26.01 [ê]
D 162.00 [mm]
Qms 1.55
Qes 0.50
Qts 0.38
Bl 7.60 [N/A]
L1K 0.79 [mH]
L10K 0.26 [mH]
Ms 27.52 [g]
Vas 78.64 [l]
dBSpl 87.48 [dB]
Cms 1.33 [mm/N]
Ma 84.00 [g]
FsMa 13.09 [Hz]
GB
So I thought I would bump this back up to the top with a couple more questions. I'm going to finalize some things this weekend, and I want all the help I can get.
My current crossover design seems to go like this.
RS225 up to ~250Hz
WR125 from 250hz to ~6khz
AC G2si from 6kHz up
All slopes will be 24db/ octave initially.
Anybody see anything fundamentally wrong with this?
Each driver will be amped with channel from a few Panasonic Equibit receivers I've got laying around, and those will receive a signal from kx project drivers, and later from BruteFIR.
I'm going to go ahead with an 85" line. I like to the way it fits with the alignment tables, and what has been said in this thread. It is tempting to figure out how to put together a 120" line though.
Thanks much.
-Steve
My current crossover design seems to go like this.
RS225 up to ~250Hz
WR125 from 250hz to ~6khz
AC G2si from 6kHz up
All slopes will be 24db/ octave initially.
Anybody see anything fundamentally wrong with this?
Each driver will be amped with channel from a few Panasonic Equibit receivers I've got laying around, and those will receive a signal from kx project drivers, and later from BruteFIR.
I'm going to go ahead with an 85" line. I like to the way it fits with the alignment tables, and what has been said in this thread. It is tempting to figure out how to put together a 120" line though.
Thanks much.
-Steve
hey joe,
Thanks for the encouragment. I'm not completely set on the T-line, or the Dayton for the matter. I've made a couple of kits now, and a couple of slightly complicated cabinets, so I decided to jump to the next level.
My thinking for the TL is that I really enjoy the sound of an open speaker with excellent transients. Also, the extension looks to be great. In general it seems like it takes care of a lot of the issues with sealed and BR boxes. Of course there's compromises, and I don't expect my first try to be perfect, but it's always a learning experience. Also, everybody has been talking about how the daytons would be perfect for a TL, but I haven't seen one built yet, so why not.
Of course, if there's something that can exceed it's performance then I'm all for it. Cost is also an issue, and the Dayton is looking good there. Please give me all the info you can. I fully plan on documenting the process and publishing it after I"m finished.
-Steve
Thanks for the encouragment. I'm not completely set on the T-line, or the Dayton for the matter. I've made a couple of kits now, and a couple of slightly complicated cabinets, so I decided to jump to the next level.
My thinking for the TL is that I really enjoy the sound of an open speaker with excellent transients. Also, the extension looks to be great. In general it seems like it takes care of a lot of the issues with sealed and BR boxes. Of course there's compromises, and I don't expect my first try to be perfect, but it's always a learning experience. Also, everybody has been talking about how the daytons would be perfect for a TL, but I haven't seen one built yet, so why not.
Of course, if there's something that can exceed it's performance then I'm all for it. Cost is also an issue, and the Dayton is looking good there. Please give me all the info you can. I fully plan on documenting the process and publishing it after I"m finished.
-Steve
Steve,
My first reaction was that you're all set for an open baffle dipole. The main benefit from that is improved room interaction; I think that Linkwitz discusses many of the benefits of open baffle dipole bass- there are many forum threads and websites if you look.
I am personally preoccupied with a system like this- http://mfk-projects.com/rs_dipole.htm - but with a $50 sound card in my existing computer instead of a $450 digital crossover
Why am I preoccupied with it? Mostly because I have limited fabrication resources right now, and I'm living in an apartment in the san francisco bay area. I don't want to get evicted, and the directional nature of dipole bass makes me think I can position the speakers so the outer wall is behind them, so bass doesn't go to the neighbors above below or to the sides. That's my reason for thinkin that's a good idea. There are trade-offs.
The benefit of doing it the way you propose is that you're quite likely to get bass below 30 hz from a single 8" driver, and it's a fairly cheap one at that. If you went open baffle, you'd want at least two 10"s- and you'd sacrifice the bottom half an octave.
One of the things that shocked me, when I built an ML-TL for an 8" driver was that I could set up some really noticeable standing waves in my room. I could play a 40hz tone, and walking around the room it would disappear in some places, and sound loud in others.
Another site that could be helpful to you are art ludwig's site- http://www.silcom.com/~aludwig/ . I don't recall what it was, but it seems to me that some room acoustics are discussed there. I can tell you that it feels kind of dumb to build a 45 inch tall speaker, and then play with positioning because 100hz doesn't want to show up at the couch!
I didn't educate myself on room acoustics first, so maybe you can learn from that mistake. I had rear firing ports pointed directly into the corners of the room. In retrospect, that was probably a really bad idea.
Good luck with it, and keep us posted
Oh, and if you have a set of numbers to run through Martin's worksheets, I can still do that so you can see some graphs.
Joe
My first reaction was that you're all set for an open baffle dipole. The main benefit from that is improved room interaction; I think that Linkwitz discusses many of the benefits of open baffle dipole bass- there are many forum threads and websites if you look.
I am personally preoccupied with a system like this- http://mfk-projects.com/rs_dipole.htm - but with a $50 sound card in my existing computer instead of a $450 digital crossover
Why am I preoccupied with it? Mostly because I have limited fabrication resources right now, and I'm living in an apartment in the san francisco bay area. I don't want to get evicted, and the directional nature of dipole bass makes me think I can position the speakers so the outer wall is behind them, so bass doesn't go to the neighbors above below or to the sides. That's my reason for thinkin that's a good idea. There are trade-offs.
The benefit of doing it the way you propose is that you're quite likely to get bass below 30 hz from a single 8" driver, and it's a fairly cheap one at that. If you went open baffle, you'd want at least two 10"s- and you'd sacrifice the bottom half an octave.
One of the things that shocked me, when I built an ML-TL for an 8" driver was that I could set up some really noticeable standing waves in my room. I could play a 40hz tone, and walking around the room it would disappear in some places, and sound loud in others.
Another site that could be helpful to you are art ludwig's site- http://www.silcom.com/~aludwig/ . I don't recall what it was, but it seems to me that some room acoustics are discussed there. I can tell you that it feels kind of dumb to build a 45 inch tall speaker, and then play with positioning because 100hz doesn't want to show up at the couch!
I didn't educate myself on room acoustics first, so maybe you can learn from that mistake. I had rear firing ports pointed directly into the corners of the room. In retrospect, that was probably a really bad idea.
Good luck with it, and keep us posted
Oh, and if you have a set of numbers to run through Martin's worksheets, I can still do that so you can see some graphs.
Joe
Moving the terminus to the front wouldn't be too miserable - you'd have one 180 bend and one 90 bend in the line to do it is all. You may be able to go with a longer line and still have good taper while allowing ear-height placement of the tweeter if you don't make the sides of your box parallel.
Though I don't know how it compares to the WR125 you're considering, the BG Neo8 in an open baffle configuration has me very very intrigued. Higher cross, but hey. The RS225 is good quite a bit higher than 250Hz, so you can, just a question of if you want to.
The other thing is you might consider steeper slopes, run the RS225 up to ~1200Hz and cross to a Fountek NeoPro5i ribbon. There goes the bank.
Of course, with some very careful crossover work, you could cross to a single Seas 27TDC or TDFC at around 1200Hz and make a 2-way. A little more output limited, since you have excursion issues with the Seas.
C
You may be able to go with a longer line and still have good taper while allowing ear-height placement of the tweeter if you don't make the sides of your box parallel.Though I don't know how it compares to the WR125 you're considering, the BG Neo8 in an open baffle configuration has me very very intrigued. Higher cross, but hey. The RS225 is good quite a bit higher than 250Hz, so you can, just a question of if you want to.
The other thing is you might consider steeper slopes, run the RS225 up to ~1200Hz and cross to a Fountek NeoPro5i ribbon. There goes the bank.
Of course, with some very careful crossover work, you could cross to a single Seas 27TDC or TDFC at around 1200Hz and make a 2-way. A little more output limited, since you have excursion issues with the Seas.
C
Well, I'm committed to the drivers I've got now. We could go back and forth forever on what a better driver combo would be. I like the looks of the ones I've got now, and they should go plenty loud (never know when you'll need that). One of my reasons behind the WR125 is I like the idea of getting as much of the vocals on a single driver. Just makes sense to me.
So now I've got to decide whether my exit should be downward at the back or facing forward. The cabinets will definately not be rectangle. Think modified B & W 801's. The tweeter and mid will be mounted in fiberglass enclosures, while the Dayton will be mounted in a rounded enclosure with an internal triangular shape. This means the first half of the line will be a trapezoid and the second half a triangle, or very steep trapezoid. Anybody see any inhearant problems with this? I've got all the geometry worked out and such, and I will draw up and autocad plan when I get back into town.
So now I've got to decide whether my exit should be downward at the back or facing forward. The cabinets will definately not be rectangle. Think modified B & W 801's. The tweeter and mid will be mounted in fiberglass enclosures, while the Dayton will be mounted in a rounded enclosure with an internal triangular shape. This means the first half of the line will be a trapezoid and the second half a triangle, or very steep trapezoid. Anybody see any inhearant problems with this? I've got all the geometry worked out and such, and I will draw up and autocad plan when I get back into town.
To get vocals on a single driver, you'd have to lower that cross frequency a bit. A lot if you use LOTR:ROTK EE as a reference. heh. Ahh well.
I am not aware that line cross-section geometry is dramatically important, but it's been a while since I went over M.J.King's work. I do know folks go with round, and the fact that you can put bends in it would suggest that it's not *that* picky.
Given the flex room you have in both taper ratio and line length, I think the biggest thing you want to do is make sure you don't go under the numbers you're targeting. Going a little bit over will not hurt (for example, the 5:1.5 taper and the 7:2 taper model out very very similarly, and the same tapers work for a range from 84-120"...)
C
I am not aware that line cross-section geometry is dramatically important, but it's been a while since I went over M.J.King's work. I do know folks go with round, and the fact that you can put bends in it would suggest that it's not *that* picky.
Given the flex room you have in both taper ratio and line length, I think the biggest thing you want to do is make sure you don't go under the numbers you're targeting. Going a little bit over will not hurt (for example, the 5:1.5 taper and the 7:2 taper model out very very similarly, and the same tapers work for a range from 84-120"...)
C
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