Hi!
I have read pretty much all the info here about the MLTL, including that monster thread of TABAQ
and want to build some folded version of it or similarly sized folded MLTL.
The driver will be 3in, fullrange, no aditional tweeter.
Still havent seen one straight answer, where is the best possible port location? Usage: general purpose, nothing special, just to obtain best possible sound reproduction.
Lets assume that the driver is at its optimal position, ~0.25-0.33 from closed end, port is at the end of the longer part, as usual. I can fold inside of it as I want, even if some of the positions are geometrically impossible. We are talking just about the port outside locations.
Please take a look at the picture:
1. "Classic" position: the same plane as a driver, in the center, but at the oposite side of it, similar to many of the BR boxes and classic TABAQ
2. The same as 1., but not on the center axis
3. Same plane as driver, as close to the driver as possible
3a. (not in the picture) The same as 3, just not on the center axis
4. Side wall of the cabinet, perpendicular to the driver.
5. Back of the cabinet
5a,b,c (not in the picture)... the variations of the height and beeing in the center or not
6. Top plane, perpendicular to the driver.
6a,b,c the same variations...
7. Other???
Please comment the positions. Appologies for poor english and painting...
I have read pretty much all the info here about the MLTL, including that monster thread of TABAQ
and want to build some folded version of it or similarly sized folded MLTL.The driver will be 3in, fullrange, no aditional tweeter.
Still havent seen one straight answer, where is the best possible port location? Usage: general purpose, nothing special, just to obtain best possible sound reproduction.
Lets assume that the driver is at its optimal position, ~0.25-0.33 from closed end, port is at the end of the longer part, as usual. I can fold inside of it as I want, even if some of the positions are geometrically impossible. We are talking just about the port outside locations.
Please take a look at the picture:
1. "Classic" position: the same plane as a driver, in the center, but at the oposite side of it, similar to many of the BR boxes and classic TABAQ
2. The same as 1., but not on the center axis
3. Same plane as driver, as close to the driver as possible
3a. (not in the picture) The same as 3, just not on the center axis
4. Side wall of the cabinet, perpendicular to the driver.
5. Back of the cabinet
5a,b,c (not in the picture)... the variations of the height and beeing in the center or not
6. Top plane, perpendicular to the driver.
6a,b,c the same variations...
7. Other???
Please comment the positions. Appologies for poor english and painting...
Attachments
Hmm, apparently not any of my numerous postings on the subject......
Port location on a MLTL is a function of its pipe odd harmonics locations, so this dictates where it goes.
Optimally, it will be in the region between [inside top 'L'*0.848] and the bottom and can be on any side you choose with the theoretical optimum being closest to a reflective boundary.
Optimal driver position is at an odd harmonic same as the vent, so 'L'* 0.21, 0.349, 0.42.
GM
Port location on a MLTL is a function of its pipe odd harmonics locations, so this dictates where it goes.
Optimally, it will be in the region between [inside top 'L'*0.848] and the bottom and can be on any side you choose with the theoretical optimum being closest to a reflective boundary.
Optimal driver position is at an odd harmonic same as the vent, so 'L'* 0.21, 0.349, 0.42.
GM
Thanks a lot, but my specific question is about folded version.
Maybe I have expressed myself wrong because of my poor english. Will try to ask simple:
If I follow all the above mentioned rules, and have an option to place port, where is the best location for its exit to outside of cabinet?
Closer to the driver?
Perpendicular?
The same plane, but as far from driver as possible?
Opposite side of cabinet?
GM did answer your question, but I guess it was lost in translation.
Like he said, the line will dictate where the exit goes.
In a typical folded version, with one turn, if you follow the line, the driver is in front, the line goes down, turns, and up.
So the exit will be somewhere on the top, behind, around the number 6 in your drawing.
Now, if you plan to hang the speakers on a wall, you can't put the exit completely behind, so, the port would be either on the top, your number 6, or on a side, next to number 6.
If you plan to have the speakers a little away from the wall, then you could put the port on the back panel, again, near number 6.
Like he said, the line will dictate where the exit goes.
In a typical folded version, with one turn, if you follow the line, the driver is in front, the line goes down, turns, and up.
So the exit will be somewhere on the top, behind, around the number 6 in your drawing.
Now, if you plan to hang the speakers on a wall, you can't put the exit completely behind, so, the port would be either on the top, your number 6, or on a side, next to number 6.
If you plan to have the speakers a little away from the wall, then you could put the port on the back panel, again, near number 6.
Hmm.... Yeah, whole thread is getting lost in translation.
I totally understand everything you said.
Lets make this even simpler: forget the internal fold, lets assume, that it can magically fold in any way we want - the better position is 1 (bottom) or 3 (closer to the driver)?
Thanx, Bjørn,
This is the answer!
May I torment you asking why it is so (the best location closer to driver)?...
And how it depends on the stuffing density?
You're welcome!
Hmm, OK, I mostly paid attention to the sketch which didn't show any fold lines.
In that case, fold to place the vent as close as practical and on the same plane to the driver. If you look at Thuras's reflex patent, one realization is the driver in the vent.
GM
OK, what part of this did you not understand or what part of your question did I not understand? Port placement variations in folded straight line MLTL (folded TABAQ)?
GM
GM
OK, both mine and Bjørn's description tells you #3 since it's the closest and on the same plane as per the original reflex patent. If it's a woofer, then laid on it's side to better couple the driver/vent to the floor is normally a good plan.
If a tower where it looks like a MLTL with the driver up high, then #2 is the best compromise since corner loading will shorten the vent and it will couple to the floor better, with #1 3rd best and most often used since folks like their baffles to look symmetrical.
As for the rest, it depends on where and how it will be positioned in room.
In all cases, best location in the pipe is required per my instructions to maximize its performance.
GM
If a tower where it looks like a MLTL with the driver up high, then #2 is the best compromise since corner loading will shorten the vent and it will couple to the floor better, with #1 3rd best and most often used since folks like their baffles to look symmetrical.
As for the rest, it depends on where and how it will be positioned in room.
In all cases, best location in the pipe is required per my instructions to maximize its performance.
GM
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