Hello. I have a question about modelling MLTL enclosures. I am trying to make a MLTL style speaker using the Dayton Audio TCP115-4 (link)
I don't know how to use Hornresp or Akabak well enough to achieve this, so I have taken to just using WinISD to design a ported enclosure, then playing with the dimensions a little bit as instructed by Xrk971 in his Accidental MLTL thread.
My size constraints are that I want an enclosure no more than 30 inches tall, and 5 or 5.5 inches wide (external). What I arrived at is a 29 inch tall cabinet with 4" width and 4.125" depth (internal) with a 1.5" diameter port that is 4 inches in length.
Now, I am getting closer to the cabinet construction phase, and I am starting to wonder how much I am leaving on the table by omitting the use of this more involved simulation software.
I want my enclosure to be no more than 30 inches tall, which if I'm not mistaken means even with advanced simulation, I am starting to blur the line between MLTL and regular Helmholtz due to the limited quarter wave resonance accentuation at lower frequencies. So, given this, is it okay to take my more rudimentary approach towards cabinet design? Thank you!
I don't know how to use Hornresp or Akabak well enough to achieve this, so I have taken to just using WinISD to design a ported enclosure, then playing with the dimensions a little bit as instructed by Xrk971 in his Accidental MLTL thread.
My size constraints are that I want an enclosure no more than 30 inches tall, and 5 or 5.5 inches wide (external). What I arrived at is a 29 inch tall cabinet with 4" width and 4.125" depth (internal) with a 1.5" diameter port that is 4 inches in length.
Now, I am getting closer to the cabinet construction phase, and I am starting to wonder how much I am leaving on the table by omitting the use of this more involved simulation software.
I want my enclosure to be no more than 30 inches tall, which if I'm not mistaken means even with advanced simulation, I am starting to blur the line between MLTL and regular Helmholtz due to the limited quarter wave resonance accentuation at lower frequencies. So, given this, is it okay to take my more rudimentary approach towards cabinet design? Thank you!
Hi CAN,
Thanks for trying the AMLTL method. This driver has a pretty low Qts and a small Vas implying it has quite a large powerful motor. Interesting performance specs for a mid bass driver at a budget price. Because the Qts is low, the AMLTL method may not be as accurate as using a real MLTL model. Your cabinet has 7.8L volume and 2x Vas is about 6.2L so I would suggest reducing the depth a bit to get closer to 6L. Maybe try to recalculate the vent for 50Hz. This will improve efficiency of the bass output and give you more power for kick drums.
Thanks for trying the AMLTL method. This driver has a pretty low Qts and a small Vas implying it has quite a large powerful motor. Interesting performance specs for a mid bass driver at a budget price. Because the Qts is low, the AMLTL method may not be as accurate as using a real MLTL model. Your cabinet has 7.8L volume and 2x Vas is about 6.2L so I would suggest reducing the depth a bit to get closer to 6L. Maybe try to recalculate the vent for 50Hz. This will improve efficiency of the bass output and give you more power for kick drums.
This looks like a pretty awesome design! Unfortunately it is bigger than what my design goal accommodates.
That is useful input. I appreciate it
In my WinISD models I have had a hard time coming up with a port diameter/length that kept velocity down and also gave me my desired tuning frequency given my limited depth. I actually initially had my internal depth at 4", but increased it to give the 4 inch port some room. Maybe things won't suffer too badly if I reduce the port diameter to 1 3/8, then I could get the tuning frequency I want, and also reduce the depth.
By the way, I love the acronym!
So it looks like the only way I could get away with a tuning frequency of 50Hz with a shorter depth would be to use a 1 1/8 inch diameter port. WinISD predicts 11 m/s at only 1 watt. Maybe I will look into a bottom firing port or a curved port
Inductance is very high so upper bandwidth is rather limited.
So 100 Hz to about 800 to 1000 is to be expected.
Not really designed for anything larger than 2 liters
impedance peak be around 75 Hz regardless.
Port velocity not really much concern.
Because the port wont be doing much.
In 7 liters expect about 3 to 6 watts linear
It is very tall box so port length round or slot has generous
amount of space for length
maybe design wide legs or wide base, since it will be somewhat unstable
So 100 Hz to about 800 to 1000 is to be expected.
Not really designed for anything larger than 2 liters
impedance peak be around 75 Hz regardless.
Port velocity not really much concern.
Because the port wont be doing much.
In 7 liters expect about 3 to 6 watts linear
It is very tall box so port length round or slot has generous
amount of space for length
maybe design wide legs or wide base, since it will be somewhat unstable
Wow that would be awesome! Well, I'd like it to play as low as possible, 45Hz would be amazing but I understand it might be a stretch. On the higher end, I don't need it to play very high, since I will be pairing it with a MarkAudio CHN40. I am not in the crossover design stage yet, but I am thinking somewhere between 400-700Hz. I'm assuming the TCP115 will be the main limiting factor in terms of SPL, so I am hoping to get away with a lower crossover point for the CHN40's. 400Hz would be ideal, but if need be I can go higher
I understand the driver was designed with a rather small enclosure in mind, but I was inspired to use it in a larger MLTL style enclosure by Dayton Audio's own MK442T speaker which uses 2 of the 8 ohm version in an even bigger regular transmission line speaker than even I am shooting for.
I am also thinking of making a base, for stability reasons and also to accommodate a downfiring port
That's an interesting idea. I think I want to do a tube port for this build, but maybe once I get a little more comfortable with woodworking I can play around with something like that.
Yeah
18ms does sound pretty high. I haven't bought ports yet, so I can buy a larger diameter one or a flared port or something if that would help. Also, I can make it downward firing to accommodate a longer port if need be. I also wouldn't mind putting the port on the back of the speaker if that would help with lowering the audibility of the chuffing. I'll be putting the crossover inside the cabinet, but other than the TCP115 it will just be the MarkAudio CHN40 for this speaker. It would be cool if I could do a dagger enclosure for the CHN40, but given that I want the baffle to be no more than 5 inches wide, I don't think I can fit it. I will probably just increase the height of the cabinet, and section off a top portion for the CHN40. So as far as the TCP115 is concerned it won't be apart of the equation. Thank you
You want to stay below 10m/s port velocity. But that’s only going to be reached at loud SPLs. Really, these are speakers meant to be played circa 1W to 4W. I don’t think port chuffing is an issue if you play these where it makes sense. As single 4in driver is not meant for anything more than 85dB at listening position.
Here you go made it super easy to build should be okay 400 or less testing would
Be needed but I see full range your using can do 300 easily. Each cube =1 inch 1-4 are segments the lines are just to show where they the segments start and stop so just just a 1x4 inch board and the longer board which is around 21 inchs x 4 is all that's needed the foam is more important then the dimensions of the box bc it screws with the tuning which is at 45hz like you wanted.
Be needed but I see full range your using can do 300 easily. Each cube =1 inch 1-4 are segments the lines are just to show where they the segments start and stop so just just a 1x4 inch board and the longer board which is around 21 inchs x 4 is all that's needed the foam is more important then the dimensions of the box bc it screws with the tuning which is at 45hz like you wanted.
I will be playing them at moderate levels in a pretty small room. Don't think I'll be pushing them very hard at all.
Wow, that is very detailed. Thank you very much! I think I mostly understand, but I have a few questions
What internal width does this cabinet assume?
There is a horizontal line in the diagram along the midpoint of where the woofer should go. That does not correspond to a board inside the cabinet, correct? Just a line that indicates the position the woofer should be at?
At the bottom of the diagram, there is a horizontal line marked 4, then two lines going down another 2 inches before cutting off, below which you write "port end". Is the base of the cabinet at the horizontal line marked 4? If not, forgive me, I don't entirely understand. I am gathering that you designed the enclosure with a tapered slot port?
Okay awesome! You've made exactly what I'm looking for! Okay, so. Just so that I know 100% we're on the same page. At the base of the enclosure, it will be a 4"x4" hole (widthxdepth) that is 2" high, and which has an opening into the enclosure that is 4"x3" (widthxdepth) that gradually tapers into a 2"x2" section by the time it reaches the woofer?