giantstairs
Find here interesting tips for stuffing and finish a MLTL, also open set of plans link
http://www.quarter-wave.com/Project04/Enclosure_Design.htm
Enjoy !!
For my MLTL prototypes I use the stuffing only in the volume that extends from the top of the enclosure to about 2 inches below the driver. No additional stuffing is needed below that point. Hence, you would have stuffing in approximately the top one third to perhaps half of the total enclosed volume. Tease or fluff the stuffing to eliminate any balls of the material so that you have even fill inside the MLTL. I typically place the stuffing inside the cabinet without over stuffing the volume.
When you locate the MLTL speakers in your room you should listen to a variety of music to ascertain how they sound. If you like their sound than you are done. But you can vary the amount of stuffing to best adapt the MLTL to your room. If you sense that you have too much or too little bass then you can experiment with the density of stuffing in your MLTLs. Adding more stuffing will reduce the bass sound or conversely removing stuffing would increase the bass.
Jim
When you locate the MLTL speakers in your room you should listen to a variety of music to ascertain how they sound. If you like their sound than you are done. But you can vary the amount of stuffing to best adapt the MLTL to your room. If you sense that you have too much or too little bass then you can experiment with the density of stuffing in your MLTLs. Adding more stuffing will reduce the bass sound or conversely removing stuffing would increase the bass.
Jim
what for me worked in a ported box with this driver is the full top half covered with 2cm whool, except the front where the driver is mounted, the bottom half is not damped
Note that the stuffing for a ported box and a MLTL are very different.
For a ported box some or even all walls are lining with a damping material. The air flow path between the driver and port is left open.
For a MLTL you fill the entire volume from the top of the enclosure to below the driver with stuffing.
Thus ported boxes are surface damped while the MLTLs are volume damped.
Jim
For a ported box some or even all walls are lining with a damping material. The air flow path between the driver and port is left open.
For a MLTL you fill the entire volume from the top of the enclosure to below the driver with stuffing.
Thus ported boxes are surface damped while the MLTLs are volume damped.
Jim
At a quick glance it appears that MJK used the stuffing density (0.25 lb/ft3) only in the upper portion and not the entire volume. Well closer, anyway, as I get different values than his.
My MLTL design for the Alpair 10.3 assumed a density of 0.75 lb/cubic feet.
Meniscus Audio makes 1 inch thick Dacron sheets which are 0.75 lb/ft3 that can be cut and stacked in the enclosure.
I'm assuming you will likely find loose stuffing material such as mattress stuffing which can be inserted in your enclosure. You could weigh material for the specified amount or just experiment with the sound of your speaker to achieve perfection.
Bonded Dacron
Jim
Meniscus Audio makes 1 inch thick Dacron sheets which are 0.75 lb/ft3 that can be cut and stacked in the enclosure.
I'm assuming you will likely find loose stuffing material such as mattress stuffing which can be inserted in your enclosure. You could weigh material for the specified amount or just experiment with the sound of your speaker to achieve perfection.
Bonded Dacron
Jim
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I tuned my box lower than the fs of the driver (38hz for the driver, 30hz for the box) and i do get a lot of bass till 29hz on low volume (<15w) when the music asks it. But when the volume rises the fs of the total speaker rises. But i don't care about that so much as 10-15 watt is loud enough for my living room.
As I related earlier, the volume that you stuff is just the 18" length from the top of the box to just below the driver. You can calculate that truncated volume which is the width x depth x length of that space. If you use inch measurement be sure to convert to cubic feet as you go. Within this truncated volume the stuffing is specified to be 0.75 lbs/ft3.
It may be easier to just insert the stuffing into the truncated space and listen to ascertain the sound than being worried about the accuracy of the calculation.
Jim
It may be easier to just insert the stuffing into the truncated space and listen to ascertain the sound than being worried about the accuracy of the calculation.
Jim
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Jim, I'm glad you clarified this aspect of your design before I began building my variant on your Alpair 6M MLTLs. I have always understood stuffing density to be related to the total volume of the box rather than just the volume where the stuffing is placed. Based on that understanding I would have grossly overstuffed the box.
Yeah, I was under the same impression hence my confusion. GM advised me to use the whole volume of the box to calculate stuffing in an earlier Monacor MLTL build. This is however Jim's design so I'll go with his recommendation as a starting point.
I don't remember how much stuffing I used but also used total volume to determine the amount of stuffing so mine are over stuffed. Thing is my Alpair 6 MLTL sound so good
I will change the stuffing density at some stage to see what changes I hear but no rush as am happy as is. I suppose the bass will become more prominent in theory but bass is just great as is the overall sound.
My build
I finally got around to building these and have not been disappointed! The Alpairs need lots of running in but their quality is already apparent. Voices sound great and there is lots of detail even at low levels.
I used mitre joints except for the back panel, which uses butt joints and cleats, and found the tops difficult to get just right. Also had an accident with one of the corners as MDF is very fragile after the cuts (and sharp! I gave myself a nice cut when picking up the sides).
My biggest regret is that I made these for a friend and did not make a pair for me! They also took more hours than I had calculated...
These are bottom firing and still need feet. Stuffing will also be determined after a few hundred hours and in the room where they will reside. So far they are really promising! Thanks for a great design Jim!
I finally got around to building these and have not been disappointed! The Alpairs need lots of running in but their quality is already apparent. Voices sound great and there is lots of detail even at low levels.
I used mitre joints except for the back panel, which uses butt joints and cleats, and found the tops difficult to get just right. Also had an accident with one of the corners as MDF is very fragile after the cuts (and sharp! I gave myself a nice cut when picking up the sides).
My biggest regret is that I made these for a friend and did not make a pair for me! They also took more hours than I had calculated...
These are bottom firing and still need feet. Stuffing will also be determined after a few hundred hours and in the room where they will reside. So far they are really promising! Thanks for a great design Jim!
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Stuffing
Forgot to mention I used a small section of fibreglass insulation panel on one side by the driver (mainly because I had already purchased it) and then stuffed with Dacron.
I placed the port on the bottom for aesthetics as the PVC pipe in a hole with silicon sealing didn't do it for me.
Now I need to try more of Mr. Griffin's designs! Any chance the Pluvia 7 will fit into one of your earlier MLTLs?
Forgot to mention I used a small section of fibreglass insulation panel on one side by the driver (mainly because I had already purchased it) and then stuffed with Dacron.
I placed the port on the bottom for aesthetics as the PVC pipe in a hole with silicon sealing didn't do it for me.
Now I need to try more of Mr. Griffin's designs! Any chance the Pluvia 7 will fit into one of your earlier MLTLs?
I drew an EL70 ML-TL for Jim. http://www.t-linespeakers.org/download/Griffin-offset-bipole-mltl-100909.pdf
P7 is really close to the EL70 in terms of loading so this will likely work with no changes, but small adjustments to the vent might be needed for optimization.
It is a bipole but 2 separate TLs stuck together back-to-back. For a single driver you could just use the front TL (and, if needed, tweak the cross-section shape)
dave