An MLTL for Alpair 10P
Taking cues from similar designs (Pensils and Jim Griffin's design, I have recently designed and built my own variation of an 'accidental' MLTL for the Alpair 10P. I live in an apartment (so lack proper power tools and work space), so I had a Lowe's employee cut the 11-ply birch plywood for me and opted to use foamcore on part of the front baffle since it is easier to cut holes in with few tools.
The boxes are 7.5" wide x 9" deep x 40" high internal, for a volume of approximately 44L after a little bracing and such. The port has area 5.625 square inches and is 3" long, so the tuning is in the lower 40's (43Hz according to Unibox). Mounting the driver 10" from the top seemed to give the smoothest frequency response in the Leonard Audio software. The top half of the line should be stuffed with at least 0.2 pounds/cu.ft. to smooth out the response peaks (see graph below). Predicted response is reasonably flat to 40Hz with an F10 in the low 30's.
The result is a rather compact floorstander (9"x10.5"x43" outside) with good bass extension. They are currently stuffed with about 6 ounces of polyfill in the top halves and a bit of foam along the lower halves. I still have to sand and finish the cabinets, but then look nice enough for now. And, they sound better every day.
Taking cues from similar designs (Pensils and Jim Griffin's design, I have recently designed and built my own variation of an 'accidental' MLTL for the Alpair 10P. I live in an apartment (so lack proper power tools and work space), so I had a Lowe's employee cut the 11-ply birch plywood for me and opted to use foamcore on part of the front baffle since it is easier to cut holes in with few tools.
The boxes are 7.5" wide x 9" deep x 40" high internal, for a volume of approximately 44L after a little bracing and such. The port has area 5.625 square inches and is 3" long, so the tuning is in the lower 40's (43Hz according to Unibox). Mounting the driver 10" from the top seemed to give the smoothest frequency response in the Leonard Audio software. The top half of the line should be stuffed with at least 0.2 pounds/cu.ft. to smooth out the response peaks (see graph below). Predicted response is reasonably flat to 40Hz with an F10 in the low 30's.
The result is a rather compact floorstander (9"x10.5"x43" outside) with good bass extension. They are currently stuffed with about 6 ounces of polyfill in the top halves and a bit of foam along the lower halves. I still have to sand and finish the cabinets, but then look nice enough for now. And, they sound better every day.
Attachments
Lowther OB - Pass Design
Purchased a First Watt F3 amp (10 watts) in 2006. Never had the correct speakers for it. Asked Nelson Pass at Burning Amp 2013 what speakers he recommended. He said mess around with Lowthers on an OB.
So guess what? Took some time, challenged my wood skills a bit (I know, it's an OB!) but the results really surprised me.
Years ago a dear friend, Arthur Dinsmore, told never ever get sucked into Lowther loudspeakers. These are the Arthur Dinsmore Memorial Lowthers.
Thanks Nelson! And Arthur.
Lowther PM6A Ticonal 16 ohm Silver Voice Coil with Eminence Definimax 15"
Firstwatt B5 active crossover.
Purchased a First Watt F3 amp (10 watts) in 2006. Never had the correct speakers for it. Asked Nelson Pass at Burning Amp 2013 what speakers he recommended. He said mess around with Lowthers on an OB.
So guess what? Took some time, challenged my wood skills a bit (I know, it's an OB!) but the results really surprised me.
Years ago a dear friend, Arthur Dinsmore, told never ever get sucked into Lowther loudspeakers. These are the Arthur Dinsmore Memorial Lowthers.
Thanks Nelson! And Arthur.
Lowther PM6A Ticonal 16 ohm Silver Voice Coil with Eminence Definimax 15"
Firstwatt B5 active crossover.
Attachments
IIRC there is a Nelson Pass OB build similar to this, but nowhere near as pretty!! I believe it's a Slot Loaded woofer. Genius IMO.
OB Slot load woofer
Gee thanks! These are the Nelson Pass design, I just built them. I put on a bit larger baffle, as big as I and the wife would tolerate.
The slot loading follows a formula based on the driver dimensions. Jon Ver Halen gave me the formula but it was angled back by NP. The math is the same. Not sure how it affects the sound.
IIRC, 2.25" for the 15" Definimax on a 16" square baffle. The angle slopes the woofer down in the rear to 1.125" and up to 3.375 in front. Sealed in the back.
Difficult for my limited wood working skills, but I got quite close.
Works too. Just listening to Cameron Carpenter playing pipe organ.
-Howie
Gee thanks! These are the Nelson Pass design, I just built them. I put on a bit larger baffle, as big as I and the wife would tolerate.
The slot loading follows a formula based on the driver dimensions. Jon Ver Halen gave me the formula but it was angled back by NP. The math is the same. Not sure how it affects the sound.
IIRC, 2.25" for the 15" Definimax on a 16" square baffle. The angle slopes the woofer down in the rear to 1.125" and up to 3.375 in front. Sealed in the back.
Difficult for my limited wood working skills, but I got quite close.
Works too. Just listening to Cameron Carpenter playing pipe organ.
-Howie
Does the 15" woofer have to fire into a slot at all? I'd be using the Alpha 15. To keep things simple I thought a frame with the woofer firing down about 12" (and up) might work too.
Any thoughts? I really like the way the front baffle is clean witout clutter and the bass functions behind the scenes.
Any thoughts? I really like the way the front baffle is clean witout clutter and the bass functions behind the scenes.
Attachments
Hi Godzilla,
If you're talking about the one in post #3164, I've built a similar thing, here: http://www.diyaudio.com/forums/mult...loaded-open-baffle-project-4.html#post2698004
It sounds very good in bass, but eventually I gave it up and built a new one.
One of the problem maybe in the woofer I use. It's 18" so the 'slot' is pretty deep, thus the strongest cavity resonance is too close to the target operating range.
Another problem is the vibration. With the driver facing down, it's difficult (for me) to make a proper 'shock absorber' to reduce the strong vertical reaction. It's too easily exiting the floor.
If you find ways to sidestep the problems I had, it's a good choice nevertheless.
If you're talking about the one in post #3164, I've built a similar thing, here: http://www.diyaudio.com/forums/mult...loaded-open-baffle-project-4.html#post2698004
It sounds very good in bass, but eventually I gave it up and built a new one.
One of the problem maybe in the woofer I use. It's 18" so the 'slot' is pretty deep, thus the strongest cavity resonance is too close to the target operating range.
Another problem is the vibration. With the driver facing down, it's difficult (for me) to make a proper 'shock absorber' to reduce the strong vertical reaction. It's too easily exiting the floor.
If you find ways to sidestep the problems I had, it's a good choice nevertheless.
