Sorry to drag this further off topic.
I'll keep this short but GG deserves an explanation.
You've since made it clear that was not your intent. I apologise for being too snappy (and now wasting more thread bandwidth!)
I'll keep this short but GG deserves an explanation.
Mostly a tone of voice (or type) - 'round here abouts [edit-geographically - not the forum] resorting to aliens a debate implies that you think your opponent is mentally deranged.
You've since made it clear that was not your intent. I apologise for being too snappy (and now wasting more thread bandwidth!)
We first need a repeatable experiment that others can recreate (or not). The hypothesis comes afterwards.
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Well, the current dimensions for the dual-416 cabinet are: 40" high (exterior), 29" wide (exterior), 24" deep (exterior), with one driver on a 45-degree slant face, and the other on a face parallel to the rear wall (similar to the drawing).
The interior dimensions (assuming 3/4" Baltic Birch ply) are: 36" high (4" reserved for 0.75" top and 0.75" bottom of cabinet, 0.75" base plate, and 1.75" vent height), 27.5" wide (1.5" reserved for left and right panels of cabinet), and 22.5" deep (1.5" reserved for front and back panels). Allowing for the area missing from the 45-degree slant panel, that gives an interior volume of about 17,667 cubic inches, or 10.22 cubic feet. (The effective volume can be shifted by 10% or more by the 2 to 4 inches of Bonded Logic filling that will be at the bottom, sides, and top of the cabinet.)
Each half of the cabinet has its own 7" circular vent that opens on to the area between the base plate and the bottom of the cabinet, with the height between the two faces adjusted by bolts at each corner. This area is a shared plenum, or common vent, with the top of the base plate covered in wool felt, or filled with Bonded Logic UltraTouch recycled cotton filling. The adjustable height adjusts the cabinet tuning, while the filling is adjustable depending on what goes in the shared plenum area.
I've thought about dissimilar cabinet volumes with slightly different tunings, but that could be awkward with a common shared vent. I don't want air going between the two sub-cabinets, and that might happen if the tunings are significantly different (easily checked by measuring the lowest point of the impedance curve of each driver, and seeing if there is difference between the two).
One of the interesting things mentioned on the Tone Tubby site are twin-speaker guitar amps that use slightly dissimilar Tone Tubby's: one 12" TT with an Alnico magnet, and the other 12" TT with a ceramic magnet. The guitarists ... who are all about tone, of course, since that's what musicians care about ... report more interesting and vivid tone colors with two slightly different drivers. Apparently having all drivers the same results in a more monochromatic sound, while slightly different drivers have more vivid colors. Tone Tubby's are surprisingly good for hifi applications; smooth and peak-free response, and really excellent subjective qualities, similar to Lowther but with better dynamics and no nasty whizzer shout.
I've thought about mounting Alnico 416's on the outer pair, and ceramic 416's on the inner pair. The outer pair would have more "sparkle" (the hallmark of Alnico), while the inner pair would have more growl, or impact. If the tone colors (which are fairly subtle differences) turn out this way, there would be a fun 3D effect, with sparkle moving outward, and impact moving inwards towards the center. I'm always willing to do little tricks to liven up the stereo soundstage; 2-speaker stereo is an illusion anyway, and anything to make it more vivid is welcome.
The use of slightly different drivers isn't the kind of thing that would show up on a FR graph (both drivers use the same cone, surround, spider, and voice coil), but would be audible subjectively. Better? Worse? I don't know, but it would be worth a try.
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Hi Lynn.
Where would you be crossing over with the two driver version? I'm sure it's in the 917 pages somewhere but I couldn't find it. Just asking because the 416s are often run fairly high - like 1200Hz in the case of the model 19. Would it cause some dislocation with the two drivers on different faces run that high?
Where would you be crossing over with the two driver version? I'm sure it's in the 917 pages somewhere but I couldn't find it. Just asking because the 416s are often run fairly high - like 1200Hz in the case of the model 19. Would it cause some dislocation with the two drivers on different faces run that high?
Do believe you're correct, somewhere around 650 or so. With as many pages between bits, it's easy to get lost in this forest
In the space of twin Altec 15's you could have taken to the highest level and actually built a bass horn!
I believe the reason may lay in how the driver responds. We could argue the differences but believe control of the driver and the apparent gains, especially at the bottom end were the reasons why he choose this route over the other.
In the space of twin Altec 15's you could have taken to the highest level and actually built a bass horn!
Yes, a bass horn that would go down to 100Hz, not 40Hz ... !
I would think 200.
Different situation but was an issue that needed to be address in my new design. Sub (midbass) driver(s) might end up being 12.5" apart and or ~66" (74" CTC) spread, what is above ¼ wavelength and how does that affect the choice of crossover point if was to be higher, say to compensate for baffle step or room interaction at listening position. Makes the head
at times.
Yes that is mostly true, an octave below this cutoff for sure.
But it was an exercise in what if, and what happens when. Could this have a negative affect summing 2? 4? Crossing pairs at different points?
Can we improve the distribution better if moved 4-10" higher/lower?
So many questions
I should explain better. The speaker as it is now on the drawing board could be configured 3 ways. All have the same MTM center section, drivers isolated sealed. The "sub" consists of two or four 6.5" midbasses, either two floor loaded ¼ wave MLTL or an additional two added to the top or two each for flanking/ceiling mount, all of the same design. Is being crossed active with eight 90w amps. Driver pairs wired in parallel 4Ω.
If you design a horn system right you can get a basshorn to go to 50 cycles in that footprint. Basshorns sound great below 200 cycles, unless of course you build or hear a bad one, a good one will eat dual 15's for lunch plus will have more control and be more sensitive and an easier load to drive. It also can give the system a much better sense of liveliness with better dynamics,tone, power and punch. To each there own I guess but 3 years or so to design a dual 15 bass system is nearly unbelievable to me.
Below 50 cycles is not that difficult either but can be expensive to do right where it will "keep up" with a fully horn loaded main system.
To each there own I guess but 3 years or so to design a dual 15 bass system is nearly unbelievable to me.Below 50 cycles is not that difficult either but can be expensive to do right where it will "keep up" with a fully horn loaded main system.
Footprint is ~21" wide x 12" deep with large radius from a 7" baffle width which rounds to create the back with roughly a 4" flat back spline. From widest point the "back" is only 3" deep.
I can get my 2 cm throat police sirens to reach 200Hz easy in an elongated Goto S-150. Using such a small diaphragm down to 200Hz seem to give much higher clarity than e.g. a Fane S 8M, which I rank as one of the top contenders to work good in a horn. I still need to fix a proper back chamber for the Fane but I can't imagine it beating the police siren. The Fane is a little more muddy so it works better for rock and roll. I am not sure it is such a good idea to try to reach lower than 150-200Hz with a compression driver. I don't have the horns for it. Yet.
My next move could have been to build a giant 20Hz basshorn that reaches out the window and far into the forest outside.
But at one point you just have to say stop. So I am planning to build a Sonotube Eminence LAB 12 sub and add a waveguide to match the directivity. If the directivity is waaay off still, then I buy another Eminence LAB 12 and finish my Labhorn. That should fit perfect wih the police siren+Goto S-150 or the Fane+Avantgarde Trio midbass horn and is quite compact for something that reaches 35Hz.
My next move could have been to build a giant 20Hz basshorn that reaches out the window and far into the forest outside.
But at one point you just have to say stop. So I am planning to build a Sonotube Eminence LAB 12 sub and add a waveguide to match the directivity. If the directivity is waaay off still, then I buy another Eminence LAB 12 and finish my Labhorn. That should fit perfect wih the police siren+Goto S-150 or the Fane+Avantgarde Trio midbass horn and is quite compact for something that reaches 35Hz.
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