OK guys, I agree to quit hijacking threads like the monopole vs dipole discussion and present my nutball ideas in their own separate playground...
This thread will document my design efforts and construction for a "compact" (sort of) line array (at some frequencies) speaker system. As presently conceived, it can be assembled in a "modular" fashion, and so I could call it the "Modula IV", as I've done three other systems incorporating line arrays and modular construction... but those will remain deep, dark secrets, shared only with my co-conspirator, ThomasW. Needless to say, we're no stranger to line ribbon arrays, having built some of these even in the mid 80's.
As described in other threads, this system will use BG RD50 wide range line transducers in concert with a "short" line array of 8 6-1/2" midwoofers on each side.
The chosen 6-1/2's are MCM cast frame carbon fiber drivers, selected for their combinationn of construction quality, Xmax, and low cost.
The monopole ribbon and midwoofer arrays will sit on woofer modules the same 16" wide using BPD1203's for the first pass; this allows a rather small net internal volume (60 liter) with Q under 0.4, and active EQ to control in room response- Xmax is about 1" each way.... with light EQ, in room flat response to 20 Hz is no big deal; compactness is the order of the day. An optimum ported version could play 3-6 dB louder at 20 Hz, but would require a box volume of 100 liters. This veresion is being optimized for minimum size. Crossover to the midwoofer arrays is planned at 75 Hz, using a Sumo Delilah II active crossover. (it was in the goodie box, it's very flexible, and the HP output uses a simple active buffer with no loop feedback...)
The upper range portion covered by the RD50 and midwoofer array will be 60" tall, and sit on the 20" high woofer module.
Yes, I realize that calling something 6'8" tall a "compact speaker system" is something of an oxymoron, but you should have seen the earlier version with a midwoofer array close to flat to 25 Hz and a ported woofer module going down to 15 Hz.... :LOL:
Maybe for fun I'll prepare concept renderings of that system just for comparison.
Anyway, here's a rough rendering of what I'm shooting for; maybe rough isn't quite the right idea, since these are based on complete detailed AutoCAD solid model drawings from which I have detailed all the board sections and sizes.
Pete's way ahead of me in building and testing hardware, but I'm gathering momentum, and have all the major bits on hand- I'll probably start buying wood this weekend....
The planned finish is "honey oak", using time tested techniques with Watco oil- and a tip of the hat to Hank for sharing his own version and recommendations with me.
The crossover for the midwoofers to ribbon will be at ~600Hz, with an external xover box- I may try both conventional 4th order L-R as well as my unpatented HiFinite Slope crossover (developed for the M8), mostly just because the latter puts anything one octave from the nominal crossover frequency about 50 dB down...
As usual, a lot of the good stuff will be due to recommendations from you guys, and I apologize in advance for the stuff I screw up due to my own lack of judgement!
Best regards,
Jon
Earth First!
_______________________________
We'll screw up the other planets later....
This thread will document my design efforts and construction for a "compact" (sort of) line array (at some frequencies) speaker system. As presently conceived, it can be assembled in a "modular" fashion, and so I could call it the "Modula IV", as I've done three other systems incorporating line arrays and modular construction... but those will remain deep, dark secrets, shared only with my co-conspirator, ThomasW. Needless to say, we're no stranger to line ribbon arrays, having built some of these even in the mid 80's.
As described in other threads, this system will use BG RD50 wide range line transducers in concert with a "short" line array of 8 6-1/2" midwoofers on each side.
The chosen 6-1/2's are MCM cast frame carbon fiber drivers, selected for their combinationn of construction quality, Xmax, and low cost.
The monopole ribbon and midwoofer arrays will sit on woofer modules the same 16" wide using BPD1203's for the first pass; this allows a rather small net internal volume (60 liter) with Q under 0.4, and active EQ to control in room response- Xmax is about 1" each way.... with light EQ, in room flat response to 20 Hz is no big deal; compactness is the order of the day. An optimum ported version could play 3-6 dB louder at 20 Hz, but would require a box volume of 100 liters. This veresion is being optimized for minimum size. Crossover to the midwoofer arrays is planned at 75 Hz, using a Sumo Delilah II active crossover. (it was in the goodie box, it's very flexible, and the HP output uses a simple active buffer with no loop feedback...)
The upper range portion covered by the RD50 and midwoofer array will be 60" tall, and sit on the 20" high woofer module.
Yes, I realize that calling something 6'8" tall a "compact speaker system" is something of an oxymoron, but you should have seen the earlier version with a midwoofer array close to flat to 25 Hz and a ported woofer module going down to 15 Hz.... :LOL:
Maybe for fun I'll prepare concept renderings of that system just for comparison.
Anyway, here's a rough rendering of what I'm shooting for; maybe rough isn't quite the right idea, since these are based on complete detailed AutoCAD solid model drawings from which I have detailed all the board sections and sizes.
Pete's way ahead of me in building and testing hardware, but I'm gathering momentum, and have all the major bits on hand- I'll probably start buying wood this weekend....
The planned finish is "honey oak", using time tested techniques with Watco oil- and a tip of the hat to Hank for sharing his own version and recommendations with me.
The crossover for the midwoofers to ribbon will be at ~600Hz, with an external xover box- I may try both conventional 4th order L-R as well as my unpatented HiFinite Slope crossover (developed for the M8), mostly just because the latter puts anything one octave from the nominal crossover frequency about 50 dB down...
As usual, a lot of the good stuff will be due to recommendations from you guys, and I apologize in advance for the stuff I screw up due to my own lack of judgement!
Best regards,
Jon
Earth First!
_______________________________
We'll screw up the other planets later....
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