While I am patiently waiting for the builders to shore up the roof in my place (after breaking some walls down), I have a bit of time to play around with audio.
In the title, I call this thing a subwoofer system because, well, you just can't call 4x 18" HE drivers doing bass duty a subwoofer. It needs the "system" at the end to provide it with the weight it deserves.
I have had these 4 18Sound 18LW800 drivers laying around for a number of months now. My initial plan was to use them in a pair of TQWT enclosures, but after calculating the weight I decided that it may be worth my while trying something else first. The problem with immense weight does not manifest itself in the single task of getting these things into the house - simple tasks such as turning a cabinet to work on another side becomes near impossible without a boom-crane of similar.
So, for those of you who don't know the driver - here it is:
After much simulating, calculation, contemplating, head scratching and general wondering I purchased the wood and proceeded to build myself the 4 H-frames to mount the drivers into. They measure in at around 60cm in each direction (cube), with the baffle being slightly forward from centre. This is in accordance with the calculations and simulations I did before starting the build.
Because this is a "trial version", I just used 22mm shutter ply to keep the costs down. I like to use a bit of a better spec shutter ply than the one you get at builders, so the price is also a bit heavier at around R 360 per board (1.2 x 2.4). The baffle is doubled up - giving me a total of around 44mm worth.
Each driver is mounted using 8x M8 hex bolts with washer and spring washer behind. They are pretty solidly held in place.
So, the configuration is 2 of these H-Frames per side - stacked on top of each other (next to the main speaker). To say that these are damned ugly is an understatement. They are F-UGLY!
Also, getting them to work sound right is a bit of a headache. Next, getting them to integrate with the main speakers is an even bigger headache. I spent about 2 hours this morning tuning them in, and I finally have the system set up to a point where I can listen to some tunes without cringing.
Major concern for me, and the single reason I have not done this before: By using this method (dipole) you give up a huge amount of headroom. Around 20dB per driver is lost trying to power through the dipole cancellation effect. To me at least that is a massive loss. Each single H-Frame is now only capable of reaching around 100dB or so before running out of Xmax. Is it worth it? I will let you know later...
The signal chain driving the subwoofers is:
Maestro A2.2 pre amplifier (via subwoofer out) --> MiniDSP board (temp solution only) --> B&O IcePower based monoblocks (550W ea).
Next there will be more tweaks and listening after which I will post some pics (not that you would want to see them) and provide my review of these ugly b@stards. The real question in my mind is thus: Is the H-Framed subwoofer system worth the loss of 20dB per driver? It will have to be pretty magical and shoot lightning bolts through it's behind to make it so - I am however open to being convinced and coerced if the evidence exists in sufficient quantity (or quallity).
Cheers,
Ian.
In the title, I call this thing a subwoofer system because, well, you just can't call 4x 18" HE drivers doing bass duty a subwoofer. It needs the "system" at the end to provide it with the weight it deserves.
I have had these 4 18Sound 18LW800 drivers laying around for a number of months now. My initial plan was to use them in a pair of TQWT enclosures, but after calculating the weight I decided that it may be worth my while trying something else first. The problem with immense weight does not manifest itself in the single task of getting these things into the house - simple tasks such as turning a cabinet to work on another side becomes near impossible without a boom-crane of similar.
So, for those of you who don't know the driver - here it is:
After much simulating, calculation, contemplating, head scratching and general wondering I purchased the wood and proceeded to build myself the 4 H-frames to mount the drivers into. They measure in at around 60cm in each direction (cube), with the baffle being slightly forward from centre. This is in accordance with the calculations and simulations I did before starting the build.
Because this is a "trial version", I just used 22mm shutter ply to keep the costs down. I like to use a bit of a better spec shutter ply than the one you get at builders, so the price is also a bit heavier at around R 360 per board (1.2 x 2.4). The baffle is doubled up - giving me a total of around 44mm worth.
Each driver is mounted using 8x M8 hex bolts with washer and spring washer behind. They are pretty solidly held in place.
So, the configuration is 2 of these H-Frames per side - stacked on top of each other (next to the main speaker). To say that these are damned ugly is an understatement. They are F-UGLY!
Also, getting them to work sound right is a bit of a headache. Next, getting them to integrate with the main speakers is an even bigger headache. I spent about 2 hours this morning tuning them in, and I finally have the system set up to a point where I can listen to some tunes without cringing.
Major concern for me, and the single reason I have not done this before: By using this method (dipole) you give up a huge amount of headroom. Around 20dB per driver is lost trying to power through the dipole cancellation effect. To me at least that is a massive loss. Each single H-Frame is now only capable of reaching around 100dB or so before running out of Xmax. Is it worth it? I will let you know later...
The signal chain driving the subwoofers is:
Maestro A2.2 pre amplifier (via subwoofer out) --> MiniDSP board (temp solution only) --> B&O IcePower based monoblocks (550W ea).
Next there will be more tweaks and listening after which I will post some pics (not that you would want to see them) and provide my review of these ugly b@stards. The real question in my mind is thus: Is the H-Framed subwoofer system worth the loss of 20dB per driver? It will have to be pretty magical and shoot lightning bolts through it's behind to make it so - I am however open to being convinced and coerced if the evidence exists in sufficient quantity (or quallity).
Cheers,
Ian.
