Thanks @koestner. I am realizing this more importantly than ever. In the past 24 hours I've read in one JBL Speaker Manual sent to me by @ditusa to use 2x4s for bracing (not just little lengths of MDF), and another technically authoritative source said that adequate bracing can make a difference of 3 dB in volume, which to me suggests the wood cabinet can absorb up to 50% of an amp's power in large cabinets, and that's absorbing half as much vibration as the voice coil is producing, which makes sense. I've never appreciated this fact before.
Question: Sub with Fs 54, but response remains above 95dB down to 27: How can I best build
I read a lot of stuff on here from guys a lot more experienced than I, so I'm hoping someone might know some answers. I've got a driver with free air Fs at 54 1w/1m, but free air response remains fairly even down to 27Hz above 95dB, and my question is how effectively can I extend response down to 27? And if so, with what type of cabinet would you recommend? Bass reflex, passive radiators, corner horn,...? What would prevent the cabinet from going down to 27? What would I have to do to make the cabinet reach below 27, to 23-25? Thanks in advance for any knowledge you can share.
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This is a bit of a story, but who else but you guys would appreciate this? A while ago my friend built a big coffee table sub with an 18" down firing driver. He got it all completed and wired up. On top of the table/sub he had a large heavy glass ash-tray. When the first bass notes kicked in the ash-tray flew up in the air about 5 inches. He thought it was awesome! But I reminded him, where did he think the energy to launch that ash-tray was coming from? I told him to remove the driver and brace the box a lot. After doing that the ash-tray stayed put. The braces made a huge difference in driver output. |
@hsbrock , the modeled response that I described up-thead checks out. It assumes 3 dB from boundary reinforcement at 40 Hz, and 6 dB from boundary reinforcement at 20 Hz, and a lowpass filter frequency no higher than 80 Hz. It also assumes the T/S parameters are correct, of course. I suggest two 4" diameter Precision Ports, each 14" long including the flares. And if you don't have an amplifier in mind, I use the Dayton Audio SA-1000 in my commercial subwoofer system. Best of luck with your project. Duke
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Thank you Duke @audiokinesis This is really encouraging. I've got the space to do 7 cu.ft., corner-horns, and to be able to get those results with an Fs 54 gives me hope. I was afraid my speakers would be a bust. Is there a modeling software you'd recommend for me? Again, thanks for taking the time to help me with this. I'm discovering the guys on here are great. |
@hsbrock , I used Bassbox Pro by Harris Technologies. I have a couple of other progams but they are no longer available. |
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