@audiokinesis Its an 15" OEM sub from AliExpress, was accompanied with the impedance & FR graphs, and I liked the Bl 23.
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.
Showing 9 responses by hsbrock
The driver is 15", VC4", Bl 23, Vas 2.2 cuft., fairly stiff suspension w/ Qms 14.5, Cms 0.05mm/N, double spider, so for this reason & the Bl I was leaning towards a corner horn, not relying on excursion w/ an Xmax of 7.5mm. Primarily will be used from its low end to 150 Hz, & in this range it averages about 98dB. The above measurements are at 1W/1M, & compared to most subs I've looked at its fairly flat +-3-4dB up to about 1100Hz, where it begins dropping off or breaking up. Primarily considering a corner-horn cabinet, facing into the corner, with maybe with a passive radiator above it. What more would be helpful to know? Qes: .51, Qts. .50, Sd 881, Vd 661, so displacement is not the greatest for a 15", but the PR and corner placement should help. Thinking of a sealed cabinet w/ PR facing into corner w/ rear chamber could be 2-4 cu.ft. This is as far as I've gotten. The Qts. suggests an open back or infinite baffle, and with the stiff suspension (which I also liked) so I hoped the sealed rear chamber w/ the PR might better load the horn. ??? |
@ditusa Wow. This is a good article. I’ll be back when I finish. |
@audiokinesis Duke, that's exactly what I intend to do - the room is of medium size and self contained, and my hope to gain 6dB with the corner-horn, so your analysis is spot on. And my incredulity is unfounded? That is, it is possible to get good response down into the 20s as long as the driver goes there, even though the Fs is so much higher? |
@audiokinesis Thank you! And so... are you telling me that, given that the speaker has good response all the way down to 27 Hz, and that IF the right cabinet is designed, it can be possible to bring a speaker's performance all the way down to those lower frequencies even if the Fs is 54Hz? |
@audiokinesis Thank you. I'll be here! |
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. |
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. |
Thanks, Duke @audiokinesis I'll check it out. |