I currently has 1x18" and 3x12" subwoofers. and assembling a second sealed 18" sub. I am pretty happy with my bass and set up, hopefully happier still with 2x18"m and 3x12". In have two BMS 18N862 subs and 3 12" Sonus faber Cremona Subs
My thinking is I can sell on my Sonus Faber subs for probably over £1k each easily, they were £3k+ new and a very good hifi sub. However building a sealed 15" with a construction similar to the 18" I have built will be more rigid no doubt, plus I can increase the cone area by 60% and focus on speed and slam by using a lightweight 30 something Fs driver and targeting 35-80 Hz with a very efficient lighweight driver. The SF subs are designed to go low in a smaller enclosure and I dont need them to hit the lows as thats for my 18's primarily. I would value views on driver options so far I am thinking of something like the Faital Pro 15PR400, the SB Audience 150B350 or even the Eminence 1525 Legend. Internal volume will be something like 90L and made with 25mm Birch Ply, heavily braced. I have the amps, so its probably under £3k all in to build 3 depending on driver cost and the number of 25mm sheets required. So its more of a swap financially !!!
The cabinet will be 90L or so and a smaller version of this, my 18" unit in assembly.
My thinking is I can sell on my Sonus Faber subs for probably over £1k each easily, they were £3k+ new and a very good hifi sub. However building a sealed 15" with a construction similar to the 18" I have built will be more rigid no doubt, plus I can increase the cone area by 60% and focus on speed and slam by using a lightweight 30 something Fs driver and targeting 35-80 Hz with a very efficient lighweight driver. The SF subs are designed to go low in a smaller enclosure and I dont need them to hit the lows as thats for my 18's primarily. I would value views on driver options so far I am thinking of something like the Faital Pro 15PR400, the SB Audience 150B350 or even the Eminence 1525 Legend. Internal volume will be something like 90L and made with 25mm Birch Ply, heavily braced. I have the amps, so its probably under £3k all in to build 3 depending on driver cost and the number of 25mm sheets required. So its more of a swap financially !!!
The cabinet will be 90L or so and a smaller version of this, my 18" unit in assembly.
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When looking at a single 15” keep in mind that 2 x 12” mounted push-push can move similar air but the active reaction force cancelation dramatically reduces the vibrational load on the bo making more a quiter woofer and one that stays in place.
I won’t build a sub again without push-push. AFAIC a no-brainer.
dave
I won’t build a sub again without push-push. AFAIC a no-brainer.
dave
Any more information on this is it just opposite firingWhen looking at a single 15” keep in mind that 2 x 12” mounted push-push can move similar air but the active reaction force cancelation dramatically reduces the vibrational load on the bo making more a quiter woofer and one that stays in place.
I won’t build a sub again without push-push. AFAIC a no-brainer.
dave
Thanks but I’d rather build a very rigid unit out of Birth plyWhen I "made" my 15" sub, I cheated and used one of these. I sealed the slot with a pool noodle.
View attachment 1099449
Any more information on this is it just opposite firing
Yes, opposte firing, wired in phase, tightly coupled together to maximize the reaction force cancelation. Estimate that some 90% of the vibrations never get to the enclosure making 15mm quality ply the matererial of choice.

More info all over the forum.
dave
If the magnets are physically connected with a tube how does VC venting work?
I'm thinking that would need working to much tighter tolerances than I am capable of.
I'm thinking that would need working to much tighter tolerances than I am capable of.
Magnets need to be physically connected or it wont work as well as it could
Yes, drivers need to be tightly coupled. Not shown in my illustration.
dave
If the magnets are physically connected with a tube how does VC venting work?
I'm thinking that would need working to much tighter tolerances than I am capable of.
drill holes in the pipe. And fill with damping.
dave
Any information on how dual opposed perform, the cabinet size I am thinking of to fit in the room is something like 460x460x630, so deep and square a smaller version of this (18" 530x530x740). Do two drivers go as low with frequencies etc
Dave, hi are you saying the cabinet is seen as 2x as large internal volume, so frequency is lower as well as SPL higher ?
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FR, extention et all all remain the same. You gain 3dB due to 2 drivers vrs 1 and you can get another 3dB wiring in parallel.
2 drivers, 2 x the box size to keep response the same.
dave
2 drivers, 2 x the box size to keep response the same.

dave
You don’t get something for nothing though. Twice as big a box. On the other hand, 2 separate subwoofers placed about the room may provide smoother in-room response.
People are impressed with a cabinet that vibrates less, but don’t forget the vibrations in your room; Probably an order of magnitude higher.
People are impressed with a cabinet that vibrates less, but don’t forget the vibrations in your room; Probably an order of magnitude higher.
That’s why you should have at least 2.
And as to box size, OP asked about single 15”, i suggetsed a pair of 12s. So you have 2 x the volume needed for a single 12 brs the box for a single 12.
dave
And as to box size, OP asked about single 15”, i suggetsed a pair of 12s. So you have 2 x the volume needed for a single 12 brs the box for a single 12.
dave
I think I'll run with single 15" subs, as I do have 2x18" and 4 'full' range speakers that measure from 30Hz up as well. Moving towards something like the Fatal Pro FH500 for the 15's to maintain rigidity but keep cone weight reasonably light ?
My second 18" is coming together, It will be quite a bit of work to build 3 smaller enclosure boxes for 15" drivers, but I do think they would be good !
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