In 30+ years of DIY speakering, I've never considered building a sub before. A recent acquisition of a used pair of KEF LS50 Meta & a simultaneous request from my son to make him something that can give near nightclub levels of modern electronic music (with the LX521-ish clones I made him last year) is making me think about subs.
I'm considering a hifi sub with SB Audience Nero-15SW800, a pro 15" driver. Specs look great for a pro subwoofer -- Fs=31Hz, Xmax=14.27, AES power=800W. Rated 96 dB/W but this looks optimistic, tho it's definitely >90 dB, amazing for an 8 ohm model (at least in home hifi).
My ideal target is -3 dB to 30Hz, up to 110 dB@1m, capacity to run up to ~120Hz. Willing to feed it >600W.
Not sure if that's realistic.
Madisound says... "Vented box of 4.0 cubic feet with (2x) 3" vent by 6" long for a 3dB down of 35Hz. 6dB down of 28Hz". That's pretty close & room gain might bring it to my target.
The diyaudioandvideo speaker box enclosure designer says...
Butterworth B4 -
Vb = 3.22 ft3 (91.07 lts)
f3 = 36.91 Hz
fb = 36 Hz
Dv = 6 in = 15 cm
Lv = 13.75 in = 33.65 cm
https://subbox.pro/ says in a 18x18x28" box (~4 ft3), a 1.4" slot 6.2" deep and the width of the 18" face will give 36 Hz tuning.
The woofer choice is not firm, but I really like this driver, which was pointed out by Joseph Crowe. He compared it favorably with a TAD TL1601B -- a US$1750 driver-- that he used in his horn loaded bass enclosure. Solen retails the Nero-15SW800 for CA$447.
I have not ruled out other enclosure types, but 4 cubic feet is about as big as I can go. I chose ported because it's the most widely used & even tho the shallower 12 db/oct slope of a sealed box is better for deep bass, I want to keep the excursion low to ensure my son gets all the bass he wants. His room is about 14 x 22 x 10 (ceiling), with big doorways into other parts of the house. I figure ported will limit excursion down in that 30 Hz region. A sharp 24/48 dB low filter will likely be applied ~20 Hz, depending on subjective perception in actual use.
Suggestion, direction, insights about design & construction are most welcome.
I'm considering a hifi sub with SB Audience Nero-15SW800, a pro 15" driver. Specs look great for a pro subwoofer -- Fs=31Hz, Xmax=14.27, AES power=800W. Rated 96 dB/W but this looks optimistic, tho it's definitely >90 dB, amazing for an 8 ohm model (at least in home hifi).
My ideal target is -3 dB to 30Hz, up to 110 dB@1m, capacity to run up to ~120Hz. Willing to feed it >600W.
Not sure if that's realistic.
Madisound says... "Vented box of 4.0 cubic feet with (2x) 3" vent by 6" long for a 3dB down of 35Hz. 6dB down of 28Hz". That's pretty close & room gain might bring it to my target.
The diyaudioandvideo speaker box enclosure designer says...
Butterworth B4 -
Vb = 3.22 ft3 (91.07 lts)
f3 = 36.91 Hz
fb = 36 Hz
Dv = 6 in = 15 cm
Lv = 13.75 in = 33.65 cm
https://subbox.pro/ says in a 18x18x28" box (~4 ft3), a 1.4" slot 6.2" deep and the width of the 18" face will give 36 Hz tuning.
The woofer choice is not firm, but I really like this driver, which was pointed out by Joseph Crowe. He compared it favorably with a TAD TL1601B -- a US$1750 driver-- that he used in his horn loaded bass enclosure. Solen retails the Nero-15SW800 for CA$447.
I have not ruled out other enclosure types, but 4 cubic feet is about as big as I can go. I chose ported because it's the most widely used & even tho the shallower 12 db/oct slope of a sealed box is better for deep bass, I want to keep the excursion low to ensure my son gets all the bass he wants. His room is about 14 x 22 x 10 (ceiling), with big doorways into other parts of the house. I figure ported will limit excursion down in that 30 Hz region. A sharp 24/48 dB low filter will likely be applied ~20 Hz, depending on subjective perception in actual use.
Suggestion, direction, insights about design & construction are most welcome.
the 4' box models well tuned to about 32 hz, F3 about 33 hz. I used 1- 5"Wx9"L round port, 2-3"Wx 6-7"L should work the same. I believe round ports work better and would encourage to use them; They also make adjusting port length easier. I would always start with a port longer than you think you need and adjust as necessary. I think this box will rattle the walls in a room that small! 🙂
@mordikai -- thanks for that!
So you used a single port 5" dia x 9" in a 4' box & got 32Hz tuning. What driver did you use?
What about the shape of the tube? Did you round off the ends and/or add a flange to shape it aerodynamically? There's that huge thread based on the research by augerpro And the thickness of the tube?
I liked the idea of the slot because it doesn't rely on thin plastic pipe which could resonate; I'll be using either 1" thick BB plywood or 5/8" BB + 1/2" MDF or similar.
Not going to go crazy with internal bracing, but will definitely put enough bracing panels that pull 4 panels together to put all the primary panel resonances >400Hz. Around 2 octaves above the expected ~100Hz top end of the sub.
So you used a single port 5" dia x 9" in a 4' box & got 32Hz tuning. What driver did you use?
What about the shape of the tube? Did you round off the ends and/or add a flange to shape it aerodynamically? There's that huge thread based on the research by augerpro And the thickness of the tube?
I liked the idea of the slot because it doesn't rely on thin plastic pipe which could resonate; I'll be using either 1" thick BB plywood or 5/8" BB + 1/2" MDF or similar.
Not going to go crazy with internal bracing, but will definitely put enough bracing panels that pull 4 panels together to put all the primary panel resonances >400Hz. Around 2 octaves above the expected ~100Hz top end of the sub.
Better too much than not enough. 😉
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I modeled the 15" sb audience you posted in winisd. The box volume and port determine the tuning the driver in that box determines the response. The 4 cu ft is a net number so you need to allow for port volume and driver displacement, bracing etc. I was not thinking it's overkill, I think you should build 4!
flared ports are always better but I wouldn't stress too hard about it, if sized properly for subwoofer use. I find by the time you are worrying about chuffing you should probably turn it down or add more subwoofer.
As long as you’re building two of them and can co locate them next to your LS50’s since you’re crossing at 120hz, you’ll be fine.
…..BUT if you plan on a single, your soundstage will collapse from the monopole bass which was most likely mixed in stereo. Vocals, kick and bass will be locked in the center.
…..BUT if you plan on a single, your soundstage will collapse from the monopole bass which was most likely mixed in stereo. Vocals, kick and bass will be locked in the center.
I know I mentioned the LS50s in the original post, but I realize this sub is not going to be that practical for them. I'd like to try both 1 and 2 really good subs with the LS521 clones in the studio. Those are good to about 30 Hz, but the scale and ease don't quite hold up as complex music with lots of bass energy is cranked up. I play the LX521 clones louder on average than I usually play music on any other system because it's so clean & undistorted but it gets less so as 100 dB peaks approach. I'm pretty sure offloading some bass material to bigger drivers that can handle it with greater ease will improve performance -- and my enjoyment.
I'm not sure if the planned 4' box + Nero-15SW800s will go lower than the 4 SBA 10" OB sub drivers, but they should go louder cleaner.
I'm not sure if the planned 4' box + Nero-15SW800s will go lower than the 4 SBA 10" OB sub drivers, but they should go louder cleaner.
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Inverse tapered horns allows a much larger vent area (Av) at a much shorter pathlength with Av = Sd being the goal.
Can you show me any examples of inverse tapered horns using a 15" woofer? And summarize the advantage of such over a ported design?
I guess you refer to something like this? https://www.diyaudio.com/community/threads/tham15-a-compact-15-tapped-horn.175658/
over 6' volume
over 6' volume
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I don't keep records of builds and just did a quick search of me to get this example, though normally it's just a rectangular box with angled baffles in reverse of what Scott normally posts for ML-TQWT, though the FH3? is an extreme example since normally the terminus/vent is a constant taper.
More powerful driver loading, gain BW, so greater acoustic efficiency for a given power input, etc..
No, that's a tapped horn = 6th order band-pass (BP6), i.e. loads both sides of the driver.
More powerful driver loading, gain BW, so greater acoustic efficiency for a given power input, etc..
No, that's a tapped horn = 6th order band-pass (BP6), i.e. loads both sides of the driver.
When the Thiele–Small parameters are fed into VituixCAD, the woofer seems to be around 94.4dB/2.83V in sensitivity, or 92.5dB/W. That's a quite efficient subwoofer driver.
Using the Madisound design as a starting point, and feeding in 50W re 8 ohms of input power, VituixCAD produced the following predictions. The air velocity in the vent is starting to get a bit high, so it would likely be better to add at least another 3-inch vent. Even with this large enclosure, the design seems to fall just a bit short of your quite reasonable target of −3dB at 30Hz. It seems clear that this driver can hit your target 110dB SPL with a relatively low power input, thanks to its high efficiency.
If we (de)tune the port(s) to Fb=30Hz instead of Fb=33.6Hz, we can get a little bit more bass extension from this vented enclosure.
I've simulated the expected response obtained for such a configuration after also adding a 2nd-order Butterworth high-pass filter with −3dB point at 15Hz, and a low-pass 4th-order Linkwitz–Riley filter with its −6dB cut-off frequency set to 120Hz. The results are shown below.
As you can see, the input power needed to be increased from 50W to 63W re 8 ohms to achieve the 110dB SPL. Note that the low-frequency −3dB point of this subwoofer system is 30Hz, right on the limit of what was specified as a design target.
If we go a bit further, and allow the high-pass filter to be a peaking filter, and tune the enclosure even lower to Fb=27Hz, we can get the following results. Here the low-frequency cut-off point has been reduced to 27.9Hz, and the displacement of the subwoofer is better controlled below the vent tuning frequency.
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I would say make it 4.25- 4.5 cu ft to account for driver and port displacement. Time to build. Make your port removable initially so you can adjust tuning.
Like BR it's a function of Fs, Vas, Qts' and IME when the pioneer's Av = Sd vent ideal gets to be much too long it's a more compact cab with overall superior performance.
Note that in either case, this assumes criticality damping them.
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I'm trying: I read your post several times & can't make sense of it. You must be using jargon I don't know or using a kind of shorthand I can't comprehend.
Am I the only one?
"pioneer's Av = Sd vent ideal"???
How does this get much too long??
What's more compact than what??
What is superior performance to what??
"criticality damping"??
Apparently don't know 😢
Av defined in post #10
Sd is driver effective piston area
An inverse tapered (ML)TQWT is normally smaller with superior overall performance than a BR with an Av = Sd vent of the same tuning
Self explaining and if its instructions aren't clear will leave it to someone who speaks your native tongue
Av defined in post #10
Sd is driver effective piston area
An inverse tapered (ML)TQWT is normally smaller with superior overall performance than a BR with an Av = Sd vent of the same tuning
Self explaining and if its instructions aren't clear will leave it to someone who speaks your native tongue