So I bought one of these: the box Speaker 18-500/8-A - Thomann UK
Obviously not something that is described as a true subwoofer in home theatre circles -- not enough Xmax, flimsy paper cone, small power handling, etc. True, won't work in a small sealed cab with aggressive EQ and a 3 kW amp. But in a large vented cab tuned low? Maybe; I shall find out in next few days. Starting to build the cabinet tomorrow.
360 litres tuned to 18 Hz looks promising. I'm trading off lots of SPL for extension, no need for 124 dB in home setting (arguable, of course
). But I should still get as much output as with Eminence LAB15 with less power -- in a box twice as big.
To be continued...
Obviously not something that is described as a true subwoofer in home theatre circles -- not enough Xmax, flimsy paper cone, small power handling, etc. True, won't work in a small sealed cab with aggressive EQ and a 3 kW amp. But in a large vented cab tuned low? Maybe; I shall find out in next few days. Starting to build the cabinet tomorrow.
360 litres tuned to 18 Hz looks promising. I'm trading off lots of SPL for extension, no need for 124 dB in home setting (arguable, of course
). But I should still get as much output as with Eminence LAB15 with less power -- in a box twice as big. To be continued...
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Your sim doesn't look right.
The best I can get with THE BOX SPEAKERS 18-500/8-A is -8dB's@20Hz for a BR, with an extended alignment of VB = 360.0 L, FB = 22.0 Hz.
https://images.static-thomann.de/pics/atg/atgdata/document/manual/193265_bda_185008a_uk_screen.pdf
The best I can get with THE BOX SPEAKERS 18-500/8-A is -8dB's@20Hz for a BR, with an extended alignment of VB = 360.0 L, FB = 22.0 Hz.
https://images.static-thomann.de/pics/atg/atgdata/document/manual/193265_bda_185008a_uk_screen.pdf
Hi Inductor,
This plot is with all the processing involved - like I said, I trade HUGE amount of efficiency/SPL for extension, EQ is necessary to flatten the response. This is also the case with modern small sealed subs.
Basically, 4th order L-R HP filter at 45 Hz flattens the response and gives F6 at around 60 Hz. Then, if room gain doesn't take care of the rest, small amount (1...1,5 dB) of boost around 20 Hz should do the trick.
Of course, one could choose a driver with heavy cone, low Fs and sensitivity and yield the same result, but these kind of drivers are expensive (e.g RSS460HO-4 - Dayton audio reference 18" Reference HO Subwoofer - Europe audio or Eminence LAB 15 - Thomann UK), need a powerful, more expensive amp and I'm on a budget here
Here is the raw response (looks awful, right? But I still have 86 dB of sensitivity at 20 Hz):
This plot is with all the processing involved - like I said, I trade HUGE amount of efficiency/SPL for extension, EQ is necessary to flatten the response. This is also the case with modern small sealed subs.
Basically, 4th order L-R HP filter at 45 Hz flattens the response and gives F6 at around 60 Hz. Then, if room gain doesn't take care of the rest, small amount (1...1,5 dB) of boost around 20 Hz should do the trick.
Of course, one could choose a driver with heavy cone, low Fs and sensitivity and yield the same result, but these kind of drivers are expensive (e.g RSS460HO-4 - Dayton audio reference 18" Reference HO Subwoofer - Europe audio or Eminence LAB 15 - Thomann UK), need a powerful, more expensive amp and I'm on a budget here
Here is the raw response (looks awful, right? But I still have 86 dB of sensitivity at 20 Hz):
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Hi technofreak,
Indeed those specs are close.
Ps have you looked at two Thomann 12-280/8-W. You have twice the the motor power, 30% more moving mass, just a little lower Fs, will need less EQ and a smaller box and can be arranged in a PPSL configuration. They will also work nice in TH's.
Cheers,
Djim
Indeed those specs are close.
Ps have you looked at two Thomann 12-280/8-W. You have twice the the motor power, 30% more moving mass, just a little lower Fs, will need less EQ and a smaller box and can be arranged in a PPSL configuration. They will also work nice in TH's.
Cheers,
Djim
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Hi, Djim,
Yes, I've contemplated almost every cheap(ish) driver out there, even wacky stuff like eight 8" drivers in one box. That 12" sure is a looker (Qms 20! Nice basket, too), but I already have the 18" one.
On T-TQWT note, my sanity check shows no real advantage in a similar total volume box. Funny thing, Hornresp shows around 3 dB more output for vented box at excursion limit (but Hornresp isn't be-all-end-all program. No simulator is). A tapped horn is on my bucket list, though, maybe with some 10...12" drivers. As for now I'm also running a parallel build of some 3-way speakers using Scan-speak, ACR and Seas metal cone and dome drivers, so my hands are pretty full
Yes, I've contemplated almost every cheap(ish) driver out there, even wacky stuff like eight 8" drivers in one box. That 12" sure is a looker (Qms 20! Nice basket, too), but I already have the 18" one.
On T-TQWT note, my sanity check shows no real advantage in a similar total volume box. Funny thing, Hornresp shows around 3 dB more output for vented box at excursion limit (but Hornresp isn't be-all-end-all program. No simulator is). A tapped horn is on my bucket list, though, maybe with some 10...12" drivers. As for now I'm also running a parallel build of some 3-way speakers using Scan-speak, ACR and Seas metal cone and dome drivers, so my hands are pretty full
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I used the cutout diameter as the Sd since I didn't see it on the data sheet. I let HR calculate the rest of the speaker parameters. This is a Tapped Quarter Wave Pipe (TQWP) or straight flare tapped horn.
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You can easy tweak a subwoofer element to reach lower fs by cutting out strips in the spider. Take a razor blade and cut stripes radially from the center to the primeter of the spider. Equally wide and at least 3. I have some JBL 2226H where i cut out 8 stripes approx 10mm wide at the perimeter and 3mm close to the coil former.
I also replaced the surrounding coated cloth, to 2235 foam surronding.
So i went from fs 41Hz to 22Hz without adding mass. I will cut out slighly more of the spider until i reach 18Hz. Works wery fine! But on your own risk. I take no responsibility if you s**** things up. If you place the driver vertically, the spider could have been veak and you may experience som sagging making the coil touch the pole piece. Do not fear! You just add a thin synthetic thread radial and vertical out from the center of the voice coil, letting it take some force from the gravity.. the length should be approx 13cm on a JBL 2226 as an example.
I also replaced the surrounding coated cloth, to 2235 foam surronding.
So i went from fs 41Hz to 22Hz without adding mass. I will cut out slighly more of the spider until i reach 18Hz. Works wery fine! But on your own risk. I take no responsibility if you s**** things up. If you place the driver vertically, the spider could have been veak and you may experience som sagging making the coil touch the pole piece. Do not fear! You just add a thin synthetic thread radial and vertical out from the center of the voice coil, letting it take some force from the gravity.. the length should be approx 13cm on a JBL 2226 as an example.
It could be that an infinite baffle sub-woofer system might work for you. SeeSo I bought one of these: the box Speaker 18-500/8-A - Thomann UK
Obviously not something that is described as a true subwoofer in home theatre circles -- not enough Xmax, flimsy paper cone, small power handling, etc. True, won't work in a small sealed cab with aggressive EQ and a 3 kW amp. But in a large vented cab tuned low? Maybe; I shall find out in next few days. Starting to build the cabinet tomorrow.
360 litres tuned to 18 Hz looks promising. I'm trading off lots of SPL for extension, no need for 124 dB in home setting (arguable, of course
To be continued...
https://home.comcast.net/~infinitelybaffled/
There is a youtube.com video on the topic at
https://www.youtube.com/watch?v=pPoblqaqhHg
It makes woofers that are difficult to use in a sealed box or vented box perform quite well.
You just need a large space, like a basement, to put the woofer into.
An infinite baffle LOWERS the fs of the speaker when done right. Low frequency responses down to 5Hz are easily attainable.
By definition, in IB will do nothing to the resonant frequency of the speaker, and the system resonance (ie, where you'll find the impedance peak) will also be at Fs, so Fc=Fs. By making the cabinet smaller, Fc goes > Fs, and system Q goes up.
Response down to 5Hz is possible because there's no external restriction on cone movement, so relatively small amplifiers can be used to produce respectable SPLs. That said, an IB only has the same excursion-limited SPL as a sealed box. The difference between the two is that the sealed box will need more power to hit a given amount of cone excursion (and therefore a given SPL).
Chris
Response down to 5Hz is possible because there's no external restriction on cone movement, so relatively small amplifiers can be used to produce respectable SPLs. That said, an IB only has the same excursion-limited SPL as a sealed box. The difference between the two is that the sealed box will need more power to hit a given amount of cone excursion (and therefore a given SPL).
Chris
Whoah, thanks, everybody, tons of cool information and ideas
Still sticking with a simple vented box and unmodified driver this time. If it doesn't quite work out, the plan B is to save money for Dayton RSS460HO (Dayton Audio RSS460HO-4 18" Reference HO Subwoofer 4 Ohm - Subwoofers - Loudspeaker Drivers By Type - Loudspeaker Components); that would work beautifully in the box I'm building. Maybe we should have a box building contest - see who can get the loudest 20 Hz out of this driver?
As for today, I got the plywood cut, but most of the day went for assembling the mid-high section of the main speakers. Should have been an easy drilling and gluing, but as usual, some interesting hiccups occured
Still sticking with a simple vented box and unmodified driver this time. If it doesn't quite work out, the plan B is to save money for Dayton RSS460HO (Dayton Audio RSS460HO-4 18" Reference HO Subwoofer 4 Ohm - Subwoofers - Loudspeaker Drivers By Type - Loudspeaker Components); that would work beautifully in the box I'm building. Maybe we should have a box building contest - see who can get the loudest 20 Hz out of this driver?
As for today, I got the plywood cut, but most of the day went for assembling the mid-high section of the main speakers. Should have been an easy drilling and gluing, but as usual, some interesting hiccups occured
Maybe we should have a box building contest - see who can get the loudest 20 Hz out of this driver?
What's the maximum size could you live with?
Probably not big enough, a low tuned TH was 1500+ L with Prof. Leach's math, so guessing ~1700 L/60 ft^3
A tapped pipe of approximately the same total net Vb [cab + vent] as the 360 L BR OTOH showed enough extra gain above ~40 Hz for transient bursts to warrant using it instead IF a < 80-100 Hz XO is used.
GM
A tapped pipe of approximately the same total net Vb [cab + vent] as the 360 L BR OTOH showed enough extra gain above ~40 Hz for transient bursts to warrant using it instead IF a < 80-100 Hz XO is used.
GM
Today's progress - front panel ready and braces glued to two side panels. If all goes well I should be able to assemble tomorrow. I hope to get the amplifier (Behringer NU1000DSP) next week.
The box is 364 liters internal, 488 external, dimensions are chosen so it can fit on two 1525 x 1525 mm plywood boards with minimal waste - front and back are from one board cut in half, the rest is fitted on the other board. Ports are four 110 mm PVC pipes, 750 mm long including 90° bend.
Its not as much the total volume as depth and width - around 450 mm depth and 1500 width are maximum, I could go higher than 800 mm that is the height of my box being built. But it would be difficult to find room for a 700 x 700 x 700 mm cube that seems to be a popular format for large subwoofers.
I kind of agree, 40 Hz is a really low tone and 35 Hz is gut-wrenching low, especially for people who're used to 50...60 Hz low end extension of cheap micro systems and home-theater-in-a-box. Plenty of people have asked me to play "that one song which has really awesome bass for subwoofer" and I'm "meh, it's just open E on bass guitar, really". But then there are songs that go 30 Hz and below, and that can be exhilarating.
The box is 364 liters internal, 488 external, dimensions are chosen so it can fit on two 1525 x 1525 mm plywood boards with minimal waste - front and back are from one board cut in half, the rest is fitted on the other board. Ports are four 110 mm PVC pipes, 750 mm long including 90° bend.
Its not as much the total volume as depth and width - around 450 mm depth and 1500 width are maximum, I could go higher than 800 mm that is the height of my box being built. But it would be difficult to find room for a 700 x 700 x 700 mm cube that seems to be a popular format for large subwoofers.
I kind of agree, 40 Hz is a really low tone and 35 Hz is gut-wrenching low, especially for people who're used to 50...60 Hz low end extension of cheap micro systems and home-theater-in-a-box. Plenty of people have asked me to play "that one song which has really awesome bass for subwoofer" and I'm "meh, it's just open E on bass guitar, really". But then there are songs that go 30 Hz and below, and that can be exhilarating.
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