I'm planning on building a compact subwoofer for (mainly but not exclusively) movies. I think a sealed enclosure with LT is the best choice in my situation.
- Smallish living room
- Listening levels are never excessive.
- Limited space to put a subwoofer
- Ample power available (Behringer Inuke NU3000DSP: should deliver 1500Wrms/4ohm)
- F3 as low as possible (aiming for 20Hz, Q =< 0.707)
Guesstimating the bracing and driver displacement for the build, I should be able to build something with a nett internal volume of 50 to 55 liter.
I think that a 12" driver would be the biggest that could perform nicely in such "small" enclosure.
What should I look for as far as T/S go?
I was thinking:
Fs = aim as low as possible
0,25 < Qts > 0.4
Vas = rather low
Xmax > 10mm one way
Rms < 4
Z = 4 ohm
The Rms spec seems important to me because I never set the volume really high. I think I'll be missing out on details when Rms is too high and the volume is set quite low.
Low distortion figures are always nice.
Am I looking in the right direction or do I make some serious mistakes?
Any suggestions?
Might a car sub be the way to go?
My doubts about car subs:
- higher distortion figures (bigger tolerances due to extreme Xmax figures)
- higher Rms due to stiffer suspension
Budget: ~ €250. I might increase it up to €300 if this allows me to get the perfect driver for my application.
- Smallish living room
- Listening levels are never excessive.
- Limited space to put a subwoofer
- Ample power available (Behringer Inuke NU3000DSP: should deliver 1500Wrms/4ohm)
- F3 as low as possible (aiming for 20Hz, Q =< 0.707)
Guesstimating the bracing and driver displacement for the build, I should be able to build something with a nett internal volume of 50 to 55 liter.
I think that a 12" driver would be the biggest that could perform nicely in such "small" enclosure.
What should I look for as far as T/S go?
I was thinking:
Fs = aim as low as possible
0,25 < Qts > 0.4
Vas = rather low
Xmax > 10mm one way
Rms < 4
Z = 4 ohm
The Rms spec seems important to me because I never set the volume really high. I think I'll be missing out on details when Rms is too high and the volume is set quite low.
Low distortion figures are always nice.
Am I looking in the right direction or do I make some serious mistakes?
Any suggestions?
Might a car sub be the way to go?
My doubts about car subs:
- higher distortion figures (bigger tolerances due to extreme Xmax figures)
- higher Rms due to stiffer suspension
Budget: ~ €250. I might increase it up to €300 if this allows me to get the perfect driver for my application.
Xmax is important for the LT-I've done a 10" in 0.126cf QTC 0.707 for my car and it's limitation is it's low Xmax-fine for the levels I listen at in my car-but if it moved it to my house it'd be overexcurting to fill my living room.
There are some excellent car drivers available, though there is a lot of crud to wade through to get there-55l is big for our 12" enclosures!
My driver is the Aliante 10Si:
Fs = 22.9
Qts = 0.28
Vas = 43.3
Xmax = 4mm one way
Rms = 9.129kg/s
Z = 4 ohm
So ticks all boxes except diameter and excursion, sounds very natural in my car-so I'd say your requirments seem spot on (though have never done LT in a house)
This looks to tick all boxes:
TC Sounds Epic 12" DVC Subwoofer 293-650
There are some excellent car drivers available, though there is a lot of crud to wade through to get there-55l is big for our 12" enclosures!
My driver is the Aliante 10Si:
Fs = 22.9
Qts = 0.28
Vas = 43.3
Xmax = 4mm one way
Rms = 9.129kg/s
Z = 4 ohm
So ticks all boxes except diameter and excursion, sounds very natural in my car-so I'd say your requirments seem spot on (though have never done LT in a house)
This looks to tick all boxes:
TC Sounds Epic 12" DVC Subwoofer 293-650
+1 on the TC Sounds drivers, you really can't go wrong with them. With the budget you have, you could probably do one of these:
TC Sounds LMS-R 12" DVC Subwoofer 293-658
Those look really interesting.
I do see some disadvantages with them (very high Le, limits upper frequency extension) but still very interesting drivers.
The Epic looks actually more interesting then the LMS-R. The Epic has lower Fs and looking at the T/S I suspect a less stiff suspension (lowers Rms).
Xmax is a little higher on the LMS-R.
I'll have tosee what they do in WinISD.
I do see some disadvantages with them (very high Le, limits upper frequency extension) but still very interesting drivers.
The Epic looks actually more interesting then the LMS-R. The Epic has lower Fs and looking at the T/S I suspect a less stiff suspension (lowers Rms).
Xmax is a little higher on the LMS-R.
I'll have tosee what they do in WinISD.
Also the RS woofers have comparable distortion figures as the Titan woofers have. (According measurements in HobbyHifi magazine)
Other drivers (Wavecor, Scanspeak, Vifa/Peerless, ...) have much lower distortion figures.
I don't have any distortion figures for the TC sounds or many other woofers, so it may not be fair to judge the Daytons against those.
Other drivers (Wavecor, Scanspeak, Vifa/Peerless, ...) have much lower distortion figures.
I don't have any distortion figures for the TC sounds or many other woofers, so it may not be fair to judge the Daytons against those.
The best driver/s for the task at hand, is that with the ability to displace the most air within the box and amplification limits set. An ideal match would be something that hits Xmax in the box volume specified, when the amplifier has reached it's dynamic limits as well, or at least, try to get these 2 limits "in the same ballpark."
Picking a very low distortion driver should only go so far as if it's being compared at equal output levels to alternative "high displacement" oriented drivers. A lower displacement driver driven to it's limits will almost ALWAYS produce more distortion than a high displacement driver operating at a fraction of maximum displacement.
Qts, Vas, and Fs are actually of very little importance here. All these specifications are going to do, is change the shape of the transform required to hit your target response. The best low frequency, low distortion performance, in the case of a fixed box size and amplification, will generally come from the driver with the greatest available displacement capabilities within the limits set. As it turns out- most of the serious contenders will have "respectable" enough characteristics regardless.
Assuming the iNUKE could hit 3000W transients, the best single driver in a 2ft^3 box is probably going to be something in the class of like a TC LMS-R 15". A heavy duty long throw 15" job is, IMO, the correct approach to a 2ft^3 LT. I wouldn't even be looking at 10-12" drivers here unless they were used in pairs with this much amplification available.
At half the price, I wouldn't hesitate to suggest the Dayton TIT400C, it fits the "in the ballpark" limits here pretty good as well.
Alternatively, to really help reduce distortion, use a PAIR of drivers mounted in opposing directions inside the little sealed box. A PAIR of RSS390HO in 2ft^3, with frames coupled, would make for a great dependable LT sub with effectively dead box movement. The lower excursions required in this application would, IMO, produce a really dead nuts accurate sounding bottom end.
If the box dimensions to support 15" drivers are out of the question, there are plenty of 10-12" drivers that should be considered in multiples.
Regards,
Eric
Picking a very low distortion driver should only go so far as if it's being compared at equal output levels to alternative "high displacement" oriented drivers. A lower displacement driver driven to it's limits will almost ALWAYS produce more distortion than a high displacement driver operating at a fraction of maximum displacement.
Qts, Vas, and Fs are actually of very little importance here. All these specifications are going to do, is change the shape of the transform required to hit your target response. The best low frequency, low distortion performance, in the case of a fixed box size and amplification, will generally come from the driver with the greatest available displacement capabilities within the limits set. As it turns out- most of the serious contenders will have "respectable" enough characteristics regardless.
Assuming the iNUKE could hit 3000W transients, the best single driver in a 2ft^3 box is probably going to be something in the class of like a TC LMS-R 15". A heavy duty long throw 15" job is, IMO, the correct approach to a 2ft^3 LT. I wouldn't even be looking at 10-12" drivers here unless they were used in pairs with this much amplification available.
At half the price, I wouldn't hesitate to suggest the Dayton TIT400C, it fits the "in the ballpark" limits here pretty good as well.
Alternatively, to really help reduce distortion, use a PAIR of drivers mounted in opposing directions inside the little sealed box. A PAIR of RSS390HO in 2ft^3, with frames coupled, would make for a great dependable LT sub with effectively dead box movement. The lower excursions required in this application would, IMO, produce a really dead nuts accurate sounding bottom end.
If the box dimensions to support 15" drivers are out of the question, there are plenty of 10-12" drivers that should be considered in multiples.
Regards,
Eric
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@mdocod: While I do agree with most of what you say, I'm not so sure about the "only" parameter of importance being the Vd at 20Hz.
From a certain point on I would need just too much compensation @ 20Hz from the LT.
Linkwitz himself advises not to go for more then 20dB, while others say over 12db is not advisable.
Is this just an advise to prevent amplifiers from running out of juice? (which might not be a problem in my case)
With regards to the distortion measurements I was talking about: They were done using the same measurement procedure, using the same set-up, in the same conditions, by the same people. (all HobbyHifi magazine, Germany) There the TIT320C-4 has considerably more distortion in the lower octaves then the RSS315HF-8 for instance. At 50Hz the K2 for the TIT is at about 2.5% where for the RSS it is at only 0.4% (90dB at 1m). Just to give an example.
@boscoe: 20L is quite small indeed. The main reason I would not do that is the amount of extra gain you would need at F3. But I still have to find out if that really is a problem when you have ample power available.
I always look for an application where I don't need to force the performance to be what I like but get as close to my goals as possible without too much compensation.
From a certain point on I would need just too much compensation @ 20Hz from the LT.
Linkwitz himself advises not to go for more then 20dB, while others say over 12db is not advisable.
Is this just an advise to prevent amplifiers from running out of juice? (which might not be a problem in my case)
With regards to the distortion measurements I was talking about: They were done using the same measurement procedure, using the same set-up, in the same conditions, by the same people. (all HobbyHifi magazine, Germany) There the TIT320C-4 has considerably more distortion in the lower octaves then the RSS315HF-8 for instance. At 50Hz the K2 for the TIT is at about 2.5% where for the RSS it is at only 0.4% (90dB at 1m). Just to give an example.
@boscoe: 20L is quite small indeed. The main reason I would not do that is the amount of extra gain you would need at F3. But I still have to find out if that really is a problem when you have ample power available.
I always look for an application where I don't need to force the performance to be what I like but get as close to my goals as possible without too much compensation.
do any of the jbl gt5 series woofers fit your application and are they available in your area ?
jbl gt5-10 gt5-12 gt5-15 ?
http://www.amazon.com/JBL-GT5-10D-1...e=UTF8&qid=1342866449&sr=1-1&keywords=gt5-10d
https://docs.google.com/viewer?a=v&...t4fuul&sig=AHIEtbT-cr0f-Ejt7BgNdsfWrhp7DHivWg
https://docs.google.com/viewer?a=v&...Ukm6jn&sig=AHIEtbTZtt5w5KJZ4QNRQlJq7Qc37eauoQ
https://docs.google.com/viewer?a=v&...6Js5dM&sig=AHIEtbRRuP7hXv4tBaIPet_pqI_xuoMiqA
jbl gt5-10 gt5-12 gt5-15 ?
http://www.amazon.com/JBL-GT5-10D-1...e=UTF8&qid=1342866449&sr=1-1&keywords=gt5-10d
https://docs.google.com/viewer?a=v&...t4fuul&sig=AHIEtbT-cr0f-Ejt7BgNdsfWrhp7DHivWg
https://docs.google.com/viewer?a=v&...Ukm6jn&sig=AHIEtbTZtt5w5KJZ4QNRQlJq7Qc37eauoQ
https://docs.google.com/viewer?a=v&...6Js5dM&sig=AHIEtbRRuP7hXv4tBaIPet_pqI_xuoMiqA
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Maybe you could have a look at the D300P04 Atohm, a very versatile woofer usable for HT and Hi-Fi.
ATOHM : NOTRE BUT ULTIME ... VOUS FAIRE VIBRER
Enclosure :
http://www.atohm.com/images/kit/FICHE-KIT%20RAFALE%20V60%20S.pdf
I own two of these sub :
I made this choice has because of the size of the enclosure ~60l with an F3 of ~25 Hz (measured).
I cross them at 120hz for HC and 250 Hz for hi-fi, i use only one for HC.
Price is 180 €, HP is made in PRC, It should be available in belgium
ATOHM : NOTRE BUT ULTIME ... VOUS FAIRE VIBRER
Enclosure :
http://www.atohm.com/images/kit/FICHE-KIT%20RAFALE%20V60%20S.pdf
I own two of these sub :
I made this choice has because of the size of the enclosure ~60l with an F3 of ~25 Hz (measured).
I cross them at 120hz for HC and 250 Hz for hi-fi, i use only one for HC.
Price is 180 €, HP is made in PRC, It should be available in belgium
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