I recently bought some 15" subs, these are the specs:
750 watt maximum power handling capability
18-100 Hz Frequency Response
Fs =21.57 Hz
Qms=9.101
Qes=0.4231
Qts=0.4043
Vas=263.27 liters
Cms=0.2562E-03 M/N
Re=3.79 ohms
BL=16.060 Newtons/Amp
Sd=0.0.85530 sq. mtrs
Mms=0.212463 Kilograms
Hvc=1.250"
Hag=0.500"
Xmax=0.375
Xlin p-p=.750
Ref Efficiency=0.6001%
Predicted Output=89.982 Db/1W/1M
Recommended box size for sealed is 42.5 liters, which gives a Qtc of 1.08, but I think that's if it's in a car and I still think it's too high.
I'm
of how big the box will have to be to achieve the box Qtc I want. 500 liter for a Qtc of .5, which is what I want because I'm interested in SQ. But a 500 liter box is way too big. WinISD recommends a .71 Qtc which is 128 liter. Is this a good compremise or is the Qtc too high.
Is there something else I can do to make the box smaller. Such as using an aperiodic vent? Do they make those vents for 15" subs, I would imagine they would have to be very big. Or is this sub not suited for a aperiodic vent.
Any suggestions are welcome.
750 watt maximum power handling capability
18-100 Hz Frequency Response
Fs =21.57 Hz
Qms=9.101
Qes=0.4231
Qts=0.4043
Vas=263.27 liters
Cms=0.2562E-03 M/N
Re=3.79 ohms
BL=16.060 Newtons/Amp
Sd=0.0.85530 sq. mtrs
Mms=0.212463 Kilograms
Hvc=1.250"
Hag=0.500"
Xmax=0.375
Xlin p-p=.750
Ref Efficiency=0.6001%
Predicted Output=89.982 Db/1W/1M
Recommended box size for sealed is 42.5 liters, which gives a Qtc of 1.08, but I think that's if it's in a car and I still think it's too high.
I'm
of how big the box will have to be to achieve the box Qtc I want. 500 liter for a Qtc of .5, which is what I want because I'm interested in SQ. But a 500 liter box is way too big. WinISD recommends a .71 Qtc which is 128 liter. Is this a good compremise or is the Qtc too high.Is there something else I can do to make the box smaller. Such as using an aperiodic vent? Do they make those vents for 15" subs, I would imagine they would have to be very big. Or is this sub not suited for a aperiodic vent.
Any suggestions are welcome.
I wouldn't make a sealed box bigger than 100 liters for that woofer. Unibox gives 101.3Liters for a Qtc of 0.707 assuming some damping mat'l on the walls. A 60Liter box with some damping material would sound fine, but I would hardly call a 40-45ish F3 woofer a subwoofer.
How much power will you feed it? If a lot, you should use a higher Qtc for driver protection. This woofer doesn't have a surplus of excursion....
Any technique you try to make the box smaller (stuffing, Aperiodic, etc) actually reduces bass (Fc will rise a bit) because it is just adding losses. It is not "equivalent to" using a larger box in anything but Qtc.
IMO, Qtc=1 sounds fine. Qtc=0.5 is not a magic number as far as sound quality is concerned - you will not hear dramatic differences in response in the 0.5-1.0 range. People who claim to hear dramatic differences in the bass response of a woofer with a certain Qtc have not tried using an adjustable Linkwitz transform to vary Qtc , keeping Fc constant while listening to music.
How much power will you feed it? If a lot, you should use a higher Qtc for driver protection. This woofer doesn't have a surplus of excursion....
Any technique you try to make the box smaller (stuffing, Aperiodic, etc) actually reduces bass (Fc will rise a bit) because it is just adding losses. It is not "equivalent to" using a larger box in anything but Qtc.
IMO, Qtc=1 sounds fine. Qtc=0.5 is not a magic number as far as sound quality is concerned - you will not hear dramatic differences in response in the 0.5-1.0 range. People who claim to hear dramatic differences in the bass response of a woofer with a certain Qtc have not tried using an adjustable Linkwitz transform to vary Qtc , keeping Fc constant while listening to music.
A lot of people consider .707 Optimum. It will give you the flattest frequency response down to cutoff.
Some prefer lower q's for better transient response, but even a q of 1 would not sound awful.
I generally aim for around .7 give or take a little on my designs. Keep in mind that a lot of the stuff you'll see on the shelves down at the department stores are using rediculous q's well over 1, so relative to all that stuff, a q of .7 is very low.
I built a box a couple years ago for some 15's and it had a q of .7 at around 500 litres. I built mine to around 450, and it sounds pretty decent. Very very low clean bass. Honestly, I don't think q is all that critical in that region, unless you plan on doing a rediculous amount of work to deal with room effects anyways.
They're 15's. Just get it in the ballpark and it'll rattle your windows.
And I wouldn't worry too much about the excursion. If your q is at all reasonable, and you're not too much into booming like a civic, (which you're obviously not if you want a low q) .3 inches is plenty even if that is p-p
Some prefer lower q's for better transient response, but even a q of 1 would not sound awful.
I generally aim for around .7 give or take a little on my designs. Keep in mind that a lot of the stuff you'll see on the shelves down at the department stores are using rediculous q's well over 1, so relative to all that stuff, a q of .7 is very low.
I built a box a couple years ago for some 15's and it had a q of .7 at around 500 litres. I built mine to around 450, and it sounds pretty decent. Very very low clean bass. Honestly, I don't think q is all that critical in that region, unless you plan on doing a rediculous amount of work to deal with room effects anyways.
They're 15's. Just get it in the ballpark and it'll rattle your windows.
And I wouldn't worry too much about the excursion. If your q is at all reasonable, and you're not too much into booming like a civic, (which you're obviously not if you want a low q) .3 inches is plenty even if that is p-p
Arx and Ron E thanks for your advise,
I'm
to hear that I don't need to build a big box for this subwoofer. And then I'm also 
to hear that an f3 of 40-45 is hardly a subwoofer. I used to have a very similar subwoofer to this one in my car; Kicker Solobaric 15 D series, this one looks exactly like it's predisessor Solobaric C series. Here's what it looks like http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3044991950&category=18804
I will power it with a 500 watts amp that came out of a Acoustic Research 315HO speaker, it powered the 15" sub. The 315HO is the earlier model of this speaker http://www.acoustic-research.com/ar1_content.asp. Still looks the same and seems to have the same amp. The amp has a 24 or 36 db/slope fix at 100 Hz.
"They're 15's. Just get it in the ballpark and it'll rattle your windows." Does that mean 15's are not for SQ, maybe I should of bought the 12" version of this sub, but nobody replied to my tread, when I asked people about their opinion on the 12 and 15" versions of this sub. But I think my amp is more suited for an 15 now that I think about it.
Arx Xmax p-p is .75"
I'm
to hear that I don't need to build a big box for this subwoofer. And then I'm also to hear that an f3 of 40-45 is hardly a subwoofer. I used to have a very similar subwoofer to this one in my car; Kicker Solobaric 15 D series, this one looks exactly like it's predisessor Solobaric C series. Here's what it looks like http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3044991950&category=18804I will power it with a 500 watts amp that came out of a Acoustic Research 315HO speaker, it powered the 15" sub. The 315HO is the earlier model of this speaker http://www.acoustic-research.com/ar1_content.asp. Still looks the same and seems to have the same amp. The amp has a 24 or 36 db/slope fix at 100 Hz.
"They're 15's. Just get it in the ballpark and it'll rattle your windows." Does that mean 15's are not for SQ, maybe I should of bought the 12" version of this sub, but nobody replied to my tread, when I asked people about their opinion on the 12 and 15" versions of this sub. But I think my amp is more suited for an 15 now that I think about it.
Arx Xmax p-p is .75"
Ron E, I downloaded unibox . . .
And with "minimal leaks" and the "walls covered" for damping I got a volume of 147.3 liter to achieve a Qtc of .707. But I was happy to see that F3 was about 35 Hz. Maybe we have different versions of unibox, mine's 4.03. You think my calculations are correct?
I might still build it only about 60 liters, I can't picture it yet. That is, whether I want to go for .707 or just a small box.
And with "minimal leaks" and the "walls covered" for damping I got a volume of 147.3 liter to achieve a Qtc of .707. But I was happy to see that F3 was about 35 Hz. Maybe we have different versions of unibox, mine's 4.03. You think my calculations are correct?
I might still build it only about 60 liters, I can't picture it yet. That is, whether I want to go for .707 or just a small box.
I'm personally using 2 JL15-W6 15'' subs in my setup, each in a seperate 2.5cf (75L) sealed chamber, powered by the plate amp in the foreground.
I'm happy with their sound using a 12db x-over at around 45hz, now I just need a set of fact mains that go that low (working on that)
What x-over point do you have in mind with yours?
An externally hosted image should be here but it was not working when we last tested it.
I'm happy with their sound using a 12db x-over at around 45hz, now I just need a set of fact mains that go that low (working on that)
What x-over point do you have in mind with yours?
I don't use the damping buttons provided by Unibox - I used Ql=20 and Qa=20.
No model using factory specs is going to tell you the full story...don't count your chickens...
No model using factory specs is going to tell you the full story...don't count your chickens...
Nah, I'm not saying there's anything wrong with the sound quality of 15's, just that the q is probably not really all that critical, as the peaks are down at a frequency where your ears aren't all that picky. Personally, I like a bit of a peak down there between 30-40 hz. And besides, you'll be getting tons of peaks and dips from standing waves in the room etc.
Another question.. Are you using a Car sub?
If so, keep in mind that they normally roll off at a higher frequency, which partially compensates for cabin gain. In a house it'll happen a little differently, so be prepared to have to mess with it a bit to make it sound right. Might need a little bit of equalization to flatten it out.
Another question.. Are you using a Car sub?
If so, keep in mind that they normally roll off at a higher frequency, which partially compensates for cabin gain. In a house it'll happen a little differently, so be prepared to have to mess with it a bit to make it sound right. Might need a little bit of equalization to flatten it out.
Volenti,
You should have my main speakers. When sealed (they have ports, but I don't like ports) they have an f3 of 45-50 Hz and of course a roll-off at 12 db/octive. They're 2.5-way, but can be made 2-way just as easy. Pair of woofers and tweeters sell on ebay (from british columbia, CA) for $130 total, sound very nice, tweeters are vifa and woofers are like Viston Al 200, except mag/copper/aluminum alloy cone.
Anyway . . . my amp is 500 watt and has a 36 db/octive roll-off at 100 Hz (it's described more above). I read that you had 2 JL Audio 15's before, but I never imagined they would be in the same enclosure. I would also like to put my subs in the same enclosure, but I heard stero subs have a more realistic sound, also small size is important.
Ron E,
You're right I should not be counting chickens.
Arx,
Yes, I'm using a sub which is designed for car use. It's very similar to the old round Kicker Solobarics (same as Kicker S15C, link to sub is above).
I thought of using a Linkwitz transformer circuit, but I think that it will require me to build a larger box, right?
You should have my main speakers. When sealed (they have ports, but I don't like ports) they have an f3 of 45-50 Hz and of course a roll-off at 12 db/octive. They're 2.5-way, but can be made 2-way just as easy. Pair of woofers and tweeters sell on ebay (from british columbia, CA) for $130 total, sound very nice, tweeters are vifa and woofers are like Viston Al 200, except mag/copper/aluminum alloy cone.
Anyway . . . my amp is 500 watt and has a 36 db/octive roll-off at 100 Hz (it's described more above). I read that you had 2 JL Audio 15's before, but I never imagined they would be in the same enclosure. I would also like to put my subs in the same enclosure, but I heard stero subs have a more realistic sound, also small size is important.
Ron E,
You're right I should not be counting chickens.
Arx,
Yes, I'm using a sub which is designed for car use. It's very similar to the old round Kicker Solobarics (same as Kicker S15C, link to sub is above).
I thought of using a Linkwitz transformer circuit, but I think that it will require me to build a larger box, right?
With a transform, you can build whatever box size (neglecting Q) you desire, then change it to whatever Q you desire - the tradeoff is amp headroom, so boosts of more than 10dB (about an octave extension) are pretty much a no-no.
Right.. That's exactly what I was thinking.
I'd recommend just building it to the largest size that's acceptable to you, and see how that works, if it's rolled off too early, which I doubt, you can eq it then.
Keep in mind wood dimensions too.
When i built my bigass speakers, I didn't, and had to go buy another sheet of mdf, just to cut one little 23"x25" panel
if i had made the thing an inch taller, and narrower, it would have fit.
although extra wood is always a good excuse to get more speakers 😉
One more thing I noticed.. Careful if you're re-using something from a powered speaker, because it may have some equalization already built in. That might be good or bad, depending.
I'd recommend just building it to the largest size that's acceptable to you, and see how that works, if it's rolled off too early, which I doubt, you can eq it then.
Keep in mind wood dimensions too.
When i built my bigass speakers, I didn't, and had to go buy another sheet of mdf, just to cut one little 23"x25" panel
if i had made the thing an inch taller, and narrower, it would have fit.
although extra wood is always a good excuse to get more speakers 😉
One more thing I noticed.. Careful if you're re-using something from a powered speaker, because it may have some equalization already built in. That might be good or bad, depending.
Yep, with limited Xmax but pretty decent power handling, it looks like a small box + Linkwitz Transform would probably get you as good of a Q and low frequency extension as you could get out of a huge enclosure, while keeping required amplifier power below Pmax. Haven't run the numbers though... just impression at a glance.
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