If you want larger Xmax the efficiency will drop
Have you modeled any of these drivers.
Looking at specs is a good start, but getting a idea of the actual mechanical ability
is more realistic.
The 3012LF is popular among DIY bass cabinets
Also its 15" Equivalent.
Dont think 40 Hz -3 dB is realistic with 12"
Its more like 50Hz
40 Hz box is more like a single 15" in 4 to 5 cubic feet
and power handling will suffer since it requires a lot of excursion.
Boxes will unload below port tune, so highpass over excursion filter will help a lot.
Unless of course you shoot for high Xmax speakers. Which loose sensitivity
Either way a Reflex box will unload quickly
Have you modeled any of these drivers.
Looking at specs is a good start, but getting a idea of the actual mechanical ability
is more realistic.
The 3012LF is popular among DIY bass cabinets
Also its 15" Equivalent.
Dont think 40 Hz -3 dB is realistic with 12"
Its more like 50Hz
40 Hz box is more like a single 15" in 4 to 5 cubic feet
and power handling will suffer since it requires a lot of excursion.
Boxes will unload below port tune, so highpass over excursion filter will help a lot.
Unless of course you shoot for high Xmax speakers. Which loose sensitivity
Either way a Reflex box will unload quickly
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If the compliance is Only 1.1 cubic feet
and FS is 44 Hz
then no.
Without even modeling this driver it would seem to be designed for very
small boxes.
Basic live audio reflex box will tune around 3 to 10 Hz above Fs
So if you build a enclosure tuned to 47 to 55 Hz
Then a -3 dB box at 40 Hz is absolutely not happening
Driver needs to have a Fs of at least 30 to 35 Hz
Lab12 is more realistically a subwoofer.
Then again a 2x12 in 5 cubic feet would limit the F3 response
Likely more realistically looking at 3 cubic feet or larger per driver to realistically touch 40 Hz F3
As noted already if this is for Rock/Blues type bands Not electronic Music
Just the smack of a kick drum or bass guitar isnt very demanding.
Even a 18" in a small 5 cubic foot box doesnt really go that low.
But it atleast allows the reflex to be tuned low around 30 Hz so its not just a blurry smear if tuned High like 45 Hz 15" boxes or 55 Hz 12" boxes.
and FS is 44 Hz
then no.
Without even modeling this driver it would seem to be designed for very
small boxes.
Basic live audio reflex box will tune around 3 to 10 Hz above Fs
So if you build a enclosure tuned to 47 to 55 Hz
Then a -3 dB box at 40 Hz is absolutely not happening
Driver needs to have a Fs of at least 30 to 35 Hz
Lab12 is more realistically a subwoofer.
Then again a 2x12 in 5 cubic feet would limit the F3 response
Likely more realistically looking at 3 cubic feet or larger per driver to realistically touch 40 Hz F3
As noted already if this is for Rock/Blues type bands Not electronic Music
Just the smack of a kick drum or bass guitar isnt very demanding.
Even a 18" in a small 5 cubic foot box doesnt really go that low.
But it atleast allows the reflex to be tuned low around 30 Hz so its not just a blurry smear if tuned High like 45 Hz 15" boxes or 55 Hz 12" boxes.
You absolutely can get flat-to-40Hz with a 12" driver. I have a little PA sub that does exactly that. The driver isn't obtainable any more, but the Faital 12HP1060 should do the job perfectly well. There's also a rubber surround variant, but the specs look pretty similar.
Chris
Chris
Looks like the 12BG76 could do well in a smaller box than the 3012LF, which is a plus for what you are want to do.
The B&C 12BG76 Xvar rating of 14mm is a good margin higher than the Eminence Kappalite 3012LF Xmax of 9.1 (Xlim is only 14.5). The 12BG76 should be able to get louder and cleaner, but will require more power to do that.
What do your sims show using the same box sizes and FB?
Does it matter now, after you already placed the order?
As for tuning, the Jr captivator pro and the Yorkville Paraline are both -3 dB @ 38 Hz. The Yorkville might be getting that with EQ, since it's powered, but the JTR is gettin that in a non-powered box. - Unless they're fibbing.
I imagine they're similar to Art Welter's famous 2X12" design. (Though I've never seen the non-eq'd specs for those.)
Anyway, it doesn't matter. I'm trying to go as close to that tuning as possible, then I'll deal with eq and HPF and such.
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It's interesting that you say more Xmax will mean less efficiency. Why is that, mechanically? I can understand needing more power to utilize that excursion (ll else being equal) but why would speaker A need more power than speaker B, if Xmax is the only difference, FOR A GIVEN VOLUME? I don get it. (I don't get a lot of things. 😱 )
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No, I still haven't found time to run any numbers. Possibly tonight, finally) I'm new to this software and figure might make mistakes, so I'm asking here first.
Also, again, I doubt Winsec is going to tell me much about sound quality. - That may be there in the numbers, somewhere, but I don't know how to interpret that, and such information is almost impossible to find online.
Likely more realistically looking at 3 cubic feet or larger per driver to realistically touch 40 Hz F3"
I can probably JUST do that, given my truck limits.
I'm running some numbers tonight, so I will go that high with the Vb and see how much it changes things.
Thx.
I can probably JUST do that, given my truck limits.
I'm running some numbers tonight, so I will go that high with the Vb and see how much it changes things.
Thx.
Short version, usual disclaimers apply (ie all else being equal etc etc etc):
Generally, higher Xmax means a driver has a longer voice coil.
That means more wire wound on to the former, and possibly a longer former too, which means more mass that has to be moved.
Uncle Isaac gave us the ever convenient laws of motion (ie F=ma), so we know that more mass is going to take more force to achieve a given acceleration, therefore it is less efficient.
... Unless you go for an under-hung motor. In that case, I think the limitation becomes the amount of magnetic field you can muster.
Of course, the short voice coil will also limit thermal power handling. All of the PA drivers I've seen have had over-hung motors.
Chris
Of course, the short voice coil will also limit thermal power handling. All of the PA drivers I've seen have had over-hung motors.
Chris
Thanks, guys.
Based on that, I don't think an extreme Xmax is really what I want. I'd rather have more drivers on stage, with less excursion, and that gives me better efficiency at the same time. (All else being equal.)
That's correct, yes?
That has the added advantage of (IMO) better throw, because you're moving more air molecules at the source.
=======================================================
So last night and most of today, I've been learning WinISD and looking at all the drivers listed / mentioned so far. (Including that FaitalPro)
The only part I can truly understand is the SPL-vs-frequency graph, and I figure a flat response, pre-EQ, has got to be the best sounding. (phase? group delay?) - and probably more efficient as well.
Based on that assumption ( 😱 ) I think Art & @Rademakers were both right: The Kappalite looks terrific, despite its limited Xmax. It's the only one that gives a nearly-flat response, with two of them in a 4.5 + ft/3 box. (It loves 5.5 ft/3 and a 38 Hz tuning.)
All of the others, including the one the B&C guy recommended, get REALLY peaky at anything over 3 ft/2. - Some much worse.
It also seems that Vas is not the magic number some had said it was. The Lab12 and Lab12C look about as bad as all the others, kind of falling apart above 3 ft/3 (again, for 2 of them) unless you use a very low "HT" tuning, and I don't want that because efficiency suffers badly. (And they have very low sensitivity to start with.
----------------------
Having said all of the above, I really have no idea what I'm doing. I wish I could see some differences in cone excursion (The graph shows very little difference) or especially differences in power requirements vs frequency.
And most of all, I wish I could see a read-out of final cabinet Qtc. It seems to me that that's the tail that wags the dog, yet I don't see this figure in WinISD.
- Is there a way to calculate it ahead of time?
Based on that, I don't think an extreme Xmax is really what I want. I'd rather have more drivers on stage, with less excursion, and that gives me better efficiency at the same time. (All else being equal.)
That's correct, yes?
That has the added advantage of (IMO) better throw, because you're moving more air molecules at the source.
=======================================================
So last night and most of today, I've been learning WinISD and looking at all the drivers listed / mentioned so far. (Including that FaitalPro)
The only part I can truly understand is the SPL-vs-frequency graph, and I figure a flat response, pre-EQ, has got to be the best sounding. (phase? group delay?) - and probably more efficient as well.
Based on that assumption ( 😱 ) I think Art & @Rademakers were both right: The Kappalite looks terrific, despite its limited Xmax. It's the only one that gives a nearly-flat response, with two of them in a 4.5 + ft/3 box. (It loves 5.5 ft/3 and a 38 Hz tuning.)
All of the others, including the one the B&C guy recommended, get REALLY peaky at anything over 3 ft/2. - Some much worse.
It also seems that Vas is not the magic number some had said it was. The Lab12 and Lab12C look about as bad as all the others, kind of falling apart above 3 ft/3 (again, for 2 of them) unless you use a very low "HT" tuning, and I don't want that because efficiency suffers badly. (And they have very low sensitivity to start with.
----------------------
Having said all of the above, I really have no idea what I'm doing. I wish I could see some differences in cone excursion (The graph shows very little difference) or especially differences in power requirements vs frequency.
And most of all, I wish I could see a read-out of final cabinet Qtc. It seems to me that that's the tail that wags the dog, yet I don't see this figure in WinISD.
- Is there a way to calculate it ahead of time?
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Cableaddict,
1)The 6.25 cubic foot (gross) JTR 212 Captivator Pro Fb (Frequency of box tuning) is effectively 44 Hz, my "famous" WS LAB 2x12" bass reflex design Fb is 36 Hz.
The JTR 212 starts rolling off at 50Hz, it is around -6dB at 38Hz from 100Hz.
Gradual decrease from top to bottom.
2)The 7.6 cubic foot (gross) 36Hz Fb WS LAB 2x12" Bass Reflex has the opposite response, a gradual decrease from bottom to top, about +3dB at 50Hz compared to 100 Hz, -3dB point around 35Hz.
You can see the WS LAB 2x12" actual response compared to the BassBox Pro simulation below. The bass "hump" was actually not originally intended- the AudioToolbox measurement mic I was using at the time had poor LF response, I thought the response was rolling off slightly top to bottom..
The box was designed using no simulations, those were done by one of the early adopters of the design. Note that the excursion is only 9mm at 800 watts, (5mm at Fb) the LABs can easily take the peak power to drive past Xmax in a bass reflex design. The grill cloth would be slapped a bit past Xmax in this design, a visual indicator of “that’s all, folks”.
Using the same box size, dropping to around a 32 Hz tuning would flatten and extend the LF response, though the excursion peak would also drop by 4Hz, hitting Xmax at around 44 vs 48 Hz, and loosing about 3dB sensitivity in that range.
3) Generally, most genres of music will have quite a bit more average power in the upper bass range, having a response sloping up from the bottom, rather than down is better from a thermal (power compression and burnt drivers) standpoint.
When I replaced four WS LAB 2x12" Bass Reflex with two Keystone tapped horns loaded with B&C 18SW115-4 (exactly the same total cabinet volume/truck space), the system LF output remained about the same, but the “chest slam” potential went up by about 6dB using the same power amplifiers. Using more power (two 18SW115-4 have less thermal issues than eight LAB12) the increase would have been even greater.
WinISD calculates frequency response, phase, max power, max SPL, group delay, SPL at any given power level, excursion, and impedance.
If you are not seeing differences in cone excursion, raise the input power/voltage to where you do. Forget about Qtc and flat response, you are going to equalize the subs to what you want their frequency/phase response to be.
Art
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Hey, Art.
Check your pm's when you have a chance. I'm ready to pay you for some help. I'm still way too in the weeds to make really important decisions and end up with an optimal result.
As to your last points:
1: I guess JTR is giving his specs based on an EQ'd plate amp. Fairly decptive since he also sells it as a passive box. - But VERY good to know. (thanks)
2: I can easily load four cabs with that total dimensional size, though again I'm not looking to use the Lab12 or Lab12C. - Mostly due to weight, but also as I don't need that kind of LF extension. I'm also now fairly sure I don't need that much Xmax. (I'd rarely even have the amperage available to take advantage of it, given the low sensitivity of such drivers.)
3: I get the frequency slope vs efficiency thing, but that's at the cost of sound quality, even with rock music. Of this I am CERTAIN. I've been playing around with what I have here, both my live rig and my big studio system, playing with EQ and such, and there's just no arguing with the "good feel" of a fairly flat LF extension.
I'm pretty sure that also allows the overall LF volume to be lower, (don't quote me on that just yet) which is probably why I got by for years with my four 18" sealed Bag End subs. They're great sounding (In a "restricted" sort of way) but have pathetic maximum volume. - And I keep melting my Lab Grupen amps. (I mean literally.)
I figure that a 2X12" cabinet with a fairly large port should give just about the same "effective cone area" as a single sealed 18", though without as even a frequency dispersion. - But more volume and a less restricted sound. So hopefully four 2X12's will work out. I dunno... Maybe four single 15's make more sense, or four small 12" TH boxes. I just need something I can get up a flight of stairs by myself. No getting past that.
Well, one step at a time.......
Check your pm's when you have a chance. I'm ready to pay you for some help. I'm still way too in the weeds to make really important decisions and end up with an optimal result.
As to your last points:
1: I guess JTR is giving his specs based on an EQ'd plate amp. Fairly decptive since he also sells it as a passive box. - But VERY good to know. (thanks)
2: I can easily load four cabs with that total dimensional size, though again I'm not looking to use the Lab12 or Lab12C. - Mostly due to weight, but also as I don't need that kind of LF extension. I'm also now fairly sure I don't need that much Xmax. (I'd rarely even have the amperage available to take advantage of it, given the low sensitivity of such drivers.)
3: I get the frequency slope vs efficiency thing, but that's at the cost of sound quality, even with rock music. Of this I am CERTAIN. I've been playing around with what I have here, both my live rig and my big studio system, playing with EQ and such, and there's just no arguing with the "good feel" of a fairly flat LF extension.
I'm pretty sure that also allows the overall LF volume to be lower, (don't quote me on that just yet) which is probably why I got by for years with my four 18" sealed Bag End subs. They're great sounding (In a "restricted" sort of way) but have pathetic maximum volume. - And I keep melting my Lab Grupen amps. (I mean literally.)
I figure that a 2X12" cabinet with a fairly large port should give just about the same "effective cone area" as a single sealed 18", though without as even a frequency dispersion. - But more volume and a less restricted sound. So hopefully four 2X12's will work out. I dunno... Maybe four single 15's make more sense, or four small 12" TH boxes. I just need something I can get up a flight of stairs by myself. No getting past that.
Well, one step at a time.......
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Very true Chris.
So true I'd completely overlooked them 😱.
FWIW, ATC have had a few underhung models (those with the "SC" suffix in the model name, for Short Coil) but they've mostly been mid or midbass drivers rather than bass/sub IIRC.