One way to find out is to calculate it based on actual movie soundtrack SPL with a 115 dB/listening position the standard goal, so need to include any loss over distance.
The Ultimate List of BASS in Movies w/ Frequency Charts
Distance loss in a closed room is not 6dB/double distance! And when in room mode area and more so when pressure zone starts there is very little distance loss, it's more differences from modes which can be huge but are not distance dependend.
After all you need to measure that at your listening position to be sure.
Short simulation - you get 112dBSpl at 20Hz with 8 SB Acoustics 12" and about 130dBSpl in the music bass range. That's ... not bad at all 🤓
I use 6 10" in my Home Cinema corner in a big room (107dBSpl @ 20Hz and 124dB music) and that's PLENTY for me. But I have a big 30Hz mode in my room (which get's EQd of course), so deep frequencies have a good boost as in most rooms.
After all you need to measure that at your listening position to be sure.
Short simulation - you get 112dBSpl at 20Hz with 8 SB Acoustics 12" and about 130dBSpl in the music bass range. That's ... not bad at all 🤓
I use 6 10" in my Home Cinema corner in a big room (107dBSpl @ 20Hz and 124dB music) and that's PLENTY for me. But I have a big 30Hz mode in my room (which get's EQd of course), so deep frequencies have a good boost as in most rooms.
Drop the inuke. Get low sensitivity very high xmax car audio drivers:
https://www.alpine.co.uk/p/Products/type-r-speakers36/r2-w12d2
get an amp that can drive them all to the maximum excursion (Admark/Gisen/Sanway). 8 of these drivers, colocated, outdoors, is giving 118dB/1m@20Hz: http://www.baudline.com/erik/bass/xmaxer.html
https://www.alpine.co.uk/p/Products/type-r-speakers36/r2-w12d2
get an amp that can drive them all to the maximum excursion (Admark/Gisen/Sanway). 8 of these drivers, colocated, outdoors, is giving 118dB/1m@20Hz: http://www.baudline.com/erik/bass/xmaxer.html
This chassis looks more interesting as I thought! Can we get usefull information for it like membrane weight and coil length? And 750Wrms from a 65mm coil which is mainly not even cooled in the gap ... of course ...
But I like their pole piece design, the scetch looks like they use a demodulating ring and the surround design is clever too! But no hint if these 20mm are real or some funny calculation like PA Chassis do.
But I like their pole piece design, the scetch looks like they use a demodulating ring and the surround design is clever too! But no hint if these 20mm are real or some funny calculation like PA Chassis do.
Not really, 91 dB is efficient only when comparing to driver specs designed for tiny boxes; at ~94 dB/m/LF my 515B Altecs are though, but require small refrigerator size boxes to go low at high SPL and require duals or a BLH to do 20 Hz at high efficiency.
It has 20 mm p/p, so 'only' 10 mm. Yes, with a 7.56 cm dia. VC it goes to ~34400/pi/7.56 = ~1448 Hz, everything above it is dustcap resonances.
FWIW, one of my dual 15" corner loaded subs from the corner horn system tuned to 14 Hz making do as a stereo system that shook my house enough to 'rain' the ceiling and its stored contents down on us during a U-571 BD depth charge scene on < 60 W.
Attachments
Indeed! And considering his locale, room size probably not enough to matter, but a lot? of us members/lurkers either have more open/lossy rooms in our locales, so I try to post for the masses when pertinent. 😉
I missed that the SB data sheet quotes its linear displacement in p-p rather than one way.
2x LAB 12s in about 60L with 600-700 W per cabinet stays within thermal rating and xmax, and then eq to taste; max 103 dB per cabinet at 20 Hz. Added benefit is mounting them dual opposed for vibration cancelling. The 6 ohm version in parallel stays comfortably above 2 ohm across its whole range, so the amp wouldn't run into issues with boost at very low frequencies. By my math each pair of 12s is slightly better than a similar xmax 15".
I haven't finished mine yet so can't comment first hand how they sound. I'll be using a Crown XLS 2500 to run a pair of these in the front corners, where I have a constraint on width.
2x LAB 12s in about 60L with 600-700 W per cabinet stays within thermal rating and xmax, and then eq to taste; max 103 dB per cabinet at 20 Hz. Added benefit is mounting them dual opposed for vibration cancelling. The 6 ohm version in parallel stays comfortably above 2 ohm across its whole range, so the amp wouldn't run into issues with boost at very low frequencies. By my math each pair of 12s is slightly better than a similar xmax 15".
I haven't finished mine yet so can't comment first hand how they sound. I'll be using a Crown XLS 2500 to run a pair of these in the front corners, where I have a constraint on width.
If the dimensional sheet is to scale, it looks like around 25mm of the 65mm coil is overhanging the pole piece, so 20mm Xmax seems quite believable.
Alpine is not messing around, this looks like a real driver.
Definitely will surpass the 23 year old LAB12 design for small sealed cabinets.
Art
I printed the scetch and measured 15mm overhang compared to 65mm diameter (not the cutout, diameter of coil is wider). With some fancy PA driver math which acounts also a part of the pole palte height you get to +-20mm.
Would love to measure one of these!
(But I put my LAB12 woofer in my new kitchen permanently installed inside the cabinets and under the stone countertop. I'm afraid I can not compare these 2 any more ;-) )
Would love to measure one of these!
(But I put my LAB12 woofer in my new kitchen permanently installed inside the cabinets and under the stone countertop. I'm afraid I can not compare these 2 any more ;-) )
Well all I know is. At the moment I sometimes don't even see the lights flash on the Inuke.. it's actually the new nx6000d. I just call it Inuke for ease.
When watching movies or playing music loud I see the first light. And never the second.
If the movie has some serious low bass and I'm listening extremely loud I still would never get to 2 lights.
But from experience when it does go to 2 lights it usually is way past what I'm comfortable with for the room and me.
As far as excursion goes..I've never been able to tell what safe travel would be. Probably more than I think when looking at it
I'm thinking from looking at various drivers and simulation. Seen as I've got the eq to hand, why not just put what I have in smaller enclosures. (say 110l) and get 2 more.
So 4 X 18" BMS. Sure that would be easily enough.
I want 4 for definite for the smoothing of the response. What's the point sidestepping to 8 12s or 4 15s when I already have 2 good 18s
Unless we are talking significant ( if any) quality increase.
When watching movies or playing music loud I see the first light. And never the second.
If the movie has some serious low bass and I'm listening extremely loud I still would never get to 2 lights.
But from experience when it does go to 2 lights it usually is way past what I'm comfortable with for the room and me.
As far as excursion goes..I've never been able to tell what safe travel would be. Probably more than I think when looking at it
I'm thinking from looking at various drivers and simulation. Seen as I've got the eq to hand, why not just put what I have in smaller enclosures. (say 110l) and get 2 more.
So 4 X 18" BMS. Sure that would be easily enough.
I want 4 for definite for the smoothing of the response. What's the point sidestepping to 8 12s or 4 15s when I already have 2 good 18s
Unless we are talking significant ( if any) quality increase.
You don't see it, but you hear it as a 'drawing out' of a note, making it sound 'flatter' with increasing frequency or whole passage if a wide band driver and push it far enough you can sometimes hear the mechanical stress and/or the peaking due to VC heat rise.
Yeah, why 'mess with success'? I mean the only reasons to use multiple smaller drivers is to make it slimmer/more compact, greater efficiency and/or need a wider BW.
I think it's about 130litre stuffed with that really bad yellow fibre glass as well.
Due to them being made of 25mm MDF and double thick front baffle. They are a bit chunky
The previous generation type R drivers where developed using a kipple driver tester and had 'kipple verified' excursion number (IE limit of compliance or BL). They are not marketing this generation as such but I would presume its real in this case.
Would not go half of that but 80L should be fine. But just do your simulations and how much EQ you want to use.
When you brace a lot 15mm birch plywood is fine for subwoofers! You need a STIFF housing.
But it can be you need some weight on top of it (stone, concrete) to keep it in place with such a driver ...
Luckily for me my friend owns a pretty big carpentry business. And he has agreed to build me 4 identical enclosures
He's going to finish it all for me. Paint it and put nice little legs on it to decouple them from the floor
Now I need a 4 channel amp to do them justice.any ideas.
I'm going down the DIY purify / ncore for all the speakers and wonder if there's something similar I can do for the subs.
He's going to finish it all for me. Paint it and put nice little legs on it to decouple them from the floor
Now I need a 4 channel amp to do them justice.any ideas.
I'm going down the DIY purify / ncore for all the speakers and wonder if there's something similar I can do for the subs.
I was mistaken, you are right.
I misread the Alpine R-W12D voice coil diameter for length 😳.
Looks like the voice coil length is only around 38mm, nowhere near 65mm.
Speaker exchange lists a Eminence LAB-12 Aftermarket Recone Kit (122133-U) 6 ohms. Parts specifications: Voice Coil: Kapton with 2.408″ inside diameter, 2.5″ form length, 1.3″ windings width.
If that is correct, the LAB12 coil length would be about 33mm. The pole plates for both look about the same, 9.53mm for the LAB12, which would mean only 2 or 2.5mm more excursion.
The strontium ferrite magnet weight is 160oz for the LAB12, only 127oz for the Alpine R-W12D, so without seeing a Klippel Bl verification, I've lost my confidence in this driver's Xmax rating.
The BMS 18N862 has a 50mm coil length, 12mm gap and over double the Sd of the 12's.
Another mistake I made in post #9, it should have read:
The BMS18N62 increases about 13dB between 20 and 100Hz in a 180liter box, 15dB in a 115 liter box, and 19dB in a 57 liter box.
It would take about 76volts to reach Xmax at 10Hz in the 57L box, 46 in 115L, 36 in 18L.
Another two 18" BMS still sounds like the way to go, though considering trojantrow is using under 200 watts per driver with two, and that is "way past what I'm comfortable with for the room and me", very much overkill.
As far as excursion goes.."safe travel" would be at least the BMS18N62's Xmax of 19mm, 38mm (1.5inches) peak to peak.
The BMS18N62 Xmech is not listed, but drivers with similar surrounds and spiders are rated for 55-60mm (over 2 inches) peak to peak.
Art
I'm not quite as technically minded as you guys when it comes to this stuff. However I did do my research on the BMS when I decided to get it.
And I mean a lot of research. Not surprising that it's a good driver and difficult to match for it's intended application.
At the end of the day in simple terms it's a good compromise between sensitivity, and xmax so good for movies and music and plays well in a small sealed box.
Has the sensitivity and xmax to be able to EQ to desired taste or whatever without too much worry.
Might as well stick. Thanks for all the input.
Now just a 4 channel amp to run them. Bearing in mind I have an AVP with Dirac.
But a bit of pre EQ would be desirable to shape the response before Dirac gets it's Mits on it
And I mean a lot of research. Not surprising that it's a good driver and difficult to match for it's intended application.
At the end of the day in simple terms it's a good compromise between sensitivity, and xmax so good for movies and music and plays well in a small sealed box.
Has the sensitivity and xmax to be able to EQ to desired taste or whatever without too much worry.
Might as well stick. Thanks for all the input.
Now just a 4 channel amp to run them. Bearing in mind I have an AVP with Dirac.
But a bit of pre EQ would be desirable to shape the response before Dirac gets it's Mits on it
Which impedance have your chassis?
You could go with 2 Hypex FA502 for your 4 woofers when you don't need maximum SPL - DSP & noise free and precise amps. Or get one per woofer and drive them bridged - but that's not really cheap.
In HomeCinema the Crown XLS is often used (Crown XLS 2502 in your case). Maybe worth a try, pretty affordable and fans should be silent. But of course - that's no nCore...
(edit - you need Xti for useful DSP ... still affordable)
You could go with 2 Hypex FA502 for your 4 woofers when you don't need maximum SPL - DSP & noise free and precise amps. Or get one per woofer and drive them bridged - but that's not really cheap.
In HomeCinema the Crown XLS is often used (Crown XLS 2502 in your case). Maybe worth a try, pretty affordable and fans should be silent. But of course - that's no nCore...
(edit - you need Xti for useful DSP ... still affordable)
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