That cuts volume in half so great for keeping it small and no need to mess with xenon. Or isobaric with Linkwitz and xenon bladder filled with charcoal? Maybe a gain of 3x to 4x volume?
Isobaric loading would certainly reduce motor distortion - you're effectively coupling two coils to one diaphram, so the power input to each one can be reduced.
It'll also help to even out suspension-induced distortion. Whether that's worth doing or not has been debated: you'd lose some even harmonics, but not the odd ones. Overall THD is reduced, but the distortion profile isn't what I'd call "natural": a decreasing trend of harmonic distortion vs nth order.
Another thing to consider with isobaric loading is whether or not wind noise from the back end is audible. I've had some drivers though with whistling sounds when really driven. Not a problem when conventionally mounted, but isobaric might be an issue.
Chris
It'll also help to even out suspension-induced distortion. Whether that's worth doing or not has been debated: you'd lose some even harmonics, but not the odd ones. Overall THD is reduced, but the distortion profile isn't what I'd call "natural": a decreasing trend of harmonic distortion vs nth order.
Another thing to consider with isobaric loading is whether or not wind noise from the back end is audible. I've had some drivers though with whistling sounds when really driven. Not a problem when conventionally mounted, but isobaric might be an issue.
Chris
Perhaps an isobaric with a mic in the middle chamber used for the feedback loop of the inner driver's amp (Borowick)
Hi mattlang8,
"...mike in the middle chamber..."
The pressure in the middle chamber should not change (or very little).
Regards,
P.S.: That picture didn't turn out well. I'll try a pdf from the drawing. Obviously, this could be a sealed box or a bass-reflex.
"...mike in the middle chamber..."
The pressure in the middle chamber should not change (or very little).
Regards,
P.S.: That picture didn't turn out well. I'll try a pdf from the drawing. Obviously, this could be a sealed box or a bass-reflex.
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XLS 12 vented 40x40x40 cm
I will be trying a 40 cm cube with a folded vent for my XLS 12 soon. It will be something like 33 liter volume, and Fo at 23 Hz (not 33 Hz as indicated on the drawing)
@ 550 W it will hit Xmax and will produce something like 106 db at 25 Hz
A step up would be to use Ace Bass to lineraize to 25 Hz and reduce distortion.
But will produce a lot of good bass without 🙂
Have tried closed box with the XLS and Linkwitz Transform, but was not satisfied witht the output ..... a port will help a lot
I will be trying a 40 cm cube with a folded vent for my XLS 12 soon. It will be something like 33 liter volume, and Fo at 23 Hz (not 33 Hz as indicated on the drawing)
@ 550 W it will hit Xmax and will produce something like 106 db at 25 Hz
A step up would be to use Ace Bass to lineraize to 25 Hz and reduce distortion.
But will produce a lot of good bass without 🙂
Have tried closed box with the XLS and Linkwitz Transform, but was not satisfied witht the output ..... a port will help a lot
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How about 6 12 inch woofers? I mean the SWR 12d4 is $120 each. So 6 of them puts you at 6000 watts of power handling for $120, feed it about 2000 watts and use lots of eq to flatten the response. Sealed enclosure clearly.
Extremely small sealed enclosures with way too many drivers is one of the best ways to get extreme output in a small space. He did mention he wants to shake the foundation, and this will do it.
I just put two of these babies together. based on Beyma sub enclosures (see 2009 version on internet), but substituted B&C driver with identical T/Ss, 12TBX100 (from earl Geddes). driver rated for 2000W rms continous so I do not expect the compression to be an issue 😀. I got sidetracked with some OB work so i did not hear these yet (one is still being smelly with car paint in the garage, and I am still debating the setup: was planning on digital inputs to miniDSP plate amps but master volume control becomes an issue 😕). I am doing it for music though, no HT goals. for that Earl's 12incher (same driver) +15" passive radiator design might be more appropriate. see his website.
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Ok, got inspired and have begun my small but capable sub.
folded slot as port, 33 liter and 24 Hz tuning, 40 cm cube.
I'm planning on giving it a layer of fiberglass on the outside, to get a smoother surface for painting, for more stifness and damping ..... will take some time 🙂
folded slot as port, 33 liter and 24 Hz tuning, 40 cm cube.
I'm planning on giving it a layer of fiberglass on the outside, to get a smoother surface for painting, for more stifness and damping ..... will take some time 🙂
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back to the core premise- a single sub that works in a given volume can be replaced with 2 isobaric clamshells, (4 drivers) allowing for 2x the displacement, much lower distortion, and 4x the power handling, in addition to the possibility of force cancellation. That's a ton of upside with the downside of having the build complexity and cost of 4 drivers.
Don't laugh. 3 x MCM 55-2421 in a ported box. 50L rear chamber + 200cm^2 port area in a coiled up port 90cm long. Corner load and feed it 70 Volt (3 drivers in series ~ 12ohm). Get this graph.
Not loud enough?
Buy 12 and run 6 pairs in isobaric clamshell, wire 3 parallel 4 series for ~5 for 6 extra decibels with an amp capable of 93V @ 5-6 ohms.
Total used air volume is 68 litres which is a 16 inch cube. Wood will make this larger, but if you can use well braced 9mm plywood it should only be an extra 20 litres.
Basically you're looking for lots of small high excursion high power handling drivers that play well in small vented boxes to the lower 30s.
Louder is released by not trying to go extremely low. Lower 30s should satisfy most music and whilst HT would ideally go lower, it will sacrifice performance.
Not loud enough?
Buy 12 and run 6 pairs in isobaric clamshell, wire 3 parallel 4 series for ~5 for 6 extra decibels with an amp capable of 93V @ 5-6 ohms.
Total used air volume is 68 litres which is a 16 inch cube. Wood will make this larger, but if you can use well braced 9mm plywood it should only be an extra 20 litres.
Basically you're looking for lots of small high excursion high power handling drivers that play well in small vented boxes to the lower 30s.
Louder is released by not trying to go extremely low. Lower 30s should satisfy most music and whilst HT would ideally go lower, it will sacrifice performance.
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Here's a suggestion with 5 pairs of isobaric MCM 55-2421. 40L + 90cm*160cm^2 port, or you may have success with passive radiator designs but I don't know much about them!
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Not laughing. Actually looking at 8 inch subs right now.
For my main speakers I'm thinking to employ multiple small subs to get a better handling of room modes (see Earl Geddes on Multiple Subwoofers in Small Rooms).
So something like 4 or 6 (2 - 3 for each side/channel) small subs.
I think 8 inch is a good trade off size which could be put into quite small boxes and still go down to 25 Hz. I think 25 would be my preffered cut off freq based on different tests I've done.
I have found that the Tang Band W8-1363 is one of the very best contenders giving up to 100 db peak at 25 Hz in a 15 liter vented box tuned to 25 Hz @ 400 Watt.
I'm thinking 2 of the subs used as the bass in the mains, and then one at the side of the room and one in the back.
The MCM is cheaper, but adding the cost of amps filters etc. it becomes more irrelevant, and with the 4 mm more Xmax which comes with the TB I would go with that. .... but the MCM is also a very good speaker.
.... all of course if the secs are correct ... goes for both the TB and the MCM ...
For my main speakers I'm thinking to employ multiple small subs to get a better handling of room modes (see Earl Geddes on Multiple Subwoofers in Small Rooms).
So something like 4 or 6 (2 - 3 for each side/channel) small subs.
I think 8 inch is a good trade off size which could be put into quite small boxes and still go down to 25 Hz. I think 25 would be my preffered cut off freq based on different tests I've done.
I have found that the Tang Band W8-1363 is one of the very best contenders giving up to 100 db peak at 25 Hz in a 15 liter vented box tuned to 25 Hz @ 400 Watt.
I'm thinking 2 of the subs used as the bass in the mains, and then one at the side of the room and one in the back.
The MCM is cheaper, but adding the cost of amps filters etc. it becomes more irrelevant, and with the 4 mm more Xmax which comes with the TB I would go with that. .... but the MCM is also a very good speaker.
.... all of course if the secs are correct ... goes for both the TB and the MCM ...
Another option is to use two drivers opposite of each each other. Push Push, each driver in it's own volume in one cabinet. This cancels out vibration of the enclosure to a very large extend. It will outperform a single woofer with the same cone area. -edit- reacted to soon, force cancelation was mentioned. How about using a high pass capacitor to get at the smaller closed box volume.
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I actually came back here to suggest the Tang Band W8-740P, seeing as you have a big budget. Although it won't reproduce the upper bass as efficiently due to a higher cone mass, it otherwise does quite well.
I only recommend isobaric when you need to cram more SPL into a small package, however - have you considered a tall thin subwoofer - e.g. multiple stacked bass reflex that you could tuck away in a corner or lay down against a wall. It's the only possible way I can think of to get 25Hz with any authority, and should - seeing as you have lots of money to spend on drivers - give a greater max SPL than a transflex/tapped horn type enclosure. Of course, making lots of single driver 25Hz bass reflex would give you freedom of placement too.
How loud do you need to go?
I only recommend isobaric when you need to cram more SPL into a small package, however - have you considered a tall thin subwoofer - e.g. multiple stacked bass reflex that you could tuck away in a corner or lay down against a wall. It's the only possible way I can think of to get 25Hz with any authority, and should - seeing as you have lots of money to spend on drivers - give a greater max SPL than a transflex/tapped horn type enclosure. Of course, making lots of single driver 25Hz bass reflex would give you freedom of placement too.
How loud do you need to go?
This element (8,75")could also work in a small enclosure. http://www.wavecor.com/SW223BD02_cabinet_simulations.pdf. 30 liters vented or PR for low extention. Long throw element, so need some power.
I meant two of these of course, don't know if that was the intention of TS?
Another solutin could be this Seas in about 40 liters: D1004-04 L26RO4Y
Two 10" or one 12" PR for 25Hz.
Let me know the prefered kombo and i'll provide you with more deetails
Two 10" PR or one 12" PR to reach 25 Hz. let me know your preferred solution and I'll provide more details
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