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I think what you are looking for can be achieved for the most part with proper integration and EQ assuming the headroom exists to reach the desired levels.

That said I can see the advantages in running the B&C 21SW152 vs. something like the SI HT18. The B&C does have thermal, sensitivity (above 45hz) and inductance advantages. It pulls far less current from the amp above 30hz (if comparing to the SI HT18 at the same input voltage) which further reduces thermal compression, in other words it is far more efficient in that range at turning electrical power into sound.

I am looking at a 25cuft enclosure with something like a 8" diameter port at 35" long to tune it around 11.5hz. Enclosure size is only that large in order to get the port length under control. You would only need 1kw per driver. 8 of them should net you 130dB+ from 10.5hz up before room gain.

Then again doubling the number of SI's has its own set of advantages, more potential output in the same enclosure volume with the same input, nearly half the cost.
 

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It's certainly possible on the distortion, but I'm not sure I think that's it...I'm quite sure I don't like flat though. The HT will have all suspended floors and then of course the risers. I'm still sort of at a loss for what exactly it is I felt was missing....I guess this experiment will tell a lot, as these should be darn clean drivers.

I'm sure none of my experience with the 24s was optimal....I'm still trying to figure out if it was the lack of midbass or just the characteristic of the sound. I spoke at length with Nick and he thought it was the actually sound signature that was were my thoughts came from. Maybe that's why this sounds so nuts to some, and maybe it's not going to wind up well, but again, I sort of think that this solution may provide the right combo of things for me.
I don't think you are at a loss... I think you are afraid it's too cliche to say, so I'll say it for you. You miss the car audio days of burping 150db+ @ 55hz.




Literally hurt him, or are you exaggerating?

I've had a single 12 mains and 6x12 subs cause me hearing pain after a 5min demo. Was more than I wanted. But I know I listen lower than a lot of you guys.
Chop used to be an MMA fighter... He literally wants to be hurt.

...literally...
 

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Literally hurt him, or are you exaggerating?

I've had a single 12 mains and 6x12 subs cause me hearing pain after a 5min demo. Was more than I wanted. But I know I listen lower than a lot of you guys.
chop seems to have neglected to point out that his theater is like 10,000 CUFT
 

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Discussion Starter #48
I was going to use 18SW115's sealed in my towers but decided to do a pair of 15's instead. I have the SW152 and it would sound great sealed but there are so many ways to get into ULF that it is rather just a choice of liking whatever and sticking with it.

I would have to second the idea of a Othorn build just to try out. Buy a pair of SW152's and place them in sealed enclosures. Have some movies and mucis sessions and see how you go. Then build some Othorns and do the same. I personally love the sound of the Pro Audio drivers over most of the subs I have tried for subwoofers. I can have my SPL wants easier with car audio and other true subwoofers though.

I have not tried the Ultra or other higher end subwoofers though. I have heard a IB that had eight 18 Sound 18" drivers and that sound fantastic. I dont know what it is but for me the BC and like 18's and up just sounded so clean and bass. Probably setup was the real winner IDK. BUT I have stopped looking at SPL charts and just built what I feel was needed after having some listening sessions.

I will be using four 15's for indoors because they are what I can afford and what I have room for. If I had the money and space I would have a LOT of SW152's. Not the best on paper option or value for sure. BUT its just what I have found that I like to my ears. Maybe its distortion like Not said. but I would just add enough speakers so that the 21's were moving to about 80% excursion at 5hz. BUT thats also because I like 3-80hz for subs. Again not the best value for ULF by any means.
I think that's sort of the road I'm starting to travel as well...trying different things and judging what to keep based on that vs modeling it all and taking the model to mean it would be best. I looked at some of the 18s like that and the BMS as well, the B&C 21 opportunity just happened to come up first so that's my first experiment.

That's sort of my plan with the 21s...if I get a couple built and there character suits me, then I'll build a few different sealed and ported enclosures to test what variance of what alignment I like better. I'm prepared to go as many as of them as is needed to achieve enough output to shape the bass any way I want, to taste. 8 will fit easily enough even in the largest ported enclosure...I think I'll be able to fit up to 16...I've scaled the screen wall, and if I go to 42" behind the false instead of 36", it makes the space so that I can get the volume in depth, fit the port length and be good. Four would be outisde the L/R respectively, and four on either side of the center channel. The outside four will be fine, but the concern with the inside four is the ports unloading on the center of the screen. If seald fits the bill, I can put as many as I could ever want back there and have no space issues. Like you said, maybe (ok def) not the best value proposition, but with regard to absolute performance and given goals, they may be the best solution, cost aside. The other thing that works with either is that they could probably easily be put at the 1/4 points of the wall and with 16 being placed, it should eliminate most issues.

I think what you are looking for can be achieved for the most part with proper integration and EQ assuming the headroom exists to reach the desired levels.

That said I can see the advantages in running the B&C 21SW152 vs. something like the SI HT18. The B&C does have thermal, sensitivity (above 45hz) and inductance advantages. It pulls far less current from the amp above 30hz (if comparing to the SI HT18 at the same input voltage) which further reduces thermal compression, in other words it is far more efficient in that range at turning electrical power into sound.

I am looking at a 25cuft enclosure with something like a 8" diameter port at 35" long to tune it around 11.5hz. Enclosure size is only that large in order to get the port length under control. You would only need 1kw per driver. 8 of them should net you 130dB+ from 10.5hz up before room gain.

Then again doubling the number of SI's has its own set of advantages, more potential output in the same enclosure volume with the same input, nearly half the cost.
Man, I really like that. I was talking with John a bit about the trade offs of the lower tune and loss of max spl jsut above that, and the higher tune, with less extension. In my head, I feel like the lower tune works better for me because I can get the extension I want and just add enough drivers to make up for the deficiency jsut aboove the peak ouput frequencies. This is my first time with this, so my thinking may be a bit off, but that's what came to mind.
I looked at a lot of different sizes and tunes myself, round and slots...any reason not to do slot?? Trying to think what will minimize port noise and keep the the first resonance up where I need to as well...which what would you guys say should be??

Agreed on the si's....I just feel like space and cost aside, I may be able to get better performance with respect to my goals out of the B&C.

I don't think you are at a loss... I think you are afraid it's too cliche to say, so I'll say it for you. You miss the car audio days of burping 150db+ @ 55hz.





Chop used to be an MMA fighter... He literally wants to be hurt.

...literally...
Hahaha...very funny sir, probably true. In all seriousness though, it's not just that. It feels like the issue for me leans toward control of the driver though...maybe that it seems the 24s got too "loose" up top. Hate to use descriptors liek that, but can't think of any other way to say it. You know what the funniest thing is...we'll bang these things for GTGs and I will on occasion, but most of the time they'll be playing pixar movies at 75db :D

chop seems to have neglected to point out that his theater is like 10,000 CUFT

Uh, yeah, theres that too :D It's a great point though because it is a lot to ask of any driver without going to a really large number of them.
 

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Figured I'd just answer your PM here...I almost went with 8 of these for my HT to replace the XXX's. In my space the XXX's can do over 130dB at the main LP from 6-7Hz on up. I never really use all that, but I like having headroom left over. I'd be giving up about 8-9dB in the displacement limited ranges by switching so my headroom would drop to about 122-124dB at 20Hz and below which technically should still be enough for me but I'd gain a lot in the upper bass. I don't have the room to go to 12-16 so I didn't switch. This is in my room which is like 3650cu ft or so. If yours is 2 to 3X the size and you have higher output requirements I don't think 8 sealed is going to be enough for you in the deep stuff. Like I said if you previously had SI24's or UXL's or LMS's you will need 2 21sw152's to produce the low bass headroom of one of those drivers. Perhaps 3 for every 2. So if you used 8 LMS's and wanted equivalent <25Hz headroom you'll want 12-16 of the 21sw152. Personally I think that system would be fantastic but it simply can't win the displacement per dollar title. If you are ok with the $$$ required to get enough of them to do the ULF I think the end result will be fantastic.

This driver really kills in horns and vented but I think tuning down below 15Hz in a huge cab is just not the right approach with it. It just doesn't have the excursion headroom in the mid band. It does its best work tuned at 20Hz or above. 25-35 is where it can really start doing its thing.
 

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I think what you are looking for can be achieved for the most part with proper integration and EQ assuming the headroom exists to reach the desired levels.

That said I can see the advantages in running the B&C 21SW152 vs. something like the SI HT18. The B&C does have thermal, sensitivity (above 45hz) and inductance advantages. It pulls far less current from the amp above 30hz (if comparing to the SI HT18 at the same input voltage) which further reduces thermal compression, in other words it is far more efficient in that range at turning electrical power into sound.

I am looking at a 25cuft enclosure with something like a 8" diameter port at 35" long to tune it around 11.5hz. Enclosure size is only that large in order to get the port length under control. You would only need 1kw per driver. 8 of them should net you 130dB+ from 10.5hz up before room gain.

Then again doubling the number of SI's has its own set of advantages, more potential output in the same enclosure volume with the same input, nearly half the cost.

for those wishing to see how that second paragraph gets quantified, the compression graphs at data-bass are worth reviewing.


that port might be one size too small. iirc, josh built a ported cab for the 21" with a 10" round port and was still indicating the presence of port compression. tough to tease out from the measurements if it was thermal or air flow resistance though. I'm aware of the tradeoffs in going to a larger port, so can understand your design choice, just figured I'd mention it. a slot may be easier to construct given that it can be angled/bent along the cab wall and would allow for variable/tuning experiments (at least in some sense).
 

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I fully understand what Chop is saying, every bit.

Unlike most on this forum my love and passion is music and the upper registers of bass and mid bass.

Here are some of my findings/observations, particularly in regards to "punch" -

1) Wide bandwidth requirements, having more or less in the upper range particularly upto 4-6Khz will change the "feeling", the mid range contributes significantly in the 300-1500Hz range

2) Phase/time alignment across the spectrum, it changes the feeling, IMO having "perfect time/phase alignment" is not always preferred by people in regards to that feeling in your chest, sometimes people prefer the feeling to "linger" in the chest and that usually means some amount of "ringing"

3) 2nd order harmonic distortion, it adds a feeling and may be desirable, particularly in the 50-200Hz range but it depends on taste and the individuals past experiences

4) If punch has a specific frequency range that is important to its successful reproduction it is 50-200Hz, had read a paper somewhere a long time ago that said the resonant frequency of the human chest cavity is around 129Hz +/- 6Hz, it had also specified a certain slope/roll off both above and below it that I do not recall

5) LF roll off around 50-60Hz makes the sound "tighter/faster" and makes it more "punchy", inherently a system with less LF is usually "faster" and "punchier", adding HF to a degree produces "faster" bass as well

6) Some people prefer a more "resonant" feeling in the chest (50-80Hz), while others prefer a more "piercing attack"(100-160Hz), the experience is of course a sum total, it is upto you where you want to focus

7) The room effects on the sound are important (obvious enough) but particularly the decay of bass in the room IMO

8) Frequency response is a LARGE contributor to "flavor" and the right "punch"

9) IME most people like some flavor, not a "flat response"

My observations have been that while you can EQ any driver to have any response within reason, the most pleasing "punch" comes from drivers that typically have an extended HF response natively and limited LF capabilities below 50Hz. IME larger "air pump" style drivers can not punch like a lighter cone driver even after matching the response, people typically like the punch of a 15 and I speculate it has just the right balance of enough vd to do 50-100Hz well (in a ported cab) but can also be made to get excellent extension in the HF, it also naturally lacks much below 50Hz which may contribute to the punchy nature. One may notice that when you have car audio 15s which are heavy cone, high xmax drivers they typically don't have the "speed" or "punch" of a pro 15 (possibly because of less HF extension) but without an A/B they might seem fine, particularly if a mid bass driver is being used that has the appropriate native response that has been EQed for the car. I personally believe that the right "punchy driver" is a matter of the "right balance" of native response,sensitivity,lack of LF and enough HF extension which a pro 15 usually achieves. I want to emphasize that people should not overlook the native response of a system or a driver. EQ can correct issues but it can not improve the drivers actual capabilities.

I would also say that the "best punch" or overall system (subjectively) would be achieved by a multiway system, if one can manage the complexity and tune the system to their tastes then they will be very pleased.


I'd do this in your case -

Make the mains with 4x15s (I believe this is important for your goals + 10,000 cubic foot room) (100Hz +)

Ported 21SWs tuned 30Hz or Othorns if you want to use the 21SW, personally I would choose something else but this should work if you are dead set on it (40-100Hz)

Use your SI24s below 40Hz in LARGE ported cabinets tuned 12Hz (Below 40Hz)

You can switch off the 24s for "tight bass" and have a saved preset that suits your taste, just load it up and off you go, when you want some low notes, switch the 24s on and load another preset.

One last note, "low bass" is inherently "slow".

Just my 2 cents, I hope I have not offended anyone, these are only my views.
 

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I looked at some of the 18s like that and the BMS as well, the B&C 21 opportunity just happened to come up first so that's my first experiment.
Cost aside, wouldn't the BMS 18N862 be an ideal driver for your goals? It has all the characteristics you seek (lighter cone, low inductance, powerful motor, low distortion, etc), similar to the 21" PA options, but having a longer xmax of 19mm, would allow it to reach a bit lower that the 21" options ?
 

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Great post, Decadent_Spectre. I too have a love for the midbass but also the deep stuff. I can echo a lot of these experiences and it was things types of things that led me to design my system as such. Massive, massive midbass capability with world class midbass drivers which are also very good to the midrange region. Also the reason why I have a front hornloaded midrange that also stretches into the low thousands. I can run massive midbass and let them concentrate on just that and have CD control and horn loaded power throughout the whole low hundreds to thousands. Deep bass is for the subwoofers and I made sure to have a ton of them. :D
 

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Discussion Starter #58
:D
Figured I'd just answer your PM here...I almost went with 8 of these for my HT to replace the XXX's. In my space the XXX's can do over 130dB at the main LP from 6-7Hz on up. I never really use all that, but I like having headroom left over. I'd be giving up about 8-9dB in the displacement limited ranges by switching so my headroom would drop to about 122-124dB at 20Hz and below which technically should still be enough for me but I'd gain a lot in the upper bass. I don't have the room to go to 12-16 so I didn't switch. This is in my room which is like 3650cu ft or so. If yours is 2 to 3X the size and you have higher output requirements I don't think 8 sealed is going to be enough for you in the deep stuff. Like I said if you previously had SI24's or UXL's or LMS's you will need 2 21sw152's to produce the low bass headroom of one of those drivers. Perhaps 3 for every 2. So if you used 8 LMS's and wanted equivalent <25Hz headroom you'll want 12-16 of the 21sw152. Personally I think that system would be fantastic but it simply can't win the displacement per dollar title. If you are ok with the $$$ required to get enough of them to do the ULF I think the end result will be fantastic.

This driver really kills in horns and vented but I think tuning down below 15Hz in a huge cab is just not the right approach with it. It just doesn't have the excursion headroom in the mid band. It does its best work tuned at 20Hz or above. 25-35 is where it can really start doing its thing.

I was thinking through these options and maybe just wasn't seeing the lack of ability to tune it lower...my thoughts were that in multiples, the lower tuned enclosure could make up the deficiency above the tune...maybe not though, you have worlds more experience in this department. My fear with 15hz or higher tune is that the ulf will be gone all together in comparison and I'll have those few movie scenes where you know something shouldbe present, but isn't..legit fear???

I've sort of gotten past the displacement per dollar idea on this one. It would be nice to do it as effciently as possible financially, but I see past the value proposition here. Whether the last few % or a particular result is worth it to each person is different, but on this one I just want to get to the end result so if that means 16 more expensive drivers to get to the same output levels, but the drivers have something I like, I'm ok with it...plus the 10+db advantage after 25hz or so looks nice :D. It sort of seems like paying extra to get the low end extension, with the slam of a ported in those higher mid to higher bass frequencies.


24s for low bass, 21s for mid and upper bass? :D
could end up being reality eventually
 

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Discussion Starter #60
@Ricci "Perhaps 3 for every 2."
you meant 'perhaps 5 for every 2' (2.5:1)?
I hope not...the way I understood it in my private convo with Josh was that it would take 6 21sw to equal 4 lms or the like, down low....that was the specific number he'd said so it would make sense that 3 21s to 2 lms also. I hope :)

I fully understand what Chop is saying, every bit.

Unlike most on this forum my love and passion is music and the upper registers of bass and mid bass.

Here are some of my findings/observations, particularly in regards to "punch" -

1) Wide bandwidth requirements, having more or less in the upper range particularly upto 4-6Khz will change the "feeling", the mid range contributes significantly in the 300-1500Hz range

2) Phase/time alignment across the spectrum, it changes the feeling, IMO having "perfect time/phase alignment" is not always preferred by people in regards to that feeling in your chest, sometimes people prefer the feeling to "linger" in the chest and that usually means some amount of "ringing"

3) 2nd order harmonic distortion, it adds a feeling and may be desirable, particularly in the 50-200Hz range but it depends on taste and the individuals past experiences

4) If punch has a specific frequency range that is important to its successful reproduction it is 50-200Hz, had read a paper somewhere a long time ago that said the resonant frequency of the human chest cavity is around 129Hz +/- 6Hz, it had also specified a certain slope/roll off both above and below it that I do not recall

5) LF roll off around 50-60Hz makes the sound "tighter/faster" and makes it more "punchy", inherently a system with less LF is usually "faster" and "punchier", adding HF to a degree produces "faster" bass as well

6) Some people prefer a more "resonant" feeling in the chest (50-80Hz), while others prefer a more "piercing attack"(100-160Hz), the experience is of course a sum total, it is upto you where you want to focus

7) The room effects on the sound are important (obvious enough) but particularly the decay of bass in the room IMO

8) Frequency response is a LARGE contributor to "flavor" and the right "punch"

9) IME most people like some flavor, not a "flat response"

My observations have been that while you can EQ any driver to have any response within reason, the most pleasing "punch" comes from drivers that typically have an extended HF response natively and limited LF capabilities below 50Hz. IME larger "air pump" style drivers can not punch like a lighter cone driver even after matching the response, people typically like the punch of a 15 and I speculate it has just the right balance of enough vd to do 50-100Hz well (in a ported cab) but can also be made to get excellent extension in the HF, it also naturally lacks much below 50Hz which may contribute to the punchy nature. One may notice that when you have car audio 15s which are heavy cone, high xmax drivers they typically don't have the "speed" or "punch" of a pro 15 (possibly because of less HF extension) but without an A/B they might seem fine, particularly if a mid bass driver is being used that has the appropriate native response that has been EQed for the car. I personally believe that the right "punchy driver" is a matter of the "right balance" of native response,sensitivity,lack of LF and enough HF extension which a pro 15 usually achieves. I want to emphasize that people should not overlook the native response of a system or a driver. EQ can correct issues but it can not improve the drivers actual capabilities.

I would also say that the "best punch" or overall system (subjectively) would be achieved by a multiway system, if one can manage the complexity and tune the system to their tastes then they will be very pleased.


I'd do this in your case -

Make the mains with 4x15s (I believe this is important for your goals + 10,000 cubic foot room) (100Hz +)

Ported 21SWs tuned 30Hz or Othorns if you want to use the 21SW, personally I would choose something else but this should work if you are dead set on it (40-100Hz)

Use your SI24s below 40Hz in LARGE ported cabinets tuned 12Hz (Below 40Hz)

You can switch off the 24s for "tight bass" and have a saved preset that suits your taste, just load it up and off you go, when you want some low notes, switch the 24s on and load another preset.

One last note, "low bass" is inherently "slow".

Just my 2 cents, I hope I have not offended anyone, these are only my views.
Post of the day anyone.. :)

Thanks for taking the time. My thing with regard to the end of your post is that I'd like to have the ability to do it all simultainiusly while whatching a flick that goes from GGun to 10hz and the earth crumbling, I'm not looking for much, just it all :D

I may end up revisiting the quad 15 version of the mains, but I think the dual was pretty potent as well. I will have the dual and some test subs in the room before I finalize everything and buy 16 more of anything. The top and bottom 15s on the seosr are modular so I can pop em' in, try them with sealed bottom dwellers and see how that works too.

Cost aside, wouldn't the BMS 18N862 be an ideal driver for your goals? It has all the characteristics you seek (lighter cone, low inductance, powerful motor, low distortion, etc), similar to the 21" PA options, but having a longer xmax of 19mm, would allow it to reach a bit lower that the 21" options ?
It may be, I looked at that as well and what kind of deal I could get on it. My concern, and why I think Josh recommended the 21sw (not holding you responsible Josh :) is that the 21 is basically idiot proof, which is good for me :D I'm not sure if the BMS would be the same, but wouldn't want to chance it if not.
 
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