AVS Forum banner
1 - 20 of 22 Posts

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #1 ·
I saw a post from several months back by a member trying to decide between the Klipsch THX U2 subs or SVS subs.


"I really can't go wrong either way, but the main question is do you all think the dual SVS's will outperform dual Klipsch THX's."


I thought it might make good basic discussion. Nothing new, but subs/bass is so emotional a subject for many. It is an area that is still shrouded in mystery and nuance with decisions often being made emotionally rather than with any scientific methodology as is used in the professional world.


Good subs don't become obsolete in the manner suggested in a post in that thread. Comparing the Klipsch THX and SVS (or other similar) subs models is not easy. It is very easy to define and predict the performance of the Klipsch KW-120-THX subs with their amp (or equivalent) because of their THX Ultra2 certification. When both subs are co-located, they will deliver a minimum 105dB with 10dB of headroom at the listening area in rooms around 6000 cubic feet in volume at very low distortion. They are anechoically flat +/-3dB from 20Hz-200Hz.


Will the SVS or other products achieve that? It is very tough to determine that. If you are a home theater designer (or enthusiast), you have to go find the answer to that. It's not easy to find.


Most subwoofer designers are putting their engineering efforts into shrinking the footprint and extending low frequency response. This pursuit ultimately results in sacrificing output capability for size and frequency extension.


How low is low enough? Many folks in professional sound (cinema, music, and studio) will make the case that subwoofers in small rooms (residential sized rooms) do not need to be anechoically flat to 20 Hz; that 35 Hz is perfectly adequate for subwoofers in small rooms because there is a ton of room gain below 35Hz in small rooms anyway. Further, these same folks say that the only thing that extra extension gets you is a rise in the deep LF response that is not sonically comparable to anything found in the cinema, live music, or, to a certain degree, studio world. It is also extremely difficult to get rid of it with EQ and filtering. Remember anechoic and acoustic response are different animals. Good anechoic response is a starting place, but small room acoustics are going to play a powerful role.


High performance subs for residential size rooms need to be anechoically flat +/-3dB from 35Hz to 120Hz and capable of very low distortion output at Reference level (0dBFS= 105dB steady with 115dB peaks) at your listening area in whatever size room you have. The bigger the room, the bigger the physical, electronic, and financial challenge. We’ll take flat anechoic response to 20Hz, but EQ will absolutely be necessary to tame it to be acoustically flat in small rooms.


It is true that most of us don't listen at Reference level. And it is true that a very cinematic experience can be had at lower than Reference level, especially with utlities like Dynamic EQ. But if your goal is to have the potential of high performance at Reference, you have to design to achieve it. If you don't have it, but don't need it, that's okay. As a designer, I always use that as a minimum because inevitably, the desire will come to let 'er rip to demo for friends, or to make the Superbowl halftime show audible above the noise floor created by his Superbowl party crowd (can you say Reference +9dB?).


The acoustic basics of low frequency response in small rooms will never change. Room proportions, location of the sub(s) in a location(s) that will result in reasonable smoothness at your listening location, and broadband absorption to reduce reverberation times (ringing), then bass management and very good EQ are the formula to success. Whether the sub is a design that is 7 years old like the Klipsch THX U2 or a new SVS (or whoever) does not really matter. What matters is whether it can deliver to meet the performance specs. If and when they do, my response to the sound will be emotional.



I would love to see some manufacturer reps join in comment on this subject. We really need manufacturers of powered subs to provide some metric (as THX has done) for us to use in predicting sub performance with regards to objective criteria. If it is a strongly built passive sub, then if we know its sensitivity, its impedence, and its anechoic FR, we can easily choose an amp that will result in meeting the output specs. With powered subs, it seems to be a guessing game.


Cheers
 

·
Registered
Joined
·
1,838 Posts

Quote:
Originally Posted by Cam Man /forum/post/18127340


I saw a post from several months back by a member trying to decide between the Klipsch THX U2 subs or SVS subs.


"I really can't go wrong either way, but the main question is do you all think the dual SVS's will outperform dual Klipsch THX's."


I thought it might make good basic discussion. Nothing new, but subs/bass is so emotional a subject for many. It is an area that is still shrouded in mystery and nuance with decisions often being made emotionally rather than with any scientific methodology as is used in the professional world.


Good subs don't become obsolete in the manner suggested in a post in that thread. Comparing the Klipsch THX and SVS (or other similar) subs models is not easy. It is very easy to define and predict the performance of the Klipsch KW-120-THX subs with their amp (or equivalent) because of their THX Ultra2 certification. When both subs are co-located, they will deliver a minimum 105dB with 10dB of headroom at the listening area in rooms around 6000 cubic feet in volume at very low distortion. They are anechoically flat +/-3dB from 20Hz-200Hz.


Will the SVS or other products achieve that? It is very tough to determine that. If you are a home theater designer (or enthusiast), you have to go find the answer to that. It's not easy to find.


Most subwoofer designers are putting their engineering efforts into shrinking the footprint and extending low frequency response. This pursuit ultimately results in sacrificing output capability for size and frequency extension.


How low is low enough? Many folks in professional sound (cinema, music, and studio) will make the case that subwoofers in small rooms (residential sized rooms) do not need to be anechoically flat to 20 Hz; that 35 Hz is perfectly adequate for subwoofers in small rooms because there is a ton of room gain below 35Hz in small rooms anyway. Further, these same folks say that the only thing that extra extension gets you is a rise in the deep LF response that is not sonically comparable to anything found in the cinema, live music, or, to a certain degree, studio world. It is also extremely difficult to get rid of it with EQ and filtering. Remember anechoic and acoustic response are different animals. Good anechoic response is a starting place, but small room acoustics are going to play a powerful role.


High performance subs for residential size rooms need to be anechoically flat +/-3dB from 35Hz to 120Hz and capable of very low distortion output at Reference level (0dBFS= 105dB steady with 115dB peaks) at your listening area in whatever size room you have. The bigger the room, the bigger the physical, electronic, and financial challenge. We'll take flat anechoic response to 20Hz, but EQ will absolutely be necessary to tame it to be acoustically flat in small rooms.


It is true that most of us don't listen at Reference level. And it is true that a very cinematic experience can be had at lower than Reference level, especially with utlities like Dynamic EQ. But if your goal is to have the potential of high performance at Reference, you have to design to achieve it. If you don't have it, but don't need it, that's okay. As a designer, I always use that as a minimum because inevitably, the desire will come to let 'er rip to demo for friends, or to make the Superbowl halftime show audible above his Superbowl party crowd (can you say Reference +6dB?).


The acoustic basics of low frequency response in small rooms will never change. Room proportions, location of the sub(s) in a location(s) that will result in reasonable smoothness at your listening location, and broadband absorption to reduce reverberation times (ringing), then bass management and very good EQ are the formula to success. Whether the sub is a design that is 7 years old like the Klipsch THX U2 or a new SVS (or whoever) does not really matter. What matters is whether it can deliver to meet the performance specs. If and when they do, my response to the sound will be emotional.



I would love to see some manufacturer reps join in comment on this subject. We really need manufacturers of powered subs to provide some metric (as THX has done) for us to use in predicting sub performance with regards to objective criteria. If it is a strongly built passive sub, then if we know its sensitivity, its impedence, and its anechoic FR, we can easily choose an amp that will result in meeting the output specs. With powered subs, it seems to be a guessing game.


Cheers

thx certification means squat when talking about QUALITY subs and yes SVS will out perform kiplich.
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #3 ·

Quote:
Originally Posted by osofast240sx /forum/post/18127370


thx certification means squat when talking about QUALITY subs and yes SVS will out perform kiplich.

That's the spirit. Sounds very emotional, though. How about some explanation for your use of "quality," and some data to support your claim of SVS (you pick the model) superiority over the Klipsch KW-120-THX. We need to know what its output is at the listening area at Reference (0dBFS) in a 6000 cubic foot room. I'm sure that it is anechoically flat. If you or anyone else can provide data and a metric by which to determine what the output is in those conditions, then we are getting somewhere. If the SVS can do it, that's great. I don't have a horse in the race; I just want to know the facts. Once I know we are comparing apples to apples, I'll concede your subjective preference is for SVS. Mine might be, also. But let's find the scientific facts first.


It is worth adding that determining this performance capabilty precisely is virtually impossible for subwoofers in small rooms because of the many acoustic variables such as reverb times, acoustic absorption coefficients, etc. But we should certainly be able to get in the ball park.


THX certification means nothing other than defining a scientific metric (what I described above for Reference) which can be applied to all systems for the purpose of design prediction. Ever hear of "the THX gain structure?" Most folks haven't. It provides specifications for Reference level from the processor in the AVR/AVC, through the amps (150mV in, 4.2V out), for the purpose of achieving a fixed system sensitivity. You only then have to factor the sensitivity of the speaker and set the relative level (the -75dBC) to know WHAT you will get at Reference (zero on the dial). That is designed to give you Reference level at your primary seat: 85dB for LCRs and surrounds, and 105dB from the LFE (offset from the other channels by design)...the same as in the cinema. If the room is small, less power is needed from the amps to achieve it. If the room is big, it will take more power to get there. It's a kind of out of sight out of mind part of THX certification that is quite beneficial. A lot of non-THX certified products now use those very specs. It was a good idea most have adopted in AVRs and AVCs. It's tougher to predict this with powered subs. That's my point.
 

·
Registered
Joined
·
663 Posts

Quote:
Originally Posted by Cam Man /forum/post/18127340


I saw a post from several months back by a member trying to decide ...

I cannot contribute too much other than (and I could be wrong on this) there is a plethora of HT gear, including subs, that meet or exceed THX standards w/o having a THX logo and certification. Whether a manufacturer decides to go through the process (and probably paying an insane royalty for the logo) to go through the certification process is up to them.
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #5 ·

Quote:
Originally Posted by dondino /forum/post/18127413


I cannot contribute too much other than (and I could be wrong on this) there is a plethora of HT gear, including subs, that meet or exceed THX standards w/o having a THX logo and certification. Whether a manufacturer decides to go through the process (and probably paying an insane royalty for the logo) to go through the certification process is up to them.

That's very true. The "THX gain structure" is not a "standard" as you or any of us would typically define. It's not based on some vague or difficult to define quality. It's pure scientific "infrastructure" to achieve a particular performance objective: Reference level. If a an AVR, AVC, or amp is to be THX certified, it will have the THX gain structure so that Reference level can be achieved without error. It also happens to ensure that the system noise is below the level of audibility. It is possible for a non-THX amp to be used in a seperates system where if the amp had a higher gain, and highly efficient speakers were used, system noise could be audible. Virtually all modern amps now utilize the same sensitivity output spec/gain as THX uses...like you point out, so this is not much of a worry unless you are getting really creative with your assembly of gear.
 

·
Registered
Joined
·
12 Posts
what we are all striving for, is that 'I am there' experience, in our home. whether its a studio, concert, or movie experience, how do we get that into our home? I think that there is so much quality gear out there that it is now quite easy to say that it terms of outright performance, there are many manufacturers to choose from.

that being said, how can we remember, exactly, the quality and emotional response of the live experience well enough to compare it to our home experience of similar material, and say 'this is better kit than that one'? there is a good chance that even if a metric was developed, we could soon learn that our home environment would destroy any chance of applying the new knowledge, usefully. one example that comes to mind is computer video cards. there are benchmarking tools, manufacturers strive for the bragging rights to say "the fastest card in the world". Great! I bring it home, put it in, start up my game only to find out that on my particular choice, this card sucks, but hey, its great for everything else.

It's a great problem, but I am sure that if we had the same gear in our different houses, the experience would not be the same. It would likely still bring a smile to one's face, though. besides enoying our music and movies, what's more fun than demo-ing new kit at home?
 

·
Registered
Joined
·
1,838 Posts

Quote:
Originally Posted by Cam Man /forum/post/18127382


the same as in the cinema.

only in the sweet spot and most of the time those seats are taken.
 

·
Premium Member
Joined
·
15,585 Posts
The outdoor, groundplane measurements are the only measurements that can be used to objectively compare subwoofer performance, as it completely eliminates room acoustics from the equation. (It's not without it's own issues, but it's better than anything else we have.)
http://www.hometheatershack.com/foru...rer-model.html


Unfortunately, Illka went to work for Genelec some years ago and stopped doing his testing. Still his were the most objective, unbiased tests of subwoofer performance I ever recall seeing.


Craig
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #10 ·

Quote:
Originally Posted by ls200p /forum/post/18128191


Reference level at your seat is supposed to be 85dBs???

I will get a very thorough explanation from a friend who is a serious player in this field and return with it. He can explain every electronic and electrical technical nuance on this subject until one's eyes glaze over.


Quote:
Originally Posted by osofast240sx /forum/post/18127953


only in the sweet spot and most of the time those seats are taken.

It's certainly not that way by design...or in reality. Every seat in a cinema is not perfect, but speakers are designed and installed for wide, full spectrum coverage. A fairly large central area will have about the same level. This is helped by the fact that sound dampening with distance changes less from seat to seat far less that it does for us at home where we are much closer to the speakers.

Quote:
Originally Posted by craig john /forum/post/18128053


The outdoor, groundplane measurements are the only measurements that can be used to objectively compare subwoofer performance, as it completely eliminates room acoustics from the equation. (It's not without it's own issues, but it's better than anything else we have.)
http://www.hometheatershack.com/foru...rer-model.html


Unfortunately, Illka went to work for Genelec some years ago and stopped doing his testing. Still his were the most objective, unbiased tests of subwoofer performance I ever recall seeing.


Craig

A member turned me on to that last night. I'm looking forward to studying his work. Bummer he doesn't do it any more.

Quote:
Originally Posted by tkad /forum/post/18127863


It's a great problem, but I am sure that if we had the same gear in our different houses, the experience would not be the same.

Well said, tkad.
 

·
Registered
Joined
·
1,838 Posts

Quote:
Originally Posted by Cam Man /forum/post/18128600


It's certainly not that way by design...or in reality. Every seat in a cinema is not perfect, but speakers are designed and installed for wide, full spectrum coverage. A fairly large central area will have about the same level. This is helped by the fact that sound dampening with distance changes less from seat to seat far less that it does for us at home where we are much closer to the speakers.

yeah i know all of the thx theories numbers ect. bottom line when i sit in the back row of a AMC theater it sounds like crap. i will take my Home theater over that back row every time.
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #12 ·

Quote:
Originally Posted by osofast240sx /forum/post/18128905


yeah i know all of the thx theories numbers ect. bottom line when i sit in the back row of a AMC theater it sounds like crap. i will take my Home theater over that back row every time.

I have no doubt. Why choose the back row? I don't think anyone will say that the experience in the back row is worth the price of the ticket.



And the basics of what I described are done by design for any descent cinema, whether to be THX certified or not. And inverse proportion regarding sound dampening is the same for everybody.
 

·
Premium Member
Joined
·
15,585 Posts

Quote:
Originally Posted by osofast240sx /forum/post/18128905


yeah i know all of the thx theories numbers ect. bottom line when i sit in the back row of a AMC theater it sounds like crap. i will take my Home theater over that back row every time.

Solution: Get there early and sit in the sweet spot.



Craig
 

·
Premium Member
Joined
·
8,838 Posts

Quote:
Originally Posted by Cam Man /forum/post/18128600


I will get a very thorough explanation from a friend who is a serious player in this field and return with it. He can explain every electronic and electrical technical nuance on this subject until one's eyes glaze over.





It's certainly not that way by design...or in reality. Every seat in a cinema is not perfect, but speakers are designed and installed for wide, full spectrum coverage. A fairly large central area will have about the same level. This is helped by the fact that sound dampening with distance changes less from seat to seat far less that it does for us at home where we are much closer to the speakers.




A member turned me on to that last night. I'm looking forward to studying his work. Bummer he doesn't do it any more.




Well said, tkad.

With regard to the tests by Ilkka, when you look at the SVS PB-13 Ultra in 20 Hz tune, you'll see a whole lot of potential. Even without room gain the 13 Ultra posted some serious numbers while also posessing the potential to go down to 15 Hz without much trouble (in 15 Hz tune). THX doesn't address frequencies below 20 Hz.
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #15 ·

Quote:
Originally Posted by spyboy /forum/post/18129373


With regard to the tests by Ilkka, when you look at the SVS PB-13 Ultra in 20 Hz tune, you'll see a whole lot of potential. Even without room gain the 13 Ultra posted some serious numbers while also posessing the potential to go down to 15 Hz without much trouble (in 15 Hz tune). THX doesn't address frequencies below 20 Hz.

I hear that the PB-13 is pretty amazing. I love having the potential to go down to 15Hz. I guess we can feel it if we can't hear it...or have any program material at 15Hz. The inevitable trade off for size and lower extention is going to be output. There's hardly any choice anymore though. Big box passive subs are pretty much gone except for the JBL Synthesis S1S or cinema subs. The cinema subs are flat to 35Hz (no EQ), optimizing output. They are spec'd to be -3dB at 20Hz with EQ, but they do point out that output will be reduced in that case. Neither the Klipsches or the SVSs...or anything else can come close to the raw LF energy that a large passive sub can achieve rather easily in an HT environment. They're actually a great choice if your are addressing acoustics well, accomplish good EQ, and can hide the ugly things.
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #16 ·

Quote:
Originally Posted by Cam Man /forum/post/18128600


I will get a very thorough explanation from a friend who is a serious player in this field and return with it. He can explain every electronic and electrical technical nuance on this subject until one's eyes glaze over.

I'm back with a better explanation. My friend reminded me of why the confusion between the 75dB number we use results in the 85dB reference level.


The test noise/tone is in our AVRs/AVCs is -10dB from reference level as encoded on the disc or produced internally by the controller product. It was determined a while back that narrowband pink noise at 85dB would startle/scare consumers trying to set up their systems. Thus, the standard test noise level was dropped to 75dB. If you had a source producing -20dBFS (150mV) at 500 Hz to 2 kHz, it would measure 85dB because although the level of the test tone was reduce to make it easier on us, the gain structure remains the same, resulting in 85dB. Cinema calibration systems aren't worried about startling the technicians calibrating the systems, so their test tones are at 85dB.
 

·
Premium Member
Joined
·
8,838 Posts

Quote:
Originally Posted by Cam Man /forum/post/18129442


I hear that the PB-13 is pretty amazing. I love having the potential to go down to 15Hz. I guess we can feel it if we can't hear it...or have any program material at 15Hz. The inevitable trade off for size and lower extention is going to be output. There's hardly any choice anymore though. Big box passive subs are pretty much gone except for the JBL Synthesis S1S or cinema subs. The cinema subs are flat to 35Hz (no EQ), optimizing output. They are spec'd to be -3dB at 20Hz with EQ, but they do point out that output will be reduced in that case. Neither the Klipsches or the SVSs...or anything else can come close to the raw LF energy that a large passive sub can achieve rather easily in an HT environment. They're actually a great choice if your are addressing acoustics well, accomplish good EQ, and can hide the ugly things.

A good number of people interested in massive output are going this route:

http://www.avsforum.com/avs-vb/showthread.php?t=1189404


I saw something about 126 db and roll-off beginning at 11 Hz.
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #18 ·
Customer service from SVS is really excellent. I brought these questions to them, and they went to work to find answers. Klipsch actually publishes the same, so that info is readily available. Cutting to the chase, these two sub systems appear very close in performance capability. That shouldn't be too big a surprise because they are similar in cabinet size, they are ported, and their amp power is almost identical. And both are very well made using very strong drivers.


Klipsch publishes the following for the KW-120-THX.


Max Acoutic Output: 130dB @ 30Hz, 122dB @ 20Hz, 112dB @ 15Hz. All with both subs placed side by side in 1/8th space (a corner). THX actually requires them to be placed together to meet their performance specs.


I don't see that SVS publishes specs like this, but they were exceptionally helpful in providing this kind of information upon request. They just took some time to talk to their engineers. It also basically jives with Ilkka's data...and may well come from it for all I know. I'm not sure if these were given to me in confidence, so I won't list them here. But they are reasonably close to each other, even with some leeway for the possibility of some differnences in measurement methodology. Ilkka's data also indicates that the PB-12 Plus is just about at its max capability at those (meaning, pushing it much further will cost in distortion, compression, or...). Probably the same can be said for the Klipsch.


An interesting thing to also consider is that although the Klipsch enclosures are passive, Klipsch only recommends that they are used with the Klipsch KA-1000-THX amp. My guess is that the amp is actually providing a bit of EQ to tune the response of the subs to reach down to 20Hz. It would appear that the SVS is doing a similar thing, but adding the interesting concurrent process of closing ports to increase cabinet volume. Kinda cool. This permits the subs to be tuned a bit to compensate for room gain while also increasing to some extent the output capability. Also cool...and desirable.


The Klipsch (actually THX) does a similar thing only in the form of selectable THX "Boundary Gain Compensation." One could infer that this means that the listener is near a boundary. But it would be better named "room gain compensation." That feature is going to induce a roll off below 35Hz to control room gain. Whether this is needed in a room can only be determined with acoustic analysis...or darn good ears.
Of course, if you have a THX certified AVR/AVC, this feature is now built into them to use if needed.


I have a dedicated theater design and install just starting up...and I think I'm going to spec dual PB-12 Pluses. I'll test with a sub to look at the best acoustic location I can find, then in the final calibration I'll be using MultEQ Pro and the Audyssey Sub EQ. I bet it's gonna rock.



Another sub I'd like to learn more about is the Epik Empire. It is similar in size and power, but its sealed design and driver configuration offer new considerations that I don't think I understand well enough yet to appreciate. I'd love to learn more. Maybe Chad will chime in.


Cheers
 

·
Premium Member
Joined
·
3,689 Posts
Discussion Starter · #19 ·

·
Registered
Joined
·
6,988 Posts

Quote:
Originally Posted by Cam Man /forum/post/18128600

Quote:
Originally Posted by craig john /forum/post/18128053


The outdoor, groundplane measurements are the only measurements that can be used to objectively compare subwoofer performance, as it completely eliminates room acoustics from the equation. (It's not without it's own issues, but it's better than anything else we have.)
http://www.hometheatershack.com/foru...rer-model.html


Unfortunately, Illka went to work for Genelec some years ago and stopped doing his testing. Still his were the most objective, unbiased tests of subwoofer performance I ever recall seeing.


Craig

A member turned me on to that last night. I'm looking forward to studying his work. Bummer he doesn't do it any more.

Hi Cam Man,


There's plenty of prior work that led to and influenced the testing method Ilkka implemented and added to over time. First was the subwoofer series in two magazine's by Keith Yates, with the more in depth work in the Way Down Deep report in Ultimate AV , later followed up by Ed Mullen's reviews personally and later at 'Secrets (prior to going to work for SVS), as well as the many tests at AV Talk .


I would argue the THX certifications are significantly over-simplified to imply every 6000 cu.ft. room will be the same. After all, they had to make the spec attainable enough so there would be some manufacturers who could meet it to charge the licensing fee.



While I applaud and support your interest for a higher confidence end solution, I think you are giving a bit too much credit to "old school" designs and lumping way too many modern subwoofer designs with the less ambitious efforts which had become so common in the retail world.
 
1 - 20 of 22 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top