Ive just found out the Kef Kube series. For my room, I guess a pair of Kubes 10b should work very well.
It's relatively small (easier to move around to reach the best location), reaches 24 Hz, looks nice on the outside, accepts speaker connection, it costs $600 each and it has good reviews.
Has anyone tried them? |
Hi guys,
I´ve been styuding about adding a pair of subs to my system.... you and Jim Smith got me convinced!
Although I wouldnt recomend bookshelf speakers with subs instead of a good pair of floorstanders, it seems that a pair of subs could improve quite a lot the sound of a full range stereo speakers. We'll see!!
I live in Argentina and it's much more expensive for me (about 50 to 100% more) to buy gear and impossible to try them home and have the chance to send it back to a dealer if I don't like it. So, I have to buy blindly, following the advice of others.
Wich subs would you recomend under this limitations:
1- My budget is about 1k top for each sub.
2- I would prefer not big subs (due to room and decor limitations). I only have two squares about 2.5' x 2.5' each, between the speakers and their respective side walls.
3- They have to be able to reach at least 25 Hz.
4- I've been advised to buy ones that can be connected to the output of the power amp, not to the preamp, to have better results.
I think the SVS SB-2000 could be a good choice, but it cannot be connected to the power amp, as I understand. How much does this issue affect the sound?
I have to mention that the distance between my amp and preamp to the possible locations of the subs is about 16/18' the longest and one of the cables for the subs (if a dedicated ones are needed) will have to share the same pipe as one speaker cable.
What about cheaper brands like Klipsch or Polk Audio?
I've had one Polk Audio PSW125 with a pair of bookshelf speakers and then with a pair of floorstanders and I didnt like the results AT ALL. Of course I didn't had it correctly voiced and it was only one sub, so I cannot blame it for the bad results.
Thank you in advance! |
Ya puts the speakers and the sub in da room and ya moves em around till day sounds da best! Badabing....hopefully not badaboom :)) |
noble100 wrote: " Duke somehow compensates for this so that the in-room bass response is flatter and more accurate but I'm not certain of exactly how he does this." According to Martin Colloms and several others, "typical" room gain is about 3 dB per octave from 100 Hz on down. Imo the implication is that a subwoofer's response should gently roll off by 3 dB per octave across the same region. This is too shallow to achieve with an unequalized sealed box even if the Qtc is very low. However it can be approximated with a vented box with the right woofer parameters, box size, and tuning. The Swarm units come very close to this target curve from 80 Hz to about 20 Hz, and since I don't normally recommend lowpass-filtering them any higher than 80 Hz, that seems to work fairly well. There is another related effect going on with a distributed multi-sub system: The subs are spread far enough apart that their outputs are combining in semi-random phase at the top of the bass region, but down at the bottom of the bass region the room size may be too small relative to the wavelengths for that to be the case, and their outputs end up combining approximately in-phase. The transition from semi-random phase combining of the outputs to approximately in-phase combining of the outputs has the effect of once again boosting the bottom end relative to the top end of the bass region by maybe 2 or 3 dB. If using only one amp, reversing the polarity on one of the subs usually restores balance to the force. If using two amps with the phase controls set for phase quadrature, that phase setting addresses the issue. Other ways of dealing with either too much or too little "room gain" include plugging and un-plugging ports, engaging the "bass boost" switch on the back of the amp, and using the parametric EQ. The goal is to end up with smooth bass, and all of these things are just a means to that end. Duke |
Yeah that’s fine Tim I got it covered. Its called room reinforcement. Every room has it to some extent. 3 dB per octave is rule of thumb. But it varies.
The free Parts Express cabs are all sealed. Frequency response of a sealed enclosure drops off very gradually, which actually turns out fine because the drop off is pretty much offset by room reinforcement. But you never can be sure your room reinforcement will kick in just right to match your speaker roll off. They may roll off early. So what Duke suggested, and I of course did, is build 2 sealed and 2 ported.
This way if it turns out I need the extra extension I’ve got it covered with the ported subs. But if it turns out that’s too much then I can simply plug one or two, in effect turning them into sealed cabs with the earlier/slower roll-off.
Some of this I have known since it feels like forever- from having built a transmission line speaker in 1980, and a ported sub about 10 years later. But a lot of the details used here, the use of room reinforcement, the sealed/ported options, and especially the distributed bass array concept itself, for all of that I owe a huge debt of gratitude to Duke. When it gets into "exactly how he does this" its proprietary info but everything else he has been graciously willing to share. As exemplified in his posts here. I only wish more were able to get their minds around this revolutionary development in subwoofer technology.
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millercarbon,
I just recalled something about the Audio Kinesis Swarm and Debra that Duke knows more about than I do; there's something called 'bass room gain' that needs to be compensated for when setting up a distributed bass array system. I believe it's a 3 dB increase in the volume of deep bass frequencies in typical rooms using subs that is the result of acoustic interactions in the room itself.
I know Duke somehow compensates for this so that the in-room bass response is flatter and more accurate but I'm not certain of exactly how he does this. Hopefully, Duke is still following this thread and will respond. If not, I suggest you pm him and ask.
Sorry I didn't recall this earlier but I think it's important for your custom DBA build.
Tim
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A 0-180 degree control is NOT adequate. It is with a Phase invert |
@millercarbon: You have referenced Floyd Toole previously. If you look on page 154 of his book, "Sound Reproductions", you will see a chart of frequency by sound attribute (direction & space + timbre & sound quality).
100Hz looks like the lowest frequency for boundary effects and envelope.
My understanding of spatial cues is that it has more to do with the time domain (reflected sound) than the frequency domain. The pro audio guys on Gearslutz are maniacal about getting their ETC curves and sound models correct. (Good resource for this stuff.)
I think we all agree that deep bass improves the SQ. |
Yes. Even at $499 some of the suggestions here should provide increased depth and bass when properly positioned and setup.
Clearly the addition of a subwoofer/s can dramatically alter a systems presentation which might be described by some enthusiastic new sub owners as added clarity.
Keep in mind an investment in a higher quality subwoofer may service you for a lifetime despite all your other audio related upgrades.
Good luck with it.
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plga-
I thought 3D sound came only from the tweeters, but it seems that long bass waves have somehow spatial information that contributes with imagin. Incredible!
While we don't hear low bass frequencies as localized sounds within a sound stage the way we do upper bass, midrange and treble, really low bass does contribute to imaging by imparting a sense of space. Really good low bass like you get with the Swarm or other distributed bass array can put you more fully in the recording venue. This reviewer explains it beautifully. http://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/
There is more to what is going on here than just the perception of what is happening in the music itself. There is also a quite startling spatial effect. We are all accustomed to being able to control room effects in the mid and higher frequencies by acoustical treatment. But this is harder to do in the bass, and in most rooms there is a definite residue of spatial signature carried in the lower frequencies. The bass is one of the main ways you sense the size and shape of the room around you, and typically the signature of the recording venue is overlaid or even swamped by the bass signature of the listening room. But the Swarm, presumably because of its smoothing out of response, largely suppresses the bass signature of your listening room. And as a result one can hear the original venue in a most unusual way. I played in a performance of the Sibelius Second Symphony recently, so I was particularly attuned to the acoustic effect this piece makes in a concert hall. Listening to Berglund’s recording for EMI with the Swarm in action, I heard a remarkable facsimile of the size and envelopment of the actual symphonic sound emerge. At the end, I felt like standing up and cheering, so close did I feel at some basic level to the real experience.
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The human audible hearing range is 20Hz to 20,000Hz
No one on Audiogon I bet, lol |
Yes, indeed. I agree Dave.
Just to mention, last night I've read the chapter "Stereo System Bass and Subwoofers" of the book "Get Better Sound" of Jim Smith, an interesting and educational book from a well known and respected expert on the audio field with several decades of experience. I didnt read this chapter before as I dont have subs in my system.
Well, Jim starts the chapter with this: "One of the greatest dissappointments for me has come from listening to stereo systems that incorporated subwoofers at shows and in home installations. I suppose it's the complexity of getting so many variables correctly adjusted".
Then, intrigued by it, I kept on reading the chapter so he provides many advices to install de subs (he suggest two for stereo) and smoothly blend them with stereo speakers. Well, it aint simple at all as I thought.
It also says something I found very interesting, as posted by @shadys telling his experience. For Jim, well installed subs can really improve soundstage holography. Ive never though it possible! I thought 3D sound came only from the tweeters, but it seems that long bass waves have somehow spatial information that contributes with imagin. Incredible!
Well, I would LOVE to hear a good pair of subs "well matched" in a nice high end system, to see how improves the sound of it. Im intrigued.
Nevertheless, do I recomend a sub for an entry level audiophile? Not, for sure.
Again, just my opinion. |
Depends on room, budget and goals really. What is the current setup, wish list and desires for sonic bliss...musical tastes etc..
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Hey Dave
A couple of questions for you as you seem to have large experience with high end hear and knowledge in audio.
As I understand, you and some other members in this thread, with more experience than me I guess, have managed to successfully match subs with high end systems with great results.
1. Was it somehow simple and cheap to get it done? I would appreciate an honest answer.
2. Would you really recomend, to an entry level audiophile (with little experience on audio), as I was just a couple of years ago and I guess (please no offense) Jazz99 is, the starter of this thread, to start improving the sound of his system by getting subs? Or would you recomend him, under your experience, to begin with something else first, like upgrading speakers, electronic and voicing them?
Regards.
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All good! Experimenting is fun...enjoy and happy listening. |
Hey Dave.
Take it easy.
Im only telling my experience. I dont doubt about yours as you mention you seem to have much with very popular brands, but that doesnt make mine not valid.
Im also aware that my room dimensiones are difficult as posted by millercarbon (thanks for pointing that out), but I cannot change them. As I said YMMV.
I also have to say that I would LOVE to hear a high end system improved by subs as I cannot imagine it with out hearing it.
Anyway, I still think that getting the best system your budget can afford and voicing it to the room should be the first step and then, with that experience on your back, if you are not happy or totally satisfied with the results, you should get with subs.
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Years ago I listened to a pair of magnepans at a dealer and the subwoofer was located a few feet behind the listening spot. It was the first time I’ve experienced expanded height to a soundstage. When they turned the sub off, the stage seemed to collapse back down. I don’t hear a lot of people with this type of placement as it usually seems to be more toward the front of the room near the mains. |
It doesn't take an engineering degree Larry but a little time spent learning a little about each of the areas involved sure does help.
Like, sound travels in waves. The lower the frequency the longer the wave length. This one simple fact seems to cause a lot of problems though because it means sound in a room behaves quite a bit different than most people think. What I mean is most people think it all behaves the same. In fact it behaves very differently depending on frequency. Not only does it behave differently, but we even hear it differently!
Its real easy to get confused by people who don't know what's going on, get their facts wrong, and talk about things like toe in and timing which do matter from midrange on up but do not matter at all at low bass frequencies.
If you want to understand there's great articles already mentioned above by Geddes and O'Toole, and of course everything posted by audiokinesis on here is pure gold. Everything else you should take with a big grain of salt. What is not flat out false is maybe even more dangerous for misleading with a grain of truth. There's also a book I can't recommend enough The Complete Guide to High-End Audio by Robert Harley.
As an example of a little knowledge.... plga has a room 14x28x9 which just that one thing is enough to know he's gonna have problems with a sub. Why? Because 28 is exactly twice 14 and almost exactly three times 9. This means nodes are gonna stack up at 40Hz and 80Hz. Why? Because at 40Hz the wave is 28 feet, at 80 Hz 14, and at 125Hz 9ft, and 125 is almost exactly three times 40. You could literally take a piece of graph paper and map out the nodes and see them.
No wonder plga has had so many problems. He's trying to solve a problem of physics the wrong way, with a sub. The key word being "a".
Now look at noble100. His room at 16x23x8 is almost as bad yet he is really happy with great sota bass! Partly this is because the larger dimensions (16, 23) aren't multiples so troublesome bass nodes are further apart. Mostly though this is because Tim has wisely chosen to solve his bass problem with an actual, bona fide proven to work solution- a distributed bass array.
A little knowledge does indeed go a very long way.
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Hey Sparky, I’ve owned Wilson 6’s, 7’s, Dynaudio C4’s, B&W 802D3’s etc and Reference hear from ARC, Levinson, Krell etc.. Been there and done the whole no sub thing. Short of those types of systems and great rooms (insert plga) a sub adds texture, spaciousness and warmth. It is not to blast more bass. Adding room correction electronics to a system, IMO adds extra artifacts and strays from the original musical content. Talk about using a computer to deal with a problem an abacus could solve...jeez! Placing a sub is hard if your hard of hearing.
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Hello Mike
I really dont know on what kind of music you will miss that bottom octave.
I think, as I guess all audiophiles do, that our biggest goal is to have a system that reproduces the music as close as possible to the real thing and I think that bottom octave, if you have it on some music, should not be your priority. I dont feel the music on my system lacking some Kind of base, quite the opposite, sometimes I feel I over boosted the bass with Dirac on some songs. I must confess, I like the music with weight, body and texture, I love a well rendered bass in the music, may be with a little excess of it.
You can ask some experts (Im not one) and Im sure they all will agree that there are many other issues to spend time and money on before getting subs.
If, and only if, you had bookshelf speakers, in most cases I agree that the bottom end will sound not too powerful or you will need a good muscle amp to get dynamics and proper bass as bookshelf speakers in most cases have very low sensitivity and they are not easy to drive.
If someone has bookshelf speakers in a medium to big room, I would advice to sell them and get the best floorstanders you can afford instead of buying one or more subs.
I would only consider buying subs if, after having a very nice and voiced 2.0 system, you dont get a convincing bass.
Also dont get confused about bass, because many of us have been used to consider excessive bass as a natural and good sounding one and it is not correct! Most of us grew up in Discoteques and going to concerts and thats not how unamplified live music sounds.
Listen some guitar, drums, sax, trompet, etc unamplified, they dont have excessive bass, they have texture, depth, dynamics, etc. And IMHO to get that you have to address some more important issues like I said.
Anyone thinking about buying a sub before getting the best system they can afford and voicing it, should first manage to listen to a very good and voiced hi end system. It will change his mind.
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@plga - thanks for sharing your experience.
I've often wondered if it's worth the trouble for me to pursue the bottom octave knowing that it will be difficult to get right. Sounds like it can be done but be prepared for a daunting task.
For now, I'm going to keep it simple. |
Dave
I already bought one once and never again!! :-)
Larry
Well, even Im not a tech expert AT ALL, it took me about a couple of years, a lot of hours and mostly some not small cash to learn it the hard way and I think the only way.... Readind, buying, connecting, selling, tweaking, tweaking again, listening, more reading, etc.
If you like this hobby like me, you will do it without getting tired!!
Cheers to both of you
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You have all lost me. Guess I need to get a sound engineering degree to understand. Wonder how you all learned this? |
So when ya ordering that sub plga? ;))
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And yes!
Audio improvement its a neverending story!!! Its an addiction!! :-) |
Hey, it is just my experience and YMMV.
For me its much more important, easier and may be cheaper to address issues like standing waves in bass frequencies, early reflections and reverberance in highs, jitter (if you listen to digital), speaket positioning and toe in, listening position, AC power conditioning, etc.
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Glad your happy plga...better off not knowing sometimes anyway. Saves money!
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Yes, Im using the Q Acoustics Concept 500 and I'm getting more bass shaking than I need.
In some reviews they mention that the bass is outstanding in this floorstanders and I couldnt agree more. It has everything, impact, dinamic, tone, etc. They have fantastic bass.
It is also true that I boosted the bass a little bit with Dirac, both the low and upper bass, along with the rest of the Digital Room Correction the sofware does.
Its incredible the bass you get with a nice pair of floorstanders and Room treatment (active and pasive).
I strongly believe you dont need more (for music) or, to have it, you have to spend a considerably amount of money, time and effort.
How much would it cost me to buy two subs at the level of my speakers?? at least 6 to 8k... and, how much time would I have to spend voicing them to the room? not even considering the space they need, that most of us don´t have. I should better spend that money on electronics as Im sure I would get much better results as I did.
Im sure with subs you can boost the bass more and have a some more impact and deepness, but for me it could sound unreal if you are not careful.
I repeat, IMHO, the musical experience is much more complex than just adding extremely low bass (under 40 Hz) and if you dont do it extremely right, Im sure you will mess up the sound of your speakers with the subs, because it happened to me and it was NOT subtle.
I repeat, if you want to get your system to sound as real music as possible, you have to address many different variables: standing waves, tone, soundstage, dinamics, detail, smooth highs, etc. If, and only if, you succeed to match the subs perfectly your speakers, IMHO, you will only get a part of the problem resolved.
And if you listen to music other than electronic (jazz, blues, rock, accoustic, etc) getting a deep bass wont give you much as many recordings in that kind of music DONT have it.
Again, just my opinion. |
Plga, are you using the QC 500’s yet? If so, you are not getting foundational bass response...you may be pleased with what you are hearing but 41hz @ -6db is not room shaking. Stereophile even mentioned that a good sub would be beneficial. |
Well, IMHO, its very difficult to deal with standing waves in rooms with just one pair of speakers.
Ive tried to make a pair of floorstanders work with a sub and I couldnt do it, nor did I have the patience to get it done. It was too difficult. It only made the speakers sound much worse and provided me a LOT of standing waves all accross the room. It blurred the sound of the speakers.
On the other hand, Ive manage to get a very nice system, without subs, that provides me an "incredible" musical experience. It has bass (a lot), depth, 3D sound, tone, dinamics, layering, detail, etc etc.
If you consider the money you have to spend on more than one sub, the time to correctly position them (the possible locations and orientation angles are a LOT), then the time to voice them, the space they need, cabling, power them, etc etc. Well, IMHO, you should have a bass made in heaven to make it worthwile.
My system provides me an incredible bass, deep, toneful, dynamic and with BIG slam (it shakes the room), when the recording has it. More it would be too much and not real.
Unless you hear only electronic, the heart of music is mostly on the mids and to have body (and good tone) in the music you need to have a well performed (a little boosted) frequency range between 200 and 400 Hz (said by experts like Jim Smith) and subs dont get that high.
Also, musical subs are expensive (about 1k each). If you need two or more, plus the speakers @jazz99 has (Focal Aria), you will need a budget around 3.5 to 4k, with out cabling.
And for that money you can have a VERY nice pair of floorstanders with all the frequency range (for music) covered very well.
IMHO, for similar money, you can get much better sound with the floorstanders, spending considerably less time and effort.
Just my 2 cents.
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More audiokinesis gold: And somewhat counter-intuitively, the more subs the easier it is, because the location of any one sub becomes non-critical. Once you've initially positioned the subs, time to adjust the controls. First the gain, then the frequency, then the phase, in that order. Then cycle through a few more times. Don't be surprised if you continue to make fine adjustments, particularly to the gain, over the course of the first few weeks. Duke
That's what I thought but still nice to confirm and clarify: "the more subs the easier it is, because the location of any one sub becomes non-critical." Totally logical once you understand what's going on and the reasoning behind the distributed bass array. It also might be my favorite thing about it. The way my room is laid out it will work out beautifully with one on the front wall left corner, one on the right side wall near the right front corner, another one far back on the right wall, and a fourth somewhere along the left side wall. Should work out great with the existing equipment, in particular a massive turntable rack that definitely is not going anywhere and despite its massive, uh, mass would rather not have a sub sitting right next to it! I got 2 sealed cabs and part of one ported cab screwed and glued together. Man they are heavy even without the drivers! Got the amps in the room, Cones, Shelfs, wire. Depth and clarity or just bass? We're working on it! |
"Getting that done WELL, but with subs, IMHO is for experts." Then there must be a lot of experts out there, because an awful lot of people have done it. And somewhat counter-intuitively, the more subs the easier it is, because the location of any one sub becomes non-critical. Once you've initially positioned the subs, time to adjust the controls. First the gain, then the frequency, then the phase, in that order. Then cycle through a few more times. Don't be surprised if you continue to make fine adjustments, particularly to the gain, over the course of the first few weeks. Duke |
I cannot agree more with erik_squires when he said "It’s not the tech is bad, it’s the complications in the setup that I’ve so often heard as poor".
Not to mention the space the subs will need in your room, powering them, cabling, etc etc.
For me, not worth it. |
Well, its only my experience.
But, its true that integrate a sub, or a pair of subs, its quite complicated and, to my taste, a nice pair of floorstanders, with a nice system behind and all of them voiced to the room, can sure give you all you need in music.
Just finding the right spot for your speakers (with out a sub) and your listening position its a big challenge. Not to mention taking care of all the rest issues to correctly voice the system to the room.
Getting that done WELL, but with subs, IMHO is for experts. If you are not one, you would need A LOT of time and patience to get it right. |
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Unless of course you have and immense room, wich its not most cases.
Mine is 14' wide, 28' long and 9' tall.
Trust me, dont waste your time and money dealing with subs, if its stereo music what you have your system for.
Movies with home theater is another story and hobby.
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Well
Ive used a sub with a pair of bookshelf speakers.
Then I change them for a nice pair of floorstanders and I couldnt make them work well with the sub as it only blurred and masked the sound of the floorstanders, A LOT.
My opinion is that it is VERY difficult to get a the same frequency integration of a nice pair of floorstanders with bookshelf speakers and subs.
Today I have a high end pair of floorstanders, with some room correction and Dirac Room Correction software and the bass is oustanding, incredible, and with out blurring or affecting the sound of mids and highs.
If I were you, I would sell the bookshelf speakers and buy a nice pair of floorstanders. Otherwise you will get into something pretty hard to resolve and you will very likely spend more money and time on the process.
Then I would spend money upgrading the source and the power amp and then time voicing the system to the room.
Im sure it will be much more productive. |
russmaleartist,
Exactly, your description of what a good sub or subs integration should do and sound like, and not sound like, is just as my expectations. On my bass system, the subs are completely silent as long as there 's no music or ht content that calls for any reproduction of frequencies at or below 40Hz. They're like an elite group of very stealthy and extremely capable bass soldiers that never give away their presence but are constantly alert, awaiting the agreed upon signals being sent before instantly springing into coordinated action, precisely performing actions with the proper application of force necessary to accomplish the mission, before returning to stealthy but alert silence once again and awaiting their next call to action. How's that for hyperbolic but accurate fun?
I believe a good sub system is not meant to be constantly heard but just when the content calls for it. In my experience, attaining this quality requires playing a wide variety of content and fine tuning the crossover frequency to be as low as possible but not low enough to prevent their contribution when needed. I've come to the conclusion that it's really just a balancing act with the best hoped for outcome actually being more of an approximation. But it's also true that a good cutoff frequency setting approximation will be perceived as seamless integration with my main speakers 90% of the time.
Conversely, setting the crossover frequency too high on a sub or sub system, imo, could be the most common and detrimental mistake many individuals make with their systems. This only results in the subs being constantly heard and a perception of the bass being disjointed and not well integrated with the main speakers.
What particular crossover frequency is considered 'too high' is subjective but I think most people will know it when they hear it.
I'll just state that, if you're constantly aware of a sub's or sub system's contribution, the crossover is definitely set too high.
Tim
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Yes...not that difficult folks. REL gives a very musical result. Move it around till you hear best bass integration. Try even with plane of speaker mid/bass drivers facing parallel or horizontal.
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In my humble estimation, a subwoofer adds those bottom resonances and harmonics that otherwise would be missing. Any subwoofer should not be noticeable as being a source of the bass, meaning that it is subtle and definitely felt and heard, but not pronounced as a sound source.
A good subwoofer will support all the other frequencies . . . and they, in turn, will do the same to the lowest bass notes, which can be attested in a balanced system where the subwoofer is turned off . . . and then back on -- the difference is most palpable and fulfilling in its supplementing the sound of the main speakers.
A good example would be a good grand piano. The soundboard resonant the harmonics as do the strings and the cabinetry. What you don't want from you subwoofers are the standing waves that excite the room into a boominess, and a sort of one-note wonder that emphasize certain frequencies in the deep bass. The subwoofer should be capable of singing and playing a bass melody . . . not just a stangnent rumble or irritating thunder for the sake of room shaking bass. To me, it is the qualty of the bass, the solidarity of the sound that give a very satisfying feel and completeness to the overall presentation of the music.
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"Xilica XP-3060 digital XO... isn't detrimental in regards to transparency" Thanks for posting this, as I like to have options. Looks like it's between two and three times the price of the subwoofer amp that I use, but that would be okay in some situations. Duke |
I've chosen a 7th order (42dB/octave) Linkwitz-Riley low-/high-pass at 80Hz for my tapped horn subs and all-horn mains via a Xilica XP-3060 digital XO - it's simply what sounds the best.
Previously I ran my mains full-range with a single SVS SB16-Ultra low-passed at 61Hz 24dB/octave (via its own build-in DSP), and while this pairing integrated very well my new setup with two tapped horns (powered by a Crown Macro-Tech 1200) and managed by the Xilica unit, now high-passing the mains, even at this rather early optimization stage sans PEQ offers better, indeed seamless integration with the mains, while lending the presentation a sense of uninhibited "breath," ease and coherency not heard with the previous single SVS-installation.
Aspects of this no doubt falls back on the inclusion of not one but two tapped horns, but running the mains full-range, by-passing the Xilica, with a lower ~60Hz low-pass of the TH's tells me all I need to know with regard to my preference; to my surprise even running the Xilica over the mains with a high-pass isn't detrimental in regards to transparency, but has a freeing effect on the sound with noticeably better energy-coherence and overall integration. If there is something robbed of nuance via the Xilica, I'm not hearing it (in indication of how good a digital XO it really is), masked perhaps (perhaps not) by the other qualities it brings to the table with the high-passing of the mains that only adds to the enjoyment and insight of the sound.
In not trying to make a case with the above as a generalization of what works the best in every situation (certainly, it depends), but simply to highlight that the typically non-audiophile approach of steep filtered, high-passing of the mains in the 80-100Hz region can work extremely well - with a pair (not four) of symmetrically placed tapped horns, no less, and in stereo mode, God forbid.
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Umm ...
To OPTIMALLY separate the (low bass) subwoofer passband from the
(mid-bass) main woofer passband, it's necessary to use a full 4th order
(24dB/octave) active Linkwitz-Riley crossover.
The electro-acoustical sum is what matters, and it's more than just what you remove, it's how the subwoofer integrates with the rest of the system. This is why THX used a sealed 80 Hz limited satellite as the standard. Add 2nd order high pass filter, and voila, you have a total 24dB/octave roll off which would integrate nicely with a sub using a 4th order electrical low pass filter. Honestly, only speaker makers and active room correction software does this anywhere near optimally, which is why I'm wary of recommending subs at all. It's not the tech is bad, it's the complications in the setup that I've so often heard as poor. Best, E |
Hello again Duke, I'm very grateful for your many contributions on this thread sharing your very relevant knowledge and experience concerning how to attain very good bass response in our home music and ht rooms. You've mentioned 'real world' examples and it made me think that's exactly what I consider myself to be. So, I thought I'd give some details about my speakers, room, how my 4 Debra subs are positioned in my room and the results just as a real world example for illustration purposes in case it might help. My combo 2-ch music and ht system is in my 23 x16 x 8 ft. living room. I have a large hdtv centered on the front 16' wall with a Magnepan CC3 center ch spkr wall mounted just above the tv and a pair of Magnepan 2.7QR speakers straddling the tv, about 8'apart and 3-4' away from the front wall. Here are the important specs on the 2.7QRs: 6' x 2' 3-way planar-magnetic panels QR tweeter : 1½″×56″
midrange : 98in²
woofer : 620in² 34Hz-26kHz ±3dB 87dB/2.83v/m @500Hz Low-Pass 12dB/octave @ 650Hz
Band-Pass 6dB/octave @ 500Hz-950Hz
High-Pass 6dB/octave @ 950Hz
bass inverted 2 of the AK Debra bass system's subs are positioned along the front 16' wall, one about 2' away from the left-front corner and the other about 2' away from the right-front corner with both behind my main spkrs and the 10" drivers facing the front wall and less than 2" away from it. The remaining 2 subs are placed along the 23' side walls, one on each wall about 2' away from each rear corner. All 4 subs are run in mono and powered by a single class AB 1K w Dayton with the cutoff frequency set at 40Hz. I experimented with the phase control, slowly adjusting it from '0' to '180' and back again numerous times while listening for subtle improvements in the bass response. I failed to notice any changes so I set this control to '0' (in phase) and proceeded to the next setup step. Once all 4 subs are setup, the instructions call for sequentially reversing the polarity on each sub to determine if the in-room bass response is perceived as improved with the polarity reversed on one specific sub of the 4. If I recall correctly, my friend helping me and I were both tired at this point and we both couldn't imagine exactly how the bass could be improved, so we never completed this step on setup day or since. It's been 3 years now and I still can't imagine how the bass in my system could be improved. Since everyone who's ever listened to my system, including my friend and I, believes the bass is sota, I'm thinking there's no good reason to mess with it now and possibly jinx it. My current opinion is that the DBA system is the best method to achieve sota bass response in any room and it will be able to integrate seamlessly with any pair of main speakers. I know I'll never need to buy another bass system again and I can use any pair of speakers I want with it in the future. The DBA concept honestly does perform that well and it costs about the same as 2 high quality subs. I also believe this system has a high WAF factor in my medium sized room. Tim |
@Jnorris Absolutely not the case. All speakers have a natural roll-off frequency beginning at their F3 frequency. If it is a ported speaker the response drops steeply and makes a perfect acoustic crossover point. You just have to find that frequency. I use RTA software and full spectrum pink noise to measure the response at the listening position. My current Harbeth C7ES3 have a very steep rolloff at ~ 55 Hz and that was the approximate starting point for my sub crossover.
Adding a high pass filter to the main speakers is something I would never do. |
Jnorris2005 wrote: "One thing to be aware of is that the sub will not add clarity to the main speakers unless the sub or the preamp provides a high pass filter to them, blocking out the bass that is now to be handled by the sub. Otherwise you're just adding murk to the low end." That is certainly a very reasonable statement, but I don't think it's an absolute truth, logical as it may be. In my experience it is possible to clean up the bottom end with subs even without a highpass filter in series with the main speakers, and depending on the specifics of the situation, that may even be preferable. I can cite examples if you would like. "Also, if your room is small, chances are you don't need a subwoofer at all. The addition of one will muddy up the sound and probably activate room nodes that will devastate the imaging and sound balance of your speakers." Agreed! The smaller the room, the worse it is from a bass mode standpoint. Chances are a single subwoofer in a small room will sound boomy, tubby, and bloomy, unless you turn its level down very far below the level of your main speakers. That being said, imo there is hope for good quality deep bass even in a small room. This is somewhat counter-intuitive, but smaller the room, the more it benefits from the modal smoothing effect of using a whole bunch of intelligently-distributed bass sources. Duke |
One thing to be aware of is that the sub will not add clarity to the main speakers unless the sub or the preamp provides a high pass filter to them, blocking out the bass that is now to be handled by the sub. Otherwise you're just adding murk to the low end.
Also, if your room is small, chances are you don't need a subwoofer at all. The addition of one will muddy up the sound and probably activate room nodes that will devastate the imaging and sound balance of your speakers. |
"To OPTIMALLY separate the (low bass) subwoofer passband from the (mid-bass) main woofer passband, it’s necessary to use a full 4th order (24dB/octave) active Linkwitz-Riley crossover." How do you know? Are you taking into account the rolloff inherent in the main speakers, and its accompanying phase shift? If so, what frequency and what slope is it? How much phase shift does it contribute? Well the answer is... IT DEPENDS! The real world is far more complicated than your "one size fits all" claim implies. I certainly do not agree with your claim that a 4th order LR crossover is "necessary". And out in the real world, my second order highpass + the speaker’s inherent rolloff will usually (but not always) come closer to a 4th order acoustic slope than what you are suggesting (4th order highpass + the speaker’s inherent rolloff). "A simple (generally passive) 2nd order (12dB/octave) crossover is simply not sufficient; the overlap is excessive." If there does happen to be some overlap, you have more than enough adjustability in the amp’s lowpass filter section to deal with it: Phase, frequency, gain, and if necessary a parametric EQ. Low-frequency speaker systems in rooms are minimum-phase systems, which means that once you get the amplitude response right, the time-domain response is also right. And the amp has the tools needed to do that in the crossover region. "Is a 12dB/octave crossover better than nothing? Well, probably; but why compromise unless there’s a cost-related cause." Yes in the Swarm I’m trying to keep bang-for-the-buck fairly high. There is always some improvement that can be made for more money, so these sorts of things are judgment calls. I don’t think it would be a wise investment for me to have custom subwoofer amps made, but if I did, I’d look into parts quality in the highpass section before I opted for a steeper slope (or ideally, a variable slope). Nobody is obligated to buy the subwoofer amp that I offer. Anyone can buy just the subs and provide their own amplifier and filtering. Duke |
To OPTIMALLY separate the (low bass) subwoofer passband from the (mid-bass) main woofer passband, it's necessary to use a full 4th order (24dB/octave) active Linkwitz-Riley crossover. A simple (generally passive) 2nd order (12dB/octave) crossover is simply not sufficient; the overlap is excessive.
Is a 12dB/octave crossover better than nothing? Well, probably; but why compromise unless there's a cost-related cause.
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Vtvmtodvm wrote: "The "distributed array" concept is worthy with one notable exception: It generally (?) recommends leaving the main speakers Unfiltered." Whether or not filtering the main speakers is desirable depends on the specifics of the situation. The same is true with ANY subwoofer system. The amplifier included with the Swarm and DEBRA systems has a fixed 80 Hz 2nd order line-level highpass filter built in, so the option is always there. If there’s a worthwhile benefit to the main speakers from using it, then by all means use it! If not, then why not leave it out of the signal path? Duke designer of the Swarm
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