I'm noticing a lot of folks into high end audio prefer smaller subwoofers (If they add one at all). What are the reasons for not going after a 15", 18" or something even larger?
Seems like the quickness issue comes up a lot, but when you think about it on a larger subwoofer the excursion is not as severe so it would be more in control. Couple that with servo technology and it can be plenty quick and tight, no?
Rythmik Audio designer/owner Brian Ding has stated that his 15" woofer is no less nimble than is his 12". He also offers subs containing 8" and 18" drivers, and states that his different size subs vary in their maximum SPL capabilities at the lowest frequencies (below 30Hz), NOT in their sound quality.
A subwoofer driver’s performance is determined by a. number of factors, of course. People often cite the lower mass of the cone of a 12" woofer in comparison to that of a 15" as being the reason (all else being equal) for the 12" being "faster". That’s an over-simplification on a number of levels, one example being: The higher mass of the cone of the 15" can be easily be compensated for by using a larger motor (magnet). But that too is an over-simplification, as the gap in the magnet is also a factor. Beware those making simple, bumper sticker slogan proclamations. They should go into politics ;-) .
I don't see much wrong with them. It's not really the larger drivers, it's more that it can be a problem of one kind or other to get them into a "small" enough box and still sound very good. And there's the problem of the lack of proper control enough to integrate them well into the room and system...which is my complaint of virtually any sub out there you can name.
I think servo subs can work well, but it's really all the rest of it that needs to be thought out most, first.
I don't like subs generally because they are designed as an "add on" to the system...a bandaid. They are designed that way because they are approached that way. "Hey, it's a subwoofer and that's what you want, right?" Just more fully resolving the bass/room/system interactions could possibly be a better thought, subwoofer or no.
The Rythmik A370 and H600 plate amps (found in the F12, F15, F18, and F25 models) are available in versions (the PEQ, not the XLR) that provide both line level (on RCA jacks) and high level (on binding posts) inputs. REL subs of course have a great rep with audiophiles, as do Rythmiks.
OK, so seems like not a problem at a fundamental level, but perhaps more of a perception and aesthetic issue (kinda like the pro gear vs. audiophile gear). 15/18 inch sub woofers are big and you can't necessarily hide them in the corner like an 8 inch - so WAF comes in to play. (Many Audiophile's hopes and dreams have been crushed by the dreaded WAF.) Also, I think big sub-woofers are perceived as meant for home theater, so they won't get as much credit for being musical. I'm thinking audiophiles could be missing out by not auditioning a big one.
I am not against larger subwoofers but I am of the opinion that smaller ones that are capable of doing the job in general are preferable. Larger high quality subs may cost a lot more and offer no distinct advantage or be needed in many cases. Also larger subs are heavy and harder to handle and perhaps even place properly in some rooms where space is limited.
For my smaller 12X12 room, for use with a pair of KEF ls50s, I chose this model that is unusually extended for its size due to use of two passive 8" drivers to supplement the main 8" active driver. This is a really good combo!!!
I believe I know what you're onto with something like the REL's and I don't doubt your voracity at all.
But I'm a different sort of customer in a sense in that if your main speakers go down low enough, then something like a REL would be a snap to recommend. But two things: first, my main speakers start rolling off at just above 200 Hz...which means I need to roll off the bass driver around 150-160 Hz (1rst order).
Normally, when the crossover frequency is low (like somewhere lower than 100 Hz), then what we're really talking about here is the "sub-bass" region - i.e., not the mid-bass. And as the design of crossover frequency rises, the more the output intrudes into the mid-bass range within the sub-bass box/driver. The most difficult range for a woofer in a box to reproduce believably is the through the mid-bass...this is where bass in a boxed woofer will sound the most "boxy". This is why most subwoofer amps (usually plate amps) are designed to not have upper crossovers much higher than about 120 Hz or so, like the REL's...no point in trying to crossover into the mid-bass range from one 'boxy'-sounding unit to another (the mains), since their differing box signatures between the sub-bass drivers and the mains will present more of a nightmare to try to integrate in the room. Just below the mid-bass is considered more ideal.
The only real-world problem with that is I, like some others, am dealing with mains that roll off at a higher frequency than plate amps generally allow for. So for me, the REL's would not be a good choice, even as much as they might be an ideal fit for someone with mains that can reach lower than mine. But (and this is my second thing from above) a 200-Hz lower mains limit is ok in my case because the mains are open baffle and if I use ob bass drivers, there is no 'box problem' for me to contend with since there are no boxes...so I'm free to crossover more successfully wherever I might otherwise need to and it all works out fine, as long as my active, digital crossovers give an infinite choice of frequency points and the needed selection of slopes (which mine do).
But, it's the active crossovers that allow me to treat the bass drivers as an extension of the main speaker design...IOW, these are truly 3-ways - not a pair of 2-ways and a sub. There is a difference in design consideration and there is a difference in performance. The ob effect this way is of increased coherence, transparency, tonal differentiation and lower distortion. There is not the same fun-factor (slam) with ob than REL's provide, but ob opens the way for a more musical or realistic experience (again with the exception of slam). But for that, I will be adding an 18" driver and 700w amp in an infinite baffle arrangement. It should be comparable to folded horn bass which can be about as good as anything out there. The last point of mine is that companies like REL can excel at coming up with very advanced drivers packed inside very advanced boxes...a fairly extreme level of both art and science. The only trade off is that it's expensive. The ob approach along with infinite baffle does not require extreme engineering which keeps cost low...the ib amp/driver combo will only cost $1200, yet the performance level is very high.
I have two Rythmik F25 subs and I don’t hate them. I use them both for home theater along with a pair of SVS SB13 Ultras and use one for two channel listening to supplement the 6 12" drivers in my Legacy Audio Focus 20/20 speakers. I know it’s not the most "refined" system you’ll ever hear but I get a lot of enjoyment from it.
Ivan, there is one sub that is usable up to 300Hz---the Rythmik Audio/GR Research OB/Dipole. You can check it out on the GR and Rythmik websites (though a result of the collaboration between GR’s Danny Richie and Rythmik’s Brian Ding, the sub is more Danny’s than Brian’s baby), as well as the GR AudioCircle Forum. A pair of 12" paper cone woofers mounted in an H-frame, with servo-feedback and dipole-cancellation compensation shelving circuits in the integral plate amp. A very unique sub, the only one of it’s kind!
Yes, thank you, I must confess I did think long and hard about Danny's servo subs. They were quite attractive to me.
I wound up going with going with Crown XTi 2 amps and a pair of Acoustic Elegance 18" Dipole woofers (on order) for the mains and a single 18" Infinite Baffle woofer to be mounted in the front wall behind the main speakers. The Crowns for their unlimited crossover, delay, EQ options (which buys me future integration with any conceivable change I might ever come up with in the future in the way of woofers, subs or placement), and the Acoustic Elegance woofers for their efficiency at lower frequencies and their unique "lambda motors"...very low impedance for an easy load for the amps.
But when I looked at Danny's Rythmik plate amp, according to its specs, while the upper crossover control went fairly high, the response of the amp itself was terminated in such a way that if I ever needed a relatively high crossover point like the one I was already contemplating, then the upper roll off in the response of the plate amp itself would leave me a slight "hole" in the crossover zone up toward the hand off point to the midrange...the very kind of response error in my setup (with smallish midrange drivers [MMTMM]) that I could ill afford to have. (I find myself currently and happily wedded to a version of Danny's superb "Wedgies" main speakers that are Well worth all this fussing over them!).
BTW, for my money, Erik nailed it when it comes to subs: integration is king!...and yes, it can be a tough thing to find.
Speed doesn’t matter. Integration is a misleading misnomer. There’s more out of date thinking on low bass than anything in audio. And that’s saying something!
Speed doesn’t matter. If speed mattered then my Talon Roc would be the King of subs. Why? Its isobaric design guarantees the driver moving the air sees no pressure variance behind it. It is indeed a very fast sub. Which does not matter. Why? Because with low bass unlike higher frequencies we don’t hear the sound coming off the driver. We hear only the waves that have been bouncing around the room many times already. Low bass waves are so long they create many modes and cancellation areas. In the modal areas the bass is so strong it takes a long time for this energy to dissipate. We hear this long slow dissipation as slow bass. So the answer to fast bass is smaller modes. The way to get smaller modes? More subs! So its not the speed or power of the subs that makes for fast bass. Its the number. The more subs the better.
The whole concept of integration is misleading. Integration creates a false impression. Integration makes people think the subs need to be similar to the mains, or aligned somehow, or that timing matters. No. Wrong on all counts. Sure levels need to be matched. Yes its nice being able to adjust phase. But nothing remotely like the way the mains require precise placement. Low bass is a whole different animal.
Big subs are great. When it comes to the lowest frequencies, you probably cannot have too big. But you sure can have too few. Until you get to four, that overshadows everything.
Yes! I'll grant you that. It's only where I (or others) try to integrate at a bit higher than typical frequencies (like 170 Hz and at 1rst order) does it seem to complicate things. In my own setup, if I deliberately mis-adjust the delay, for example, I can Easily hear it at the lp.
Ivan, while the controls on the Rythmik Audio plate amps (Danny sells the Rythmik A370 amp for use with his paper-cone version of the Rythmik 12" aluminum-cone woofer, but the amp was designed and is built by Brian Ding of Rythmik) indicate that low pass filtering is possible up to "only" 120Hz, the amp is also available in a special version which has been modified by Ding for use in the OB/Dipole sub; that is the version of the amp which provides output up to 300Hz. Kind of confusing!
Actually, I should say that integration issues (one by one) become increasingly less problematic the lower in frequency the crossover point goes (generally) and that integrations problems will not usually altogether ’disappear’ until that point is rather low. But, "low bass" is not "all" the bass. There can still be a lot of bass performance left on the table, unless your mains are so good that they lack for nothing in the bass save for very low-end augmentation only.
Personally, I like a pair of 5'x3'x2' cabs with 24" Hartley woofers. They only needs about 200 RMS/each (if anyone still cares about that measurement) to run and if you brace the cab in the corners with 4"x4" wooden posts, it holds together rather well. You do need big wheels to roll it into place, but a pair of them really add to the concert hall sound of the orchestra.
Group delay is important. Ported designs can have high levels of group delay. Group delay can be like having the bass fundamental 10 feet behind the harmonic overtones. This muddies everything and changes timbre.
That said, most audiophile speakers suffer from this problem already.
I heard a REL S3 subwoofer demoed with a pair of Vienna Acoustic Mozart tower speakers and had a difficult time hear the difference when they plugged in the REL and unplugged it. I thought I had good ears for music. I wonder why I wasn't able to hear much of a difference. However, I continue to hear great things about how musical REL subwoofers are. The T/9i's are only 300 watt subwoofers compared to the S3's which have 400 watts. This seems very low in comparison to other subwoofers on the market. REL as well as the dealer told me it is not about watts but the way REL images seamlessly with left and right front speakers.
However, I did hear a difference when they demoed a pair of Dahli monitors with REL's small Tzero series. The sales person did the same exercise by plugging in the subwoofer and then unplugging it to hear the difference. The first time he did that I was unable to hear the difference. Before he did this a second time, he asked me to listen more clearly. I did not notice much of an increase in bass, but what I did hear was more clarity in the vocals. The salesman told me I should be hearing more space and dimension to enhance the sound stage so I could visualize the artists sitting in front of me performing.
The salesman told me if I was expecting to hear a throbbing bass, the REL's are not designed to do this because if I did, they would eventually drive me out of the room. He said they were designed to make the front speakers sound better with more clarity to enhance what they were designed and capable of doing. I wonder what others think in the group. I am afraid when adding a pair of either T/9i's or even a pair of S3's to my system my wife will not hear the difference and will be upset with my spending the money.
I think you’re original question about large subs can also be about visual integration and optimal placement. The bigger the box the more visually dominant it is in your room. That’s not always attractive. They are also harder to place. Any sub stuck in a corner won’t sound it’s best. Unless you want that movie theater bass flab. The audiophiles I know that have experienced a well integrated sub/subs are no longer against them.
@ivan_nosnibor, the amplifiers in the Rythmik plate amps are not bandwidth limited, they are "normal" Class A/B (the A370 model) or H (the H600 model) full range amplifiers. It is the filter settings chosen by the user that determines at what frequency roll off occurs. All Rythmik plate amps provide controls related to low-pass filtering (the frequency at which the sub's output is rolling off at the upper end of it's operating range), and even a filter for rolling off the low end of the sub (at either 14, 20, or 28Hz), along with a "damping" control, with high, low, and medium settings. One model plate amp (the A370PEQ) also provides high-pass filtered outputs on a pair of RCA jacks (that output signal is sent to the amp powering the main speakers used with the sub). That high-pass filtering is achieved via opamps (as it is in most crossovers), which are in general not "audiophile approved" ;-) .
@bdp24, thank you very kindly for the scoop! I may have some figuring to do in the long run. I'm trying something else for now, but it's definitely nice to have a plan B to turn to if things here don't pan out well!
In audiophilia in general, certainly since the 50’s or so, it appears speaker size (and this naturally includes subs) is more or less everything - that is, the want for limiting size led on by the need for convenience, spousal demands and interior decoration. It’s as well a convenient (and false) argument that "speed" is supposed be an issue with larger diameter drivers; if anything speed is not the proper descriptor here, but transient ability and group delay are relevant factors with bass reproduction, so is headroom/ease (and, ultimately, efficiency), whether a driver is direct radiating or hidden inside the enclosure, whether there’s impedance matching between the driver and the air to which it loads (via an acoustic transformer; a horn), whether the mains are high-passed, tuning frequency, and so on.
(re: @millercarbon) I disagree with the notion that time-of-arrival (and symmetry with the mains) doesn’t matter with low bass reproduction with subs in the mix, as well as the disregard for the importance of similar design principles when integrating subs with mains. Certainly all-horn main speakers benefit from being coupled to horn subs in some iteration when compared to being augmented by direct radiator subs, for a variety of reasons really, but notably the horn-loading of a bass driver creates a different feel of the low frequencies that’s typically somewhat smoother, more refined, dynamic, air-shaking/floating, and present/enveloping (people would know this if they knew what horn bass sounds like, but few does). I won’t argue the overall benefit of multiple subs, benefits that are, but this approach is not going to sonically alleviate different sub topologies; bass is not just bass that sees its unifying "redemption" in coverage alone. The ’dissipated energy in relation to modal behavior’ argument is compelling within a given bass principle.
Big subs, not least in pairs or more, are impractical, ergo they’re undesirable for many an audiophile for whom practical considerations like the above mentioned weigh in. Home audio reproduction therefore often, if not mostly finds its outset in "function follows form" (and not, what it rightfully should, the other way round), leaving us nonetheless pestered with claims about how smaller bass drivers are "faster," the virtues of narrow baffles, small speakers for small(er) rooms, etc. This is also constitutive of an audiophile mentality that ridicules or even detests subs (or mains) that are capable of delivering sonics with brute force down to 20Hz or deeper, typically signified via their large size and occasional use of pro drivers, that supposedly makes them sound less refined or whatever.
(re: @Elizabeth ) My take on the general goal of audiophiles is that their endeavor is typically less about "realism" than cultivation, but the cultivation of what? This is up to each individual, it seems, within the practical provisos mentioned above. I’d wager realism would dictate size not being a constraint, nor frequency extension, ease, SPL-capabilities, dynamics, etc. Trying to reproduce organ concerts at home anywhere near what is remotely realistic, indeed one of the absolute most trying challenges of any hifi-setup, is not only about frequency extension (as your recommendation of a "big sub" would point to), but about scale, size, image stability, impact, spatial acuity, etc.; nothing less than big will do here.