I was surprised to see the REL recommendation on gain and crossover. I was under the impression that most had the gain set too high. I did.
Subwoofer speed is in the room, not the box
First, if you like swarm, that’s fine, please start a thread somewhere else about how much you like swarm.
I want to talk about the impression that subs are fast or slow compared to planar or line sources.
The concern, and it’s correct, is that adding a subwoofer to say a Martin Logan or Magneplanar speaker will ruin the sound balance. That concern is absolutely a valid one and can happen with almost any speaker, not just speakers with tight dispersion control.
What usually happens is that the room, sub and main speakers aren’t integrating very well. Unfortunately for most audiophiles, it’s very hard to figure out exactly what is wrong without measurements or EQ capabilities in the subwoofer to help you.
So, there’s the myth of a small sub being "faster." It isn’t. It’s slower has worst distortion and lower output than a larger sub but what it does is it doesn’t go down deep enough to wake the dragons.
The biggest problems I’ve heard/seen have been excessively large peaks in the subwoofer range. Sometimes those peaks put out 20x more power into a room than the rest of the subwoofer. Think about that!! Your 1000 W sub is putting out 20,000 watts worth of power in some very narrow bands. Of course that will sound bad and muddied. The combination of sub and main speaker can also excessively accentuate the area where they meet, not to mention nulls.
A lot is made about nulls in the bass but honestly IMHO, those are the least of our worries. Of course too many of them can make the bass drop out, but in practicality is is the irregular bass response and the massive peaks that most prevent any good sub from functioning well in a room.
Bass traps are of course very useful tools to help tame peaks and nulls. They can enable EQ in ways you can’t do without it. If your main speakers are ported, plug them. Us the AM Acoustics room mode simulator to help you place your speakers and listening location.
Lastly, using a subwoofer to only fill in 20 Hz range is nonsense. Go big or go home. Use a sub at least at 60 Hz or higher. Use a single cap to create a high pass filter. Use EQ on the subwoofer at least. Get bass traps. Measure, for heaven’s sake measure and stop imagining you know a thing about your speaker or subwoofer’s response in the room because you don’t. Once that speaker arrives in the room it’s a completely different animal than it was in the showroom or in the spec sheet.
Lastly, if your room is excessively reflective, you don’t need a sub, you need more absorption. By lowering the mid-hi energy levels in a room the bass will appear like an old Spanish galleon at low tide.
106 responses Add your response
Just want to point out that the usual raison d’etre for line arrays in a home is to use pistons with much longer combined size than the wavelengths of the frequency they are reproducing. Please, buy as many subs as you can afford, but you are going to have a very tough time creating a line array that is 56’ long. My only point is that yes, I love line arrays, but I’d have a tough time imagining that I’d get the same benefits for the same reason with an array of subs against a wall in my house. Of course, more IS better. 😂 If you are willing and able to put in multiple subs, SWARM may be a better value overall. In my modest home, one sub is my absolute limit. |
That is a neat trick to use with lower frequencies ( = long-enough wavelengths in-room)! Especially considering the lateral boundaries ( = sidewalls) will be of similar/same composition ( = permeability / reflectivity to lower frequencies) more often than not.
I’m surprised that composition of room boundaries hasn’t come up yet. Of the subwoofer “speed” and surely overall performance, I’ve found it (in my limited experience) to have a profound effect on how multiple subs couple either together or with themselves (in the case of one sub per-Ch), due to variation in room (boundaries-mediated) gain. I get incredible bang-for-the- I suspect the ceiling, in particular, being equally reflective of low frequency, helps. Most sub frequencies should be more vertical line array-like behavior under normal height ceilings (~12’ or less) unless you go by 1/2 or 1/4 wavelength rule-of-thumb. A sub as a point-source (vertically-speaking) seems converse to how wavefronts should work, at least in nearfield, no? [Vertical reflections-mediated] room gain in this way should be considerably skewed anywhere studs and drywall are used over a slab foundation - highly unequal boundaries in the vertical realm for many (most?) listening rooms. |
@phusis The Sound quality at stadium concerts is in general awful, but that is not the point. The line arrays project power better which is what it is all about at these concerts. Exactly, the horizontal array of subwoofers forms a horizontal line source. Who says a line source has to be vertical? If the subs are stereo, they are matched to the main speakers in time and phase, and the volume is set correctly you can not localize a sub running up to 100 kHz rolled off at 48 dB/oct. If you could I would not be using that combination. There is no such thing as too much head room:-) There is nothing wrong with a proper point source system. The image will be smaller and the acoustic power will roll off faster with distance. All other aspects of sound quality are the same. Many people prefer the point source presentation. They do not like sitting up front. That is the usual complaint with ESLs, they are too polite and if you make them do low bass you are correct. THEY HATE MAKING BASS! Which is why I got into subwoofers back in 1978. I had Acoustat X's and they were way too polite. Taking 100 Hz and below away from them unleashes a lion. With an 8 foot tall line source ESL in a room with an 8 foot ceilings they are more powerful than most horn systems, but they do not go as loud. I can get up to 105 dB and that is it. The ESLs do not give up. I run out of power. By more powerful I mean things like snare drum snaps and bass drum kicks have more visceral content. The problem for ESLs is, to get reasonable efficiency the stators have to be as close to the diaphragm as possible and the diaphragm has to be stretched tight. There is no suspension. Thus, an ESL does not have enough space or compliance to make low bass at volume. The diaphragm excursions are too long for them. But, take 100 Hz and below away from them and you can not see the diaphragm move at all. The only limiting factor is transformer saturation. The Sound Labs have two transformers separated by a 6 dB/oct xover at 5 kHz. I am going to remove that crossover and use another amp and a digital xover to run the high frequency transformer. The major benefit of both our systems is the controlled directivity of both horns and dipole line sources, minimizing room interaction which produces a much finer image. Both have ultra low distortion. Because of their efficiency, horns will go louder and require much less power to do it. The ESLs will produce a larger image moving you to the front of the venue. All roads can lead to Rome if close attention is given to every aspect of performance from cartridge alignment to matching the amps correctly to proper control of room acoustics. It is much, much easier to obtain great results with a digital preamp in both systems. Having complete control over frequency response allows one to match the channels perfectly obtaining the best image obtainable. Digital crossovers are superior to analog ones and jacking the bass at 6 dB/Oct below 100 Hz produces lifelike results at reasonable ear saving volumes. |
@mijostyn wrote:
Exactly.
Bring on the pictorial!
You mean as a horizontally configured subs array?
If addressing the full audible frequency spectrum the problem to me is not a point source being a point source, but rather merging more of them and instead have a single ditto cover a suitably wide range to minimize issues. That’s what’s I do having a single point source from just over 600Hz all the way up to about 17-18kHz, while - importantly - controlling directivity down to the crossover region with a fittingly large horn for a smooth dispersion pattern transition to the vertically mounted woofers below. Next step, in theory at least, would be a Synergy horn for a single point source all the way down to the 100Hz, if proper energy coherence can be maintained handing over to the subs - certainly when thinking of the lack of a dedicated midbass section.
My aim is for at least 20dB headroom in the bass region on top of the max. desired SPL level. That’s when efficiency comes in handy, at the expense of size (and, ultimately, ultra low end extension), but sonically it makes a difference few have experienced. Yours is simply a different approach with multiple woofers and a bucket load more power that’s needed here, but you’ll have even deeper extension (flat to 15-ish Hz?) and a no doubt excellent performance in the lower octaves when dialed in. Honestly, I’ve never much cared about the sound of curved line arrays at concerts. They very generally lack midbass presens and impact. I would have preferred the industry officials here cared more about sound than catering to install convenience from smaller boxes and being indifferent to power requirements. Moreover, the variety of bass horns I’ve heard from concerts are vastly better sounding than those typically dual 18" ported subs with their pounding out one-note LF, which is just tiring.
It comes down to listening evaluations eventually. If it works out with higher high-pass, it works out. If not, ~85Hz is where it’ll remain.
My gripe with ESL’s in general has been a lack of overall substance or density to their sound, certainly compared to larger horn variants or hybrid iterations with large woofers. To you that may be about cone-based speakers being too thick (i.e.: slow) sounding, but to me it’s about what lends itself more naturally to my ears. Never heard those Sound Labs - they may be different in this regard due to their sheer size and ceiling-to-floor termination. With regard to large woofers (say, 15") as mids, they do cover less range upwards compared to smaller drivers for them to really be called midrange drivers, but importantly they have a power region fullness and realism here that smaller drivers can only dream of. It’s no comparison, period (when they’re high-passed accordingly they’re even low mids rockets, and run actively will give you another level), so all that talk about smaller drivers being more ideal as mids, when also going down into the upper bass area, fails to take both of these aspects into consideration. ESL’s when large enough, or so I gather, are no doubt different beasts with regard to speed and lack of inertia.
If you cross the subs at 100Hz the subs can be localized no matter how steep the slopes. My subs are positioned close to and symmetrically to the mains and configured in stereo, so no issues here. And I fully agree; when the subs are dialed in correctly it’s just a coherent of-a-piece presentation. I love how the lower octaves "morph" effortlessly in intensity and presence depending on the material. Great bass just "happens" in the air, right in front of you between the speakers or as this immersive presence. |
@phusis Thanx! I think it is more a matter of, you have this idea in your head and dam the torpedoes you are going to do it regardless. I certainly am that way. Each enclosure has 84 individual pieces. I have a total of 4 coats of polyester lacquer to spray, wet sanding between coats and the last coat has to be sanded 4 times to 2000 grit then polished two times. I am putting together a pictorial diary of their construction in case someone wants to give it a go. I am not making any more for any reason ever. I have a much different situation than you. My main speakers are line sources all the way down to 1 Hz. The subwoofers, in order to match the volume at increasing distance have to act like line sources. I achieve that by spacing the drivers at the right interval right into both side walls so that they are acting acoustically as one driver, a bass line source array. No matter how large and powerful you make a horn it is still point source unless you space one every four feet from wall to wall. Instead of one very efficient driver in each channel I use four 12" drivers in each channel and 2500 watts per woofer. The over all distortion at any given volume below 100 dB (already too loud) is probably about the same. You do not see horns at big concerts any more. They hang two 40 foot curved line arrays and A LOT of WATTS. Who cares about electricity bills? @100Hz and 36 dB/oct you will only be 20 dB down at 200 Hz. Imagine a phono stage with a signal to noise ratio of 20 dB. using 48 dB per octave you will be 60 dB down at 200 Hz which is low enough to be masked by louder signals. Other drivers are better at doing midrange than big woofers, that's just life. With ESLs there is a stark difference. If the subs run into the midrange you will easily be able to localize them which to me is very annoying. The subs are integrated correctly when the low bass is there, more felt than heard and you would swear there wasn't a sub in the room. |
@mijostyn wrote:
"Practicality" mostly comes down to convenience, aesthetics and making a decision about something, not what's strictly and barely possible to physically and acoustically integrate in one's home surroundings. You are right about the majority of audiophiles balking at grand size, to which manufacturers certainly cater, but who cares about the majority of opinion when all that matters is meeting a performance envelope in a dedicated listening space, from a DIY-approach and defined by oneself? I don't care about practicality or what's at first easy, as long as the damn things can get through the doors and be properly located in the listening room. Done. Henceforth (or for a while) they're no longer impractical and are well out of way in their respective corners - even at 20 cubic feet per cab. It's really about the will of things and what one sets his mind on. And you don't think 8x12" sealed cab woofers crawling below 20Hz can make things rattle at elevated SPL's? My TH's will bend the windows at war volume, but there's no reason to go there. It's about how they sound at listening levels we're usually exposed to, and that there's an abundance in reserve even at our max. desired SPL's. Ease of reproduction is paramount. Please keep us updated on your quad cab subs development. They look great even with raw surfaces, and I'm sure the sonic outcome will turn out to be quite awesome.
We'll see what comes of it. If we're able to sufficiently clean up the upper band of the TH's I feel rather confident maintaining 36dB/octave slopes will do fine.
As can I. |
In another vein, yes a small sub is "faster" than a larger sub at the same volume level. Ultimately the volume is directly related to the volume of air moved. Because a smaller cone must move further to displace the same volume of air as the larger cone, and it must make its displacement in the same amount of time (Hz), it travels a further distance in the same amount of time. Speed is defined as distance over time and a faster speed means that a further distance is moved over the same time frame. So, then, the smaller cone is ligher making it easier to move, possibly reducing "flop/flutter". But again, the cone travels faster and force is defined as mass times velocity squared. So while mass is a linear function, speed has more impact on the force required to make the cone change direction because it is based on the square of the speed and these forces must be overcome at each cycle of the cone. |
If you put the mains through a capacitor that was not previously there, what does that do to the overall phasing of the drivers, including the mid and high that now have an additional capacitor in their circuit? I run my speakers at 2.5 ways using an 18", a 9.5", and a Heil. I’ve put the cap on the 9.5" (run as three ways) and it is a loosing proposition as I lose a lot of the low end volume near the crossover frequency. I’d never considered it with respect to soundstage and imaging. Also, different types and makes of caps have slightly different sounds. It seems that putting a cap on the mains will then create some degree of coloration that would not otherwise be there. |
During the development of their sensor technology beginning with the SMS-1, Digital Drive and finally with their DD Plus, Velodyne Acoustics (USA). While it doesn't talk it simply listens to the mains, subwoofers within the room as it makes your suggested adjustments and many more. Briefly, using a Texas Instruments platform and Code Composer Studio which enabled a broad range of coded controllers of multiple variable parameters within multiple low frequency bands. The end result are audibly and graphically viewable automatic and manual parameter adjustments saved to memory presets. With the Plus release the manufacturer fully adopted the subwoofer crawl as the first step implementation. |
Your subs look great. Are they push/pull or dual opposed? Have you ever tried precast concrete tubes? FYI..I don't use REL subs. I just use that crossover/volume method. My experience has yielded a great end result that's cheaper and easier and sounds great to me. An advantage of going to an audio show is you get to hear some of the best speakers in the world and then go home and compare. Otherwise the imagination can take take over in beliefs that are not based on reality. IMHO. |
@clio09 Again, Roger is correct. Power and damping drive subs the best. But the real difficult aspect of ESLs is the very low impedance way up high. My tube amps have an output impedance of 1.75 ohms, but my speakers drop down to 1 ohm at 20 kHz. If you look at the system's amplitude curve, it starts rolling off at 12 kHz and by 20 kHz it is down 60 dB! I just got my DEQX Pre 8 digital preamp and the plan is to bi amp the transformers. I am going to use a Bricasti Design M25 to drive the high frequency transformer. The Bricasti has a very low output impedance and will easily take the speakers up to 20 kHz. It also has a huge power supply and will continue doubling down to 2 ohms. Sonically it reminds me of my old Krell KMA 100s. I ran those till they self destructed. Roger West recommended a crossover frequency of 5 kHz, so I will start there. In an interesting inversion the tube amp does a stunning job of driving the lower frequencies and would happily take the speakers down to 24 Hz, If I let it. Solid state amps suffer because of the high impedance, the MA 2s do not. @gdaddy1 That is true, the first motive of any company is to stay alive and to do that they have to sell product. The problem with REL is it seems to be the only motive. Anyone can shove drivers into a box and make up a marketing story. If you want really bad bass and a lot of distortion follow Rel's instructions. I have been using subwoofers since 1978 with electrostatic speakers and have been through every possible permutation. Commercial subwoofers are so bad I design and build my own. Randy Hooker made the best subs you could buy, brilliant design, but way too big for modern sensibilities. Mine are the best subwoofers you can't buy, but unlike Hooker's subs you need a lot of power to drive them. I took me 30 years and 3 trials to get them right. You can see pictures of them in unfinished form at the link below. They are finished in high gloss black polyester and clear coated. If you have questions about the design fire away. There will be a full pictorial of their construction in case anyone wants to have a go at it.
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Yes. The majority of the speakers were very capable of producing strong, impactful bass without using a sub. So, they were fed the full unrestricted signal. So my point is why on earth would you restrict and high pass filter using any of these speakers when they are perfectly capable on their own? For this reason you don't see any restrictive high pass filtering method being used. @mijostyn Not wishful thinking, just a fact. Very simply put... these speakers are allowed to perform as they were designed by the manufacturer without any unnecessary attempts to make them sound "even better" by choking them down and adding complexity. @mijostyn ... I believe ALL speaker manufacturers are looking to "sell speakers" not just REL.
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@mijostyn that is kind of my point for crossing over as high as possible, but Roger always told me the amp has a say in this so for the mains speakers if we can keep the amp from seeing difficult loads it will be happier and run more efficiently with less distortion. Case in point is a Music Reference RM-10 on a set of QUAD ESL speakers. While on it's own it does a fine job, in a active bi-amp arrangement with a 100 Hz LP and HP it relieves it of having to drive the high impedance in the bass. For the bass speakers Roger just advised me to get a decent solid state amp with good damping. |
@clio09 I did not know anything about Roger until I bought some of his tubes, the best I ever had. I use Sound Labs speakers and before that Acoustats. I have been crossing between 100 and 125 Hz for 30 years. It requires a very steep slope to keep the sub out of the midrange. The reason so high is that full range speakers are very susceptible to Doppler Distortion. I chose 100 Hz because that is the point that I could not see the diaphragm move. Aside from lower distortion I get another 10 dB of headroom. ESLs will go extremely loud if they do not have to make low bass and they don't have to force an amp to drive a 30 ohm load. |
@gdaddy1 Subwoofer manufacturers are in business to sell subwoofers PERIOD. They could care less about the performance of your system. Rel is handily the worst but the vast majority of them do the same half baked thing and supply their subwoofers only with low pass filters. Their reasoning is if they make things more complicated and expensive nobody would by their units. The sad thing is they are right. Digital subwoofer management has been around since 1995, invented by Radomir Bozevic (the Boz of TacT Audio). Some subs include a watered down version of room control but without a high pass filter they have no control over the main speakers which is 50% of the issue. Proper bass or subwoofer management has to know what the main speakers are doing to mate the two correctly in time and phase. Then there is the marked improvement in main speaker performance when you relieve them of the lowest octaves. This can only be done by direct measurement of a system in it's own environment. Any other way is wishful thinking which you seem to be very good at. There is, at this time, only one best way to integrate subwoofers into a system and that is with Digital bass management. There are now units available from MiniDSP and Anthem that are very reasonably priced. Benchmark Media Systems uses a MiniDSP SHD Studio with two of their DACs to run their own system and they get great results with it. (Dirac Live) For people who can spend more there is the Trinnov Amethyst and the DEQX units which will be available to the general public shortly. The Anthem STR preamp is 1/2 the price and a great performer. @clio09 One of the best thing about digital signal processing is you can add subwoofer and eliminate the "bump". Full range speakers like ESLs benefit the most from a high pass filter. |
@gdaddy1 wrote: "I couldn't find ONE room where anyone cut the main speakers with high crossed subs. Not one... "So the question is... If the high pass method makes the speaker sound so much better, wouldn't every speaker manufacturer use this superior method?" Did you ask any of them why they chose to not high-pass filter their main speakers? |
Well.... funny you should mention this, because they DO! Look at it this way. Every multi-way speaker incorporates high and low pass filters in their crossover. Adding a subwoofer is no different in my mind than increasing the number of drivers in a box. It is precisely because I approach adding a subwoofer as a speaker maker that I always consider a high pass filter as part of the process. |
If anything is silly its this statement. The better solution isn't always the one that the majority of manufacturers would choose to market or the one that consumers would choose to employ. It's been proven many times over with products across multiple industries. From a business perspective it's almost always about following the money. I find it a bit strange no one to this point has brought up the amplifier in this conversation. If the amplifier could talk and express an opinion on filters, slopes, and frequencies, not to mention phase and damping we might be a bit surprised. After all its the amp that is coupled to the speaker. Lastly, one of the reasons I actively bi-amp using separate amplification for the mains and the passive woofers is I still don't feel an amp, let alone a plate amp belongs in a box with the low frequency driver(s). I'm sure over the last several years the technology has improved but I still remain a bit stubborn here, as I once was about using subs altogether. Maybe I just need a bit more time. |
So I say I, I 😅 am the one to alter the art (italics in quote mine for emphasis). I think this may be the true discrepancy. I do not share a hands-off [the proportional frequencies] mindset, as the work of some masterings is just tailored for a bass environment I don’t recognize. I much rather not run plate amps near max to squeeze more convenient control over this (seems simply a psychological conflict of interests in my case - ease of control vs. concern over fatigue to sub amps); but again - I surely don’t argue this is the most conventional and hassle-free approach once subs are properly integrated. This article helped my thinking on the matter; it was published about the same time I finally started realizing just how (file-/pressing-/master-) version-dependent music playback characteristics can be, before the mechanical / layout characteristics of the kit and room factor in. It’s also part of the reasoning I’m not bashful in thinking glorious bass doesn’t necessarily require taking whatever proportional level the (re?)masterer determined. Just my perception; subject to change without notice. 😉
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Is it just REL you think is silly or are all sub manufacturers silly? I just came back from the Tampa audio show and had this very discussion with SVS. They said they don't suggest higher than 50hz. Cutting off main speakers that are perfectly capable of producing deep base is something they don't recommend. Their words, not mine. Silliness prevailed.... I couldn't find ONE room where anyone cut the main speakers with high crossed subs. Not one. Many of the displays had NO subs and the speakers alone were more than capable of producing deep powerful (dare I say fast?) bass. Their display only used subs for home theater demonstration. 2 channel stereo was speakers only. So the question is...If the high pass method makes the speaker sound so much better, wouldn't every speaker manufacturer use this superior method? Are all these displays competing for high end sound missing the secret sauce that would make their speakers sound even better? Are they ALL silly?
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@benanders The solution to your problem is digital bass management with room control, which is really speaker control. You can change the volume of the subs instantly with sliders for each individual channel on the computer. Room control will even out the frequency response of the sub with the best response at the listening position. I advance the volume of the subwoofers by 6 dB. with the crossover point and slope I use this gives live recordings the thump of the real experience at less than ear damaging levels and I do not change it at all for any given recording. These are choices that the mastering engineer makes and who am I to alter his art? Digital bas management uses measurements you make of your system. It sets the crossover point and slope, and aligns the subs with the mains in time and phase perfectly. After the system is set up it will be flat and your only adjustment by ear or feeling is relative volume. Low bass you feel more than hear. Go to a live jazz club and feel the bass and drums. That is what you want at home without being able to identify the subwoofers by ear. If you can hear the subs as individual drivers you need to rethink your integration. |
@phusis I have no experience with horn subwoofer. For most of us they are impractical do to size constraints. For sure distortion will be lower for any given size driver due to efficiency. They problem is low bass will rattle and resonate almost anything. IMHO is is much easier to make a small enclosure resonance free with clever design and balanced force construction. It will not come remotely close to the efficiency of a horn but is way more practical from a size perspective. You are doing exactly as I suggested for crossover and slope. The game is keeping the sub out of the midrange or you will have mud. You are running 85 Hz @ 36 dB/oct. If you move up to 100 Hz you will have to steepen the slope. I can change crossover points and slopes on the fly which is very helpful for AB comparisons. @audioquest4life The largest I would go is 15". The reason is the larger drivers have more trouble maintaining pistonic motion, they wobble. If you want more subwoofer use multiples of smaller drivers. Two 12's make a 15. Two 15s make an 18. So, go with four 15s. I use 12" drivers because the 15's would require a larger enclosure which will not fit in my situation and larger enclosures are more difficult to control from a resonance perspective. @gdaddy1 Rel is only interested in selling as many subwoofers as they can. Their method of implementation is worse than silly.
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My (limited) experience agrees with properly aligned bass being largely equitable across music genres, @phusis @mijostyn , but I found subs with considerable room gain become less predictable according to how a given track/album was mastered - variation in bass gain seems extreme for certain album versions. Specifically: this variation (in bass gain) does not seem to scale with genre, rather, it seems aligned with specific masters / remasters, some albums / versions having very low bass levels and others (at the same subs’ level) being far too high and exciting room modes that are not heard on other versions. This seems independent of overall SPL for the whole audible frequency spectrum, I should note - i.e., it doesn’t seem to be simply because some albums / versions are simply mastered louder overall. I could make up a rule that it seems more pronounced in stuff mastered for OST’s or something like that, but trying to ascribe a pattern would probably just be misleading and pointless. This tendency is pronounced enough that I’ve considered getting a Goldpoint passive attenuator or similar device from which to run my subs - reduce the # level dials to turn by 50%, but I’ve concern over running the inbuilt plate amps on high level (downstream of a passive attenuator) for each listening session. Thoughts? |
@mijostyn wrote:
That’s a bit of an absolute. Generally we agree, but less than 8th order will do, and obviously it’s also co-dependent on the upper range performance of the subs. Tapped horns, that I use, are bandwidth limited by nature, meaning the lower the tune the more restricted the upper range extension. Even with the same tune though different implementations wrt. compression ratio (depending also on cone rigidity), the specific horn expansion, number of horn folds etc. will have implications on how ragged or not the upper range, outside its intended span, will be. Long story short: even with limited upper end extension of my TH’s, sans corrections in their upper band, I’m applying a low-pass at just below 85Hz, 36dB/octave L-R with great results. Raising the LP just a single Hz or two however reveals a progressively more "rowdy" character - again, sans correction - towards 100Hz, so obviously the uncorrected upper range limit area is entered here. I intend to experiment with some corrections however, aided by measurements, and aim for a low-pass closer to 100Hz. Should be interesting to see the effect of that. As is the subs are essentially "characterless" with two minor PEQ’s in the central bass area. Lastly here: I use the same slope steepness throughout into the mains, also the high-pass over the TH’s at 20Hz (though Butterworth style), and 48dB/octave didn’t fare as well sonically. To me in my setup context 36dB/octave L-R is the sweet spot; neither more or less.
Arguably it’s also a more pressing matter with direct radiating woofers and their mechanically induced noise to boot. Coming down to it I find enclosure "noise"/distortion is less of an issue than that created by the exposed driver itself, unless large quantities of drivers with larger diameter cones like in your (future) case are used, without solving the issue completely though. Or, like in my case with partially hidden woofers with cones that move little due to high efficiency and excursion minima at the tune (that is, the horn/enclosure does the heavy lifting), contrary to sealed, direct radiating designs that are inefficient and have excursion maxima at the tune. Horn design cabs are also inherently braced from the horn path innards, on top of added bracings, and built with interlocked and CNC-machined 13-ply Baltic Birch panels, like my TH’s, are structurally very sturdy.
Per above paragraph of mine, I disagree.
I agree re: subs gain when correctly* implemented. With both music and movie reproduction I never change subs gain as it sits where it’s supposed to for overall balance, although I can understand if some would want to go bonkers with the subs gain lever to suit a particular mood and/or occasion. With regard to measurements, they’re certainly indispensable in many regards and as an outset at least with some parameters, but to me it always comes down to fine tuning per ears as a last tweaking measure - if not in all aspects. Gain structure however I always fiddle into place by ears (like filter slopes), and that in 0.25dB increments; eventually I know exactly where it’s supposed to sit, and no measurement can tell me otherwise. So, it’s a both/and scenario here. |
"I listen to everything from Nine Inch Nails and The Red Hot Chili Peppers to Cherubini String Quartets. I have eight 12 inch drivers in a 16 X 30 foot room, each one powered by 2500 watts. I am into chest thumping as much as anyone. My subwoofers are EQed up about 6 dB so I can get the live concert experience at more reasonable levels. They run up to 100 Hz and are cut off at 48 dB/oct. I never change settings for any type of music and I can thump your chest into the next state and soar with The Lark Ascending, all on the same settings. The music has the choice of how it wants to sound." That is great, I mean fantastic, and I don’t doubt you are having an excellent listening experience...I just need more than that. Liberal volume adjustments of the subs via the SMS do that for me. These are two different perspectives, and my way works great for my use. My new subs are a quad of 18" which will be added to the stereo setup. If I can’t shake the foundation, then 21" drivers are next. This of course is way off topic. Look, I am not speaking against optimizing the listening room and integrating subs as best as possible. We all must take the time to do that ensure we are getting the best from our systems. Been there done that and I feel okay with the way I integrate the subs. It just so happens to be different than that of others. There is no one way or the highway or absolutes in doing some things, it is all subjective, regardless of measuring. My ears will tell me and if they contradict measurements, so be it. I am not going to lose sleep or fret about it. I just want to enjoy what I have and tweak like the rest of us to our "own" satisfaction. Sounds like you have eclectic musical tastes, same here. I could easily listen to Rush, Queensrÿche, Avenged Sevenfold, Bad Wolves, as well as Miles Davis, Rodrigo, John Coltrane, 1812 Overture, Pachelbel’s Canon, Wagner, etc. BTW, listen to Tears Are Falling from Kiss and hear that drum by Eric Carr, the drummer at the time. Incredible playing. Sadly, he passed away from cancer. This is the type of drum beat that I like. In your system, I am sure it will be thunderous. Happy listening. |
@mijostyn "A speaker that is more omni direction is going to sound brighter, even sibilant in a room as compared to a directional speaker with the same specs." I'm curious: Besides tending to sound brighter than more directional speakers in real room conditions, are there any other general characteristics that you'd attribute to more omnidirectional speaker designs? Any typical differences in, perhaps, crossover frequencies with subwoofers? For example, is there any crossover frequency above which the often-noted "airy" or spacious quality of omnis could be impacted? I ask because I have a pair of Ohm Walsh 200 Mk-2 (semi-omnis?) that I'm still trying to integrate with a pair of subs that I recently purchased. Thanks! |
@audioquest4life I listen to everything from Nine Inch Nails and The Red Hot Chili Peppers to Cherubini String Quartets. I have eight 12 inch drivers in a 16 X 30 foot room, each one powered by 2500 watts. I am into chest thumping as much as anyone. My subwoofers are EQed up about 6 dB so I can get the live concert experience at more reasonable levels. They run up to 100 Hz and are cut off at 48 dB/oct. I never change settings for any type of music and I can thump your chest into the next state and soar with The Lark Ascending, all on the same settings. The music has the choice of how it wants to sound. @erik_squires Excellent! Speaker specs are worthless. Amplitude curves taken at 1 meter mean almost nothing. A speaker that goes down to 30 Hz at one meter might make it to 60 Hz in real situations. A speaker that is more omni direction is going to sound brighter, even sibilant in a room as compared to a directional speaker with the same specs. It is more important to understand what the design of the speaker is capable of and how to choose one that fits your needs and situation. Most people choose a speaker that looks good or suits their wife's sensibilities paying little attention to speaker design. They might look at the specs and if they do misinterpret them. Not all speakers are designed intelligently and some are awful. |
Too many speaker buyers take the speaker specs far too literally and think that knowing the -3dB point of a speaker in an anechoic chamber will be close to what happens in their room. From their perspective, if you want more bass you need a speaker with a lower -3dB point.
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@mijostyn "If subwoofers and main speakers are integrated correctly there is no reason to turn the subs up or down with any genre of music. A system that is tuned correctly does not care what genre you are playing. When I use the term , system I include the room in that category. Most audiophiles are ball parking it with their ears which are extremely poor calibration devices. There is no substitute for measurement/ " I completely understand the audiophile aspect but that is not the point I was trying to convey. I use technical measurements, not all ears either. It is entirely irrelevant for me to put an audiophile hat on when I want gut wrenching bass that overwhelms the room and senses. I am literally talking loud parties, disco bass, chest thumping rock, not wine sipping bourbon tasking listening sessions where I am trying to listen to the wood thwack on the drum set or listen for the shimmer of the cymbals. That all goes out the window for me when I am in party mode. Yes, a properly EQed system will provide some of what I am looking for, but this does not fit my lifestyle 100%. I believe OP implies not all things are equal for everyone. I have spent in excess of 100K in building a new listening room in our new retirement house with acoustics in mind. Trust me, I get the bass rationalization. However, I don’t feel the need to split the main audio signals when I can take accurate measurements and feel just as content in my own world. I have had drummers come to the house and listen to my system and tell me this was the only system they ever heard that played drums the most realistic they have ever heard, outside of a live drum session. That is enough for me. I will conclude that yes, the OP has a valid point and something that audio enthusiasts should be aware of but there are many aspects to consider when getting your system optimized. Been doing this for 40 years. Remember, there is world of counterfactuals out there. |
Same sentiment here. Perhaps not “silly” so much as unnecessarily complicated. 😅 I think the main crux of this topic is the cultural inertia that floor-standing speakers enjoy, as the overall concept predates active subwoofers, especially active subs implemented and EQ’ed as > 1 unit. The exact topics as covered in this (highly informative) thread seem rare convo’s among folks employing line arrays, since many (hifi) examples do not reach very far below 100 Hz (mids/high drivers). Sub crossovers below 80 Hz accordingly and quickly become irrelevant for such cases. |
Good thread, I don’t have a lot to contribute that has not already been said. But I have been highpassing all my speakers with an active crossovers for about 10 years now. Every speakers has sounded better with a highpass of 60hz or higher. The improvement subs bring is staggering when done right. With a 24db slope on both ends 80hz is about a high as I can go before I “hear” my subs (probably need better subs to go higher). 70hz is the sweet spot with my current speaker location and 24db slope. It measures flat and sounds good, I do have pretty large capable speakers that handle 70hz and up just fine. I find it silly when people chase bigger and bigger speakers at sky high prices for better bass, but refuse to try an actively passed sub system.
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@audioquest4life If subwoofers and main speakers are integrated correctly there is no reason to turn the subs up or down with any genre of music. A system that is tuned correctly does not care what genre you are playing. When I use the term , system I include the room in that category. Most audiophiles are ball parking it with their ears which are extremely poor calibration devices. There is no substitute for measurement. |
I think what you are missing from the original thesis is that how a speaker performs once placed in a room is very different from the measurements. Sometimes in good ways sometimes in terrible ways. Your experiences are going to be very room dependent. In your room and with your speakers plugging those ports may sound "thin and anemic" which in another situation might sound less boomy and better balanced. I’ve heard from one A’goner that they found the perfect balance by plugging 1 speaker but not the other. Nowhere do I universally suggest you should plug all main speakers, but that if you are adding a subwoofer it may be a good option to make it easier to integrate a subwoofer. What matters is the in-room bass response and which option causes fewer headaches to deal with in equalizing the entire system.
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“Using my ears (crazy isn't it?) I concluded that if your main speakers produce good bass down to 50hz why restrict them? Why? Because it sounded better, fuller, more glorious. Plugging ports and making a sealed cabinet restricts cone movement. Makes the main speaker sound thin and anemic. IMO... if you want a sealed main speaker then it should be properly designed to work that way. Sealing ports and restricting quality speakers as an after thought is a mistake.”
I can rationalize that statement as I feel the same way. I was not sure if the original post is specific to home theater or two channel audio. My use of subs with my current speakers is only to exaggerate bass from old rock albums. Something like Back in the Saddle by Aerosmith or any glam rock bands of the 80s where double kick drum was predominant in the music. Def Leopard and Aldo Nova come to mind as well. During those sessions I rock out and am not really interested in the audiophile aspect per se, since the music is loud. When listing to more settled music such as jazz, or easy listening, say Eagles or Fleetwood Mac, I find myself turning the subs down or off..unless of course I want to feel that added bass because we are partying. I love the overall sound of my speakers as is, Classic Audio Field Coil Loudspeakers T. 1-5 Reference with 18” downward bass and 15” front mid bass, horn loaded with Fostex beryllium tweeter.
What Erik Squires mentioned about bass being omnipresent in way that feels as if it’s an event is usually realized when the subs are playing louder and providing that emphasis, or the main speakers have been castrated and a portion of the bass region output has been shifted to the subs. It’s definitely a feeling and sometimes more is more and maybe better. I just don’t see me adding another layer of crossover complexity to my straight audio chain since the designers of very capable speakers meant for their speakers to be driven with their designed crossovers to give the best sound for their speaker.,
I hate taking the time to see if this piece of music sounds better with that added feeling, when before, it sounded great as is, especially with big big extra large speakers that can play thunderously loud with pronounced bass depth when required. So, for me, bass augmentation is used sparingly. I am long past the crawl method, injuries prevent that, but situating subs in good locations as a starting point and measuring away goes a long way. Check phase, and don’t be afraid to aim subs in directions that are not typical. Also, to add more complexity, what about Speaker Boundary Interference Response (SBIR)? This will surely come into play when setting up subwoofers. |
@clio09 Then I will say it. John Hunter is wrong. He is interested in selling as many subwoofers as he can and not in designing the best possible subwoofer. @tomic601 @erik_squires @phusis This is not all that complicated. Most of you are right, you just need to be able to explain it better. The speed a woofer cone travels is a sinewave function. The average speed to produce a note at a given loudness is a function of size. The smaller woofer has to travel farther to displace the amount of air required to produce the note at that volume so it has to travel faster. The speed is not an issue but "farther" certainly is. Dynamic speaker suspensions are linear only for a very short distance. At some point, depending on the suspension's design, the suspension becomes progressively stiffer until it can not move any farther without ripping it apart. Because of this non linearity distortion increases logarithmically with excursion distance. This is why larger drivers or multiples of smaller drivers have lower distortion levels. They do not have to move as far so they do not have to travel as fast. Bigger is always better, not worse! Boominess has two causes, the subwoofer running into the midrange and a resonant, shaky enclosure. To keep the sub out of the midrange people historically lowered the crossover point. This is a problem for a number of reasons. Much of the impact or dynamic factor comes at higher frequencies in the 80 to 100 Hz range. You want the sub running certainly up to 80 Hz and I will go no lower than 100 Hz. The solution to this problem is running steeper filters, not lowering the crossover point. The problem here is analog filters are terrible at this. You have to have a digital crossover then 8th order and higher is no problem. Running that high a high pass filter for the mains is mandatory or you will have a hot mess. This is advantageous anyway from a distortion and headroom perspective. Making an enclosure that does not shake or resonate is a very hard problem to solve. The easiest part is using a balanced force design. You put a driver in opposite ends of the enclosure running in phase. The Newtonian forces then cancel out. Making an enclosure that does not resonate is much tougher and very expensive, more expensive than most commercial manufacturers will tolerate because they have to remain competitive. This is the reason I make my own. You can see a picture of the final versions before finishing. I plan on doing a full pictorial of their construction so others can copy them if they are inclined. These will be high gloss black. The walls are 1 7/16" thick. Plywood was used instead of MDF because it is stiffer. The individual sections are only 4" wide. The subs sit on the floor horizontally on two spikes right up against the wall. They lean on a special pad. Because they do not vibrate at all nothing will get transferred directly to the wall. Small sealed enclosures are always best with subwoofers but you have to have a lot of power and high resolution digital EQ. Then you can make any sub run flat as a carpenters dream. The last problem is time alignment and this is best done with a digital crossover and room control which is really speaker control. With subs running up to 100 Hz and cut off at 48 dB/oct or higher, if you want more impact just turn the sub volume up a little and you can have it without affecting the midrange or treble. I run mine hot by about 6 dB which gives the music a "live" feel at less than ear shattering levels. A great subwoofer system is more felt than heard. In reality, the faster a subwoofer cone has to move the worse will be it's performance.
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@sfgak wrote:
The XP-3060. It's controlled wirelessly via my laptop, which makes setting filter values for every driver section on the fly from the listening position a very straight forward approach. Neat. @tomic601 wrote:
I was going to say reaching 20Hz is the easy part, but making that last audible octave and a half matter (say, down to 15-ish Hz) is no small feat. For it to really matter you need prodigious cone/air displacement area, ample power and/or high efficiency, proper flooring and overall room construction, etc. Numbers are easy; how they're real-world applied and experienced is quite another thing. Not saying what you've achieved with your subs setup is this, that or the other (obviously, I don't know), but all things being more or less equal (and that's the tricky part) the larger and more efficient subs setup will reproduce the lower octaves more effortlessly, relaxed and viscerally. Whether 20, 30 or more Hz at play here is at first secondary vs. how these frequencies are reproduced. That horn sub variants need to be indeed very large just to reach 20Hz is another matter, not least with non-truncated Front Loaded Horns (I mean, for all practical intents and purposes in anything other than houses: forget it), but here I've found tapped horns to be the best option and overall compromise. For what they do at their size (20 cubic feet per cab with a 23Hz tune) with low distortion, high SPL output there's really no equal to my mind. |
Thanks. I love the speakers. I know some don't like the voicing (bump up at ~4 kHz), but I'm mostly a relatively low-volume listener. I have a very odd shaped room with many non-parallel walls; not bothering to post because I'm moving to Europe soon and will have a more normal-shaped room. Current room has a few modes (left sub has a deep cut at 68 Hz and a very slight boost at 130 Hz, right sub filter cuts a bunch at 55 Hz and a tiny bit at 350 Hz). But with the subs where they are, I get "glorious bass" in and near my listening position. Every room is different, so it is possible that, when I get to my new home, I may be in a position to place the subs more symmetrically with respect to speakers and cross them lower than 70 Hz. As Erik points out, that might allow crossing at a lower frequency. But every room is different, so I'll measure, experiment with various configurations, and listen carefully in the new location. And just in case, I am building an audio conduit to a location that allows flexibility in sub placement, and that location is part of the dedicated audio circuit to help minimize the chance of a ground loop. |
Well, I meant to talk about the enclosure, not how a driver is loaded out the front. I hope most people understood I was specifically comparing acoustic suspension to ported enclosures and not trying to extend that to horns as well. I thought that would have been clear since I was clearing up the efficiency of ported speakers myth. Sorry for any confusion. |
@erik_squires wrote:
Except with horns. The cabinet/horn does the heavy lifting, not the driver - very neat. When the driver has the sole burden to carry, you hear the effort, but it requires of one to have experienced the difference to assess its impact, and react on it. The next step, if one ever gets this far, is actually implementing horn sub variants in your home, but most would be intimidated by the sheer size demand of such solutions. @gdaddy1 -- Different ways to skin you cat. Implementation is key for whatever route is taken here, and being I favor active configuration from a DIY-approach setting filter values of both the mains and subs, high-passing the mains lends itself even more naturally; although housed in different boxes, each sub and corresponding main speaker channel is treated as a single L/R system. The important thing is we're happy with whatever path we're choosing. It seems you are, as am I. @sfgak wrote:
My point was that with a limited amount of bass sources both nulls and peaks are unavoidable, and not boosting the nulls here can certainly be an issue - just like failing to address peaks. Another issue comes from the lauded flexibility of placing, say, two bass sources diagonally to try and address room modes, which I've tried several times with countless filter permutations and room treatments without ever getting to a satisfying result (even with a fairly low XO-point). It may look good "on paper," but I far and away prefer symmetry of subs-to-the-mains placement with all that it entails. Sidewall placement, symmetrically, has proved is viable solution as well.
Unless the subs are placed fairly close to and symmetrically to the mains.
This is of course a cardinal point. I would never do with a built-in DSP/filter of a sub, instead using a Xilica DSP for both the mains and subs, actively, with elaborate filter settings and finely scaled adjustments.
FIR-filter would be helpful here, but using IIR-filters of the Xilica with 36dB/octave L-R slopes produces very good results. 48dB/octave slopes didn't fare as well sonically in my setup context. @tomic601 wrote:
Forest for trees, as they say; engineering only gets you so far when the physical framework is stunted as an outset. |
@avanti1960 got it right…. and building an inert cabinet for those massive low THD but high IMD woofers is not trivial…. but then cabinet movement = trash = output = “ efficiency “….. funny how systems engineering just creeps in….. |
Without wading in too much to solutions, the THX standard of 4th order low pass, 4th order high pass at 80 Hz is really convenient. Keep things in mind though, the goal is 4th order response includes the speaker response, and that we do in fact use assymetrical crossovers in speaker building all the time. 2nd HP and 3rd LP is very common for 2-way speakers. The point is, if all you can do is add a cap to your amp to create a 1st order HP filter, it’s worth it. At the end of the day though, you can't get to a 4th order electro-acosutic response unless you actually measure your starting and end point. |
Agree completely with @erik_squires, @audiokinesis and others regarding treating the peaks with EQ, but not trying to boost nulls. Multiple subs helps with that (not wading into the swarm debate). One tradeoff I have not seen explicitly mentioned (although @phusis hints at it), is that setting a higher crossover point gives you more freedom in placement of the speakers vs. placement of the subs. Leaving the issues of room treatments aside, place your speakers for the best soundstage and imaging, and place your subs to minimize the problems associated with the long wavelengths of low frequencies (which create both nulls and peaks). Most room mode problems tend to occur with sub-125 Hz frequencies, although depending on room characteristics, they can go higher. But certainly, the lower you go, the more bothersome these tend to be. Flexibility of where you can place one or more subs helps tremendously. However, if you cross over at 35 Hz, for example, then you have pretty much lost that flexibility. You really can’t just move one of your main speakers 3 to 6 feet to deal with a peak at, say, 50 Hz, because moving them will ruin your soundstage. Crossing higher provides more options for sub placement to deal with troublesome modes. So, up to a point, the higher you can cross over, the better, up until where you can start hearing the directionality of the subs. This is room-dependent and person-dependent, but typically is around 80 Hz. I experimented with 50 Hz to 80 Hz, and for my situation, crossing at 70 Hz sounded best. The other issue sort of mentioned so far that could be stated more explicitly is phase-matching the mains and the subs at the point of crossover. This requires two things: (1) a continuous phase adjustment on the subs (like on those by Rythmik) or digital PEQ; and (2) a very steep and symmetrical crossover, typically implying an active crossover. That means both low-passing the sub and high-passing the mains are important. Because the wavelengths change quite a bit from 20 Hz (56 feet) to 80 Hz (14 feet), the mains and subs can only be in phase at a small range of frequencies. That is why the steep crossover is needed. Otherwise, even if the mains and subs are in phase at 70 Hz, with 6 dB/octave sloped filters there will be audible overlapping of the subs and mains from the lower audible limits all the way up to ~250 Hz or so. Because all filters have a frequency-dependent phase shift, most of that overlap is out of phase and contributing to "smudging" that translates to "slow bass." For my Dali Epicon 6’s, what has worked well for me is an active crossover (24 dB/octave) crossing at 70 Hz to a pair of Rythmik F12G-SE’s with the GR-Research drivers. Mains about 7 feet apart works well for my space; the subs are in diagonally opposite corners of the room. Since I exclusively listen to digital, I can use Roon’s PEQ on a per-channel basis to remove the peaks from the room modes (almost entirely in the range the subs operate), and then careful placement allows each sub to fill in the other’s nulls. After the digital is converted to analog, I want to retain my Denafrips’ sound signature, so I don’t use digital PEQ involving more ADC and DAC conversions. Instead, I am using a Sublime K231 active crossover; the Burr-Brown op-amps used in it don’t seem to color the sound much. |
@gdaddy1 I have to believe your experience, but I also wish you had measurements to show us what was happening at the same time.
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