Eh hem!...Subwoofers... What do ya know?
http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm This is the design used to build the subs . I built them exactly to design , 12cuft version |
I would think that within a certain distance . One opposing driver would either assist or hinder the other at a given frequency. Taking all walls and reflective surfaces out of the equation . Dead of space. Think about a truly tuned exhaust. It reflects a sound wave within to increase power . At some point i would assume the area of an 18” speaker would be affected by the other . In phase. Question is how. |
davekayc, two drivers operating in phase with each other are acting acoustically as one driver if they are within 1/2 wave length of each other at their highest operational frequency. It does not matter where they are pointed. As an example if the woofers are crossed out at 100 Hz, 100 Hz has a wavelength of 10 feet. If the woofers are closer than 5 feet they are functionally one driver assuming they are operating in phase with each other. I have two 12" drivers pointed right at each other 3 feet apart right up against the middle of the front wall. There are two other identical woofers one in each front corner. They are placed so that the edge of the driver is right up against a wall. They are over twice as efficient this way. They are all acting as one driver, one wave front. Since the woofers are right up against the wall the first reflection off the front wall is exactly the same as the initial propagation so essentially there is no first or early reflection. Since the drivers form an infinite line source there is no reflection from the side walls either. |
Duke has made available to audiophiles an integrated multi subwoofer system at a great price. Kudos to him. There are three considerations when it comes to accurate bass performance. The woofer itself by which I mean the driver and it's enclosure, the amp driving it and it's integration with the satellites including crossover cut off points, slopes, phase/ time alignment and room control. There are plenty of high powered amps capable of great bass. More electronics are including digital bass management and room control with delay capabilities which makes integration a snap TACT, Anthem and Trinnov come to mind. It turns out the most difficult part to do correctly is the subwoofer itself. Making an enclosure capable of perfectly isolating a high power, long excursion 12" driver is very difficult. Put you hand on your subwoofer while it is playing. Feel that vibration? That is distortion. Any flex or movement of the enclosure is distortion. The ideal enclosure would be infinitely heavy and infinitely stiff. It would be a concrete bunker. This of course is commercially impractical. Designing the internal dimensions of a sealed subwoofer enclosure is easy. Making it acoustically dead is another story altogether. This is where the home hobbyist has a great advantage. There are a slew of great drivers out there and you don't have to worry about shipping and labor costs. You can make an enclosure as heavy as you want as long as it does not fall through the floor. We made killer enclosures with a sandwich of Corian and 1" MDF Corian/MDF/Corian 2" thick. They weighted 250 lb each and when you put your hand on them you felt nothing. |
Does anyone technically know what happens when you aim two subs at each other? Say a foot or 2 feet apart . What do you mean? In phase? Or out of phase? Is there an ideal distance apart to do with frequency? What do you mean? Are we still talking about pointed at each other? Why would you even want to do that? Does it have an affect on the opposing woofer itself such as improving the rearward movement of each other? Would have to be a specific distance i assume . A possible equation ? Only thing I can think you might possibly be trying to get at is what's been covered a zillion times, that waves propagate and bounce and reinforce and cancel, everywhere and all the time, and at all frequencies. And regardless of which direction they were pointed first. |
Duke LeJeune is Da Man. Aka Audiokinesis, he has done more for this than anyone, which this will probably instigate a reaction owing to the fact his one fault is being blessed with an overabundance of modesty. Seriously though the research goes back to Dr Earl Geddes, and another whose name eludes me just now. Anyway, point being what Newton said, if we seem to see far it is because we stand on the shoulders of giants. These guys did the heavy lifting, the down and dirty grunt work of painstakingly measuring actual room modes in actual rooms with different numbers of actual subs in different locations. And then as if that was not enough they applied the brain power to first work out and then ultimately demonstrate- prove!- just how well lots of subs really does work. Duke however is so much a part of the whole thing that not only did I learn about this from him here, but when I went looking for Swarm type subs and was able to find only two systems on the market, it turned out the other one was designed by Duke as well! Anyway, congratulations! You did the research, asked the questions, learned what needed to be learned, and then had the courage to buck the trend and the trolls and do what's right. Good for you. Enjoy! |
And these are not my ideas or research, you can ask Duke LeJeune with Audiokinesis from which I learned everything I know about subs and which swarm array (trolls like the word or not) is the best bass solution I found after trying the conventional ones, he is IMO the one source of truth to go for these matters, I think he have commented in this thread already |
Does anyone technically know what happens when you aim two subs at each other? Say a foot or 2 feet apart . Is there an ideal distance apart to do with frequency? Does it have an affect on the opposing woofer itself such as improving the rearward movement of each other? Would have to be a specific distance i assume . A possible equation ? |
Hi m-db, I wish I could speak to it but I didn’t take advantage of the SVS DSP. I didn’t think it could really compare to the processing power of REW and MSO. Using those programs with the Earthworks Mic I could see what was happening in the room and angle, move, shift the speakers for an optimum result. As others have noted, placing four 150lb subs in the room can be challenging. I also was integrating two subs that don’t have the DSP built in so I opted for one total solution rather than mixing them. It’s pretty exciting to see the hot spots and what MSO does to combat them using time delay, inversion and some wild looking slopes. I also time aligned my mains to the listening position at the same time. It’s easier than you think once you try. It’s just a path that isn’t well tread and it took me a lot of reading and trial and error to get it all to work. I’m a firm believer that the two most important parts of the system are first your speakers then the room. I bought the SVS because of their quality 1,500W MOSFET amps and massive driver motors and bracing they have internally. They can keep up with the Kinergetics driven by my Pass amp very well. I will also say that the SoundPath feet offered by SVS are a huge bargain. I had nasty vibration induced distortion in the room till I bought those and put them on all the subs. The rubber durometer is perfect and totally isolated the subs from the floor and the bass became so much clearer. I also have everything connected via balanced cables, it’s dead quiet. You can hear a pin drop and the ‘lovely’ tape hiss on older recordings. The OP asked when we learned about Subs and I knew how important it was playing in an orchestra as a kid. There are vibrations from a live performance that can’t be “heard” but are essential to the experience. That’s when I started reading about music reproduction and the physics behind it. . . Love how accessible sound is. The highest sound we can hear is 1” long the deepest is 50’ long. It’s amazing. And once you know the science it makes sense why a sub array is such an effective tool to counteract the physics of the room. You’d need 50’ of dampening material to absorb the wave and prevent a back wave from reverberating in the room which simply isn’t possible and why one sub is usually so hard to integrate properly even with DSP as the other speaker waves are truly the vehicle for DSP to be effective. What a great hobby. . . |
I am reading the JL Audio article on sub integration. I'll be responding to it shortly. Honestly it's a bit of a mess, but I agree with their main points. As much as I like how well their room correction works, I find this article attempting to make things a lot harder to understand than really necessary. It's trying to scare you out of trying. But their main point, that adding a sub is like adding a driver to a speaker design, is spot on, and exactly what I've said before. Like they'd loose any money. :) |
I have 20.7 Maggie’s running full range with two stereo Kinergetics sub towers of 5x10” subs and two SVS 16 Ultras. When I hooked up the Ultras to complete my sub array I scared the s**t out of myself and literally jumped off the couch as my stomach flipped, water rippled in a glass on the table, wife jumped out of the shower and yelled about the thunder that was shaking the house to turn off the stereo due to the storm. That was out of control bass and what I suspect is the issue for a lot of people with integration. I have a fully active set up with a Mini DSP, used REW with an Earthworks +-30k to measure the speakers and room. I followed the tutorial and used my own data in MSO and made 12 biquad filters per channel (8 of them) to optimize the room and have reached sub bliss. It is absolutely perfect and there are no modes. I had a friend over for an extended listening session and they asked to take the subs offline because the 20.1’s are full range. They couldn’t believe the difference as they couldn’t “hear” the subs but not being on made a world of difference. No room for the subs as I read above? Make them into end tables like I did. Very WAF friendly with a 1” thick piece of glass on them. Guests have no idea they are speakers. If you can take the time to do it right with a sub array (four is the minimum in my opinion) you won’t regret it. |
Dpac996 place your main speakers where they sound best first, then place your sub-woofers. Symmetrical placement looks good but may not result in the best sound. Use the sub crawl if you can place them anywhere in your room. If you have limited placement options, put them where you can and tune them the best you can. Also for measurements use your main listening position. I made the mistake of pointing the mic forward when I began trying REW. The microphone should be on a mic boom, pointing up, where your head would normally be. Downloading REW is free, you do have to join the forum. REW comes with a test tone generator that will sweep all speakers or just subs. The results from the sweep can be displayed in several ways. You won't need an O'scope. There is a learning curve and some equipment to buy but there are several tutorials available if you search. There is also a forum where you can ask questions. Good Luck! |
Good idea davekayc Keep all options on the table!! The JL E-112 subs have a fair amount of built in tuning so hopefully this proves helpful; Since I am nuts about this stuff, I am going to grab our nice Oscilloscope from work and my omni mics (or use a Laptop with some USB mics) and capture the onset of various test tones; Once I have alignment temporally (overlapping first cycles of sine wave) and magnitude wise, I can play with the sub gain setting if the actual listening test prove excessive bass or what have you. I think the sub/speakers must align time wise for max potential, at least this is what I have read and it makes sense, on paper; I was going to place a mic directly in front of the sub 3 inches away; same for the speaker woofers mic; Cue up some bass tracks or just a sine test tone, trigger the scope on one mic and see how they line up. I am 100% positive if I run the sub off the amp output; the acoustic rising wavefront (the first cycle) will arrive at least 10 ms after the rising slope on the woofer output, due to the delays in the sub; I will repeat the test at the listening chair to see how the alignement changed after wave fronts traveled 9 feet; Once the entire room "pressurizes" does this time alignment still matter that much? -- we don’t listen to successive impulse trains...we listen to music in a complex environment with lots of interference patterns; I can, in theory adjust the JL phase to exactly overlap the sine waves but the sub woofer will always lag the speaker woofer by a whole cycle. This may mean absolutely nothing sonically, or it may be perceived as muddy or too fat. It’s going to be a fun few weeks figuring all this stuff out! If I end up hating the subs / can’t get them to gel, I guess I can toss them in our home theater or sell them; |
I would try everything. Even keeping that position and aiming at each other . You may find only one is needed there and another in the back corner . Take one of them place it on your chair and check the room for standing waves as noted before . Then place the sub where the bass was the loudest. And keep them turned down . Or the bass will sound loose . |
@erik_squires thanks good info; I agree the using a pre-out (or active crossover) the preferred way and so does JL audio, but in my case I am running my XLR only DAC directly into my Amp; I will need to play around in the speaker level input regime until I either get an active preamp or the JL CR-1 (preferred); I actually sold my preamp because I found no real advantage using that vs DAC direct; So, with those funds I diverted into the JL subs and some cables (I digress); Now, it seems that plan was half baked and I would have been better off keeping the pre and stretching the budget to get the subs but I'm already way over my audio budget for the next 10 years, lol Anyone: please take a look at my setup; do you think the subs should go on the inside or outside? https://imgur.com/Paj46Ti -Cheers |
So far this turned out to be not another non sense poisoned discussion, seems subwoofers are "a thing to avoid" for the usual trolls,which is great We are getting now into time alignment, dsp and such, keep it coming, I will take my minidsp mic and rew out of storage and do some measurements on my own system. Thanks to the OP, I bet the short cryptic title is a deterrent 😉 |
Hi @dpac996 So, if I understand correctly, you want to take an amplifier’s output as the input to the subwoofer, correct? And that this output would be shared beteen your main speaker and the subwoofer's input? If not, disregard all of this. :) Now, onto theory and experience! Measurements show that while the effect of an average speaker load on a solid state amplifier is small, it isn’t zero. If you look at the Stereophile simulated speaker load, https://www.stereophile.com/content/real-life-measurements-page-2 they estimate a minimum impedance in the bass of around 6 Ohms, while my experience says this is often in the 3 Ohm or less. So, take a moderately solid integrated, like the Luxman 509, whose deviation from flat based on that load is here: https://www.stereophile.com/content/luxman-l-509x-integrated-amplifier-measurements The effect of the simulated speaker is very slight, honestly, around +- 0.1 dB. So lets say that at 3 Ohms that’s twice as much, +- 0.2 dB. My experience has shown that this is sometimes audible, making speakers seem more demanding of an amplifier. For this reason, if you can take the signal from the preamp instead, which will have a flat impedance presented to it, you can avoid any such issues. In other words, while I understand the math of output impedance, speaker impedance, voltage and current, my experience says that around 3 Ohms is enough to demonstrate a difference among a lot of amplifiers. I wouldn’t want to use that as a reference voltage for that reason. PS - I own a Luxman 507ux myself. Very happy with it, but when I set up my sub, I’ll be taking the signal from the pre out. :) Best, E |
@erik_squires Can you detail this thought please: "Speaker level inputs are subject to the amp/speaker impedance matching" My amp's Zout is much less than an ohm (according to Luxman the damping factor is around 700); The Zin of the powered sub, according to JL's manual is about 4,500 ohms; The back EMF on the speaker cables should be super low, as the speaker "sees" a super low "load" across a very low DCR speaker cable; If I was using an amp with high Zout (say 1ohm), then I could do some math and find, possibly in the 30-100hz region a reactive speaker impedance appearing to be "real" resistance of a similar magnitude to the zout of the amp, then causing a voltage drop the speaker sees, basically a frequency dependent voltage sag; But how would, even in a high output impedance amp, this affect the signal at the amps output eventually reaching the active subs 4.5K zin? My main concern about taking the signal to the sub from the amplifier output terminals, is the time delay that can never be made up by any adjustment in the subs crossover settings; I could delay phase by a full 360 degree to align the peaks, but i'm actually off a whole cycle. This seems bad for impulse response, bass drum hits, bass guitar lines, etc, might be perceived to be "fatter" but smeared. I don't know, maybe i'm going off in the weeds here and none of this actually amounts to a loss in perceived fidelity at the chair; I guess I will find out soon enough. I can see myself diving into the active crossover just because it seems so elegant and proper-- here we have total control over the timing latency and sub/main handoff; Cheers |
+1 for measurements +1 for Mini-DSP Audiophiles make fun of the home theater crowd. The home theater crowd makes fun of audiophiles. Both groups can learn something from the other. Subwoofers should be sized according to the room. I had Vandersteen 2ci speakers in a small room approximately 11x14 and they sounded great, I moved them to a much larger space and the magic disappeared. I did not need a subwoofer for the smaller room. I did need a subwoofer or more for the larger room. Timing matters! I do not have automatic room correction. I use two JTR, S2 subwoofers in the basement. A friend familiar with free REW software came over to help dial them in. My room is 29 feet long. One subwoofer is in the front left corner. The other sub is located in the right rear of the room. The subs were level matched so they both played at the same volume at the major listening position. The subs were then individually measured and the individual measurements laid over one another via the program. The goal was to make two sign waves from two subs appear as one. The delays were made in the Mini-DSP until the sign waves were as close as possible. My friend then proceeded to time align each speaker to the subs. Again the goal is to over-lay all individual measurements and have them appear as one sign wave. We did not get it exact. We gave my multi-channel system a tune up. Now instead of an 8 cylinder engine running on 6 cylinders I had a system working together as intended. Prior to my friend coming over, I had pulled out a tape measure and set speaker distances. The distance measured by tape was different than the distance measured electronically. After timing alignment, I was able to reduce my listening volume by 10db and maintain the same enjoyment and listening intelligibility. I know many use automatic room correction and assume it is correct, you don’t know until you measure. You cannot just do the math to determine delays, the room and things in the room affect how sound travels. According to the math I should need 7-8 seconds of delay. Measuring with a mic resulted in 5.811 second delay. After alignment my system measured +/- 3 Db from 100Hz to 6Hz. I tried to listen to my flat system and did not enjoy it. I tried increasing the overall sub volume, but that resulted in bloated bass. I finally did some equalization in the Mini-DSP and the system came alive. I was able to reduce the overall sub volume back to where it initially measured flat. As someone mentioned earlier, we do not hear all frequencies at the same level. Lower frequencies must be louder to be heard evenly. Equalization helps accomplish this according to individual taste. My system produces great bass for movies but for music you may not know the subs are playing. After the changes, there have been a number of times I have really been surprised at the bass content while viewing non-action movies. I use Innersound Eros speakers for two channel listening. The speaker is essentially two electrostatic panels on top of two ten inch transmission line subs. Bass is omnidirectional but there are recordings where two instruments that produce notes below 80 Hz are used. There are recordings where two pianos or two drum sets are used. A properly set up system can reveal that multiple pianos, drums, guitars are being used, just as a quality set of stereo speakers can reveal multiple singers harmonizing as one. In my humble opinion stereo subwoofers can help a listener detect the dual instruments in those recordings. In my humble opinion, from my humble experience |
pretty solid article on sub integration. https://jlaudio.zendesk.com/hc/en-us/articles/205061040-Adding-a-Home-Audio-Subwoofer I am preparing to integrate a pair of JL E112 subs in my system...showing up in a few days... I will first try high level connection right from the amp terminals to the subs HLE input...then try a Jensen Iso-Max speaker level to line level isolation device...I think ultimately though the JL CR-1 (or similar) the ideal solution for integration mostly because the latency can be better controlled; I initially plan on placing them like this (on the insides of the speakers); https://imgur.com/Paj46Ti feedback welcome! |
Erik said it best, "
Hard to integrate well. Glorious when done right." I've used subs for many years now, mostly to augment stand mount two way's. Up until I had my current setup, my system had to work the best it could in our living room, with minimal options to make changes to the room to accommodate the sub. Now that I have a dedicated room, one that is much larger than the living room and whose dimensions are nearly square, integrating my current subs was incredibly frustrating! Before applying room treatments, the only way to minimize the room adding a single note to whatever the bass line in the music was, was to position them behind the sofa, in approximately the mid-point of the room. The problem with that was the "disconnect", where the performers seemed to be in front of the listener, but the impact of the low bass came from behind. I eventually was able to "tame" the added "single note" by purchasing a calibrated microphone and REW, to help place 10 bass traps. Now when I listen, as my wife says, it's in my "padded cell". |
n without using high pass filtering, matching the stand alone subs to the speakers presentation is impossible. @m-db is not impossible, on my specific case the subs and the speakers are manufactured by the same company, speakers crossover and speakers themselves are tuned to the 4 subs and integrated with dsp amps. The beauty of it is you can follow the designers integration recommendations or you can try to play and better the designers intentions (not that you could have a real chance to improve it much) tweaking dsp etc. As and added convenience 2 out of the 4 subs share the same footprint as the speakers so no extra space needed. I have to add that I personally like the idea of separate subs from the speakers better in terms of location, true you need some extra real estate but not much and you have more options to locate the subs, you can even tweak with the vertical plane and locate 1 or 2 in your ceiling if you are up to the task (I am not) In the case the designer is not the same you still can find speakers with proper integration, most speakers are ranged starting at 50 hz 60hz you could use dsp to match these values as well or modify the xover like you mentioned |
redmosessc10 posts12-16-2019 11:35amEverytime i hear a rig with a sub for 2 channel, i can HEAR the subwoofer, its not a balanced / natural tone to my ears. I know this can be tweaked but i have yet to hear one that i liked. Golden Ear, Martin Logan and other speakers that have self powered subs do a better job at integration than an external unit but i still always HEAR a sub in the room. I do have a sub for cinema but when listening two channel i prefer a passive speaker configuration. I agree. Speakers with built in subs can have better speaker to sub integration. Unfortunately optimal speaker locations may be a poor choice for subwoofers with extra low frequency capabilities exciting a rooms bass modes and nulls. Raising the speaker subs low pass filter helps but defeats the subs capabilities of producing a surprising amount of recorded ELF. Multiple stand alone subs can reduce or eliminate room interactions but that's only one aspect of subwoofer integration. Unless there is some means of comprehensive multi-band parametric frequency equalization, Q, and gain control through the crossover region without using high pass filtering, matching the stand alone subs to the speakers presentation is impossible. An alternative is to select a hard crossover point and reduce the gain until the subwoofers noticeability is reduced which many consider state of the art. Its not. |
Just wanted to add that using the downloadable calculator here I think the measurements I entered fairly well replicate what I am hearing. For fun I put in specs for speakers I am interested in and they really do add seem to alleviate the issues. Assuming this calculator is symbolic of my issues of course. I didn't enter what Focal says the low frequency roll off is, but rather Stereophile's summed measurement at -3db |
Everytime i hear a rig with a sub for 2 channel, i can HEAR the subwoofer, its not a balanced / natural tone to my ears @redmosessc if you ever close to Miami lakes, FL let me know so you can come by and listen by yourself, I have 4 subs and you need to put your hand on the driver sometimes to check if these are working. Of course you can hear what they produce but not in the boomy subwoofery effect, very natural indeed |
I’ve always been able to hear where they are . And thats not good .Then they are running higher than 80Hz. To hear sound below 30 you need way too much volume. That would disturb my neighbors below.This is entirely incorrect. There is no 'bass soundstate' at less than 80Hz; below that frequency bass is perceived as omnidirectional. It is the harmonics of the bass instruments that gives you the soundstage. In the meantime, multiple subs get rid of the 'peaks, valleys and echo slap' since bass 'echo slap' is what causes standing waves in any room. |
Don c55 have you exhaustively set up , tweeked then disliked 4 subwoofers ? It makes your sound stage that much bigger. The beauty part is that you dont make your bass any louder. each device runs a bit lower . And if set up properly , puts the bass focused where you want it. If there was content would you not want to hear it ? Especially considering its at the portion of the audible spectrum that doesnt require bat ears . Your sound stage is freed of the mud that is made with poorly set up system . |
WOW! What a bunch of total bass freaks! My magnepan 3.6’s drop off at 30 Hz and sound great. Bass quality has a lot to do about power amp quality. You can not be a cheapskate. How much musical info is below 30 anyway? To hear sound below 30 you need way too much volume. That would disturb my neighbors below. And the peaks, valleys, and echo slap are too much to deal with. Multiple (4 or 5) subwoofers ruin the bass sounstage. |
Everytime i hear a rig with a sub for 2 channel, i can HEAR the subwoofer, its not a balanced / natural tone to my ears. And this is the problem for me, who bats for team sub. Most subwoofers are not integrated well. When they are, they are magic, when not, they call attention to themselves. When speakers and subs are done correctly with moderate room treatment and EQ they all disappear. The benefit of the sub seems to improve the performance of everything, not just percussion and movies, and extend the dynamic range apparently to infinity. So, what to advise a music lover who just wants good sound? That is the question. Get a big enough speaker, and you end up with the same issues. Get naive or poor room EQ, with poor room acoustics, and you end up with a frankenspeaker effect. |
I’ve always been able to hear where they are . And thats not good . Its the room and the placement and its the equalization. I am happiest I’ve ever been after duke and tim shed some light on dukes swarm . Its incredible. What it did to my mains and the whole room is beautiful. Unfortunately not everyone is going to have room for 4+ subs. A single high dollar sub would cost as much but not be able to compete sound wise. |
Everytime i hear a rig with a sub for 2 channel, i can HEAR the subwoofer, its not a balanced / natural tone to my ears. I know this can be tweaked but i have yet to hear one that i liked. Golden Ear, Martin Logan and other speakers that have self powered subs do a better job at integration than an external unit but i still always HEAR a sub in the room. I do have a sub for cinema but when listening two channel i prefer a passive speaker configuration. |
@vuongp, The CLSII are a new experience for me. Hard to describe but the notes just seem to have so much precense and air. When I first got them and started playing them my wife and daughters came out and sat and listened, they were wowed. My current speakers are the Vandy 5a, Von Schweikert VR4 Gen III HSC and a recently aquired pair of Mezzo Utopias but the CLS panels are what made them come out and listen. The Vandys have terrific bass and great detail but they dont do well with rock. When I play jazz or blues they are great. As to the power, my main system is comprised of: Musical Fidelity M6PRE Musical Fidelity M6PRX amp Denon DP80 in custom plinth with 12in Jelco and Ortophon 2M Black Mytek Brooklyn Dac + Nuc running Roon Rega Apollo as a transport I am running the Utopias in a second system with a Levinson 27 and an audible illusions pre |
This may sound like a dumb question but since the sub has three drivers firing in different directions does this create the effect of multiple subs ? It does give you more bass than a single 8" driver would otherwise, but it’s not like having separate subs individually placed. The direction they are pointing in is kind of irrelevant assuming they can all breathe. Using three 8" subs you get the surface area of around a 12" sub, maybe a little less. The direction they are pointing in probably has more to do with aesthetic choices. The reason for using multiple separate subs is to try to equalize room modes. The situation where you have big peaks and valleys in the bass response. I notice it has no built in EQ. You absolutely want to use an EQ with a sub. It will make integration a lot easier. So will bass traps if you find you have big nulls. |
