Bryon, it might be helpful to explain what you mean by transient response.
Lyngdorf systems (most probably also TACT ones) that have the room correction module do exactly what you have described under point 3 in your post. Thus, what follows is based on my experience with Lyngdorf systems.
When set up right the Lyngdorf room correction system can indeed work wonders, i.e. significantly improvs in the bass response, imaging and coherency (which is related to the transient response you were talking about) of a system. However, unless one goes for the top of the line Steinway Lyngdorf system this often comes at a price, i.e. dynamics (which on one hand is what most system lack anyways, and one the other hand is the main requirement for having system that sounds life-like).
On the other hand, if set up wrong (which often happens in untreated rooms) the Lyngdorf room correction system will literally such out all life from the music. One will be left with a good bass response, a good transient response, good stereo image but crappy lifeless sound...
I would rather opt for speaker designs that attempt to time align the drivers and use a subwoofer that is cross-overed as low as possible, e.g. a REL. Of course, I am just a hobbyist and my opinion is based on my experiences so far :).
Jb8312 To be honest, I cannot "fathom" a sub integrating into 2 channel so well it is seamless, completely cohesive and disappears into the music…
It can be done, but it is very difficult. IME, seamless integration is only achieved when BOTH frequency response AND transient response are optimized. The problem is that it is very difficult to optimize both, and optimizing only one results in an audible "disconnect" between the sub(s) and the mains. To quote myself from another thread...
Much of the time and effort that goes into subwoofer setup is spent optimizing frequency response. That is typically done in one of two non-mutually-exclusive ways: Sub placement or digital EQ. Either of these approaches can result in a much flatter frequency response, making the bass sound less bloated. But both of these approaches can result in a sub-optimal transient response, due to the time misalignment between the sub and the mains. That makes the bass sound slow. To elaborate…
If placement is used to optimize the sub’s frequency response, then the sub often winds up closer to or farther from the listener than the mains, thereby misaligning the sub relative to the mains. Alternatively, if digital EQ is used to optimize the sub’s frequency response, then a processing latency is introduced into the sub’s the signal path, but not into the main’s signal path, thereby misaligning the sub relative to the mains. Hence either approach to optimizing frequency response can disturb the system's transient response, making the bass sound slow (or “out of sync”). On the other hand…
If you set out to optimize transient response, you will usually place the subs on a plane very close to that of the mains. Now the bass no longer sounds slow. But, due to room modes, this kind of placement often results in a highly uneven frequency response. Now the bass sounds bloated again...and so on.
The result of all this is that, when trying to optimize both frequency response and transient response, you often have the experience of chasing your tail. That is what I mean when I say that, under many circumstances, optimizing frequency response and optimizing transient response is a zero sum game.
IMO, the way to defeat the zero sum nature of this game is to:
1. Place the sub(s) to get the best frequency response (varies from room to room) and fix transient response problems with DELAY. This assumes you can independently delay the sub(s) and the mains, which doesn't seem to be a common capability in audiophile systems.
-OR-
2. Place the sub(s) to get the best transient response (i.e. roughly coplanar with the mains) and fix frequency response problems with EQ. But to the extent that the EQ introduces processing latency, you will have to move the sub(s) CLOSER to the listener than the mains. Again, this doesn't seem to be a common arrangement in audiophile systems.
-OR-
3. In light of (1) and (2), the most effective way to optimize both frequency response and transient response is to be able to INDEPENDENTLY CONTROL BOTH THE EQ AND THE DELAY OF BOTH THE SUB(S) AND THE MAINS. That allows you to correct for room modes (better frequency response) and time align the various speakers (better transient response). Very few systems have this capability, and for this reason, very few systems seamlessly integrate subs.
Irv, I have a large aquarium in between my speakers so I have never been able to locate the sub near the middle. Who knows, if I had I might never have been driven to try stereo subs. I guess the plot thickens as our system details come out. In my setup with the tank in the middle two subs to my ears are conclusively better. I suppose the bass blend across the soundstage could be inhibited by the half-ton body of water in the middle!
NVP: All very good points. I was thinking more in terms of getting the easiest in-phase blend wherever your listening position. With a sub in a different place than the the mains, the phase relationship changes as you change listening positions. But as you say, the subs may need a different position for smoother response and better room coupling.
In my own setup I have a compromise between the two. I run a stereo pair of subs, but they need back wall reinforcement for any meaningful low bass, so I position them as stereo pairs against the wall and directly behind the R-L mains. That way I get the room reinforcement and only have to adjust the phase control a little bit, and the frequency range stays pretty uniform throughout the listening area.
Another advantage of separate subs is that the mains and the subs can be built and optimized to their frequency ranges, and it keeps the internal vibrations produced by very low notes (and contained within the sub) from smearing the cabinet vibrations handling the midrange and treble.
Interesting. Since your post, Bizango1, I've more carefully listened to see if I could tell where the subwoofer is in my room. I have to admit the results inconclusive, for two reasons. First, my sub is positioned about midway between my main speakers (though not exactly midway), making the sub more likely to appear blended. Second, a lot of recordings are mixed with mono bass. Perhaps most recordings. This, of course, means that a centrally placed sub will blend even better. So it possible that the only reason I can't tell where my sub sits is because that's how the bass would sound even if the sub weren't present.
Irv, you may have hit on something. I am less than 12' from my speakers due to my smaller room so there is less chance for the sound to blend before I hear it. I wouldn't call my setup nearfield but it isn't "farfield" either. I thought that when I went to full range floorstanders the subs might be too much in the room but that is not the case with the proper (to my ears) adjustments.
Johnnyb53, the speaker position in a room gives the most natural midrange will almost never yield also the best bass response. Whether or not one will obtain good results by placing the subwoofers close/next to the main speakers depends entirely on the room geometry - it is certainly not a given. Having the ability to place the midrange-high frequency source in the ideal place and the bass source in its (different) ideal place is the main advantage of using a subwoofer.
And I meant to add, "Yes, JL Fathom subs are really that good." My local high end dealer carries Wilson, Magnepan, B&W, Vandersteen, Vienna, Wisdom, PSB, Meridian, and for subwoofers ... JL. They do the best electrnoics/room/cable/speaker matching I've ever heard from any store over the 40+ years I've been hearing demos. They could carry any brand sub they want but chose JL, and their setups have proved to me how seamlessly JLs can be blended and how they augment the soundstage and presentation to a higher level of musical involvement, dynamic range, imaging, detail, you name it.
If they'll blend like that with Wilson, Magnepan, Vienna, Wisdom, and Meridian, they'll probably blend with pretty much anything.
The easiest way to get a seamless integration and reasonable phase coherency throughout the room is to use two matching subs placed adjacent to the main speakers. I have something similar now with my Mirage OMD-15 towers and MM8 subs.
And the best most seamless sub/main integration I've personally heard was a pair of JL Fathom F212's flanking a pair of Magnepan 20.1's. There was no discontinuity in timing, timbre, tone, nor noticeable nonlinearities by frequency.
Irv, Omnidirectional means that it radiates equally in every direction from the source. I think we agree on that. My thing is, the farther away from the source you are the lower the amplitude will be. (All nodes aside-different subject) If you had a big room with one sub positioned to one side it probably wouldn't be as loud on the other side of the large room even below 100Hz. If it was, it would be omnipresent as well as omnidirectional. A really loud car stereo radiates its insane bass omnidirectionally but you're glad it is parked far away. Electronic music artists-I'm a fan-take many liberties of production and can stick a 50Hz tone in the left or right as they please and I enjoy hearing it. At least I BELIEVE I can hear it! At least after 40+ years of hifi with no sub/one sub/two subs I know what I like and I'll bet you like your setup too. Always fun discussing and if you're in the neighborhood stop by for a beer and a demonstration.
Irv, I would say that most often integration problems between the main speakers and subwoofers are not caused by the fact that the two are not time aligned. For example, if we place a subwoofer between the speakers and then we move it say 2 meter away from the plane of the two speakers, then at the listening position we will have a time delay of approximately 6 milliseconds between the frequencies emitted by the woofer and by the speakers. As far as I know, most experiments show that the brain considers all frequencies detected within a 50 milliseconds window as par of the same direct sound, i.e. it will detect no echo (repetition of the same sound) for such small intervals. Consequently, I would that this is a second order effect.
On the other hand, destructive and constructive interference (which creates bass nulls and/or significantly reinforce some specific frequencies) cause much more significant problems. Since this depends entirely on the room dimensions and position of the speakers and subwoofer(s) in the room, I would say this is by far the most important complication one faces when trying to integrated a subwoofer into a stereo system.
Regarding two subwoofers vs. one subwoofers issue, two subwoofers yield a more even response in the room (i.e. less null or reinforcements). Most often one can get just as good results with only one subwoofer but this requires very careful set up (this is not two say that dialing in two subwoofer is a piece of cake - not by a long shot).
it's all about the set-up interface and taking the time to do it right. if the set-up software is not up to snuff, the resulting sound will also be sub-par. same applies to taking your time and getting it set-up right (to your liking).
can't comment on JL but it took many weeks working with my velodyne dd12 to get it right....it is truly seamless.
two things i discovered during the journey (for my set-up)
1)much better sound running good mains without a cut-off. this allowed me to back off heavily on the sub volume while still adding the right amount of slam way down low (below 50)
2)there is no single best configuration for all music types. i set-up 4 different audio profiles and depending on the music, a specific sub set-up really makes a difference (rock vs r&b vs classic ect..)
if you do it right...a good sub can really make a positive, seamless difference.
Bizango1, if bass is omnidirectional, and that's a physical fact below 100Hz, then by definition you can only localize a source by means other than listening. :-)
Bass is a funny phenomenon because you feel it as much as you hear it. Your sense of touch does not work like your ears. Hearing is logarithmic. It takes a doubling of power to produce a small difference in apparent loudness levels (3db), yet as everyone knows a doubling of mechanical force feels like a doubling of mechanical force. So a 3db increase in sound level at 40Hz can result in a feeling that you've really turned up the bass, because you're feeling it.
Regarding JL subs for 2ch audio, the only thing that kept me out of an F212 was that it didn't have a high-pass filter for the woofers on the mains. All of my demos of various subs I did revealed that unless you use a high-pass filter, preferably at about 60-80Hz, the bass sounded muddy and over-blown. Yes, I know this is a highly controversial point. Some folks like that bass-heavy sound, but not me. I looked into a Bryston 10B-SUB to perform bass management, but F212 + 10B-SUB = big bucks. I just got a Velodyne DD18+ instead. A pair of SVS SB13-Pluses are also a good choice for music, and include high-pass filters.
I bought one f113 and it took me close to 10 weeks to fine-tune the position, cross0ver points and phase (plus break-in) and all I can say is these are the fastest and best subs I've yet owned. Prior to this I had 2 REL Stentors and had issues with reliability but these JL's seem to be built like a battleship! (Dealer disclaimer - not for JL at this time)
Yes they are very very good and very fast. There is no problem integrating them into a 2 channel system, it just takes time and more of it if you are using 2.
Bass may be omnidirectional but that doesn't mean you can't localize the source. I think that would be called "omnipresent". Like when my wife spots an audio purchase on our credit card online statement within minutes or hours of a new transaction.
If you place one sub in the same plane as the main speakers you can't tell where the sub is, assuming a 60Hz 12db/octave crossover. If you place the sub closer or farther from the listening position than the mains you may have to adjust the arrival time (which is tricky stuff).
Bass sounds are omni-directional, but in a car the shock waves through the structure of a car aren't, and that's why you can tell where the sub is. Even in a house I can tell that the bass is coming from somewhere in front of me, but I can't discern the sub's position between the speakers. Or even that it exists.
Still, I have to agree, two subs are better than one, and optimum positioning seems to be one near each main, assuming that's a good position considering room modes. (It often isn't.)
Larry, I completely agree with you on bass being somewhat directional. If I had to go back to using a sub I would buy two and set them next to the speakers aimed at the listening position. In my car the sub is behind the seat and crossed over at 60hz. I can clearly tell were the bass is coming from.
Yes...and I started to give a one word answer. I recently designed a Home Theater Room for an old friend. Everything done as well as I know how to do it. So, dry wall with OSB glued and screwed non consecutive seams...Golden Ratio 'shaped' room. Incorporated were a pair, (two, not one) JL Fathom Subs. The blend is marvelous. They are fast, faster, fastest...and very smooth. Typically I have never been a fan of trying to blend subs...but let's get real here. What floor standing speaker has sub/bass response? Not many. The JL's are just about perfect to my ear...and when you play a 20Hz, sweep to about 200Hz, there's this incredibly smooth blend that just makes you smile. I chose two, not just because he could afford it, but because regardless of what some say, bass is not 'non directional', just 'less directional' and the two gave me great in room 'balance'.
Way to go guys! Very useful responses so far ... u don't know how to set up... I tweak... I measure .... patience ...
Jb8312, I have seen on your system page that you have the Verity Audio Parisfal Ovation speakers. If I am not mistaken their bass module can be placed so that the woofer fires either towards the listener of away from him (i.e. towards the back wall). Because some of the low frequencies will be reproduces by the Parisfal bass modules and also by the subwoofer, the orientation of the subwoofer with respect to the bass modules and also the placing of the three bass sources in the room is very important. Thus, your situation is not exactly the typical case.
Try to following set-up procedure:
Part One: determine decent parameters for the crossover and volume settings of the subwoofer
1) Play a double bass jazz piece. I usually make a loop using the loop function of my cd player. Most often I use the beginning of the track 3 from Norah Jones' Come Away With Me album, i.e. the first measure of the starting bass piece (3-4 seconds).
2) Than using some common sense settings for the crossover and volume settings of the subwoofer move the subwoofer around the room. You are looking for the ideal place to placed the subwoofer, i.e. the position that will give you no significant resonance or nulls at the listening position. This step is best accomplished with the help of a friend/wife.
3) Once you have found a good place for the subwoofer start playing with the volume and crossover settings for the subwoofer. Your goal is to make the double bass notes to sound all even (i.e. having the same volume) and tight (when you close you eyes you should be able to imagine that these notes are produced by the double bass cords).
Part two: determine the best place for placing the subwoofer
1) Now with the volume and crossover settings determined in Part One, move the subwoofer in your listening position.
2) Play again the same loop with the jazz walking bass and walk around the room looking/listening for the places where you get the best bass sound. Here you should look for the places with good sound when your ears are about at the same height as in your listening position. Most likely you will find more than one palce. Mark the one that is convenient for placing the subwoofer.
3) Change the phase of the subwoofer and repeat step 2.
Final step: move the subwoofer to the place (determined in the previous step) that gave you the best bass integration, and of course keep the phase setting that worked best. At this point it might still be necessary to slightly adjust the crossover and volume settings of the subwoofer but only slightly.
After caring out this procedure, you might want to repeat it with the bass cabinets of your speakers reversed. You never know, you might get even better results.
I have a REL Stentor 3 subwoofer and I have used this procedure successfully a few times already. This "procedure" is a bit of a hybrid between what REL recommends and what I have read here and on other forums. I "come up" with it while looking for bass in my new room. I ended up with the REL somewhere between the two speakers and I get much better bass integration and volume than when placing the subwoofer in the corner as recommended by REL.
Edattalo, correct me if I'm misunderstanding you, but after comparing the two and finding that the Velodyne set up quicker, had higher sound level and better low frequency extension, your friend wanted your JL F112??? I dont understand.
I had a JL Fathom 112. Once it was set up properly, the bass was tight and true. My friend had a Velodyne Optimum 12. One Saturday we thought we would compare the two side by side. The Velodyne was over 10 pounds lighter and set up in less than 30 seconds. At higher volumes the sound level was higher in the Velodyne and low frequency extension was lower by 10hz. I remember how difficult it was to setup the JL. Anyway my friend wished to trade the Velodyne plus $1,100.00 cash. I did because I bought the JL used for $1,900.00. My best advise is to find a store that will let you try a demo and judge for yourself. JL has a lot of hype and there are better subs for the money out there.
In general, I agree with all responses here in that it's all about setup when integrating subs into a 2-channel system. If the setup is not done properly, one will feel that subs will not bring any appreciable or beneficial results when the sound is ruined further. If the setup is done properly, one will be amply rewarded by the full extended bass that the main speakers fail to reproduce. The key is countless of hours of trial and error and patience with a wide variety of listening material, and a reasonably good set of ears.
For my 2-channel customers, I typically recommend a sub for each channel. This adds some benefits for difficult rooms. I also like subs with larger drivers in a sealed enclosure. It can be trial and error and does take some patience, though.
In the first step, I deal with the main speaker acoustics only.....measurements and tweaking, until I get a fairly smooth freq response, and with a smooth rolloff (no large peaks/dips)
In the second step, I deal with the subwoofer acoustics only....same as above, measurements, tweaking, ect
In the third and final step, I am simply bringing the two speaker systems together, to join as one integrated system. This is the hard part, and where crossover points, filter slopes...and maybe some tricks, and trade offs begin.
If I've corrected most bass problems, in steps one and two...that only leaves the unexpected compounding problems to correct, as the two systems interact in the room.
Some small amount of EQ'ing could help here.
My room is fairly large, my speakers are planer types (Apogee Duetta Signatures)...and my subwoofers are large monopole cone types (VMPS passive subwoofers)....integration is top notch. As a matter of fact, I've "never" had anyone pick up on the fact, that the subwoofers were in play...they always think it's the Apogees speakers only.
I use a small sub (Sunfire HRS 8) in my bedroom system and a larger sub (Essex SW 2) in my main system. The rooms and systems are very different, but I've been able to seemlessly integrate both subs. I believe that component/speaker matching and set up are the key.
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