[Kevin Haskins]

Getting good performance is just a matter of using the tool right.

If you want state-of-the-art performance <300Hz you need to measure and have some equalization tools.    I can design a system with multiple subs and a pair of main loudspeakers and get better performance down low than any mega-dollar 2-channel system in the world.    It is just a matter of knowing what you are doing.    The right room helps and having a dedicated room where you can arrange or design it from scratch is highly useful too because down low... it is just a matter of the dance between your loudspeakers and the room.

But.... I'd happily give someone an unlimited budget on 2-channel loudspeakers and give me a $2000 limit on subs/EQ and a pair of loudspeakers and I can beat the unlimited 2-channel budget in blind testing nearly 95% of the time over a given listening area.     

[pardales]

But.... I'd happily give someone an unlimited budget on 2-channel loudspeakers and give me a $2000 limit on subs/EQ and a pair of loudspeakers and I can beat the unlimited 2-channel budget in blind testing nearly 95% of the time over a given listening area.     

Wow. 

[JackD201]

I believe the purist mantra has been no bass is better than bad bass followed by the justification that x percentage of music lives in the midrange.

It is hard to argue against this unless that is you can find a way to get good bass.

I like the tools analogy. I listen three quarters  of the time to large orchestral works. With such a diet, I need full range sound. Bandwidth limitations just take away too much from the music itself. As such I am open to any way I can get true full range and not just a mid-bass hump. Good bass to me after all more felt than heard. It supports the midrange by providing a solid foundation not thickens it.

The problem with subs is not that they don't work, it's making them work. By that I mean learning and then knowing how to do it and having the perseverance to see it through until they are dialed in just right to your ears. What makes it difficult is that there are 3 major factors on which success depends, placement, crossover (point and Q), and level. Changing one parameter changes both of the other parameters to some degree. One sub in my experience is the hardest to integrate in terms of reaching the sonic goal while two are easier in this respect but also require twice the moving and fiddling.

What gives subs a bad rap is that most folks simply tend to run them too hot.

[Niteshade]

I have been asking the same questions. A couple of good people have been spending allot of time answering my questions: http://www.audiocircle.com/index.php?topic=78511.0


It's an intriguing topic to say the least! What brought me to start asking questions was a well made recording of a Jr. High band. (Seems unlikely, but it was done very well!) The dynamic range was ungodly and the number and variety of instruments was impressive. There were drums used in some songs as well as other bass instruments. What captured me was the 'aura' of the drums. A couple of mics must have been fairly close to them and when they were hit...all I can say is: WOW! Not only did it nearly blow me out of my seat, but it wasn't just a subwoofer blast. It was an enveloping, dimensional sensation unlike any I have ever heard before. It truly sounded like being there. I was using two speakers with 15 inch accordian surround woofers in a tuned port enclosure. My listening position is about 8ft back, with the speakers around 8ft apart. The speakers are directed towards my listening position and provide excellent stereo separation as well as that  "center channel" sensation for mono recordings, where both L & R speakers seem to disappear. The speakers are elevated about 10 inches above the floor for better imaging.

Most recordings do not sound like that one- in fact, none of mine do! I noticed the same dimensional, tactile sensation regarding bass and other instruments as a bluegrass jaboree recently. Simply stunning! I was not far from the performers- maybe 10ft. I changed positions a few times to see how the sound field changed. Quite fascinating!

That is my story. I'm not trying to disagree with anybody- these are just observations. As was stated, high frequencies playing along with the bass notes might be responsible for the noticed bass behavior. I do think there is more going on, but don't know what it is yet based on what was told to me.

[Quiet Earth]

Sound Labs uses a similar distributed resonance with their electrostatic panels. Their idea being, rather than try to tame a single resonance of the large panel, divide it up into different sections and let the smaller individual resonances sum into the voice of the speaker. Redistribute the energy rather than try to damp it.

Audio Note also uses a similar idea when it comes to their speaker cabinet resonance. Don't waste the energy, tune it along with the voice of the drivers and crossovers.

This makes sense to me.

Is the "multiple sub" idea similar in that you are summing the room peaks to get an average response, or are you placing subs everywhere that there is a null? It sounds kind of complicated . . . . (Edit : It sounds complicated for the user, not the manufacturer.)

I would think that you should be able to get away with some small, low powered subs if you are summing a bunch of them. Especially if your main speakers already have bass into the 30s. Enlighten me please!

[Duke]

Sound Labs uses a similar distributed resonance with their electrostatic panels. Their idea being rather than try to tame a single resonance of the large panel, divide it up into different sections and let the smaller individual resonances sum into the voice of the speaker.

I hadn't thought of that, but in my opinion it's a good analogy.  A multisub system isn't nearly as precise as what Dr. West is doing in his speakers, but the idea is that a lot of little peaks are much less audible than a few big ones.

Is the "multiple sub" idea similar in that you are summing the room peaks to get an average response, or are you placing subs everywhere there is a null?

The technique I embrace is quite forgiving regarding sub placement.  In theory I recommend one (but no more than one) sub in a corner, one along each of the walls opposite the corner, and one somewhere else, and ideally one should be closer to the ceiling than to the floor (very few people go to that extreme).  In practice, the subs end up going where there's a place for them, and it works out just fine.

I would think you should be able to get away with some small low powered subs if you are summing a bunch of them.

Yes, you can get away with smaller subs.  Four 8" subs have approximately the same surface area as one 15" sub (though excursion and enclosure type also play roles in maximum output).  Two things to consider, in my opinion, are the slope of the low-pass filter, and effects that tend to boost the in-room bass.

Basically, you want a steep enough slope, and/or a low enough crossover setting, that your subs aren't passing lower midrange energy loud enough to betray their presence when the whole system is playing.  You may be able to hear where they are with the mains off, but that's not an issue if you can't hear where they are with the mains on.

Room gain will boost the lower bass, and to a certain extent so will the interaction of the scattered multisubs.  The latter happens because the subs sum in semi-random phase in the upper bass region, transitioning to in-phase below the lowest room mode frequency.   Geddes recommends using one sub that goes very deep and others that do not go as deep, and I think this addresses the bass-boosting issues.  I use identical subs whose anechoic response is approximately the inverse of typical in-room bass-boost, rather than usings subs that are "flat" anechoic. 

[Quiet Earth]

Wow, there's a lot more to it than I thought.

  In practice, the subs end up going where there's a place for them, and it works out just fine.

I think that's what I really wanted to know. Thanks Duke!

[Kevin Haskins]

Wow. 

The reason is pretty simple.   The 2-channel loudspeakers are limited in placement by how they have to be placed for stereo reproduction.   That location is pretty much never the optimal for bass reproduction.     With a couple small subs, a DSP and some room measurement capability you can get much smoother in-room response and it won't matter that the unlimited budget 2-channel system is using some multi-thousand dollar drivers because their response in-room is determined by location and their dance with the room.   

FR isn't everything but it is damn near impossible to have a system with +/- 12dB FR swings down low and have it sound good.   It won't matter how much you spend on it because the bass performance is determined by the device, its location within the room and the relationship with the listening location.     Duke's method of using multiple smaller subs is an excellent strategy and if you can have DSPs on them, that allow you to adjust for delay and properly cross them over to the main speakers you will have much better bass reproduction than you will with just two stereo loudspeakers.   Done right it is completely unidentifiable from a good 2-channel setup with the exception that the bass will be improved.   The DSP will also allow you to use a couple bands of PEQ if you need them.   Every room is different so I do believe in using a little EQ if it helps.   You have to measure multiple locations for the reason Duke pointed out and using too much EQ is almost always worse than using none but there is no simple rule.   You have to measure.   

In terms of what Earl says.... he is right.   Under about 30-35Hz you start to universally pressurize a room (depending upon size/dimensions).   At that point you are below the region where room modes matter and the response is pretty linear compared with 30-250Hz.   Of course for 2-channel use response under about 25Hz is not needed for most music.   But if you are spending $10K on a pair of loudspeakers there is absolutely no good reason not to use these techniques to improve the bass.    It is simply insane to live with +/- 12dB ripples in the measured response in a system in that price range.   

Of course the final issue that isn't solvable with any loudspeaker or room is the fact that recordings are not mastered universally the same.   Especially in the low frequencies you have significant differences in how they were mastered/recorded.   You are ultimately limited by what is in the recording and since there isn't a universal standard for studio monitors or the room, there ultimately is no standard for the bass that goes on the recording.    That is why it is sometimes more frustrating to have extended bandwidth than to have a limited bandwidth.   Also... the less bandwidth you have the less you stimulate room issues so often people prefer to have a system with modest bass reproduction because it is the lessor of evils.   

[mort]

Getting good performance is just a matter of using the tool right.


But.... I'd happily give someone an unlimited budget on 2-channel loudspeakers and give me a $2000 limit on subs/EQ and a pair of loudspeakers and I can beat the unlimited 2-channel budget in blind testing nearly 95% of the time over a given listening area.     

Amen brothea

[pearsall001]

I'm running dual Velo SPL-1200R subs & the listening transformation has been unbelievable. Now that I've heard what dual subs bring to the table there's no turning back. Once one understands that a floorstander is simply competing against itself & the room & it just can't be a jack of all trades for reproducing the full spectrum of music then one might realize the benefits of adding subs into the mix. The term "fullrange" is so misleading & is so overused. I doubt that there are any speakers that wouldn't benefit from a pair of well integrated subs. And by all means it's not all about the bottom end. 

[Quiet Earth]

Of course the final issue that isn't solvable with any loudspeaker or room is the fact that recordings are not mastered universally the same.   Especially in the low frequencies you have significant differences in how they were mastered/recorded.   You are ultimately limited by what is in the recording and since there isn't a universal standard for studio monitors or the room, there ultimately is no standard for the bass that goes on the recording.

Which is why I can't get excited about the "speaker vs. sub budget challenge" posted earlier. What's the point in achieving technically perfect subwoofer bass if there isn't any in the recording? I would guess that at least half of my CDs/records start to wimp out before they even get down to the low E string of the bass.

And if you've ever played in a band or gone to a concert, the bass is never perfect in those situations either.

[zybar]

Take a look at this article:

http://www.ultraaudio.com/twbas/twbas_20100301.htm

Not only does the writer think main speakers + sub(s) is a great way to go...he thinks it allows you to obtain SOTA sound at "reasonable" prices.

George

[rollo]

 If done right there is No going back. I would perfer a speaker that goes dow flat to 20 Hz in one box, however that appears to be a problem in speaker land.
   Why is the lower bass so expensive ? Never made any sense to me spending over $5000 and the bass goes down to 40hz. Piano goes down to 29Hz.


charles

[Housteau]

My systems in the past, the Infinities and my current VMPS have all been four speaker systems.  That is, I use two speaker enclosures per channel, one for the higher frequencies and the other as a low bass tower.  What is different here though is that this is by system design.  As mentioned in previous posts it allows ideal placement of the upper frequency unit for imaging and all the other stereo goodies we shoot for.  The bass unit in turn can be positioned for the best bass and often that is just a foot, or two away from the main channels.  In a way the bass tower works in the similar way that multiple subs do rearranged about in a room, but it works in the vertical dimension only.

There is something I have not noticed being talked about enough and that is the possible problems with phase.  I have experienced this even with stereo bass towers, but I would think it would be much worse with summed mono sources.

With multiple sources and locations of the same frequency within a room, timing differences will cause some to combine and others to cancel.  It is the same effect that room modes produce.  If I understand the use of multiple subs correctly, if set up properly multiple subs can use these timing differences to counter the natural fixed room boundry issues.  However, if set up wrong they can add to them.

[mort]

There is something I have not noticed being talked about enough and that is the possible problems with phase.  I have experienced this even with stereo bass towers, but I would think it would be much worse with summed mono sources.

Most good powerd sub's will have a phase controll

[Wayner]

Here is the problem I have with smaller rooms and jumping on the separate subs band wagon. A 20 hz cycle wavelength is 56.6 feet, 30Hz is 37.6 feet, 40 Hz is 28.3 hz, 50 Hz is 22.6 and 60 hz is 18.8 feet, rounded of for my pleasure. A 10 x 14 foot room will not allow these frequency nodes to develop, as the room is physically not large enough to accommodate the wave lenghts. Now you will get 3/4 or 1/2 wave lengths, but I can't imagine the phasing problems or other stange nodes that will develop with the hopes of obtaining heavenly bass bliss.

I also find it interesting how one bunch of AC'ers are single driver folks, looking for that perfect point source sound (which I truly respect) and another group that insists on more drivers then a Greatful Dead concert.

I am not making judgment here, but I will say there is  more to great sound that a flat frequency response, because there are always design trade-offs. You just can't have everything, the laws of physics get in the way.

Wayner

[zybar]

Here is the problem I have with smaller rooms and jumping on the separate subs band wagon. A 20 hz cycle wavelength is 56.6 feet, 30Hz is 37.6 feet, 40 Hz is 28.3 hz, 50 Hz is 22.6 and 60 hz is 18.8 feet, rounded of for my pleasure. A 10 x 14 foot room will not allow these frequency nodes to develop, as the room is physically not large enough to accommodate the wave lenghts. Now you will get 3/4 or 1/2 wave lengths, but I can't imagine the phasing problems or other stange nodes that will develop with the hopes of obtaining heavenly bass bliss.

I also find it interesting how one bunch of AC'ers are single driver folks, looking for that perfect point source sound (which I truly respect) and another group that insists on more drivers then a Greatful Dead concert.

I am not making judgment here, but I will say there is  more to great sound that a flat frequency response, because there are always design trade-offs. You just can't have everything, the laws of physics get in the way.

Wayner

Wayner,

Don't just focus on the absolute very lowest bass (we are already in agreement that there is very little information below 30Hz or so) .  Well implemented subs can easily cross over to the mains as high as 70-120Hz.

With my Salk SongTowers, they definitely sound better when crossed over in the region I stated above and mated with dual subs.  Not asking the smallish drivers to handle 100Hz down cleans up the midrange and allows me to focus on placement the maximizes soundstage and not worry about extracting as much bass as possible.

My 2 channel speakers (Vandy 5A's) are sort of a hybrid to what people have been discussing here.  They have self powered subwoofers built in so that the amps don't have to worry about driving big woofers.  They also have 11 bands of eq (with Q and output control to fine tune) to help handle room issues.  This approach means I don't have to worry about time and phase issues that placing multiple subs around the room can cause.

George

[Wayner]

George,

I agree with you. I have my sub in the large room crossed over at 80. I find the blend very fulfilling. My main concern is the use of subs in smaller rooms. I'll bet your system is in a nice big room, too. In fact, a long time ago, I tried a sub in my studio and It f'd everything up. I could pin-point the sub's location, it didn't blend well at all (you knew you were listening to a sub) and the room gave me a headache. Now, was it the right sub, I don't know, but I felt then, as I feel now that small rooms and subs are not friendly to each other. Perhaps I need a jack-hammer and make this room more friendly.

Wayner 

[whell]

The idea that the earth goes around the sun was once considered blasphemy. 

There is also the idea that for some this is a hobby, and trying different configurations in one's own system is part of the fun of the hobby, measurements be damned.  If the individual throws in a sub or two or three, and they like the results, more power to them. 

Measurements have their place in the hobby, but I think no more than to provide general guidance.  Sometimes getting in there any playing with your hobby will provide very enjoyable results to some ears, while it might drive a "meter reader" to drink. 

[Duke]

Here is the problem I have with smaller rooms and jumping on the separate subs band wagon. A 20 hz cycle wavelength is 56.6 feet, 30Hz is 37.6 feet, 40 Hz is 28.3 hz, 50 Hz is 22.6 and 60 hz is 18.8 feet, rounded of for my pleasure. A 10 x 14 foot room will not allow these frequency nodes to develop, as the room is physically not large enough to accommodate the wave lenghts.

The room you mention will have major peaks and dips from bass modes down to about 40 Hz.  Small rooms are actually worse than big ones, as the peaks and dips end up being farther apart and therefore more audible and distinct.  If the peaks and dips are very close together, the ear can average them out and the perceived sound is a lot smoother than what the eye would judge from looking at a measurement.  Counter-intuitive as it may seem, smaller rooms benefit more from a scattered multisub system than larger ones do; this is because they are so much worse to begin with.