Will a subwoofer add depth and clarity to my system, or just bass?


hi folks,
I just purchased a set of Focal Aria 906 speakers with stand, powered by a Bluestream PowerNode (not my ideal system but I had a limited budget).  I think it sounds really good, but am wondering if an upgrade to a subwoofer is worth it, and if so, what would pair well with this system -- my audio guy recommended the JL Audio D110 10" Dominion Subwoofer, but that's out of my price range.  Perhaps a SVSPB1000, for $499?  My room isn't very big, and I don't use the system for movies, just listening to mostly jazz and rock (and classical).
Thank you!
jazz99
A well integrated sub can be transcendent. The key part being "well integrated."
Most hobbyists don't want to buy a sub. They want to buy room correction with a sub attached, and that room correction varies a great deal.

If you can swing it, treat your room first, it will make your speakers sound larger and fuller. It will also help your room like a variety of speakers, including subs.

Audition the sub's room correction. Pay attention to room treatment the dealer may have.

JL Audio has amazingly good room correction, but IMHO it's hard to justify their prices overall.
@jazz99

From my perspective, a well integrated sub can do four things for you

1.  Enlarge the soundstage
2.  Improve the sense of ambiance
3.  Balance a loudspeaker/room that seems too bright
4.  Add a feeling of impact

If you have reasonable flexibility of where you can place the sub, you may not even need room correction or room treatments to get all of these benefits...but with room correction/treatment, you will most likely be able to optimize them.


And with the SVS 1000....if it doesn't do the trick for you...you can send it back.
Subwoofers will not add clarity to a system. They will add impact in the form of notes you can feel as well as sound stage volume.

The problem with them is that very few people know how to integrate them optimally- including the manufacturers!!!. Getting a smooth frequency response with or without room correction is missing the point big time. Subwoofers need to be "timed" to your main speakers- synchronizing the beats at your listening position so that the pulse of the subwoofer is at its peak when the pulse of your main speakers are at their peak.
Getting the timing wrong will cause cancellation and ill formed notes.
Get them timed right (i use the New Order song Blue Monday") and it’s magic.  Just play the music and adjust the subwoofer continuous phase control in small increments until it sounds the best at your listening spot.  
If the sub does not have continuous 0 to 360 deg phase control- forget about it!  
Post removed 
Subwoofers will not add clarity to a system. They will add impact in the form of notes you can feel as well as sound stage volume.


This is kind of true but kind of isn't. I mean, clearly, there is a low pass filter involved. However, the effects are a lot more than what you would expect from this description.

From a perception point of view, they make everything feel more open and larger.


I say this as a man who builds his own speakers, and does his own room correction. I know the measurements and the effects. Well integrated, a sub adds a lot more than just what I quoted above.


Best,

E


a well integrated, high quality sub, can do wonderful things for mids and highs...I have REL T7i in small system, S/5 SHO in main system

The ear simply does not have the time-domain resolution to hear a slight timing mis-match in the subwoofer region. The ear is UNABLE to even detect the presence of bass energy from less than one full wavelength, compared to which small timing errors are insignificant. What the ear IS very good at, is detecting SPL differences in the bass region. This is implied by the bunching up of equal-loudness curves south of 100 Hz. So the ear can indeed hear something going on as you fine-tune the phase control, but what it’s hearing is the effect on the frequency response.

If the main speakers are a bit muddy in the upper bass, you can have the subs overlap them a bit and then use the phase control to dial in some cancellation, thus improving the clarity.

I’ve had many customers claim to hear an improvement in clarity from the addition of subs without highpass filtering the mains, and I’ve heard it too, but cannot explain it, apart from the occasional situation described in the preceding paragraph. Of course there is also the improvement in clarity that can come from highpass-filtering the main speakers to reduce cone excursion, in which case the transparency of the highpass filter can be a factor.

Regarding adding a sense of depth or sense of envelopment/immersion, if you have two subs, you can place one at either side of the listening position and dial in 90 degrees of phase difference. This will tend to synthesize hall ambience. Credit to David Griesinger for this idea. The 90 degree phase difference ("phase quadrature") will also tend to improve the modal smoothing.

Sometimes adding a subwoofer to a tonally well-balanced system tips the spectral balance to the dark side.  When that happens, we can bring balance to the force.  We can add a rear-firing tweeter to just nudge the spectral balance back to normal, without messing up the imaging by adding another source of first-arrival sound. 

Duke

I think when you use a subwoofer one tends to not need to go crazy with the volume . This leads to less distortion on your main speakers . Sounds more pleasing in general . The only reason I ever crank music is when there is bass present in the recordings . without a sub in a system and running speakers with under 12' drivers you need to raise volume to pressurize the room . 
Duke "Regarding adding a sense of depth or sense of envelopment/immersion, if you have two subs, you can place one at either side of the listening position and dial in 90 degrees of phase difference. "

Probably a dumb question, but I have my two subs phase set to 0.  To achieve the above should I leave one at 0 and turn the second to 90?  Does it make a difference if I put one at 90 and the other at 180?  Is one better or even different than the other?
 Thanks

Jetter, I don't know how to reliably predict in advance what would be the ideal, so some trial-and-error is probably called for.   You might even find that something in between, like 45 and 135 degrees, works best.  Or you may find that it makes little difference.   And it doesn't have to be 90 degrees on the dot.  I've gone a bit over 90 at times. 

Phase quadrature will result in something closer to semi-random-phase summing of the outputs of the two subs in-room, which implies partial cancellation, so you might need to increase the level of the two subs just a little bit.   

Is "Jetter" said with a French pronunciation? 

Duke

Hello jazz99,

     For your situation, I'd suggest the SVS SB1000 (12"driver in a sealed box) would be the better choice than the SVS PB1000 (10" driver in a ported box) although either would provide a dramatic improvement over not using any sub with your Focal Aria 906 speakers..  They're both priced at $499 and are powered by the same 300 watt class D amp.  
     The PB1000 is slightly larger and generally considered better for movies and the SB is slightly smaller and considered better for music. 
     Your Focal bookshelf speakers on stands are only reproducing bass down to about 55Hz.  The human audible hearing range is 20Hz to 20,000Hz, with 20Hz being the lowest audible frequency and 20,000Hz being the highest audible frequency.  
     Your current system is reproducing none of the frequencies on your music between 20Hz and 55Hz.  Adding either SVS sub to your system will fill in this gap and you'll be amazed at what you were missing.  I believe the SB1000 sub will reproduce bass frequencies in this missing  frequency range more accurately and integrate more seamlessly with the sound frequencies reproduced by your Focals than the PB1000 sub can.
    For best bass response in your system and room, it's also very important to properly and precisely position the sub in relation to your listening seat.  Here's my suggestion of how to do this:


1. Disconnect your Focal speakers and place them and their stands temporarily outside your room.  You can mark the positions of the stands on the floor (colored tape works well) or just optimize their positioning as a final step in this procedure.
2.Hook up the sub and place it at your listening position.
3. Play some music with good and repetitive deep bass.
4. starting at the right front corner of your room, walk counter-clockwise around the perimeter of your room and determine the exact spot where the bass sounds best to you.  This is a critical step, so take your time and walk the perimeter multiple times if needed to find the precise spot that the bass sounds best to you (natural and detailed without being over-emphasized or attenuated).

5. Reposition the sub to the exact spot the bass sounded best.

6. Sit on your listening position seat and replay the music with good and repetitive bass.  Verify the bass now sounds just as good here as it did at your identified spot.  If it does, your sub is optimally positioned within your room.  If it doesn't, you'll need to repeat this procedure from step#2.

7. Reconnect your Focal spkrs and place them on the stands at the marked positions or reposition them again in relation to your listening seat for optimum tonal response and imaging.  I'd recommend running your Focals full range and connecting them to your amp as usual rather than connecting them to the SVS sub.  There's also no harm in trying both methods and using whatever method you prefer.

8. Set the desired low frequency cutoff frequency on the SVS sub.  This is an important step with the goal being the smooth and continuous blending of the sound from the sub and your Focals.  This will probably require some experimenting with the ideal cutoff frequency likely being somewhere close to 55Hz.  

     I believe an ideal cutoff frequency setting could be determined mathematically if we had all the relevant data but you're likely to arrive at a setting that's very close just doing it by ear and what sounds most seamless to you.  Try to avoid creating any holes in the combination's frequency response.

     My opinion is that, when you have everything positioned and configured properly, anyone listening to your system from your listening seat will just assume you have the best sounding pair of bookshelf speakers they've ever heard.  
      Lastly, I want you to realize that this system will sound great from your listening seat but there is a compromise that cannot be avoided when only a single sub is used; the bass response will not be optimized at multiple other specific spots in your room.  Less discriminating listeners will probably not even pick up on this unless they're sitting at a spot in the room where a bass mode exists.
     Bass modes are specific spots in any given room where the bass will sound exaggerated, attenuated or even absent.  I can explain bass room acoustics in more detail but I'd like to avoid turning this post into an even longer book.
     There are bass systems that eliminate the vast majority of bass modes existing in a given room which results in very good bass response throughout the entire room but they're more expensive and require more subs. I use one of these systems, called a distributed bass array system, but I think it's too expensive ($3K) for your budget, more elaborate (4 SVS SB1000 sized subs with a separate 1K watt amp) than is practical for a small room like yours and not necessary if you're content with optimized bass response at a single listening position.  

Hope this helped a bit,
Tim 

Post removed 
jazz99,

     Woops, forgot about room correction.  You can run bass room correction optimized to your listening seat as part of step#6 above.  It should just further fine tune bass response at your listening seat but will have little to no affect of improving bass response elsewhere in the room.


Tim
Yes a very good quality sub at least in the $1k andup club 
will give great precision in the Bass and bass fundamentals 
up tothe midrange  which for sure adds depth and coherence to the musical performance.
hi folks,
Many thanks to all of you for your advice and recommendations.  I have a lot to learn about optimizing music and sound in general.

I'm just back into good audio after earlier stints with Vandersteen speakers and Grado RS-1 phones, but with a limited budget.  So all of this information is really helpful.  I suppose one rule to follow is... audition a piece of equipment and if it doesn't do it then return it (easier with a store nearby).  Given my small budget I may start with the SVS SB1000 and perhaps try the 2000 if that becomes possible.  My understanding is that the SVS line is the best at this price point (under $1000).  

Tim, thank you for your detailed information about setting up the system. hat will take some time, but it appears to be time well spent in really getting the right balance.  It helped a lot.

I really like how the speakers sound, and the PowerNode II with Bluos app running Tidal CD quality tracks is easy to use.  But this set of comments reinforces the idea that a sub is the way to go to make the system really sing.
thank you!
paul
Look into Rythmik subs. Powered, servo controlled, with a good set of adjustments available, not very expensive. I made heavy sealed boxes for a couple of their 12" kit. They also sell finished subs. Also look into their double 8" subs, also servo controlled. These have the advantage of being able to play higher (to 150Hz, easily) which could be an advantage with standmounts. 
Yes, a sub makes a positive difference. Best to check it out in your own home to see if it’s worth the money. Read into the MartinLogan Dynamo 800x. It’s a bit more than $500. Features Anthem room correction and tons of other settings. This way from your app you can blend the sub and fine tune every setting. This is a good situation if you are running a 2 channel rig without room correction. It’s a compact sealed design. Super fast and punchy. Many online retailers offer generous exchange policy. Ultimately the in home trial is the only way to be sure. Good luck and great question.
I am convinced that adding a pair of subs 
1. Improves the bass range
2. Cleans up the midrange 
3. Widens the sound stage .
the key being placement and tuning ie the phase setting and volume of subs.
i use my pair of kef blade 2s along with a pair of Jl Audio f113 v2. The sound improvements after adding the subs were phenomenal through the entire spectrum.
i am not a profound supporter of room sound correction programs .
noble100 was right on the dot till recommendations no 5, from that point on I tend to differ from him. Not saying he is wrong but saying his techniques are different .
i would recommend you contact Barry Oder ie the sound doctor. His experience with subs spans over 4 decades. I spent a weekend with him and learnt a lot which I have used for setting up my sound . If you call Jl Audio for help they would guide you to the white papers written by Barry . He is a true guru .
http://www.soundoctor.com/whitepapers/subs.htm
Read the above paper written by him and you can contact him over phone . He is a tremendous resource and loves to help people who love bass. Who doesn’t . 
You don’t need a Jl Audio sub to make great music but you need to have it perfectly aligned with your main speakers to sound great .time domain is in my opinion crucial . 
Only way to know is to add a sub. I’ve always found it to be complimentary to any system as a sub can make movies really go wow! Not sure about room correction, I move the sub around and tune it constantly until I achieve what I need to integrate it. Sure there will be imperfect moments within certain songs but overall it’s much more fun to listen with a sub.
I would add a pair of REL T/9i's.  I listened to the Focal Aria line and I kept asking myself where is the bass.  I also asked myself if audiophiles do not like bass in general.  Even their largest 948 aria speaker lacked in bass extension.  Adding two T/9i's will really help.  
The best thing about subs is that you don't need them when your speakers are good. And if they are not good - replace them. And don't forget good source, electronics and cables.
More Audiokinesis gold:

The ear simply does not have the time-domain resolution to hear a slight timing mis-match in the subwoofer region. The ear is UNABLE to even detect the presence of bass energy from less than one full wavelength, compared to which small timing errors are insignificant. What the ear IS very good at, is detecting SPL differences in the bass region. This is implied by the bunching up of equal-loudness curves south of 100 Hz. So the ear can indeed hear something going on as you fine-tune the phase control, but what it’s hearing is the effect on the frequency response.

If the main speakers are a bit muddy in the upper bass, you can have the subs overlap them a bit and then use the phase control to dial in some cancellation, thus improving the clarity.

I’ve had many customers claim to hear an improvement in clarity from the addition of subs without highpass filtering the mains, and I’ve heard it too, but cannot explain it, apart from the occasional situation described in the preceding paragraph. Of course there is also the improvement in clarity that can come from highpass-filtering the main speakers to reduce cone excursion, in which case the transparency of the highpass filter can be a factor.

Regarding adding a sense of depth or sense of envelopment/immersion, if you have two subs, you can place one at either side of the listening position and dial in 90 degrees of phase difference. This will tend to synthesize hall ambience. Credit to David Griesinger for this idea. The 90 degree phase difference ("phase quadrature") will also tend to improve the modal smoothing.

Sometimes adding a subwoofer to a tonally well-balanced system tips the spectral balance to the dark side. When that happens, we can bring balance to the force. We can add a rear-firing tweeter to just nudge the spectral balance back to normal, without messing up the imaging by adding another source of first-arrival sound.

Duke


More pure gold. I’ve copied the whole post just to pose a pop quiz and see if anyone can answer: what one single letter best differentiates Duke’s highly informative post from all the rest?

Hint: to understand the answer is to understand the problem.
I use a dual 8” sealed sub with Silverline Minuets in my bedroom. The speakers are wired off of the sub, and the sub volume is set low.

The sub seems to add additional dimension (and lower bass) to the music/soundtrack. I notice the difference when the volume triggers the sub to kick in. I think I would miss the sub if it were removed from system.

Regards,
gary
A subwoofer to reproduce and enhance the lowest frequencies will definitely add "presence" to your music and movie watching. Most natural sounds are in the low frequency range. Furthermore low frequencies are felt by the body as much as heard by the ears.  Most modern amps that are designed for surround sound will have a dedicated subwoofer output with the correct phasing and crossover otherwise many subwoofer designs offer built-in crossovers.  The most extreme important task when setting up a subwoofer is ensuring the phase of the subwoofer matches the phase of the main speakers.
millercarbon:
"More pure gold. I’ve copied the whole post just to pose a pop quiz and see if anyone can answer: what one single letter best differentiates Duke’s highly informative post from all the rest?

Hint: to understand the answer is to understand the problem."

Hello millercarbon,

     I completely agree with you that audiokinesis keeps delivering audio gold by sharing his vast audio knowledge and experience with his thread posts.  I always learn a lot from his posts. 
     Now, your pop quiz question has me stumped:
     What one single letter best differentiates Duke’s highly informative post from all the rest? 

     I really have no idea but I'll take a stab just for fun.  

     Is it 'G'? 
As in g, I didn't know that.

Tim

Today’s post is brought to you by the letter "S".

The letter "S" has the Super Power of being able to turn singular into plural. But not always! Due to a design flaw it can only do this when used at the end of a word. Luddite Forces in the Audioverse exploit this weakness. In a typical mind-trick they say, "This is the subwoofer you are looking for." See what they did there? The original quote was, "These are not the DroidS you’re looking for." They dropped the "S"! Pulling you back, always back, to the singular.

It’s a trap!

Don’t go over to the Dark Side. Unleash the power of the letter "S". Use four subs.
Subwoofers will not add clarity to a system. They will add impact in the form of notes you can feel as well as sound stage volume.
I’m not sure of the logic behind this statement, but it is at least subtly wrong. In a small two-way system, the woofer covers both (sorta) bass and mid-range. The large excisions of the bass modulate the mid-range, since the mid-range is superimposed on a vary-ing, larger, bass excursion. This HAS to muddy and distort the mid-range. And in my listening, it does (or did, its been a while)

Beyond that, yes, it will add weight, impact and richen the timbre.
Now, all this depend son proper setup, and you need to remember that the subwoofer must be phase aligned with BOTH speakers, and that phase alignment is perfect only for one listening position. Do the math. Its worth spending some time to get the position right, and if the crossover may be varied, to find out which one integrates best with your main speakers.

I really like sub-woofer / satellite systems if all the above are observed.
Some of my fav’s from the way-back machine were Spica TC-50is and Sequerra Met-7s with a decent woofer such as an Audio Pro (about $1000, 30 years ago).
G


+1 on ML 800x for configurability
600x is $600, ported and might integrate better with ported mains

A sub MUST have 0 to 180 phase control, phase invert, 3 and 4th order slopes in addition to level and frequency.

The ML x series do and have the advantage of being adjustable from a smart phone. With the ARC microphone and Anthem Room Correction software, room faults can be somewhat mitigated.

IMO, you should roll the low end out of your mains. This effectively increases main amplifier power and makes integration with the sub easier.  Do NOT use the sub the sub internal XO. Depending on the room and sub, you may choose different frequencies. A single polypropylene, Teflon or polystyrene cap can suffice for a start. See http://www.ielogical.com/Audio/SubTerrBlues.php/

Learning to use something like REW [Room Eq Wizard http://www.roomeqwizard.com/] will pay huge dividends

Adequate low end room control is big, expensive and ugly. Judicious furniture placement and main/sub location can get you most of the way there. Just don't listen in a sparely furnished room with bare walls and floors.

I disagree that one can't hear phase in the bass. Having spent 1000s of hours in studios with time aligned monitors, getting the low end phase as good as it can be is essential. When it's not correct, kicks and snares are flabby, upright bass strolls and live orchestras have no focus.

A good sub properly integrated improves the listening experience out of all proportion to the frequency band.
The letter is "C" for correct.
@audiokinesis

Adjusting the continuous phase control provides much more than a slight amount of timing adjustment and my ears were quite capable of hearing when I had the correct phase setting. With such a range of adjustment it is possible to ruin the sound or optimize it with proper listening and technique.
Same for my car subwoofer- with time delay I was able to fine tune the proper delay relative to my main speakers and once you find the spot- car or home- the bass becomes effortless, deep, powerful and fully coherent through the range. The subwoofer then complements and works with your main speakers rather than fighting against them.  But again, the key technique was using beat pulses rather than pink noise.  
Thanks again, all, for an interesting weekend of reading and learning. I suppose one has to make a decision at some point, so will try to decide (after auditioning) between the SVS SB1000 and the JL Audio Dominion D110, which is unfortunately twice the price (but perhaps twice as nice).  I'm grateful for all of you for taking the time to weigh in on my question.
happy listening (and trails),
paul
You can lead a horse to water....
You can lead a horse to water....

If you build it, the horse will drink lols.

I’ve had many customers claim to hear an improvement in clarity from the addition of subs without highpass filtering the mains, and I’ve heard it too, but cannot explain it, apart from the occasional situation described in the preceding paragraph. Of course there is also the improvement in clarity that can come from highpass-filtering the main speakers to reduce cone excursion, in which case the transparency of the highpass filter can be a factor.

I don't think I know why for certain but I can talk about some of my experiences.

When I replaced the cap in my tweeter xover with an expensive cap, one of the biggest improvement was the bass.  Also, if I disconnect the tweeter, the bass became a bit indistinct and mushy.  Why would the treble have anything to do with the bass?  

When the drum is struck, the initial impact from the drum stick creates a lot of high frequencies extending up all the way to the treble frequencies.  Then followed by the decaying sounds which are lower and lower frequencies as the decaying dying down.  So the drum is not just bass, ti has a lot of frequency contents - from bass to treble.  In the actually event, although the drum sound has a lot of frequency contents, all of them all arrive from one source therefore the sound is time and phase coherent naturally.

But when the sound of the drum is reproduced in a 2way or 3way speakers, the high frequcies and low frequencies of the drum all come from separate sources (tweeter, midrange, bass drivers) and our human hearing has to somehow reconstruct all those frequencies to give us an impression of a drum sound.  If your speaker is not well tuned, then the drum may not sound clean or well defined because my guess is the treble and bass frequencies are not as time and phase coherent.  If you have too much treble, then the soundstage my not be enveloping and so on.  If you have a lot of bass and not enough treble, the soundstage will be vague and not quite transparent.  Everything is is somewhere in between.

For example when I listened to Margin Logan, I always got an impression that the bass, midrange, and treble somehow are disjointed and not quite integrated, because subwoofer and the panels have so different speed that the sound stage is sort of odd.  So in this case, having a subwoofer does not automatically mean "better".  

And likewise so, if you already have a perfectly setup system, adding a subwoofer may actually be more harm than good.  So you have to be careful.   And of course, if your system may be a touch lean, not enough bass, then adding a subwoofer will compensate for the "leaness" and add some clarity to the soundstage.

Also it may have to do with a subwoofer filter design.  The subwoofer may use a shallow slope filter, hence its frequency response may extend all the way to the upper mid range or treble which in turn will have a lot  more affect on the overall soundstage - good or bad.  But if the subwoofer has a steeper filter design, the frequencies will be mostly in the bass, therefore the affect may be just bass impact and not as much in term of overall soundstageor clarity.  


@avanti1960 wrote: "Adjusting the continuous phase control provides much more than a slight amount of timing adjustment and my ears were quite capable of hearing when I had the correct phase setting."

And I totally believe that you are quite capable of hearing when you had the correct phase setting. I just think you are most likely hearing the frequency response improvement that arises from your phase optimization. Whatever the case may be, thank you for throwing a spotlight on the improvements possible from adjusting the phase control.

Duke

One must remember that a filter alters both the phase and magnitude of the signal. This is represented by a phasor vector. See https://www.electronics-tutorials.ws/accircuits/phasors.html

Adjusting the phase control does not adjust level, only phase. When correct, there is minimum deviation in the vector sum, even though the level sum is relatively unchanged

See http://www.ielogical.com/Audio/SubTerrBlues.php/#Phasors for illustrations of how vector sum affects sub response.

If your sub does not have phase control, phase invert and variable slope, you have to be very lucky to achieve optimal integration.

In the immortal words of an LA musician, composer and all around genius:
¿¡¿¡¿¡¿¡¿ Those little speakers aren’t putting out all that gorgeous bass ?!?!?!?!?
<- No, there’s a Force subwoofer at the end of the sofa. ->
Every other subwoofer I’ve ever heard just boomed!!
And I totally believe that you are quite capable of hearing when you had the correct phase setting. I just think you are most likely hearing the frequency response improvement that arises from your phase optimization
- audiokinesis

Hey Duke that is an interesting point you raised there. Reading between the lines you seem to be implying two distinct aspects- timing and frequency response. The way I've been thinking of phase is it sort of emulates location. Like, if the wavelength is 10 feet and you move the speaker 5 feet its the same as 180 degrees in phase. Yet I know that's really simplistic, its not just the one 10 ft wave that was shifted they all are. So is that why the setup (if I even understand that fully!) is first to get the four subs located one by one for flat response, and then fine tune with phase? To minimize messing up timing in the process of trying to get flat response? 

Millercarbon, my suggestion is this:  Once you have placed the subs, first adjust the gain, then the frequency, then the phase on the sub amp.   Expect to cycle through gain-frequency-phase several times.  

The word "timing" seems to me to imply "arrival time".  The ear/brain system is not very sensitive to arrival time in the bass region, but it is sensitive to decay time, because decay time translates to frequency response in the bass region.  Let me explain:

Because speakers + room = a minimum-phase system at low frequencies, the frequency response and the time-domain response track one another.  When you have a time-domain problem, you either have a peak or a dip.  The good news is, when you fix one, you simultaneously fix the other.   So bass traps reduce the decay time and thereby fix the frequency response along the way.  Likewise when a distributed multisub system fixes the frequency response, it also fixes the time domain response along the way.  Peaks take longer to decay into inaudibility than the rest of the signal, which is why they make the bass sound "slow". 

Back to "arrival time" for a minute.  I read an AES paper several years ago where they played signals of less than one wavelength at bass frequencies through headphones.  The listeners did not detect any sound.  They could not detect the presence of bass from less than one wavelength, and had to hear multiple wavelengths before they could detect pitch.  This implies that relatively small timing differences - "small" relative to the wavelengths in the bass region - are not going to make an audible difference in and of themselves. 

But in the bass region, the ear actually has a heightened sensitivity to differences in sound pressure level.  This is shown by the way equal-loudness curves bunch up south of 100 Hz.   A 6 dB difference at 40 Hz is subjectively comparable a 10 dB difference at 1 kHz.  This is why we can hear the bass so much better when we turn the volume up.  This is also why it takes so long to dial in the correct gain setting on a subwoofer amp - if we're off just a little bit, it's distracting.  Finally this implies that the subjective improvements from smoothing the response in the bass region are greater than we would think simply from eyeballing before-and-after curves.

So I think that where the phase control makes an audibly significant difference ends up being in the frequency response domain, especially in the region where the sub is blending with the mains.  I believe that the correct phase control setting is the one that results in the smoothest frequency response, but this is found in conjunction with the gain and frequency controls.  They all work together... gain makes the biggest difference so we adjust that first, then we adjust the lowpass filter frequency, and then the phase, and then we cycle back through fine-tuning at least once.

Imo, ime, ymmv, etc. 

Duke


Duke,

Excellent explanation and it all makes perfect sense to me.
I was thinking, however, that I may understand better than some reading it since I’ve experienced the transformation of perceived bass response in my room by using a DBA (distributed bass array) system.
I think the practical consequences of designing a DBA system based on utilizing the principles you explained does not really become fully understood until an individual actually hears the transformation themselves.
I remember James Romeyn describing the bass response I should expect in my room from his Audio Kinesis DEBRA DBA system and thinking it all sounded too good to be true.

In fact, I recall being skeptical right up to the point I pressed play after setup was completed in my room. It didn’t take me long to know James was telling me the truth. My honest opinion is that the transformation of the bass response in my room to state of the art was nothing short of miraculous, especially considering it was affordable ($3K) and done without any mics, room correction, room treatments or other special equipment.
I know you’re too much of a gentleman to use a thread post as a sales promo for your own products so I’m taking the opportunity to do it for you and Jim as a very satisfied customer. Besides, no one ever accused me of being a gentleman.
I can state with certainty that the DBA system works extremely well whether it’s an Audio Kinesis Swarm or Debra complete system or a 4 sub custom configuration with subs of your choice.
My main point being that I could write a book on how well it performs and convince no one but it only requires a short audition to prove to anyone. To mangle an old expression, a listen is worth a thousand words.

Tim

@noble100 , thank you for taking the "leap of faith" in the first place, in spite of your totally reasonable skepticism.  And thank you for posting your experiences here.

I try to promote the CONCEPT of a distributed multi-sub system (which I learned from Earl Geddes), rather than specifically "my way" of doing it.  Obviously I put some thought into "how to do it well" at my chosen price point, but a distributed multi-sub system is a cat which can in more ways than one be skinned. 

Anyway I think it's great that you find Jim Romeyn's DEBRA to exceed your expectations and continue to make the magic happen for you over the years.  His subs arguably have a bit more practical footprint than mine do, as his hug the walls better.  

Duke 


Repeating a bit here but all my experience trying to get really good accurate low bass had me pretty well convinced it was impossible. Yet this experience wasn't all wasted. It resulted in a solid base of understanding from which to evaluate alternative approaches.

Because of this, when I happened across Geddes/Swarm/DEBRA it was immediately apparent this held promise. It still took a lot of reading to confirm. Fortunately between threads like this and the articles and reviews it led me to there is no shortage of information out there. Hard to overstate how disappointed I am that so few people are interested. Equally hard to overstate how happy I am that Duke and Tim are interested enough to share and help. Thank you guys. Bigly!

On that score, can't help but note that reading about the DEBRA setup Tim uses part way down the page it states, "Conservatively rated by designer Duke LeJeune for 113dB output @20Hz" and  “Room Gain Complementary” tuning (Duke LeJeune)." http://jamesromeyn.com/old-pages/home-audio-gear/dsa-1-0-distributed-subwoofer-array-5-pieces-4k-usd...  So DEBRA or Audiokinesis  http://www.audiokinesis.com/the-swarm-subwoofer-system-1.html either way you are getting Duke. Which I was all set to buy, its almost a no-brainer, except I had all these sheets of MDF just taking up space in my shop! Lol! 

Way back in 1980 an article by Roger Sanders in Speaker Builder explained the challenges of bass reproduction clearly enough to compel me to invest what was for me then not inconsiderable time and money building a set of his transmission lines. With zero personal feedback from anyone having used them. Based entirely on my understanding of the principles. Worked out far better than I ever dreamed. 

Didn't see it as a leap of faith then. Don't see it that way now. More like a slam-dunk. Thanks to you guys.

Millercarbon wrote: "Hard to overstate how disappointed I am that so few people are interested."

The following is just my guess:

One of the things that is an awful lot of fun about high-end audio is, pride of ownership in a piece of equipment that has astonishing and enthralling characteristics. In a subwoofer, "astonishing and enthralling characteristics" usually have to do with how powerful it is, how deep it goes, how much air it moves, and how impressively it renders highly challenging program material such as cannon shots, pipe organ, depth charges, and dinosaur footfalls. That stuff is as engaging and entertaining as understanding and appreciating what’s under the hood of a sports car and how it translates into raw, adrenaline-jolt performance.

With a distributed multi-sub system, your budget is spread across (typically) four subwoofers, so the individual subwoofers will fall well short of what you could have in a single sub for the same price. It’s like you can have four Toyotas or one  Lamborghini. And it is not at all obvious that those four Toyotas used properly might be able to do something really cool, something even better than that one Lamborghini.

The IDEA that four (relatively) small subs can successfully address what is arguably the most important issue (room interaction) rather elegantly is competing against far more widely-accepted, and frankly far more self-evident, ideas about "what really matters" in a subwoofer system. Thank you for helping it to do so.

Duke

millercarbon,

       I'm glad you're becoming a believer in the distributed bass array concept but I'm a little confused, have you decided to buy an AK Swarm or Debra?  Or have you decided to build your own custom DBA?
     Whatever you decide, I'll be happy to help you out. 
     I set my Debra DBA system about 3 yrs ago and I'm still grateful every day that I did because I truly believe the bass response in my room is state of the art for music and ht.  
     As Duke and I've said before, there's really 3 good methods you could use to set up a DBA:  1. Buy the Swarm, 2. Buy the Debra or 3. Buy 4 subs of your choice and setup a custom system.  Both the Swarm and Debra are excellent bass systems and come with everything you need except for a interconnects and speaker wire.  But if you want the ultimate DBA, you could buy 4 top of the line subs and just follow the positioning procedure.
     I have little doubt a custom DBA with 4 top of the line subs would outperform either AK DBA but it would likely cost at least 3 times as much and the subs would be larger and more intrusive.
    Let me know if you'd like my assistance either on this thread or pm me.

Thanks,
 Tim     
noble100

I was all set to buy the Swarm and almost did. But towards the end of the research phase came across the idea of building my own. At first it was just to use up some MDF taking up space in my shop! Using the first suggested drivers it looked a lot cheaper too. But then I came across this Morel driver https://www.parts-express.com/morel-ultimate-uw-1058-10-subwoofer--297-130 which is a lot better and comes with a free cabinet. While I wanted to use up my MDF the thought of the sawdust alone was enough to jump on this deal. Good thing too, they are now sold out!

UPS delivered drivers and cabs, ports, terminals. Pretty impressive looking drivers! Amps aren't exactly lightweights, either. 

Duke has been kind enough to provide some really valuable insight and encouragement. Frankly everything is available on-line but its still so nice to be able to confirm you are on the right track with someone with experience. 

So the plan is four subs. Two sealed, two ported. The ported enclosures will be the Denovo freebies expanded out to the larger volume the ported enclosure requires. Parts Express has a page where you plug in some numbers and it spits out some more numbers. I know they are accurate because they're the same as Duke pulled off the top of his head! Lol! Seriously, the guy is that good!

Every enclosure however good it is still has its own sonic signature inevitably imparted, unavoidably audible. Splitting the 4 into two shapes helps break that up. My plan is to go even a bit further, using a bit different or thicker material on at least one of them. Got this idea from one of the other DBA builders. 

Haven't even built them yet but already pulled out the old wire drawer and found power cords and interconnects for the amps, speaker cable, cones... looks like everything should fit.

Will need to build something to hold the amps. My main question or problem would seem to be, the sub amps require line level inputs but my integrated has no pre-out. It does however have a couple unused inputs. Figured I would just re-wire internally to connect the volume output to one of the input RCA. Could also hard-wire direct but the internal re-wire will look better, work better, and make changing interconnects a lot easier.

Probably not the kind of assistance request you were expecting. Lol! Oh well I'm sure I will be able to figure it out somehow.




Hello millercarbon,

     Very exciting, sounds like you have a good plan.  It seems like you're off to a good start with the drivers, amps and enclosures already having been delivered.
     I'm glad to assist you as much as I can.  However, I think you should know that my main areas of knowledge and experience are as a DBA system room configuration person and user.  Unfortunately, I have little knowledge and experience with DIY electronics and speaker projects.  I wouldn't describe myself as totally useless in these areas but I'm certainly in that neighborhood.  I'd suggest you rely on Duke's or others' advice on these matters.  If I do offer advice in these matters, I'll be sure to qualify it with an accurate estimate  of my degree of certainty. 

    Here are a few thoughts I've had thus far:

1. Don't forget the footers, spiked for carpet and something softer for a hard floor.  Mine have 3 screw-in spiked footers on each sub that work fine on my carpet.  There's no wobble at all with only 3 footers but it's your choice whether you want to use 3 or 4.

2. The Debra subs have the speaker terminals on the bottom of each sub but, according to a photo of your sub enclosure, their terminals are on the back.  
     Remember, your subs will be positioned facing the nearest wall and just about an inch away from it; this means the back, 2 sides and the top of each sub are the only visible portions.  My wife loves this because, if the wood is finished well, these subs look like elegant and stylish wood pedestals like those seen in fine stores and galleries. Any visible speaker terminals and connected wires will ruin this sleek and stylish look.   She normally has either a vase of fresh flowers or some other smaller objects she thinks looks good highlighted on these . 
 . 

3.  You said the amps (plural) were delivered. How many did you buy and did you purchase the same dedicated Dayton sub amp that comes with the Swarm and Debra? 

4.  The Morel 10" woofer looks very nice, especially when you get a free sub enclosure with each.  The only possible issue I see is that these drivers are 8 ohms while the 10" drivers used in the Swarm and Debra subs are 4 ohms.  I believe the class AB Dayton subs double their output wattage as impedance is halved from 8 to 4 ohms, from 500 to about 1,000 watts.  This is a good subject for you to discuss with Duke to understand how this could possibly affect performance.  
      I faintly recall at least one of the subs having dual sets of + and - terminals with the others just having single sets of terminals. I think you should check with Duke on the internal wiring of the subs with dual sets of terminals and how many subs should have dual terminals and how many should have single terminals. I know the subs are wired in series and I'm about 70% sure this affects the actual impedance the amp recognizes.  I should be able to find the instruction sheet for my Debra system for relevant details and let you know.  

     That's about all the topics I thought you should be aware of thus far. If you'd like, I can offer more thoughts as your custom  DBA project progresses.


Later,
Tim     
No worries. Line level comes in, goes to input selector, goes to volume, should be pretty simple to take the volume out and wire it right back to a pair of RCA's on the back. Hard to see that one getting complicated on me. Just never done it before is all.

Already checked, I have enough BDR Cones for everything, speakers and amps, including BDR Shelf for each amp, pure gold (or silver, or both) wire for internal wiring, Synergistic Research Looking Glass Phase II with Active Shielding IC for the amps, more SR speaker cable for two subs, and enough rather ordinary wire for the other two subs including all the internal hookups.

The amps are the same Dayton that Duke uses. Two of em, which depending on how I connect the speakers will be running into either a 4 or 16 ohm load. You're probably thinking of the driver with two voice coils at 2 ohms each that can be wired for 4 ohms for more loading options when several are used. Mine are just straight 8 ohm.

The enclosures I have aren't cut for terminals. I was planning from the beginning on coming in from below and got angled terminals to make that easier. The two that are ported, the enclosures will be enlarged from a cube to a rectangle. Ported requires this both for volume and the extra length needed for the port. Ports will be down-firing so they will still have the clean look of the sealed ones. Just need to make sure the feet/cones on those are high enough to avoid chuffing from air noise if too close to the carpet.

These'll be hooked up soon as possible in plain old MDF. Only after everything is proven to work, then they'll be covered in veneer to match my Talon Khorus. That was my WAF. She also thought it would be nice to match their tapered obelisk look. Was right of course, but I did that on my power line conditioner and all those angles, no way! Got trouble enough finding time for simple pre-cut cubes and rectangles!



 
Sub will add depth, weight and fullness but not clarity. 
I continue to be amazed by the knowledge of this group.

i wonder why the group does not talk about master setting speakers.  One of our local dealers demonstrated the art of master set.  He demonstrated this in one of his listening room.  When he moved the right speaker 2 feet, we suddenly had to raise our voices to hear each other.  I also noticed how I suddenly began to hear right and right speakers.  The sound also was not relaxing.

This dealer is one of the largest REL dealers in the country.  During his demo he donstrated adding a REL S3 to a pair of   Vienna Acoustic Mozart’s and I had a difficult time hearing a difference when adding the sub.  I wonder if this was because the Mozart can get down to 24 Hz.  Have really good ears and wonder why I couldn’t hear the difference.  I was expecting to really hear the bass beat.  I do think I heard greater in the mid range.  I purchased a pair of Paradigm Prestige 85F’s and now feel they sound harsh in the mid voicing.  The dealer came to my home and told me they needed to be master set. He also suggested adding a pair of REL T/9i’s.  He told me this would clear up the mid’s And make them sound less harsh.  Based on this discussion this must make sense.  However, before buying the REL’s I wish I could hear the difference in sound.  The dealer told me REL’s are not designed to pound out the bass and if they were they would eventually drive me out of the room.  So far, I am saving up to buy the REL’s.

I listened to a pair of SALK Song3 Encore’s at the RMAF and had I listened to them before buying my Paradigm’s would have never purchased my Paradigm’s.  I certainly would not need to add a sub other than for home theater.
A couple of clarifications…

One of the major benefits to be derived from the addition of self-powered subs (use at least two, generally spaced wide, and towed-in from the front wall corners) is that they'll help you defeat room mode peaks/nulls. They're the next best thing to 4 inch thick broadband bass traps.

Another important benefit is that they'll allow you to take the heavy lifting off your main woofers/power amplifier. To do so, you'll need to install via an external active 4th order electronic crossover controller. Marchand's XM66 is a good solution.

Yes, proper integration is vital. You need to accurately phase-match the subs with your mains at the crossover frequency, and you need to assure that you've properly set the subs' input gain (at xover frequency) so that it's +3dB more than mains output. I have very recently posted a paper about how to do this (with instruments) on the Classical Candor website.

In quickly surveying this site it's evident that some commenters confuse phase-coherency with timing. Yes, it's vital that you synchronize the phase of your mains and subs (at xover frequency); however, that does NOT mean that wavefront time-of-arrival will be matched. An inherent time-of-arrival disparity will still remain because the related low-pass filtering entails group delay on the order of some 12-16 msec. in the crossover region, so subwoofer output will lag the main speaker by about one full wavelength (equiv. 13.5-18 ft.). Regardless, after the two signals are accurately phase-matched at the listener site little evidence of this timing offset will be apparent. A good self-powered subwoofer that offers a continuously variable phase angle control over the span of 0 to 280 degrees will provide sufficient additional delay to allow you to accurately phase-match with your main speakers' output. A 0-180 degree control is NOT adequate.