Eh hem!...Subwoofers... What do ya know?


Subwoofers are a thing.  A thing to love.  A thing to avoid.  A misunderstood thing.  

What are your opinions on subwoofers?  What did you learn and how did you learn it? 


Previewjbhiller

If subs aren't the most misunderstood thing in audio, I sure don't want to know what is!

Take me. Been into audio since the early 70's. Built my first amp in high school. My first speaker was a transmission line in 1978. Thought I knew all about sound and even so never could get really good bass. Thought it was physically impossible.

Until about this time last year, when quite by accident came across some posts about the Audiokinesis Swarm and started reading articles on the physics and psycho-acoustics of low bass and something called a distributed bass array.

This sounded promising and so after reading a ton of both technical theory type articles as well as feedback from experienced users I decided to take the plunge and built my own distributed bass array.

Based on the same Dayton amp and 10" drivers and cabs similar to the Audiokinesis Swarm this has turned out to be probably the most revelatory improvement ever. 

Combining reading and theory with a lot of hands-on experience this is why I say its so misunderstood. Almost don't know where to begin.

The problem of integrating bass isn't in which sub is used. Its in how many. Every sub no matter how good or how crap has the problem of room modes: some areas too loud, some too quiet. Most try to solve this with more power, or EQ, neither of which does anything but make the fundamental problem- which is physics- even worse.

With lots of subs (I run five) no one individual sub has to put out much power. So they all produce modes, but different modes in different areas because the subs are all over the place. All these small modes average out and the result is impressively smooth, fast, articulate and deep bass.

Integrating or matching with speakers is a non-issue. Read the reviews, the bass is so fast its a match for electrostatic speakers.

Low bass is non-localizable. But read that carefully. That means only you cannot tell where the subs are located. It is as if they don't even exist. It does not mean the bass they produce is unfocused. Quite the contrary, the sense of 3D location of bass is even more focused than anything else I've ever heard.

Location with one sub is everything. You can spend a lifetime moving here and there trying in vain to find the magic location with smooth bass. Placement with a DBA is trivial. You can go the Full Monty if you want. You might even notice an improvement. Or you could just plop them down one near each wall, bothering only to not have them be symmetrical, and congratulate yourself on your expert placement. Either way, state of the art bass.

Almost everything people "know" about bass is wrong. Take timing. Experiments show we cannot even hear low bass at anything other than a full wavelength. That means a 20 Hz wave has to last 0.05 seconds or you won't hear it- at all! Midrange though you can hear in a tiny fraction of that. The same timing that is crucial to imaging and midrange on up simply does not apply at all to sub frequencies.

I could go on and on. Which I tend to do, both because this is so important as well as its really hard to understand. Took me a few weeks of research to really be sure myself. Sure enough to invest $2k anyway. Which is a stone bargain. Nowhere else in audio can you blow away so much expensive gear so easily for so little. Provided only that you actually understand what it is that you're doing.
(1) One sub is not enough, for reasons given by @millercarbon. (2) Subs can be used to extend LF, but the most important use in many systems will be to fill nulls unavoidably caused by main speaker placement and room geometry. (3) It’s easier to get them right if you have measurement capability. (4) I prefer to have a high-pass filter on the mains and a low-pass filter on the subs. (5) If you know when the subs kick in, you've done something wrong.

@millercarbon - do you run your array in mono? Just curious.
@millercarbon - do you run your array in mono? Just curious.


The smart-alecky answer would be yeah, because all low bass is mono. Seriously. It is.

Which I know from Duke reporting on what's his name Floyd O-Toole? Or the other one? Whatever, the car audio engineer who analyzed a couple hundred recordings and they were all mono so he called it good and designed for mono bass.

Me, having 2 Dayton amps allowed trying stereo, 2 on each side, and two per amp. Also tried mono. Tried mono connecting all 4 to one amp, mono 2/2. These were all different. But not because of stereo/mono. Because, all low bass is mono. Oh there may be an exception out there somewhere. He only tested a couple hundred, after all. So if anyone reading this finds one send it along, as nobody who's looked into it has found any, they will think its cool. 

What does make a difference though is impedance. Wired 4 ohms the bass is just a bit tubby to my ears. Wired 8 ohms the bass is not so tubby. Wired 16 ohms the bass is tight, taut, articulate, like way better than anything I ever heard anywhere else. Not lean. Plenty full. But fast. Clean. Maybe even a tad more dynamic.

Technically you do trade off some peak power, so if those last few dB of volume really matter and you like really full round bass then wire for 4 ohms. 16 to me is so much more articulate and tuneful, and I like that enough to put up with the occasional clipping when the movie effects go boom.

In terms of stereo/mono though one of the more amazing parts of the whole DBA thing is the way such low bass, which we really cannot localize, nevertheless somehow manages to image so well. I can only guess that what happens is when the low bass is this good then when we get the location from the midrange it blends seamlessly into one whole and so it seems the bass is as much grounded in a real place as everything else in the sound stage.

This is a whole different thing from the way midrange on up works. Anything much above 120, 200, somewhere in there, if its mono its gonna be between the speakers. Where exactly, not my thing. Duke would know. Duke knows everything! (Seriously.)

For those who haven't heard this (DBA) I don't want to give the wrong impression. Its not like the bass is always imaged the way everything else is. Sometimes the bass is completely enveloping in a diffuse, this is just the size of the room kind of way. This I think is one way really good bass improves imaging, by extending it to the point you are enveloped in it. But its also something that is very recording dependent. If its not on the recording you aren't going to hear it no matter how many subs or what kind. Sometimes when listening its like man are my subs even on? When it is there on the recording though, wow!
What are your opinions on subwoofers?


Hard to integrate well. Glorious when done right.

What did you learn and how did you learn it?

That’s a really good question. I started off with an M&K satellite/subwoofer system. Bought into the hype, used a passive 2nd order crossover (yeah, enormous toroids) and a couple of different RTAs to attempt to get the two to play well. Honestly they never did. The best I was able to do was use a little room math to damp the peaks.


The rest of my answer is a little long, but the short version: I integrate subs as if I’m building a speaker.



Here’s the long answer:


The V1B subwoofer eventually fell apart and I parted it out on Ebay, sold the S-1Bs.

Years later I was in San Francisco and got into upgrading speakers, and that led, very rapidly to learning speaker analysis and making my own. Now mind you, I have some professional background in analog and I was lucky enough to audit classes at Georgia Tech when I was too young for the math. Point is, I didn’t just jump into speaker design from zero.


One thing that changed a lot in my favor was the availability of cheap test and simulation tools. DATS, OminiMic and XSim made everything I wanted to do a lot easier, but none of them were useful without having a background already. The other thing that was new was miniDSP having a number of affordable and very high feature active crossovers.


Even with this background I made a couple of choices that really made everything a lot easier:

  1. Stick to 2-way designs
  2. Measure the bass response in place.
  3. Use OmniMic instead of REW, just because for my needs OmniMic held my hand a lot more.


Had I not done that, I would have made plenty of mistakes in analyzing the mid-bass response, or gotten overwhelmed with the quasi-anechoic requirements of a 3-way (this is short-hand, please don’t jump on this sentence).

Anyway, after this I returned to wanting a sub. Based on reviews including those at:

data-bass.com

I went with a Hsu. They were out of the model I wanted, but for a couple of hundred I could get the next larger unit. What arrived was the size of a small refrigerator, and me in a small apartment!! Hahahaha.


Anyway, I tried a number of ways to integrate the sub, bought a pair of GIK Acoustic soffit traps, and the miniDSP HD balanced. What finally worked for me was this:

Treat the sub exactly as if I was adding a 3rd driver to my speakers.

Which meant measuring the acoustic distance, putting in the response of the satellites and subwoofer into XSim, phase/time matching them and then using OmniMic to simulate EQ’s.

Pant flapping glorious.
@millercarbon - Thanks for the reply. I have had the same experience, that a well-integrated set of subs *seems* to image with the rest of the range. I hear the upright bass coming from in front of me, even though the two woofers are behind me.

I've been intrigued by the DBA since REG's review in TAS. But given the lack of space in my room & the great results from 2 mains + subs (which it took years to place), I haven't tried it yet. Maybe someday.
So is it the consensus that 2 cheap Dayton or BIC subs are better than spending $500 on a SVS or Rythmik?

if I rabbit hole here I wouldn’t go more than 2 subs and my cheapy 200 watt sealed sub seems to be doing ok (can’t find a 2nd one anywhere sadly). And that a 2nd sub should NOT be placed on the other end along the same wall (front) as the other sub?
I started with one sub years ago,added another last year,read posts from miller and nonoise,and was intrigued.After reading everything I could find about "the swarm" I added two more.I already had room treatments which smoothed the bass nicely and got rid of the 'sonic boom'.I don't think about the bass anymore because it sounds perfect to me no matter what the recording.I never wish it was tighter,fuller,more accurate or dynamic.It's always just right.
Are 2 subs better?

Honestly a lot of this is an economic problem. Not just expense of the sub, but the room. Can you afford / do you have the space to locate each sub ideally?

If so, then yes.

If not, a good compromise is room acoustics, 1 sub placed as well as you can plus an EQ.

In my own situation, I really really don't want to be moving a sub 6" 12 times to compare and measure. I have about 2 locations where this 100lb beast can go,  and I'm going to put it there and EQ it and call it done. :)
I guess I’d have to see what “placed ideally” equates to. Some light reading have the impression that one on each wall was the answer. How true that is I do not know.

if 2 $500 subs are better overall than 2 $200 subs then so be it. I’m just genuinely curious  as the “4 is better than 1” motto never mentions “good ones“ versus “ones that should work ok”.
2 subs are better in that you have more power, and more driver pushing air.

So absolute terms, sure, you can increase output by 3 dB with lower distortion.
But if you place the subs symmetrically, I would imagine that you end up reinforcing the same mode and anti-modes. Maybe some one has a better idea?

As far as I know, you place the first sub as well as you can, and then place the second sub so that it fills in any nulls.

Is this not how the cool kids do it today?
A very interesting, and appealing discussion. I've never heard a subwoofer swarm demo--perhaps a demo in Florida in February (he said, hopefully)? Two questions please:
1) From what I read here, it seems like multiple  in-wall subwoofers would be a good swarm solution...yes/no?
2) Millercarbon: what subwoofers do you use for 16ohms?

Best wishes from Atlanta, where Christmas buyers are also swarming...

@erik_squires  placement in terms of nulls makes perfect sense.  I will read more into that
Whoever is interested in subwoofers for his audiphile setup shall strongly consider "The Swarm" subwoofer system from Audiokinesis (or some simmilar setup of 3-4 small subwoofers). I'm using this kind of system (4 subwoofers) with Soundlab electrostatic speakers and I enjoy it so much. Previously I've used a single REL subwoofer with Quad speakers but the marriage was not realy good. 
1) From what I read here, it seems like multiple in-wall subwoofers would be a good swarm solution...yes/no?

Yuck! The beauty of DBA is quantity matters more than quality. But, come on! A man's got to know his limitations.
2) Millercarbon: what subwoofers do you use for 16ohms?
Morel 10", which are a nominal 8 ohms each. With four subs and two amps you can get a total 4, 8 or 16 ohms simply by changing the way they are connected to the amp(s). 

Post removed 
I only have 1 powered sub. No DBA. I found that modeling my room, which is an “L” shape, and using it to model a horn, resulted in incredible bass, fast and tight. 

Pouring money into the problem is back-asswards.
I use just one ML Dynamo 700w sub right now to compliment my Maggie's.
Strongly considering adding another though.
Room can really only handle two as far as placement goes.
Would a pair work diagonally opposite each other?
So say one front left, the other rear right or?

And I don't suppose anybody would know if  just one wireless transmitter would send signal to both of them?
After doing lots of reading, research, and listening, I went with a pair of the new Vandersteen Model 3 Subs. I liked the way they integrated with the main speakers. I will take delivery in a couple of weeks--they are in shipping. I will let you know how they work.
uberwaltz:
I use just one ML Dynamo 700w sub right now to compliment my Maggie's.
Strongly considering adding another though.
Room can really only handle two as far as placement goes.
Would a pair work diagonally opposite each other?
So say one front left, the other rear right or?


Say, does that Dynamo hum? Frank Zappa's did.

Placement is all about figuring out where to put one speaker to get the smoothest response at the sweet spot. With more subs it matters less and less where they go. You actually want them different places, particularly asymmetrically different places, because the more different sources the more different modes and they all average out to much, much smoother bass.

With my 5, one is front wall left, two on each side wall, and they are each a little bit different distance from the corners. Tim on the other hand (noble_100) took a more systematic approach and wound up with one in each corner. His room is almost exactly same as mine, like within about a foot each way. His listening is closer to the back wall, but as I recall its dual use, he sits more to the wall for movies, further out for music. Loves it either way.

Stories like his, plus my experience, and Duke's, all agrees with the early papers (Geddes, et al) conclusion of random or at least asymmetrically located is best. 

With 2 I'd put the second one diagonally opposite and spaced a little closer or further from the corner than the first one. With just two you might hear a difference moving them around. The more there are, the less it matters where they are.
I just went through all this since the golden ear accolades for the swarm set up .I have  spent every waking moment working on it for a couple weeks until it is so perfect its real. Running 2 18” ,2 15” and 2 10” placed with help from tim. The idea of spending thousands on one killer sub seems idiotic to me now . Any one of them is barely percievable that they are even on when you walk up to them . But the entire room is alive. (2000sqft) no boomy voices or having to reach for the remote because things seem suddenly ridiculous. The hardest part was just properly running the wires. All mono . Using a bx63a crossover. The main subs are under the floor suspended from the ceiling . Aiming each other 20” apart. The rest are placed in the standing waves of the room. I feel like the subs are part of the room now and i can audition any main speakers i want .  Room treatment seems less and less necessary the more dialed it gets.  
I have had a powered sub woofer in my audio system for 25 years and wouldn't have it any other way. Started out back in the day with Paradigm 20 monitors with Servo 15 sub woofer because of room constraints. Moved to new house and upgraded to Dunlavy SC lll's with the Servo 15 doing double duty 5.1 and two channel. When dialed in correctly it sounded amazing. No one, but no one back then that I new had two subs. Now in my retirement home with audio room contraints again I now have two separate systems in my small man cave, a dedicated two channel setup with a tube pre amp and tube amp and a 5.1 AV pre amp with a 5 channel power amp. For both systems I have the SVS ultra 13 Subwoofer. I don't have room for two unfortunately. But maybe I have something close to a sub swarm setup as my main speakers have built in powered sub woofers that will go down to 20hz. So along with my SVS Ultra 13 sub woofer the full audio range is pretty prodigious and well integrated with the help of Dirac EQ. I'm just amazed how well my system produces full range music, and for movies also, for that matter!
gochurchgo-
I guess I’d have to see what “placed ideally” equates to. Some light reading have the impression that one on each wall was the answer. How true that is I do not know.

if 2 $500 subs are better overall than 2 $200 subs then so be it. I’m just genuinely curious  as the “4 is better than 1” motto never mentions “good ones“ versus “ones that should work ok”.
Highly recommend searching and reading just about everything posted by Audiokinesis. Awesomely succinct, won't take long, just don't read fast there's a lot to absorb.

The quality/quantity thing is admittedly a hard one and doesn't sort out nice and clean. There's overlap, where one kilowatt 18" REL might be better than four 8 inch Hsu tubes. But not if total cost is the same for both.

Better quality is always gonna sound better. When I told Duke which 10" Morel drivers I bought he had no problem saying mine will kill his. By and large though my sense of it is for the vast majority of choices out there four of just about any of them will beat any one you can buy for the same amount of money.

Put another way the typical Swarm type DBA runs around $2-4k and I just don't think there's any one or even two subs anywhere near that much that can come even close. Just look at the comments. Pretty much everyone who's done this says its the best bass they ever heard. Not the best for $3k. The best, period.

Duke even had a customer choose his Swarm, and he had I think a $20k budget. Not for the system, just for the sub. Coulda bought a $20k sub. Listened to subs in that price range. Thought the Swarm was better.

That's why this is such an uphill battle. As if the physics, psycho-acoustics, mono, and "integrating" aren't hard enough, you got to try and convince people the concept is so powerful it overrides the need for great big expensive drivers. Oh, and lamp cord will do just fine. Its just too much to swallow. Even though its all true. 
I have Harbeth C7 mains, 2 Lyndorf BW2 subs, one in each corner, a Lyndorf 2170 amp. The Lyndorf can set a crossover for the subs/mains, I chose 100Hz 2nd order, you tell it the distance from the listening position to the mains and the subs so it corrects for time alignment, you then run the RoomPerfect room correction function and it perfectly integrates the outputs to match the room. So neat, tidy, easy. How does it sound? Bloody marvellous.
I have detected a few tracks that definitely have stereo bass, and that is a new experience to hear!
It would be helpful if you could describe your goals (music, video, both?)
better, best, best indeed!
room size/setup/placement options?
existing mains? new mains intended?

generally, not to make it work for you, just clues for us


I'm 71, have tried/learned several bass setups over the years.

I encourage tubes, and vinyl, reel to reel, so efficient speakers to reduce tube power needs. Entire system: darn good, not perfection, more money saved for more content to enjoy.

I go for darn good directional stereo bass for main listening,

listen to this, you will want directional bass. 

https://www.amazon.com/Double-Bass-Niels-Henning-rsted-Pedersen/dp/B00000G62F/ref=asc_df_B00000G62F/?tag=hyprod-20&linkCode=df0&hvadid=312683822382&hvpos=1o1&hvnetw=g&hvrand=18279210393491330306&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003512&hvtargid=pla-540093611693&psc=1&tag=&ref=&adgrpid=65958438881&hvpone=&hvptwo=&hvadid=312683822382&hvpos=1o1&hvnetw=g&hvrand=18279210393491330306&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003512&hvtargid=pla-540093611693
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Amount of bass: avoid too much, seems cool at first, but detracts from your delightful mains imaging, and loses bass direction. Extend system as desired, but not too much, yet definitely aware when you turn them off.
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Very careful consideration of room/placement/control options in advance
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music system, medium sized room: pair of subs and delightful mains:

pair of self powered directional subs. When mains not trying for low bass, mains are smaller, easier to place, and, importantly, main amp can be lower power, easier to use/try tubes.

very strong magnetic control of sub's woofers, avoid unwanted delay/distortion, preserves direction. Perhaps servo control of sub needed, depending on sub size/design.

solve location of mains without subs, then find nearby directional location of subs, refine sub crossover and volume control. 
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Sub remote volume control. Not common, or critical, BUT, remote control of sub volume is handy, especially home theater. Consider ease of use: internal sub amps with that feature, in-line volume control, home theater receiver easy menu access to adjust, exterior dedicated amp with remote volume. Individual remote volume control of pair of subs can make a difference.
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home theater, office (not big ones).

Single self powered sub, non-directional, added to smaller mains in home theater, or bookshelf in office. Same reason, mains can be smaller, easier placement.
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other considerations.

delightful mains, tweeter ear height, mid close to that, no ports.
ability to locate/move mains away from rear and side walls (less critical when they make less bass)

If need to move speakers back, forward only when listening, no spikes, heavy, i.e. sand/shot filled movable base, i.e. felt slide-able bottom.
 
16 ohm comments. my mains are 16 ohm, incredibly efficient. no matter what the math says about reducing the amps power, they are the loudest speakers I have ever owned, need no moe than 30 wpc (perhaps less, never tried). I think the other way: 8 and 4 ohm speakers increase the
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NEED for more power. Considering amp cost, size, weight, heat, large amps are generally to be avoided IMO. Especially if using or will try tube amp.

You won't avoid 8 ohms today, you can avoid 4 ohm speakers, and certainly, to use tubes, avoid inefficient speakers. Let the subs have their own power, remove bass needs from amp before it goes to mains, otherwise the mains will get the bass signal, they and amp will try and fail.

millercarbon, others:

I suspect many of you have a far larger listening space than what I am discussing. I am not meaning to contradict your advice for what I never experienced.
As per the instructions i received . I put a powered sub on my listening seat and then played a 30hz tone . While it and only it was playing i went around the room with a measurement app on my iphone . I looked for hotspots reaching high and low everywhere . The locations were oddly NOT symmetrical to the room . One 10” is 13ft to the right of my right main against the wall . The other 10” is up high in the far left back corner almost 30ft away , the 15” subs are downstairs to my left fore and aft to me and the 18” subs are opposing each other between the sweet spot and the mains under the floor . But when all the subs were placed in those locations and wires ran and tweaked for output it is incredible . I used to have my 18” jbls under my mains . They are no longer there as there was a hot spot in front of ONE main and not the other . Due to the size of these subs (12cuft) i removed them both for aesthetic reasons .  The mid and high detail as well as the 3d image is very engaging . The placement went against everything i thought i knew about sound. Completely makes sense now. 
Unless you really need the deepest room shaking notes found on that occasional track or action movie sound track- a full range (or near full range) speaker driven by plenty of power is a better solution for me.  
100 watts driving the main speakers just won't compete with subwoofer amplifiers of 500 to 1000 watts or more. 
Drive your main speakers with 200 / 250 watts at 8-ohms and the need for a subwoofer greatly diminishes and becomes a better case set of compromises than even the best subwoofer setup. 
You have $ to invest in a subwoofer system? invest in a bigger amp instead IMHO.   
REL, REL , REL, oh did I mention REL, and the post that started this thread is correct, you must first understand what bass really is, how it is distributed, and how to properly integrate it i to (your system).
Every system dynamics are different due to room size etc, and as mentioned before if you know where the bass is coming from you have set it up incorrectly, not only will a properly set up sub allow your main speakers sound like they are bigger then life ( not only bass but in mid range also), also learn what High level connections can do for you when it comes to a sub. I recently upgraded to a line array system for my 2 channel system (if I could post pics here I would) , and was simply blown away , granted They consist of 28 6.5" woofers and 38 3" Motorola ceramic piezo tweeters in each column , using one REL Britannia B1 sub (yes its older but works as it should), the sound is phenomenal , and breathe taking , speakers and sub are controlled through a Samson S3 crossover network, and of course bi amped . 
Subs rule , but IMHO buy from a manufacturer who only builds subs for the best quality and technological attributes towards your systems dynamics.
  

Correction 28 tweeters , mis type
Miller.
I have just ordered another ML Dynamo to match existing one.
If it does not play nice by wireless then I can wire it as the wireless transmitter also has RCA out.

By my room I really have to have them diagonally opposite as I said especially to keep well away from my tables.
I could possibly get to three subs but due to layout that would be it and third one would go left rear.

I will try the new one to the rear right but not exactly in the corner and play around a bit and see what improvement I can realize.

Not that I am unhappy right now but you usually do not know what you were missing until you find it!
It really is easy, go big or go home! Just get a Wilson Audio Thor's Hammer and call it good. Kidding. Lot's and lot's of good info here. In the end though, one way or another, a compromise must be met. Budget constraints, testing capability, room realities etc. Not all can have the perfect acoustic room. Like Eric mentioned, get what you can, dial it in to what sounds good to your ears and call it good. OR, go all in, have the room tested, do all the treatment, demo locations/subs and take that route. I recently eliminated my sub for my two channel setup. My room constraints wound up creating more problems than I could/want to try to "fix" so I binned it. Being a drummer I like the low end, but at the end of the day, once my ears changed a bit and the low boomy bass I "thought" I liked, was actually a very real negative. Anyway... I compromised and now I'm happy. (for now) haha!
I think everyone is on the right track relating to their own likes . I agree having lots of power to mains is important. My mains are 3 way bi amped . 150w solid state to the 15” woofer and 100wch tube to the horns, tweets. Asking the woofers to reach down to the basement takes away from their clarity . Subs reinforce those very low notes and in this way gives an omnipresent feel to the sound . With my remote on my c46 preamp i can cut the outputs i used to engage the subs . Sound is still beautiful but having that ability from your chair to turn them on and off sure trains you to set them modestly as to only give the full picture nothing more.  Think of the 20th century fox orchestra intro where the last sound is made by a very large drum kind of a whomp powerful yet subtle . Can you hear a sub? Or the room that drum was recorded. The silence between notes is the most beautiful sound. 
"It really is easy, go big or go home!....  I recently eliminated my sub for my two channel setup. My room constraints wound up creating more problems than I could/want to try to "fix" so I binned it"

geof3,

I guess going big didn't quite work out.
My main system is Apogee Duetta Sigs. They don't go down much below 40-50 Hz, so I added a Paradigm 15 Ref Servo sub - sounded good. Then I added a 2nd 15 Ref Servo sub and it sound great!. I have them wired in stereo and positioned as if they were part of the Apogees - in other words - right next to them. Works for me.
millercarbon2,139 posts12-06-2019 9:01pmAlmost everything people "know" about bass is wrong.
Location with one sub is everything. You can spend a lifetime moving here and there trying in vain to find the magic location with smooth bass. 
Do you have any experience using the Crawl Test for anybody locating less than four subwoofers?

I could go on and on. Which I tend to do, both because this is so important as well as its really hard to understand. Took me a few weeks of research to really be sure myself.
Thanks for sharing your knowledge. How would you determine crossover frequency and gain with less than four subwoofers?

Subs for music vs Subs for HT. Big difference in what you trying to accomplish sound wise, IMHO.
I use a large woofer that is not that accurate for HT set up...and two REL T5i's for my big rig. The T5i's are very fast ( therefore they do NOT interfere with my main speakers..which is the goal) and are invisible SQ wise in the blend. What two subs do is exactly what REL states they do, which is to smooth out the response in your room. Unfortunately, setting up two subs is IME a ton more time consuming than setting up just one....but worth it in the long run.
richmos,

I had Duetta Signatures some years ago and they were really something special. They were very current-hungry and I ended up buying a Krell amp to feed them. They also liked lots of space behind them, but the sound was unmatched.
" How would you determine crossover frequency and gain with less than four subwoofers?"

Buying a sound meter is a good idea, sub woofer(s) or not.

You can determine when the bass starts to drop off from your mains, IN YOUR ROOM (not factory data sheet, that is 'roomless'.)

Use meter to find the best trouble free location of your mains first, then, get the answer when they start to lose bass, use a bit below that as a starting point for the sub crossover, then use your ears.

It's like an old carbureator, you have to adjust two factors (air/fuel mixture and idle speed) with each other, not separately.
This is what Vandersteen has said for years.
Do you have any experience using the Crawl Test for anybody locating less than four subwoofers?


This is the one where you put a sub in the listening spot and walk or crawl around looking for where the bass is best, and that's where you put the first sub. So there's your answer. Because the first step is simply repeated again and again until you run out of subs. 

I did try this and unsurprisingly all the best bass was in the corners. Which anything else would have been a surprise. Bass is always stronger near the walls than out in the middle of the room. No wonder when Tim did this he wound up with speakers in the corners. But that's not hardly even the point. The real point is Tim has great, awesome, impressive, bass that continues to please after many years, and with both movies and music. He does move his chair for music but that only goes further to emphasize the point that having a DBA means having great smooth bass that is not fussy when it comes to speaker or listening locations.


Thanks for sharing your knowledge. How would you determine crossover frequency and gain with less than four subwoofers?

Same as always- by listening! 

Oh, you can use meters too. But there's a problem with that. A really big problem. One that far as I'm concerned kills the whole idea of EQ. That being, meters measure sound all nice and flat and without regard to volume. But people don't hear like that. Really low frequencies we don't even hear at all until they get fairly loud. That's why they made the Loudness switch! Don't believe me? Look up Fletcher Munson Loudness Curves.

Got it? All those lines on the left pointed up and converging? What this says is, if you set your bass to measure flat, you will indeed be able to get it to measure flat, but you will NOT be able to get it to SOUND flat except at one volume level. Then even if you get it to sound flat, it will only ever sound really flat at that one volume level. Turn it up, it will sound like more bass. Turn it down it will sound like less. 

The only real solution is to listen. Listen a long time, and to a lot of music. Listen at or close to whatever volume level you use when you really want it to sound good. Tweak tiny amounts until you're happy. You'll wind up with a little more bass at higher volume, a little less at lower, but there's quite a range recording to recording anyway. 

Doing it this way takes a little longer and if you're one of those needs validation types sorry, but its the best we got.
Validation? Nope, If you're happy, I'm happy.
I'm interested in subwoofer variable crossover control methodology.

Thank you Miller and Elliott for taking the time.    
I sold my active subs and got Duke's (audio kinesis) swarm with 4 subs and 2 amps, you locate the subs 2 in the front of the room the other 2 wherever just not together, these are very small units (wife loves to put things on top which are constantly falling as you could imagine), I just don't care about improving bass anymore it is so perfect, I will never use anything different than a distributed array ever again.@millercarbon I have mine on 8 ohms but I will be trying the 16 ohm series config, not sure with my listener skills I could hear it but willing to try, thanks for the tip

...

That’s why this is such an uphill battle. As if the physics, psycho-acoustics, mono, and "integrating" aren’t hard enough, you got to try and convince people the concept is so powerful it overrides the need for great big expensive drivers. Oh, and lamp cord will do just fine. Its just too much to swallow. Even though its all true.

@millercarbon --

Something to consider: if the 10" Morel units of yours are anything to go by two "big expensive drivers" from the pro sector, like 21" B&C’s, in a given enclosure design (like the "Skram") would be no more expensive or probably even cheaper than four Morel’s. Add in the need for two extra amp channels for the quad-approach while factoring in that a pair of 21" drivers are ~10dB’s more sensitive and sports more than twice the radiation area. "Overriding the need" as you point out in this context dismisses the importance of headroom, although to some a quad array of 10" subs would seem more than enough (and it well may be in a specific context). And yet, a dual 21" set-up like the one suggested would excite more air (even with less cone movement) and have lower distortion at a given SPL, all of which translates into an even more relaxed and effortless presentation of the lower octaves. You’d miss out on the advantage of going quads in regards to response smoothness sans digital correction, but a great result is still attainable via duals without excessive use of DSP and maintaining a fairly even coverage for more than one listener.

You could even go with smaller and (all things being equal) cheaper drivers, like a 15" driver in a horn variant and end up with a bigger effective air radiation area, force multiplied by the horn, than a 21" direct radiating driver (the 21" in the "Skram" isn’t DR, I might add, but rather hidden inside the cab and loaded on both sides of the cone), in providing a better coupling of the cone to the air and a different (to my ears ’better’) bass presentation (my preferred choice of dual-sub approach, actually). The downside: a need for a bigger cab and thereby wood.

A 4-sub approach with, say, 10" drivers like you propose in all likelihood will find more wide-spread use in hifi-systems than what I’m advocating, and they would have excellent augmentation in the bottom octaves. That being said and to reiterate: there are other excellent sub-solutions, and adhering to physics I’d say my dual-sub propositions will fit the bill quite nicely as something that can’t be overridden as an essential in bass augmentation, but that are nonetheless typically overlooked.
@phusis apologies in advance as you were addressing someone else, I understand the bass augmentation can be achieved easily with the distributed array, there is such a thing as too much bass, in my array (4x10 inches not morels) I have to tune down the amps to 50 percent and sometimes plug one or two ports, I also understand that if you add more 5 6 even 8 small enclosures which are easy to hide the effect increases even more. I had 2 powered subs with dual 18 inch drivers before and it didn't sound natural (to me), also from the amps you can change phase for two subs etc. which blends the bass even more.
I'm not trying to be argumentative with you but I respectfully differ from your opinion
Luis
@luisma31 --

apologies in advance as you were addressing someone else, I understand the bass augmentation can be achieved easily with the distributed array, there is such a thing as too much bass, in my array (4x10 inches not morels) I have to tune down the amps to 50 percent and sometimes plug one or two ports, I also understand that if you add more 5 6 even 8 small enclosures which are easy to hide the effect increases even more. I had 2 powered subs with dual 18 inch drivers before and it didn’t sound natural (to me), also from the amps you can change phase for two subs etc. which blends the bass even more.
I’m not trying to be argumentative with you but I respectfully differ from your opinion
Luis

No apologies needed, and I like a difference of opinion - oftentimes it makes a conversation more interesting. To "diagnose" a difference of opinion though and where it really rests some effort must be made as to the context and more precise nature of each of our viewpoints; sometimes what we initially deem ’different opinions’ is muddled by factors like lack of context and insufficient information rather than actually being in disagreement on a subject - were we to have a more "level ground" of understanding (which, for obvious reasons, we usually don’t have from the get-go). That being said there certainly are preferences, and I find them inspiring as it can lead myself to change or modify a direction, or simply appreciate and ponder other choices (just as well as it can reassure my own direction).

"Too much bass" as you write to me is simply about level adjustment rather than the capacity at hand. Practically I don’t find one can have an over-abundancy of bass capacity (as is similarly the case with dynamics), for as they say: headroom is your friend, so embrace all there is and even wish for more (to a certain point at least, but usually more than many would deem necessary). So long the enclosures themselves do not obstruct the acoustics too severely I’d have no problem adding their size or numbers as space and/or spouse permits.

Let me be clear that I only have few reservations with the multiple sub approach, the only real one being the potential lack of symmetrical placement of the subs in relation to the mains. This is controversial, it seems - i.e. mono vs. stereo bass and the supposed lack of directionality in the lower frequencies. To my sensory abilities spatiality in particular is aided more effectively via symmetrically placed subs (usually a pair, coupled in stereo) relative to and in close conjunction to the mains, and while we may not be able to distinctly assess, via our ears, where bass is coming from (depending on the chosen lower cut-off), I’d wager we can feel it via our bodies. On whether actual stereo information is available in the source material (digital), also a controversial matter, it is hardly debunked from testing a few hundred titles (a very obvious case of the problem of induction - if one were to side with named, limited testing).

On your less than favorable experience with the twin dual 18" subs, I find it hard to comment other than asking for more specifics (context) and what in particular you found less satisfying about their sound. A friend of mine is using a pair of cinema subs fitted with twin 18" drivers as well to augment his mains, and while I find they’re very capable, tuneful and rather successfully integrated, I’ve never warmed to them fully. My main gripe mainly has to do with some acoustic challenges here (generated by the floor), but also the fact that they’re direct radiators. I favor bass cabs with hidden drivers, preferably loaded via horns, but that’s another subject entirely.

Implementation is paramount. I’m using a Xilica digital cross-over that provides ample adjustment possibilities, while tentatively using DRC Designer for digital correction in both amplitude and time domain from the outset of a measured performance, choosing a target curve, specific filter types used, etc.
@erik_squires,

In my own situation, I really really don’t want to be moving a sub 6" 12 times to compare and measure. I have about 2 locations where this 100lb beast can go, and I’m going to put it there and EQ it and call it done. :)

I love my 2 PSA 1801 subs but am really tired of moving the equivalent of 2 fully stocked refrigerators every time I want to try different placements for ’sound checks’ when I have to do the ’sub crawl’. And for some reason, I’ve tired of having to look at those beasts all the time.

Not to mention sub placement is very limited - and I’ve made my mind up to upgrade/downgrade to 4 of the smallest active/powered PSA subs for - better sound and much more choices of placement. And PSA will, take PSA trade ins/upgrades and or downgrades.

@millercarbon

Morel 10", which are a nominal 8 ohms each. With four subs and two amps you can get a total 4, 8 or 16 ohms simply by changing the way they are connected to the amp(s).

Will a Y cable with 1 male/2 female RCA jacks in both the left and right sub outs (pre outs) give me 16 ohms? I assume probably not cause it sounds to simple and easy to do! Maybe 8 ohms might work for me? 

Anyway thanks for posting, as last time I was privy to your knowledge on this very issue it got a little ’Eh hem!’ heated but your sharing of this information to me - is the reason for the season... And I did take your advice and read the papers by Geddes. By the way I’m in metro Atlanta, you still in the ATL?
Does the direction of either the mains’  midbass driver or the sub make any difference?
Like if I point my mains away from a bass null would that help negate it?
No, its the physical position of the sub that dictates where the standing waves end up . Put the sub on your listening chair , now go around the room and find where the bass is loudest. Now put your sub there. The end. Leave your mains off during this. Makes it easier. And less violently loud while you figure it out.