size of subwoofer drivers vs. size of main speaker drivers

ACHiPo

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Feb 22, 2015
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Hi

My posts will sound like heresy to many here. I have not heard the Wilson subs but contend with certitude that for the same cash outlay of a Wilson Thor Hammer or Magico equivalent, one shall obtain much better results by using the budget for more of much less expensive subwoofers.

If one wants to have a glimpse, just turn off the main and listen to a sub .. not much going on .. right? mumble, rumbles and if the high-pass crossover cuts around 100 Hz with a any steep slope not much else ... That is what subs do.
I know the original post was about sub driver's size but allow me...

Now, Any subs from whatever manufacturers you choose, even those made of Fairy dust have to abide to the laws of physics, to the laws of small room Acoustics. A small room is any of the listening rooms that all of us here at the WBF is likely to have unless we have our own private concert hall and even then ... It has been shown by many that the best way to have a smooth bass in a room is to use multiple subs. The recommendations are not the same .. The Harman people: Devantier , Welti, etc, recommends multiple subs at specific placements namely middle of the listening room walls. Earl Geddes recommend semi random positioning. This is the idea of a "swarm" and it works for music or movies. The better the response in the room the better the bass. Furthermore, the more subs the less each individual sub has to work for a given output. If a driver works less it tends to produces less distortion. Moreover several subs tend to work in making the in-room bass frequency response more even, i-e less bumpy. This again translate into better bass.
Our hobby is dominated by several myths some of these very comfortable .. The idea of special fairy dust or manufacturer special sauce to "voice" his subs is one of these and Wilson or Magico or whoever cannot be faulted for providing uds with what we desire and to feed our imagination (insecurities?). At a budget similar to the Thor hammer + High End amp ( A Crown Class D pro amp would have been superb at the job but no one that would go for a Thor Hammer would ever consider mating it with a lowly Pro amp) A little over this budget, or at the same ... . One would buy you four (4!!) JL Audio Fathom 212 or two Gotham or 4 (!!!!) Paradigm Sub2 or to me a much better solution 5 pairs of Seaton Submersive and still find some left over money to hire a serious acoustician and have them integrate the subs in your system…
Of course subwoofers integration is not a given. It is not a plug and play affair. It requires patience and dedication to make it work. it also require an open mind. Audiophile from both side of the aisle do have the dedication, what is often missing is the willingness to accept a novel idea, to understand that the cost /price of a solution has little bearing to its effectiveness, to learn the basic physics underlying bass reproduction in a room and likely the most difficult for many to accept: that DSP in the bass does more right than wrong. In the bass the room takes over almost enirely and the best way to diminish its contribution are DSP and multiple Subs .. Preferable a combination of both.

So RonR please consider that array of multiple 15 inchers ( or the "swarm" idea you mentioned. if well executed (not a given) it has the potential to provide you with a level of reproduction you may have never experienced.
Frantz,
I think you're spot on. Nicely said.
AC
 

ACHiPo

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Feb 22, 2015
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A single sub in a corner is going to have high efficiency but also massive frequency response swings. Here is a fluid dynamics simulation of that for our theater. Each color represents a different pressure level (volume) at that frequency with red being the highest, and blue the lowest. Shown is just a horizontal slice at the ear level.


If you are sitting in the center line of the room, putting the sub along that axis will kill one of the modes in the middle. The trade off is that you will have less efficiency so going to a larger sub would be a good way to compensate.

By far the best thing you can do is make sure the sub has programmable EQ for at least a couple of frequencies. Without it you are guaranteed to get bloated bass. It will sound good one minute and overpower the mains the next. That is what you are seeing in the simulation above where depending on what play, i.e. what frequencies exist, you can get huge variations in level (and smearing in time domain).

Amir,
Interesting and enlightening simulation. Kinda hard to see the legend--I assume the color is SPL? Is the model for a single frequency?

AC
 

FrantzM

Member Sponsor & WBF Founding Member
Apr 20, 2010
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Corner placement for multiple subs are not that bad.. you get a ton of spl and depth out of them, leading to major cuts with DSP which in turn increases amp overhead and thus they work a lot less for the same bass ... the same swarm approach with speakers smoothing room nodes will still work.
Lots of target curve based DSP out there that can see the system as a whole and make for easy setup and integration..their results are nothing short of amazing these days..

A while back I ran a set of Meridian dsp6000's .. with 8 x8" woofers and a set of SVS sb 13 utra subs and had amazing integration using a Dspeaker antimode 2.0.. it was so easy to do..

I agree.. Dropping just one sub in a corner is invitation to disaster. Using more than one corner sub with the help of DSP can lead to stunning results. The multiple subwoofer approach works for any speaker. Be it dipole or else . In the ver low frequencies. most if not all speakers (there is an exception that I noticed in WBF, a speaker presented by Purite Audio that actively control its directivity in the lows ..don't know how well that works but ..it is worth mentioning) All speakers radiates omn-idirectionally under 60 Hz... regardless of the woofer/subwoofer position on the cabinet.. Bass is omni..Period.

There are a number of superlative subs out there that are frowned upon by many audiophiles. They lack the cachet of the uber-brands. yet some of these would run cicles around many offering from brands very dear to audiophiles, when it comes to performance. One example is the aforementioned Seaton Submersive, another are the stupendous subwoofers from a master in loudspeaker design:Tom Danley who used (sometimes) to post here. His tapered horns subwoofers are legendary in sound reinforcement and have found their ways in many home systems... They are worth investigating too.
In the low integration with the main is key and is better accomplished with DSP. Easy is a subjectivew notion but if the prejudices are set side, the vast majority of audiophiles are eminently capable of integrating a main with subwofers. it won't be plug and play but the results will be worth the effort.
 

amirm

Banned
Apr 2, 2010
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Fantastic Amir! Thank you!!! A few questions:
Thank you for the kind words. By the way, if you ever wanted to do this right, that service whose simulations I used is available by Keith Yates. You can give him a drawing of your room and he can model and suggest number and locations of subs (you tell him the constraints of how many and where you would be willing to put them). It will cost the same as a high-end subwoofer so not cheap but will give you piece of mind that it is done right.

Here is that simulation but now with an optimized setup using three subs (one in ceiling):


The circles are the ear height slice. Notice that at many frequencies we are getting equal response in all seats rather than massively varying one for one sub in the corner. Also, don't forget that subs can be in-wall and in-ceiling as is the case here and completely hidden. At one point we had no less than 8 subs all invisibly buried in our home theater at Madrona! No matter what you do though, you still need equalization as even the three-sub configuration has uneven response in the full frequency response sweep.

So if you are building a custom room, give this option a serious try. Here is a picture I post recently showing one set of our in-wall subs:



They are rather anemic JBL subs so I don't recommend them unless you double them up like we have. But there are other solutions all being able to be built in-wall.

The other way to do it is with computer optimization (http://www.madronadigital.com/Library/Computer Optimization of Acoustics.html). That unfortunately is a full system. JBL did build a box called BassQ for a short while that had the same logic for up to four subs but discontinued the product. A search for used ones may turn up one.

1. While the speakers are 15' into the room (firing a further 25' down to the far end), the seating position is at that far end...and the only position in the room that does not intrude on living/dining space is the corner directly to the left of the listening position. Are we in for a load of trouble if the sub will be shut above 40hz?
If you don't have a rectangular room, it is very hard to predict its response using simple math (need above simulation). But there is good news here. If you can limit the response to 40 Hz, chances are you only have one room mode that is below that frequency. With judicious location optimization of the sub and listening position, you may be able to avoid it. And a single Parametric EQ is all you need to optimize it. The lower this frequency, the more possible this option becomes.

Of course you have not fixed the overall problem because now your mains are subject to all the room modes and if you can't move them, you are kind of stuck there. Putt them at 25% positions in a rectangular room can help with cancelling a couple of the modes.

2. There is a very very slim change we could do a 2nd sub in the corner on the right of the listening position (doubt it due to built-ins). Big improvement possible?
As micro said, without computer optimization or the simulation, it may be very challenging to make two subs randomly positioned in a room to sound good. It is not the automatic addition of a sub that helps. It is having both and then optimizing their response and or position that makes them do that. As a minimum, you need to learn to measure the room response and ability to move the subs around to get optimal response.

3. Assuming 2 above is out...so only 1 sub...when you say the sub has some EQ, have you ever played with the big Velodynes or their software? Just curious as to whether you feel that is 'sufficient' EQ. i understand some people simply buy the Velodyne crossovers/software to use with other subs so hopefully this is a good sign.
I have not unfortunately. The requirement is rather simple though. Make sure it allows you to dial in an EQ with a resolution of 1 Hz or so. If you give me a link to the specific product, I will take a look.

In a nutshell, once we get past a certain level of power, mass...it seems set up (both physical and electronic) seem to matter quite a lot in subs by the reading here as well as the demo above you show where the sound gets wildly out of control at certain frequencies...fair takeaway from your post?

Thanks again...very helpful...
Very true. The reason to choose one sub over another is maximum SPL and how clean it is (i.e. does it bottom out and get distorted). Almost none of the other parameters matter relative to optimization in the room. If you are going to shake the foundation of the house, then you start with the selection of a sub that can do that. If you are just wanting to augment reasonable listening levels in a rom then that is not critical and the topics we are discussing become paramount. Of course you don't want to buy a junk sub but within reason, it would not be a barrier to good sound.
 

amirm

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Apr 2, 2010
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Amir,
Interesting and enlightening simulation. Kinda hard to see the legend--I assume the color is SPL? Is the model for a single frequency?

AC
Thanks. Go full screen and select HD and you should be able to see them. But yes, the vertical scale on the right and color are the SPL (roughly the volume). And the change as the simulation goes, is the frequency. You are seeing a 3-dimensional view of how sound pressure changes in the room based on each frequency that is playing.
 

ACHiPo

Well-Known Member
Feb 22, 2015
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309
310
Pleasanton, CA
I would toss Rythmik in the ring of excellent "after market" subs, a very nice servo design from a very sharp designer. Jim Salk uses them in his speakers as well.

+1 I've started my swarm approach with a pair of their 12" sealed subs (augmenting full-range Kef Reference 207/2s) in stereo. I did the "subwoofer crawl" and found that of all the viable positions, flanking the mains in the front of the room in the top 4 positions (the other 2 requiring some wiring work which I haven't gotten around to yet). Thinking of adding a sealed Rythmik 15" next to the listening sofa, as that was also a prime spot.
 

Bruce B

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Apr 25, 2010
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Fortunately no one I know about puts subs in the corner! Please note this is the same argument some people use against the absolute need to use golden rule or similar criteria for room dimensions

When Bob Hodas did he acoustics of my room with WP7 and WatchDogs, the subs were placed directly firing into the corners.
 

DonH50

Member Sponsor & WBF Technical Expert
Jun 22, 2010
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Sub, or just speaker, placement is highly dependent upon the room and desired response. For audiophiles there is also aesthetics and possibly limited placement options due to multi-use rooms (or just the desire to not stumble over your sub in the dark!) For some the corner boost adds a desirable amount of bass extension, for others it just adds "boom". I have always based placement on sound and measurements within the set of spots available in the room.
 

ddk

Well-Known Member
May 18, 2013
6,261
4,040
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Utah
Hi

My posts will sound like heresy to many here. I have not heard the Wilson subs but contend with certitude that for the same cash outlay of a Wilson Thor Hammer or Magico equivalent, one shall obtain much better results by using the budget for more of much less expensive subwoofers.

I'm puzzled by your certitude when you haven't even laid out any definition for the desired qualities of a high end sub! Specially since you haven't even heard what the Thor is capable of, no less setting one or more up to get a better understanding of this incredible sub!

If one wants to have a glimpse, just turn off the main and listen to a sub .. not much going on .. right? mumble, rumbles and if the high-pass crossover cuts around 100 Hz with a any steep slope not much else ... That is what subs do.

That's what the crappy ones sound like, properly designed subs like the Thor fed from correctly with quality electronics are worlds apart from the type of sub you describe here.

I know the original post was about sub driver's size but allow me...

Now, Any subs from whatever manufacturers you choose, even those made of Fairy dust have to abide to the laws of physics, to the laws of small room Acoustics. A small room is any of the listening rooms that all of us here at the WBF is likely to have unless we have our own private concert hall and even then ... It has been shown by many that the best way to have a smooth bass in a room is to use multiple subs. The recommendations are not the same .. The Harman people: Devantier , Welti, etc, recommends multiple subs at specific placements namely middle of the listening room walls. Earl Geddes recommend semi random positioning. This is the idea of a "swarm" and it works for music or movies. The better the response in the room the better the bass. Furthermore, the more subs the less each individual sub has to work for a given output. If a driver works less it tends to produces less distortion. Moreover several subs tend to work in making the in-room bass frequency response more even, i-e less bumpy. This again translate into better bass.
Our hobby is dominated by several myths some of these very comfortable .. The idea of special fairy dust or manufacturer special sauce to "voice" his subs is one of these and Wilson or Magico or whoever cannot be faulted for providing uds with what we desire and to feed our imagination (insecurities?). At a budget similar to the Thor hammer + High End amp ( A Crown Class D pro amp would have been superb at the job but no one that would go for a Thor Hammer would ever consider mating it with a lowly Pro amp) A little over this budget, or at the same ... . One would buy you four (4!!) JL Audio Fathom 212 or two Gotham or 4 (!!!!) Paradigm Sub2 or to me a much better solution 5 pairs of Seaton Submersive and still find some left over money to hire a serious acoustician and have them integrate the subs in your system…
Of course subwoofers integration is not a given. It is not a plug and play affair. It requires patience and dedication to make it work. it also require an open mind. Audiophile from both side of the aisle do have the dedication, what is often missing is the willingness to accept a novel idea, to understand that the cost /price of a solution has little bearing to its effectiveness, to learn the basic physics underlying bass reproduction in a room and likely the most difficult for many to accept: that DSP in the bass does more right than wrong. In the bass the room takes over almost enirely and the best way to diminish its contribution are DSP and multiple Subs .. Preferable a combination of both.

So RonR please consider that array of multiple 15 inchers ( or the "swarm" idea you mentioned. if well executed (not a given) it has the potential to provide you with a level of reproduction you may have never experienced.

The laws of physics also dictate why size matters when it comes to low frequency. Just visit a church with a pipe organ and look at the 16hz pipe! There's no substitute for experience, you'll know the difference once you properly set up a real subwoofer like the Thor with high end amplification and quality analog crossover, it neither rumbles nor mumbles, its very eloquent and natural!

david
 

JonFo

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Jun 11, 2010
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...
What do you think would be the ideal subwoofer system for ML Neoliths? Four BalancedForce 212 subwoofers (eight 12" drivers in total, but only 22" tall) spread around the listening room or two tall subwoofer towers each composed of two, vertically stacked modules of pairs of dual-opposed 15" Seaton drivers (eight 15" drivers in total)?

While the idea of towers of stacked dual-opposed drivers get me excited, I think that the additional units in 4x BF212 scenario would yield a more even result.

But as noted by others, the integration effort is non-trivial as is placement selection. So while the BF212 has PBK that can be applied individually, I'd still recommend a pre-amp our outboard crossover with DRC.

Just as a data point, a few years ago when the topic of multiple subs came up on the MartinLogan owners forum, I decided to see for myself just how hard it might be to deploy 4 into my secondary system (very run-of-the-mill stuff, mostly used for watching TV) so I bought four cheap ML subs and while it took a bit of effort, the results really surprised me (for the cost invested). Way better than expected. Wrote it all up and posted the measurements in this thread over at the MLOC.
 

LL21

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Fantastic Amir! Thank you!!! A few questions:

...3. Assuming 2 above is out...so only 1 sub...when you say the sub has some EQ, have you ever played with the big Velodynes or their software? Just curious as to whether you feel that is 'sufficient' EQ. i understand some people simply buy the Velodyne crossovers/software to use with other subs so hopefully this is a good sign.

Thanks again...very helpful...

Thank you for the kind words...I have not unfortunately. The requirement is rather simple though. Make sure it allows you to dial in an EQ with a resolution of 1 Hz or so. If you give me a link to the specific product, I will take a look.


Very true. The reason to choose one sub over another is maximum SPL and how clean it is (i.e. does it bottom out and get distorted). Almost none of the other parameters matter relative to optimization in the room. If you are going to shake the foundation of the house, then you start with the selection of a sub that can do that. If you are just wanting to augment reasonable listening levels in a rom then that is not critical and the topics we are discussing become paramount. Of course you don't want to buy a junk sub but within reason, it would not be a barrier to good sound.

Fantastic!!! Thank you!!! This is the link to the Velodyne DD18+ (one generation newer than my DD18). http://velodyne.com/subwoofers/digital-drive-plus-18.html
 

Rodney Gold

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Jan 29, 2014
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DD18+ is a great sub , I auditioned a pair and really wanted them .. but the pricing in south Africa was horrendous!!!
I ended up with twin SVS SB13 ultras which I thought were exceptional.. and they shook the house (and ended up with cracks in my ceiling..honest) and they were merely "idling"
its much better to do external eq of the sub than use their inbuilt DSP capabilities, you have a lot more fine control..and most external dsp will allow you to sit and listen whilst you fiddle..
 

Ron Resnick

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Thank you, Jonathan!
 

amirm

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Fantastic!!! Thank you!!! This is the link to the Velodyne DD18+ (one generation newer than my DD18). http://velodyne.com/subwoofers/digital-drive-plus-18.html
I took a look at the user interface of the software and it seems very capable. Has both auto-EQ and manual programming. Resolution of the user interface for each filter is down to 1 Hz which is good. And very easy to use UI for creating the overall filter response. Also has multiple configurations for different types of use/content. I think this is the same hardware/software subsystem used in a number of high-end subs these days.

On note though: the software is Windows only. And uses serial/COM emulation for USB communication which may mean trouble if you try to use it with Parallels on Mac.
 

Mark Seaton

WBF Technical Expert (Speaker & Acoustics)
May 21, 2010
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Some of us like to add one or more external subwoofer systems to even large, full-range speakers with 15" woofers (such as XLFs and Neoliths) for low frequency extension down to 20 Hz or below and for enhanced soundstage ambiance. Many of the subwoofers available today solve for small footprints (e.g., JL, Paradigm) with the result that the drivers in the subwoofers are smaller in diameter (10", 12", 13.5") than the woofer cones in the main speakers which are being supplemented.

Other than manufacturers' desire to solve for a small footprint to avoid a large, tall tower subwoofer system, presumably to minimize cost and to maximize "wife acceptance factor," and other than the theoretical advantage that smaller drivers have less inertia than larger drivers, does it make any sense that our subwoofer drivers should be smaller than the woofer drivers in our large, main speakers?

There just seems to be something theoretically inelegant about having 12" cones in the subwoofers supplementing 15" cones in the full-range speakers.

1) If a main speaker has a 15" woofer, wouldn't we want, ideally, the subwoofer also to utilize 15" drivers?

2) If the 15" woofer in a main speaker is in a ported enclosure as part of the main speaker cabinet, is it technically suboptimal or sonically problematic for the subwoofer to be a sealed box? (I know that Wilson and Martin-Logan use ported cabinets for their 15" cones but I have always been a bit skeptical about that, at least from a theoretical point of view.)

Hi Ron,

I'm a little late to the party here, but good questions. I see both useful and entertaining discussion in the past 50+ posts, but I wanted to first circle back to the original question.

1) We want the low frequency compliment to a large speaker to be more efficient, lower distortion, and higher in peak capabilities than the main speakers... at these lowest frequencies. While a large speaker with less extension might be >90dB in it's operating range, it can be abysmally inefficient at the lowest frequencies. Depending on the space, available locations, components available, and aesthetic constraints, that solution might be multiple modest size woofers or a few very large woofers. I have tested woofers as large as 24" diameter and built surprisingly deep extending, modular subwoofers with 5" woofers. There are exceptional and crappy examples at both ends of the spectrum.

I believe a better general expectation should be that the lowest frequency device should have equal or more radiating area (cone area) along with greater excursion capabilities for all but a few unique exceptions (mostly horns and related transmission/tapped lines). That radiating area may be in the form of multiple drivers which could be smaller than a robust midbass driver.

2) While I'm slightly biased, I do still feel a sealed design is the preferred solution for any reasonably enclosed listening space. Large ported enclosures can make for less expense or reduced power requirements near the port tuning, but given enough quality drive units in the same size enclosure, I'd rather go sealed where you can take great advantage of gains provided by the solid boundaries of the room to achieve extension below 10Hz at the listening position. Also realize I have built some custom and limited production vented designs with tuning frequencies as low as 9.5-11Hz.

While these are 2 fun means to fill a room:
Devastator-w-Mark.jpg TF-D18-pair.jpg

I tend to prefer the results achieved from this dual stack of 8 separate sealed modules (18" driver, 23.5" square x 18" deep) I just installed a few weeks ago:
F18i-LED-Dolby.jpg CR-Front-Wall.jpg Mark-4xF18i.jpg
 
Last edited:

amirm

Banned
Apr 2, 2010
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Is this where your in wall subs are located?
Those are the subs in the one wall. There are multiple sets.

Where's the one in the ceiling?
I don't have a picture of that handy.

Crossover points?
80 Hz.

(Eidt) Is this a picture of your actual listening room or a rendering?

david
It is the real room. Everything is normally hidden behind fabric though. We have a set of LED lights that when you turn them, you can peer into what is behind them. Here is a side-by-side view, with and without back light:

 

LL21

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Dec 26, 2010
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I took a look at the user interface of the software and it seems very capable. Has both auto-EQ and manual programming. Resolution of the user interface for each filter is down to 1 Hz which is good. And very easy to use UI for creating the overall filter response. Also has multiple configurations for different types of use/content. I think this is the same hardware/software subsystem used in a number of high-end subs these days.

On note though: the software is Windows only. And uses serial/COM emulation for USB communication which may mean trouble if you try to use it with Parallels on Mac.

Thank you!!!
 

Brucemck2

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