[DavidS]

I have been thinking about adding a sub to my system and have a couple of questions that I was hoping I might get some help with:

1.  I listen to music 90+%.  I have a 2 channel system (Ellis speakers - good to about 40-45hz, modwright sony player I use for both music and movies, audio note preamp, ps audio amp).  Not sure if my room is large or not - it is 18 by 32 rectangle - 10 foot ceilings - pretty ideal for audio.  Should I look at Maestro or Titan in a room of this size and for audio mostly?

2.  I had a very large B&W sub until about a year ago.  It was boomy - great for movies but to be honest I turned it off for music - couldn't dial it in for music with my speakers.  Since adding the modwright player I love my mids and highs - but find the clean bottom end is just not there (could be my amp as well).  Don't want to repeat my failed experiment with the previous sub though.

3.  Putting a budget together for a sub.  Do you need to purchase upgraded interconnects and power cords to use with ACI subs.  What are people using - what is quality that comes with sub.  Not even sure upgraded cords will make a difference with subs - hope this is not a can of worms question...

Thanks for sharing your experience.

David

[denjo]

David
I can understand what you mean about boomy Subs! I had the same experience with the REL Strata more than a decade ago and swore never to invest in another Sub ever! Like you, I always felt that I was missing the bottom end. After some due diligence, I decided to give ACI's Force XL a try. I must say that I cannot be happier! The Force XL has given me more bass bloom but without the boom or bloating. Music is much more realistic now. When I watch the odd movie (VCD or DVD-video), the Force XL gives much more impact and involvement than without the Sub. I don't profess to have tried all the Subs out there but can only say that the Force XL is staying in my system!
Denjo

[Tinkerer]

I bought an SVS sub recently.

Upon measuring the SPL vs. frequency response, and in subsequent discussions with SVS, I discovered a truth about subwoofers and rooms - one not mentioned by subwoofer manufacturers in their advertisements:

All subwoofers in typical-size rooms create standing waves and other acoustical problems, in the subwoofer frequency range of 15-100Hz.

This is due to natural interactions between room and the sound waves at wavelengths inherent to these low frequencies.  Although a high-quality subwoofer may have advantages over a cheesy subwoofer, the resulting sound in the room will nonetheless be affected in the same ways by room interactions with the low frequency sound waves.

For example, my room has problems with standing waves at about 43 to 55Hz.  This creates a large region in the center of the room where the bass response drops by more than 10dB in that frequency range.  But around the edge of the room the bass response does not have this "hole", and actually increases bass response in certain frequencies.

Other problems related to the room itself can include boominess or unnatural resonances or peaks in SPL response at certain frequencies, echoes, muddiness, etc.

Bass frequencies are more prone to these room interaction problems than higher frequencies.

Your subwoofer experiences probably result from your room interactions problems.

You can overcome some of the problem by experimenting with placement of the SW and your listening position.  But in my case, I can't limit my listening position to the outer edges of the room.

The solutions involve acoustical treatments such as bass traps.  I put $350 worth of corner bass traps in, but that only helped a little bit.  To fully treat the room for bass would probably cost another $1000 or more, and I just don't have the time or $ right now.  Plus, complete acoustical treatment for low frequencies takes up significant amounts of space, since the treatment pieces must be relatively large/thick to be effective.

If I had known about these simple facts of applied sound physics prior to buying the subwoofer, I probably would have decided to not buy a subwoofer.  (I remembered looking at standing waves way back in college, but did not realize that the effect is so strong in subwoofer frequencies in typical rooms, until I experienced it first-hand.)

Good luck with YOUR subwoofer fun.

[DavidS]

One of the reasons I have been looking at a sealed sub like the Titan is that I have read the bass is cleaner, less boomy and not impacted by room issues as much.  Clearly I am not interested in anything that will shake the windows and pictures except when I have a movie on. 

My room probably has less issues than most being a good rectangle with no real openings other than one doorway but it is also a living room so bass traps other than curtains on windows aren't going to work.  Look forward to reading more discussion on this.

David

[Tinkerer]

If you are producing sound waves from 15 to 100Hz in a typical size room (that is, something other than a concert hall or a stadium, etc.), the room will have natural resonant frequencies / modes that will result in standing waves in frequencies within the 15-100Hz range.

My room dimensions yield standing waves in frequencies from low 40s to mid 50s Hz.

It does not matter what kind of subwoofer you use.  A better subwoofer will produce cleaner waves, so to speak - but any/all subwoofers will nonetheless produce standing waves in a given room, with the attendant problems of nodes or areas of attenuated SPL, plus antinodes or areas of "boosted" SPL, for frequency ranges depending on the room dimensions.

The only way to prevent this problem is to use the subwoofer in a free field environment, ie., outside with no walls or ceiling whatsover.  But then you lose the bass-room coupling that actually comprises the full bass response system.

Using a sound system & subwoofer inside a room as most people do, bass traps can supposedly reduce the problem.  How much, I don't really know, because as noted I don't have the $ or time to fully trap the room, presently.  Lab testing of bass trap products is notoriously lacking, due to lack of standards for sub-100Hz testing, supposedly high error levels in those low frequencies, and due to expense of large structures and other material required to do the testing, from what I can gather.

There are lots of good info sources on the web.  Watch out though, because some of them are selling their own bass trap & other acoustic treatment products/services, so they are not exactly unbiased sources.

There's also a lot of ripoff products out there (just like any product type in the audiophile marketplace).  I bought some bass traps that were about 30% less than anything else out there of that same type - but they were still way too expensive, imo:  $350 for UL94 rated polyurethane foam traps for the 4 corners of the room.  Sheesh.  They seem to help somewhat, but I still have the problem of the standing waves and nodes in the room center.

Good luck.

[Mike Dzurko]

I have been thinking about adding a sub to my system and have a couple of questions that I was hoping I might get some help with:

1.  I listen to music 90+%.  I have a 2 channel system (Ellis speakers - good to about 40-45hz, modwright sony player I use for both music and movies, audio note preamp, ps audio amp).  Not sure if my room is large or not - it is 18 by 32 rectangle - 10 foot ceilings - pretty ideal for audio.  Should I look at Maestro or Titan in a room of this size and for audio mostly?

>>> You have a pretty large acoustical space. A Titan XL will certainly fill in the last octave below your Ellis'  . . . but if you want to be sure you have plenty of clean output for any recording, at any level you want to play, I'd get a Maestro.

2.  I had a very large B&W sub until about a year ago.  It was boomy - great for movies but to be honest I turned it off for music - couldn't dial it in for music with my speakers.  Since adding the modwright player I love my mids and highs - but find the clean bottom end is just not there (could be my amp as well).  Don't want to repeat my failed experiment with the previous sub though.

>>> Our subs are known as some of the most musical and accurate you get own . . . once properly setup, you won't need to work about bass quality. Not only will you have the weight and impact of that last octave, you'll also improve the sense of space and ambience when playing many recordings.

3.  Putting a budget together for a sub.  Do you need to purchase upgraded interconnects and power cords to use with ACI subs.  What are people using - what is quality that comes with sub.  Not even sure upgraded cords will make a difference with subs - hope this is not a can of worms question...

>>> The DH Labs subsonic cable is a terrific interconnect at a very reasonable price.  The Titan's power cord is not replaceable, the Maestro cable is and you could certainly try a DH Labs power cable and see what you think.


Thanks for sharing your experience.

David

[Mike Dzurko]

It does not matter what kind of subwoofer you use.  A better subwoofer will produce cleaner waves, so to speak - but any/all subwoofers will nonetheless produce standing waves in a given room, with the attendant problems of nodes or areas of attenuated SPL, plus antinodes or areas of "boosted" SPL, for frequency ranges depending on the room dimensions.

There's also a lot of ripoff products out there (just like any product type in the audiophile marketplace).  I bought some bass traps that were about 30% less than anything else out there of that same type - but they were still way too expensive, imo:  $350 for UL94 rated polyurethane foam traps for the 4 corners of the room.  Sheesh.  They seem to help somewhat, but I still have the problem of the standing waves and nodes in the room center.

Good luck.

You bring up good points about room modes, standing waves, etc. In room bass response is certainly a function of both the sub and the room . . .  and winning a wrestling match with the room can be a real challenge. However, what sub is used most definitely matters . . . they don't all sound the same. A LOT of folks prefer a good sealed sub over a vented sub for sound quality.

Subwoofer placement can be the difference between good sound and great sound. Unfortunately a lot of folks are constrained in their placement options.

Room treatments can make a huge difference . . . but you need a lot of treatment to be really effective at subwoofer frequencies.

There's another option that can really tame the room beast . . . equalization. A device like R-DES can do a fantastic job of flattening out the room response . . . and it's generally a lot more affordable than acoustic room treatment. 

[Tinkerer]

<snip>
Room treatments can make a huge difference . . . but you need a lot of treatment to be really effective at subwoofer frequencies.

There's another option that can really tame the room beast . . . equalization. A device like R-DES can do a fantastic job of flattening out the room response . . . and it's generally a lot more affordable than acoustic room treatment. 

Equalization can help with reducing response peaks caused by room interactions.

However, equalization cannot change the spatial SPL distribution problems that come from standing waves.  My room has a serious drop-off of SPL (aka volume) in the center region of the room.  The outer edges of the room do not have this problem.  The standing wave problem is due to the unavoidable physics of the low frequency sound waves constrained in the room - it is simply that the low-frequency waves have longer wavelengths that are 1/2, 1, 2, 3... multiples of the room dimensions, causing standing waves. (The node in the center of this particular room is a "null" portion of a standing wave, with wavelength equal to 1/2 the room length.)  It can be alleviated somewhat by large areas and thicknesses of bass traps, but it probably cannot be fully cured - in this room.

If I used an equalizer to cut all frequencies but the standing wave frequences, this would apparently correct the problem in the central region of the room - BUT it would cause all other areas of the room to have unnaturally cut frequencies outside the standing wave frequencies.  Hey, great idea - solve the problem in one area, create a new problem in other areas.  (Hear my sarcasm?)  And, no, I cannot limit my listening position to one small area in this room - it is a multi-use, multi-activity room.

The sub placement does indeed affect the sub + room system response - BUT:  The standing waves remain, regardless of where the sub is placed.  Basically, placing the sub in a corner will maximize the room response component of the system, and placing it away from the corner will reduce the room response component.  But the standing wave spatial-SPL problem still occurs, no matter where the sub is placed.  The room itself is the dominant factor in the formation of the standing wave.

The old debate about sealed vs. ported subwoofers:  I used to think that a sealed speaker enclosure is best, based on some old sealed 3-ways with 12" woofers I owned and also on others' opinions.  But the SVS PC-Ultra subwoofer I bought is not sealed, and it sounds great, other than the room physics problem that would affect any subwoofer at these frequencies.  It is not "sloppy" or uncontrolled at all - it is very tight, fast, clean, and accurate, as far as I can tell.  Then again, it has a monster of a driver with an amp to match, especially given that it is ported.  (The ported Klipsch RF3 speakers I bought several years ago also sound great, imo.)  I haven't done a true double-blind listening test, though, to compare sealed vs. ported speakers.  (However, I doubt very many actually have done a true double-blind listening test, and besides, it is impossible to compare apples-to-apples, since speaker A might sound better than speaker B for reasons related to things other than sealed vs. ported design.)  I honestly believe that ported speakers and subwoofers have gotten a bad reputation due to the fact that there are a lot of crappy sounding ported speakers out there, even by supposedly high-quality marques.

[launche]

I previously owned a PC Ultra and now own an ACI Maestro and I much prefer it to the Ultra, sealed design and all.  The Ultra is a nice sub but the Meastro is in another league, as well it should be, IMO.

I much prefer the sealed subs I've heard to the ported ones I've heard.  I think transient response would be the big difference for me overall.  The ported units just sound slower and more loose in comparision.  The Ultra driver is a nice unit and the sub itself has many happy owners and I was one of them.  I contemplated buying another to run duals but decided on a Meastro instead and have never looked back and may never go back to a ported design, unless it's done very well to match what I hear from a sealed design.  If not wanting to spend alot more, based on my experience I would have sold my Ultra and bought 2 used Hsu VTF3 II and would have improved my sub system for just a tad more money.  The VTF3 II is a great budget sub found used at around $500-$550 ea.  two of those would do the average HT proud.  Hell on a budget, the Mirage S12 were going for about $400, 4 of those EQ'd would be very satisfying for HT for under 2k...hmmm maybe I could go back to ported..nah.

The subs I've recently had in my room:
ACI Maestro
Hsu VTF3 II
Paradigm Servo V2
Velodyne DD18
PC Ultra
Mirage S12

These are all good consumer units.  I've also heard some really nice custom and DIY subs that outshine all of these just wish I had the space and sub budget. Hopefully infinite baffle is in my future.

[Mike Dzurko]

I previously owned a PC Ultra and now own an ACI Maestro and I much prefer it to the Ultra, sealed design and all.  The Ultra is a nice sub but the Meastro is in another league, as well it should be, IMO.

I much prefer the sealed subs I've heard to the ported ones I've heard.  I think transient response would be the big difference for me overall.  The ported units just sound slower and more loose in comparision.  The Ultra driver is a nice unit and the sub itself has many happy owners and I was one of them.  I contemplated buying another to run duals but decided on a Meastro instead and have never looked back and may never go back to a ported design, unless it's done very well to match what I hear from a sealed design.  If not wanting to spend alot more, based on my experience I would have sold my Ultra and bought 2 used Hsu VTF3 II and would have improved my sub system for just a tad more money.  The VTF3 II is a great budget sub found used at around $500-$550 ea.  two of those would do the average HT proud.  Hell on a budget, the Mirage S12 were going for about $400, 4 of those EQ'd would be very satisfying for HT for under 2k...hmmm maybe I could go back to ported..nah.

The subs I've recently had in my room:
ACI Maestro
Hsu VTF3 II
Paradigm Servo V2
Velodyne DD18
PC Ultra
Mirage S12

These are all good consumer units.  I've also heard some really nice custom and DIY subs that outshine all of these just wish I had the space and sub budget. Hopefully infinite baffle is in my future.

We ought to get a second Maestro into your system and you'd probably lose all desire for an infinite baffle 

[circularduck]

I just wanted to point out, in case it isn't obvious, that standing waves will occur whether the source is a sub or main speakers.  The difference is you have more placement options with a subwoofer to try and control the standing waves.  Also, most people have to concede to the fact that their system is optimized for a certain "listening area".  It would be near impossible to have the same frequency response throughout the whole room.  That is why usually you optimize the placement of the sub first, to limit as many of the room modes as possible, then add room treatments to try and tame some of the peaks and nulls, and lastly, apply an eq to correct for anything left.

[Tinkerer]

I just wanted to point out, in case it isn't obvious, that standing waves will occur whether the source is a sub or main speakers.  The difference is you have more placement options with a subwoofer to try and control the standing waves.  Also, most people have to concede to the fact that their system is optimized for a certain "listening area".  It would be near impossible to have the same frequency response throughout the whole room.  That is why usually you optimize the placement of the sub first, to limit as many of the room modes as possible, then add room treatments to try and tame some of the peaks and nulls, and lastly, apply an eq to correct for anything left.

The standing waves are most prominent and noticeable in the lowest audible frequencies, for several reasons.  (There is enough information on the reasons to write an essay on that subject alone, so I'll spare you.)  If your main speakers have a lower end all the way down to 20Hz or below (at the lower 3 dB dropoff point), then of course they will produce significant standing waves that you may notice in a typical room, just like a decently capable subwoofer would.

But most main speakers do not extend that low, so the standing wave problem may only become apparent once a subwoofer is added.

At least, that was the case for me.

Again:  The standing waves form, with about the same locations of the nodes or "nulls", no matter where the sub is located.  Locating the sub in the corner does maximize the room response to the sub, but the dang standing waves form in any case, with about the same spatial distribution in the room itself, regardless of the sub location.  I've verified this.  The room itself forms the waves, not affected much by sub location.

Before the standing wave problem became apparent, my "listenable area" was pretty good for most of the room.  Not ideal, but pretty good.  Now, with the standing wave problem, this is no longer the case.

My point was also that it is interesting that subwoofer sellers make absolutely no mention, in their marketing glitz, of this problem born of a fact of physics in real life.  I only discovered it when testing frequency response with an SPL meter and test CD, and then confirmed it by the seller's response to my questions on the subject. 

Deception by omission can be considered deception nonetheless, in many cases.  I think this subwoofer sellers' information omission is one such case of deception in marketing.  (If they are good enough to design and build great subwoofers, then they know about the standing wave problem.  SVS does, that's for sure.)

As noted, if I had known beforehand about this problem, I probably would have skipped the subwoofer, and perhaps bought a damn good set of headphones instead - because it will take thousands of $ to mitigate the standing wave problem using room treatments.  (No, the equalizer will NOT cure it, the best it can do is to cure it in some room locations while creating new inaccuracies in others, because of spatial variations in the room response and the standing waves themselves.  No, I'm not going to limit my listening position to one tiny spot in the room.)

[circularduck]

Deception by omission can be considered deception nonetheless, in many cases.  I think this subwoofer sellers' information omission is one such case of deception in marketing.  (If they are good enough to design and build great subwoofers, then they know about the standing wave problem.  SVS does, that's for sure.)

As noted, if I had known beforehand about this problem, I probably would have skipped the subwoofer, and perhaps bought a damn good set of headphones instead - because it will take thousands of $ to mitigate the standing wave problem using room treatments.  (No, the equalizer will NOT cure it, the best it can do is to cure it in some room locations while creating new inaccuracies in others, because of spatial variations in the room response and the standing waves themselves.  No, I'm not going to limit my listening position to one tiny spot in the room.)

I wasn't suggesting that you have to limit yourself to one tiny spot in the room, that's why I chose the word "area" to describe the listening position.

I also don't agree with your position about subwoofer companies being deceptive.  They produce a product that performs a certain task as well as possible.  The fact that it creates problems in your room is not their responsibility.  There may be people out there that have large enough spaces that are treated properly and don't have any issues.  A manufacturer of SUV's does not go telling every potential customer that the vehicle may not fit in their garage, it's not their problem.

My point is still that if you want to play music or movies with low frequency content, you will still have the potential for standing waves whether the source is your main speakers or a sub.  Either way, it's not the speaker manufacturers problem to deal with, it's yours.