rear sub

[Yamahaluver]

<font color='#0000FF'>How many agree that a rear sub is neccesary for a proper HT setup.

Using a rear sub enables one to use LARGE speaker setting for rear speakers in the HT receiver/amp. In my experience, it widens and opens up the soundstage significantly and adds the resonace in DTS. Most DTS setups call for large full range speakers in the rear. By using a active sub, one can use bookshelf speakers for better imaging and avoid a logistical nightmare of placment. Also an active sub uses it's own power, thereby relieving the HT amp to give high dynamics to the rear speakers and leaving the power robbing job of bass to the sub.

In my opinion, a rear sub is way more important than a rear center speaker.</font>

<font color='#000000'>I must respectfully completely disagree with you.

Locating a sub in the rear will definitely cause both destructive and constructive interference based on the dimensions of the room, the location of the listening position and the position of the subs.

Standing wave phenomona (modal frequency peaks and dips) for low frequency sound is a given in all home HT environments, and typically gets worse the more subs you introduce into the room.

I've used sophisticated MLS (Maximum Length Sequence) based acoustic measurement systems to locate and correct these issues for the last 5 years. &nbsp;Believe me, this is the least understood issue for most HT enthusiasts.</font>

[Yamahaluver]

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Guest : <font color='#000000'>I must respectfully completely disagree with you.

Locating a sub in the rear will definitely cause both destructive and constructive interference based on the dimensions of the room, the location of the listening position and the position of the subs.

Standing wave phenomona (modal frequency peaks and dips) for low frequency sound is a given in all home HT environments, and typically gets worse the more subs you introduce into the room.

I've used sophisticated MLS (Maximum Length Sequence) based acoustic measurement systems to locate and correct these issues for the last 5 years. *Believe me, this is the least understood issue for most HT enthusiasts.</font>
<font color='#0000FF'>But in a 24x17 room, chances are much less. Have tried it with and without and can tell you that the dynamics are vastly improved with a rear sub. Even Yamaha recommends it for large room instalations. Lets put it this way, if you were to use a powerful amp with a large floor standing rear speakers, then you are coming to almost the same results as rear floor stander with amp combo can give you serious bass although not as low as a sub.</font>

<font color='#000000'>I'm sorry, but a 24 x 17 room is still considered a small room (&lt;4000 ft3) with standing waves by anyone who does acoustics for a living.

In other words you are likely still creating destructive and constructive interference with standing waves in that setup, it's just the law of physics.

You may like it, but that doesn't make it sonically correct.</font>

[Yamahaluver]

<font color='#0000FF'>I agree with you on the physics issue however sound is way more than physics and the depth extension with the rear sub is way more justified for me than what any law says. The directionality of the bass effect is preserved specially wathcing DTS with Yamaha Cinema DSP engaged. If I turn the rear sub off and direct the bass to the front subs the loss is apparent.</font>

<font color='#000000'>Simply more proof of the acoustical effects caused by room dimensions, driver placement and listener placement, i.e. frequency anomolies from standing waves.

Sorry I don't buy your &quot;directional&quot; bass argument, more than likely it's the harmonics from the drywall and floor vibrating or other things in the room vibrating.

Bass below 80Hz just isn't directional.

For a better understanding of these issues, I'd recommend the book &quot;Master Handbook of Acoustics&quot; by F. Alton Everest,
a highly respected leader in the field of acosutics.</font>

<font color='#000000'>Sorry Bruce, music to me is all about ears, not text and my floor is all marble and the walls are all solid brick. There is no source of vibration to my knowledge.I never go by any book when it comes to music, just my own and other's experince.

This means, you would also recommend against the use of large floor standing towers for the rear.Since you are pretty experienced in this feild, would you agree that the bass component for the rear channels is delayed my few milli seconds, therefore if there is a scene with gunshot or other heavy bass in the rear, would you prefer that it comes from your front sub?</font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> I never go by any book when it comes to music</td></tr></table>

That explains why you don't understand the physics of acoustics. *Your call, but then you cannot speak with any sort of credibility if you don't have a detailed understanding of acoustic principles.

I also use my ears for music pleasure, otherwise why would I even care to listen. *The key is I back up my auditory perceptions with measured and documented evidence.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> would you agree that the bass component for the rear channels is delayed my few milli seconds, therefore if there is a scene with gunshot or other heavy bass in the rear, would you prefer that it comes from your front sub?</td></tr></table>

The purpose of digital bass management is to correctly time-align the production of bass frequencies for all channels. *

Because of this time-alignment and the fundamental nature of bass frequencies themselves, you won't be able to tell where low bass frequencies originate from, so it doesn't matter if the sub is in the front.

I would also guess there is not much bass in a gunshot, mostly frequencies &gt;100Hz.

Again the simple physics of acoustics if you were just willing to open a book and learn.</font>

[Yamahaluver]

<font color='#0000FF'>Why do I have to bother when I have tried both and this works out better for me. Your attitude is very rigid. When you learn to drive a car, do you read a book to do so or go by your gut instinct and please dont preach me about books or physics. I teach math at the university so have done my fair share of reading and still do. I dont neccesarily believe in the rigidity of all the theories. Each and every theory is an evolving process. Things which were taken as science few years back are now shattered.

In your case then. Yamaha and DTS are stupid to give bass component to the rear speakers. They sould then follow the older method of 20 watts in the rear. Why do you think people use 200x7 amps for HT? No full size speakers in the back either. I have worked in the department of psychoacoustics while doing my Ph.D. at Rutgers and can tell you that there are many variations to any given theory. This is just like cooking where different chefs will give you different versions of the same dish.</font>

<font color='#000000'>Everyone can have their own theory and opinion, but that doesn't make it right.

You are certainly free to like what you like, but that doesn't make it right for you to state absolutes from your experience. &nbsp;After all it's just your experience, not a fact.

You sure don't seem to know much about acoustical wave phenomena or DSP algorithms regarding bass management, but that's OK, you are still free to like anything you want.

I just need to take what you say with a large grain of salt.</font>

[Yamahaluver]

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Bruce : <font color='#000000'>Everyone can have their own theory and opinion, but that doesn't make it right.

You are certainly free to like what you like, but that doesn't make it right for you to state absolutes from your experience. *After all it's just your experience, not a fact.

You sure don't seem to know much about acoustical wave phenomena or DSP algorithms regarding bass management, but that's OK, you are still free to like anything you want.

I just need to take what you say with a large grain of salt.</font>
<font color='#0000FF'>Never said or claimed that my experience has to be the aboslute, just wanted other's response. You have no idea about sound or DSP for that matter. Yamaha gives the LARGE setting for people using subs in the rear. It is stated in the manual as well as recommended by Yamaha techs.

I guess Yamaha being pioneer in the DSP feild do know a thing or two about it. Going by your theory, there should then be no bass component at all in the rear and that is absurd.

You are entitled to your opinion just like I am entitled to mine. No need to get personal. I did the math for the dept. of Physics at Rutgers and therefore do know a few things about acoustics as that was the research matter on which I had to work at. Anyway, thanks for your opinion and I guess it is time for anyone else to post regarding this issue.</font>

<font color='#000000'>I see you left when everyone questioned your knowledge about acoustics and bass propagation in this thread
here (http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=140792)

I see you want to keep avoiding the issue of &quot;REAL&quot; knowledge about room acoustics, so I will say goodbye for now.

Glad you like what you hear, let's just leave it at that.</font>

[Clint DeBoer]

<font color='#008080'>Unneccesarily combative... not sure why.</font>

<font color='#000000'>Didnt leave. just avoided nuisance, sometimes best to do so, knew you had to be a ghost from there, so do your trolling there and leave me in peace. I avoided that forum because of people who are biased and also because that forum, unlike this one, is partisan as it is sponsored by few particular manufacturers who are the hallowed ones and are off limits to any criticism, constructive or otherwise.

Even the moderators of that forum are foolish and irresponisble unlike here. Gene, hawke are much more knowledgeable and responsible persons and I value their opinions, write ups and general perspective much more than I will do to a book or a bunch of constricted persons.

I enjoy and look forward to this forum and people here so dont ruin it here for me otherwise I would have to take appropriate steps. Go enjoy your company in the biased forum and leave us in peace.</font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">so dont ruin it here for me otherwise I would have to take appropriate steps. *</td></tr></table>

And so what is that a threat? *At least I have the integrity to use my real name.

Well I must say you don't seem to have much decorum. *At least I know how to carry on a discussion about facts and at least be civil without threating people.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">I avoided that forum because of people who are biased and also because that forum, unlike this one, is partisan as it is sponsored by few particular manufacturers who are the hallowed ones and are off limits to any criticism, constructive or otherwise. </td></tr></table>

Just because someone doesn't agree with you, you take it upon yourself to denegrate and insult them with this nonesense? *Look in the mirror, you might be surprised at what you see.

Last time I checked this was a free country. *You can leave any time!!!</font>

[Yamahaluver]

<font color='#0000FF'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Bruce : <table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">so dont ruin it here for me otherwise I would have to take appropriate steps. *

And so what is that a threat? *At least I have the integrity to use my real name.

Well I must say you don't seem to have much decorum. *At least I know how to carry on a discussion about facts and at least be civil without threating people.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">I avoided that forum because of people who are biased and also because that forum, unlike this one, is partisan as it is sponsored by few particular manufacturers who are the hallowed ones and are off limits to any criticism, constructive or otherwise. </td></tr></table>

Just because someone doesn't agree with you, you take it upon yourself to denegrate and insult them with this nonesense? *Look in the mirror, you might be surprised at what you see.

Last time I checked this was a free country. *You can leave any time!!!</td></tr></table>
As you said, it is a free country, so go troll elsewhere. My posts were all decorum till you brought out your real motive behind your posts and that is trolling.

Since as it is a free country, I also reserve the right to defend my point of view and dignity.

BTW: my name is there for all to see, just click on the profile if you have the dexteriety to do so. I have nothing to hide and my monniker reflects my love and bias for a certain brand although I have always given other brands equal leeway.

In case all of you are wondering why this post suddenly gets a response, here is some background which I hope would help clarify things a bit.

This man (Bruce) has been hurt at the HTR forum because I had the misfortune of saying something bad about his favorite company. From that time onwards, his mission in life has been to taunt me and confront me in every which way he can. Now he has decided to follow me here and get the same negative attitude going.

I have no desire to leave this forum as I like the people and the atmosphere here more than other places. This will be my clarification and last post regarding this issue and I would only response to genuine arguments for or against rear subs from anyone else apart from the HTR forum crowd.

To assume digital management in receivers is the only way to get bass is ridiculous and anyone going through Gene's articles on bass management would know better. The 90Hz cut off frequency used by most companies is still pathetic to say the least as this range of frequency is still directional.

The other problem comes when you have good, bass capable towers mated to a separate main amplifier with high wattage. It becomes very difficult to integrate the bass from the subs with the main speakers. Many only use main speakers for stereo with the sub off for this very reason. The sub is only used for HT for this same problem as most find the bass overwhelming and intrusive. This is not only my opinion but the opinion of persons like Gene, hawke etc. if one were to go by the various informative bass management articles in the Audioholics site.

The reason I was propagating the use of rear sub is because of compensating for using a small bookshelf speaker to preserve logistical sanity. Ideally all HT amps would benefit from full range speakers matched but very few of us can really achieve this in reality. By putting a rear sub and small bookshelf speakers for rear channel, a compromise of sorts is achieved where the DSP and DTS/Dolby would send full range signals to the rear instead of diverting the &lt;90Hz signal to the sub. My experience (others may differ by all means) is that the combination of front and rear sub with Large settings for front main and rear surround speakers has been pretty good in a sense. With Yamaha?s excellent Cinema DSP modes, adding the rear sub gave a much greater degree of ambience than with the front subs alone and rear speakers set to Small. I also set my subs in the front to 65Hz when I am in stereo mode to integrate them with my towers which can go down to 40Hz comfortably. By adding the rear sub and crossing it at 100Hz my bookshelves now sound much better and the dynamics in the upper mid and treble region are much improved.

Just my clarification.</font>

<font color='#000000'>Interesting discussion guys, if a little acrimonious...

For what it's worth, my current understanding of bass handling in HT set-ups suggests that Bruce is technically correct, and there are likely to be considerable distortions if an extra sub is added at the rear. However, some experimentation with positioning the subs may be able to minimize these effects, and, of course, you may find the distortions quite acceptable - they don't necessarily make the listening experience less enjoyable (after all, many audiophiles like the 'warm' coloration of some amp and speaker technologies when it is clear this is a [benign?] sonic distortion).

I can't see how placing the sub in the rear would give any true sonic advantage over two front subs, unless the perceived impovement is due to higher frequency directional sounds from the subs rather than true (non-directional) bass, although the distortions already mentioned may play their part. I assume the small rears in this case are fed from the sub output so as to benefit from filtering out the low bass, otherwise setting them to 'Large' is very likely to cause unpleasant distortions as they will be handling bass they are not designed for, which will degrade their performance all round.

When all is said and done though, there is more than pure physics involved, and depending on the environment and the listener, a less truly rendered sound field may sound much better than one configured by the book and SPL metering, etc. Yamahaluver is right to point out the primary involvement of human physiology and psychology - the perceived sound is what counts for most of us, regardless of physical accuracy. It is entirely possible that in some situations the auditory system may filter and 'compensate' more accurately reproduced sound fields to produce a degraded perception, yet the same psycho/physiological 'corrections' on a distorted sound field may result in a superior perceived sound. When listening at home in the lounge, the accoustics are different, we know we are not in a studio or concert hall or club, and so does our auditory processing system.</font>

[Yamahaluver]

<font color='#0000FF'>Hi Dave,

The rear subs are placed exactly as you percieved, they are attached to the speaker cables and then the cables and from the sub, the cables are taken to the bookshelf. My purpose was to get the same dynamics and sound as if we were to put a large floor standing rear speakers. As I mentioned, I am quite aware of the problems witnh multiple subs but in case of HT it is the sound we are after, not the purity. For pure music listening, I only use the two front speakers or my dedicated Accuphase DP-70 CDP/Yamaha MX-1000U amp and a pair of Yamaha NS-1000x speakers.

Since HT is all about creating soundfeild, my experience with multiple subs have been pretty good and this is also the comment of others who have heard my system. I started with a single sub and set it with the Avia and S&amp;V test disc and a Radio Shack SPL and gradualy have come to this stage. <img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'></font>

<font color='#000000'>I have no argument with the perception that a rear sub may sound OK to the listener.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">The rear subs are placed exactly as you percieved, they are attached to the speaker cables and then the cables and from the sub, the cables are taken to the bookshelf. My purpose was to get the same dynamics and sound as if we were to put a large floor standing rear speakers. *</td></tr></table>

Even full-range towers all the way around will produce unwanted standing waves in the bass frequencies that will disrupt the frequency response at the listening spot. *This frequency disruption is caused by the constructive and destructive interference of standing waves. *This will show up as frequency peaks and dips at the listening position.

This happens with any multiple (two or more) sources of bass frequency drivers in a small room (&lt;10,000 ft3) whether they are subs or full range speakers doesn't matter. *

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> To assume digital management in receivers is the only way to get bass is ridiculous and anyone going through Gene's articles on bass management would know better. </td></tr></table>

I certainly don't assume that, in fact I don't even like the crossover setup in most processors, as they assume your speakers have an acoustical rolloff of 12dB/octave for the high-pass portion to add with their 12dB/octave electrical filter. *Few if any speakers actually meet this criteria, although THX certified speakers do @80Hz.

Because of this I prefer to use a Marchand XM9-L (http://www.marchandelec.com) symmetrical 24dB/octave Linkwitz-Riley active xover @60Hz *between my sub and mains, not using the sub-out on the processor at all. *i.e. Sub=No, Mains=Large, center=Small, Surrounds=Small.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> This man (Bruce) has been hurt at the HTR forum because I had the misfortune of saying something bad about his favorite company. </td></tr></table>

By the way, I'm a member of about 10 audio forums for the last 5 years and don't frequent HTF that much, I much prefer AVS, AA, HTT, HTGuide.

Hurt??? Not at all, I simply want to make sure forum readers get a truer look at what falsehoods you are propagating.</font>

[Yamahaluver]

<font color='#0000FF'>Have you lost your mind? Where is the falsehood that I have propagated?

I just put my experience up and wanted other's opinion. Everyone here is free to do whatever is appropriate for them.

It seems you have a personal issue with me carried over from HTR forum. In that case take it elsewhere. If I am to post an opinion which is my personal and am looking for reflection from others, there is no need for personal hostility. I do whatever I feel with my HT equipment and dont have to be stuck with any kind of rigidity. Now if that hurts your point of view, do you think I care? Next thing you will tell me is to change my religon or my name or my nationality. Rigidity gets you nowhere and neither does so-called books huge amounts of worthless text. Perception of sound differs from person to person as does food and culture. In your way, there can be no variations to any given situation.

In case of sound, it is a more personal feild and depends largely on people's perception of sound. Going by your way, there should only be one company making speakers sticking to the laws of physics. This way, all amps should sound the same with the null test and all speakers also should sound the same. Just because I dont care or consider your opinion on the issue of rear sub seems to get your adrenalin going.

Cant help you there except that we avoid each others posts in the future. I am staying here and I guess so are you. In view of preserving sanity, let us not cross our ways in the future. It looks like neither of us has any desire or respect for each other's opinion. <img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/sad.gif" border="0" valign="absmiddle" alt=':('></font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">The reason I was propagating the use of rear sub is because of compensating for using a small bookshelf speaker to preserve logistical sanity. &nbsp;</td></tr></table>

To be utterly simplistic, a rear sub is not necessary in this example, and provides no specific benefit (detrimental in most cases), except that you seem to want to &quot;propagate&quot; it's importance.

If you like the way it sounds that's fine, I just want other forum members to be aware of all the issues with regards to your opinion.</font>

[Yamahaluver]

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Bruce : <font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">The reason I was propagating the use of rear sub is because of compensating for using a small bookshelf speaker to preserve logistical sanity. *

To be utterly simplistic, a rear sub is not necessary in this example, and provides no specific benefit (detrimental in most cases), except that you seem to want to &quot;propagate&quot; it's importance.

If you like the way it sounds that's fine, I just want other forum members to be aware of all the issues with regards to your opinion.</font></td></tr></table>
<font color='#0000FF'>Let the others be free to experiment as I have and come to their own conclusions. Why prevent them from doing so if they have the means?</font>

[gene]

<font color='#000000'>Guys, normally I don't interject on our forums as I feel people contributing on our forums don't need constant babysitters to moderate like some other audio forums. &nbsp;However, when personal attacks take over the actual discussion, I feel it is appropriate to interject as the debate has outlived its usefulness and usually only degrades to further insults and offense to both parties, as well as the readers. &nbsp;At this time, I would ask for both parties to limit this debate to the topic at hand and refrain from further insults.

For the record, I am not a degreed Physicist and have only my EE background as well as my hobby reading on this topic to voice my perspective. &nbsp;From my experience, implementing multiple subs in a home theater system can be very challenging. &nbsp;I have usually discovered better results by placing the multiple subs at a common location. &nbsp;Based on my subjective DBT listening tests, I believe I can localize a bass source if it is located behind the listening position and crossed over above 60Hz (24dB/Octave filter). &nbsp;This is why I have my sub located at the front of my room and crossed over at 60Hz. &nbsp;Also, there is something to be said about using multiple bass sources to average out room response. &nbsp;That being said, I have found that when using large main tower bass capable speakers, coupled with a very musical and capable sub, crossed over below 80Hz, I can usually average out room response better than setting the main speakers small, or not using a sub at all. &nbsp;

I still cannot get rid of all the nulls in my room, since I am limited to placement and room treatment options. &nbsp;This doesn't however deter me from enjoying my equipment, it just leaves the door open for improvement and it has convinced me to build a dedicated home theater room in my next home.

RBH Sound has a pretty interesting solution that I may review in the future. &nbsp;It's their new T3 speaker system that sandwiches two active subs between each main speaker. &nbsp;They claim this will help average room response and eliminate most nulls. &nbsp;I will have to hear it to believe it. &nbsp;

RBH Sound T3 (http://shows.soundstagelive.com/shows/avtour2002/ced_dly_28.shtml)

Bruce, you seem quite knowledgeable about the physics of sound, perhaps one day, time permitting, I will share with you my measured room response and you could offer suggestions. &nbsp;

Yamahaluver, you seem to have a good knowledge base that like me, helps me to configure a system as best as possible given the constraints I previously mentioned.

Bottom Line:
I am not a big fan of multi sub systems, and feel they usually perform best, and are easiest to set up, when placed at a common point. &nbsp;I am more than satisfied with setting my rear speakers to small and letting my sub handle the rest.

I hope we can all continue this discussion with more civility. &nbsp;What do you say guys? &nbsp;I don't want to loose either of you as members as a result of this disagreement.
<img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/sad.gif" border="0" valign="absmiddle" alt=':('></font>

<font color='#000000'>Gene,

You're on, I only want to help people find and discover information that helps them decide for themselves what sounds best. *For those who are new to audio/HT it can be confusing, and we should try to make it easy for them to understand.

There are generally accepted guidelines we can all follow, but in the end you do what makes you feel good. &nbsp;It's best if you have as much information as possible to make an informed decision.</font>

[Yamahaluver]

<font color='#0000FF'>No hard feelings then, I too appreciate Bruce's knowledge in Physics but have learned to go by my gut instinct rather than theory when it comes to sound. Being a researcher myself, I have learnt that nothing can be considered the absolute truth and in life that is even more applicable.

I have got a lot to learn from you Bruce so as Gene suggests, lets call a truce if you are willing.

My point in this is why then do manufacturers insist on option of rear Large and high power for rear?</font>

<font color='#000000'>A truce sounds good to me.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> . . . why then do manufacturers insist on option of rear Large and high power for rear?</td></tr></table>

I'm not sure I follow which manufacturers you mean. *If you are referring to SACD/DVD-A, the problem is basically we're forced to use analog outs from the players with poor to no bass management in the signal path (from either the player or the HT processor). *So, the manufacturers take the easy way out and specify full-range for all channels with SACD/DVD-A, pretty lame in my book. *I think they should get their act together and finish a digital link - protected if necessary.

If instead you are just referring to manufacturers allowing you to set rears to Large, well then that is just an option like everything else.

Since I prefer 2-channel for my music consumption, I tend to ignore the multichannel music setups anyway.

IMO, most of 5.1/7.1 systems are designed to accomodate the normal-sized HT rooms found in many homes (&lt;4000ft3), with 90% not able to really fit large floorstanders all around. *This is why smaller monitors are popular for HT systems and the reason bass management (with re-directed bass) is necessary.

Not many speakers are truly full-range anyway. &nbsp;To be called full range they would need to hit 105dB down to 20Hz at the listening position (not many if any truly fit this bill). &nbsp;The multiple sources of bass would be very difficult to balance-out without wide peaks and dips in bass response, unless you had unlimited funds to acoustically treat the room.</font>

[Yamahaluver]

<font color='#0000FF'>Bruce,

Majority of HT receivers have LARGE settings for their rear speakers and some in their manuals advice to use full range towers for rears.

The point is that if the rule of non directional bass is so rigid, why even incorporate the option and also, why the need for higher wattage.

For stereo, I have a Accuphase CDP connected directly to my Yamaha MX-1000U power amp and listen them through a pair of NS-1000x speakers. There are no pre-amps in this equation and no tone controls either. Just pure sound from the components in the chain. <img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'></font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> Majority of HT receivers have LARGE settings for their rear speakers and some in their manuals advice to use full range towers for rears.</td></tr></table>

I agree, most (All?) HT processors (receivers and prepros) offer the Large settings. *

In all the manuals I've read, Meridian, Theta, Outlaw, Rotel, and Fosgate, among others, none have ever advised using Large rears in typical HT rooms. *They offer the setting because in a &gt;10,000ft3 room you are much less likely to experience bass standing wave problems (or space problems either) and you could actually take advantage of large speakers all around.


<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> The point is that if the rule of non directional bass is so rigid, why even incorporate the option and also, why the need for higher wattage.
</td></tr></table>

They incorporate the option because some users may actually have &gt;10,000ft3 rooms. *

Bass frequency reproduction always draws more power from the amplifier than higher frequencies. *That big and heavy bass driver motor assembly takes more power to drive than a tweeter or mid-range driver. *So if the speaker can reproduce low bass frequencies it will draw more power. &nbsp;Which means it needs an amp with higher power ratings to keep from clipping.</font>

[Yamahaluver]

<font color='#0000FF'>Bruce,

One of the reasons I put the subs in the back was for the exact resons you describe above, to prevent the amp from being used up for bass signals. Also, my bookshelf were sounding taxed even when they were set to Small as there is lot of high &gt;90Hz mid bass component. When using DSP with music mode, there was quite a few times, the woofer seem to be bottoming out. Now all those problems are gone. One question for you, even though there is a general consensus that bass below 90Hz is non directional, would you prefer situation in the movie where a gun is fired in the back to come from the front.

Also in the Yamaha receivers and amps, there is BOTH setting for speakers and this effectively puts all the bass component to the sub and the main speakers simetaneously. Yamaha recommends this in case one has good floor standers and a high powered main amp. I keep my settings at that and get massive amount of SPL which after all is the WOW! factor in a typical HT. HT and DSP never stood for pure accurate sound so if novelty is what we want, we have to divert a bit from accuracy, it is a trade off of some sorts but one that sure makes you feel good. Yamaha's advice is to use same type of speakers for main and surround, only the front surround are recommended to be smaller. Since I have their full size front speakers and centers, it is near impossible for me to puit the same in the back, thus I decided to add the subs in addition to the subs I have in the front. My sub volumes are set pretty low to avoid the dreaded clash with the one in the back.

I do have fair amount of sound proofing done near the three subs I have and there is a good amount of standing wave breakers like heavy sofas and draperies all over the room and the room has no back wall.The ceilling too is peaked. One of the reasons I guess, I havent had bad audible results with three subs.</font>

<font color='#000000'>Yamahaluver,

Every room is different, so it's hard for me to comment on your specific setup without actually being there.

I can only offer a few thoughts.

One of the reasons for using prepros and external amps (or receivers and external amps) is to get away from the fundamental limiting factor of a receiver, smaller amps/channel. *Personally, I like at least a 1.6 kVA Toroid power transformer and at least 100,000 µF of power supply filter capacitance which won't fit in a receiver chassis.


<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">One question for you, even though there is a general consensus that bass below 90Hz is non directional, would you prefer situation in the movie where a gun is fired in the back to come from the front.</td></tr></table>
If you were to use an acoustic analyzer to detect the frequency of a gunshot, I think you would be surprised to find out that it's mostly composed of non-bass frequencies, probably higher than 200Hz.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">Also in the Yamaha receivers and amps, there is BOTH setting for speakers and this effectively puts all the bass component to the sub and the main speakers simetaneously </td></tr></table>
Yes, many receivers have this setting, but unfortunately this setting really exacerbates the standing wave problems (multiple sources of the same bass frequencies) tending to become the dreaded *&quot;boomy&quot; (modal peak) one note bass.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">. . .HT and DSP never stood for pure accurate sound . . .</td></tr></table>
You are quite correct, as DD and DTS are lossy-based *formats that compress the source signal by actually taking away original signal content.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> My sub volumes are set pretty low to avoid the dreaded clash with the one in the back.</td></tr></table>
If they clash, then that is probably a good example of bass modal peak constructive interference. *Do you set the rear sub's phase switch to an opposite 180 degree phase setting from the sub in the front? *

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> I do have fair amount of sound proofing done near the three subs I have and there is a good amount of standing wave breakers like heavy sofas and draperies all over the room </td></tr></table>
To be even minimally effective in the bass frequency region (&lt;150Hz), sound proofing needs to be a minimum of 6 inches thick. *So heavy sofas qualify here, but not drapes.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">. . . *I havent had bad audible results with three subs.</td></tr></table>
I can't argue with your satisfaction of your current system setup, but I think you would be quite surprised at a bass frequency response graph of your system from your listening position. *It would clearly identify the modal peaks and dips in your multiple sub setup.</font>

[Yamahaluver]

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Bruce : <font color='#000000'>One of the reasons for using prepros and external amps (or receivers and external amps) is to get away from the fundamental limiting factor of a receiver, smaller amps/channel. *Personally, I like at least a 1.6 kVA Toroid power transformer and at least 100,000 µF of power supply filter capacitance which won't fit in a receiver chassis.

My MX-1 and MX-1000U Yamaha amps qualify in that criteria pretty well. Both of them have two 750VA transformers and 100000 pico farads of capacitance.





Yes, many receivers have this setting, but unfortunately this setting really exacerbates the standing wave problems (multiple sources of the same bass frequencies) tending to become the dreaded *&quot;boomy&quot; (modal peak) one note bass.


I can't argue with your satisfaction of your current system setup, but I think you would be quite surprised at a bass frequency response graph of your system from your listening position. *It would clearly identify the modal peaks and dips in your multiple sub setup.

As I have no back walls in my room, the reflection part is solved to a great extent. My rooms is constructed of solid bricks with marble flooring.

In the end, my experiment works out for me. When I get some time, I will do an in depth frequency analyisis and post the results.</font>
<font color='#0000FF'><img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'></font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> As I have no back walls in my room, the reflection part is solved to a great extent. </td></tr></table>

I say this in gest, *<img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'> * you mean your room is open to the outside? *<img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'>

Actually, all openings in your room that lead to other parts of your house have an influence on the size of the room that bass frequencies work in. *

I mean that if you don't actually have an acoustically sealed room, then the bass frequencies will reflect off the parallel surfaces and out those openings --helping to eliminate some of the standing wave problems.

Think of standing waves like waves you can cause with your hand in a bathtub. *The bathtub is small and the waves easily bounce off the sides of the tub and collide with each other. *Those waves exactly in-phase double their size, those exactly out-of-phase cancel each other out.* If it was an outdoor pool instead (like a much larger room), it's likely the wave you make with your hand would never get back to you at all.</font>

[Khellandros66]

<font color='#000000'>I beleive a rear sub sounds like a nice idea, but what about colliding wave patterns? &nbsp;if you want two subs use them in the front of the room, this creates a more open soundstage in the sub 100Hz range. &nbsp;Plus it is far less directional.</font>

<font color='#000000'><img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'> When I said no back walls, I meant that there are no walls behind the rear speakers or sub like the tradational HT setup where the rears are mounted on the wall. One of the reasons the rears get a bass boost which is not available to me.

Khellandro 66, I do have two similar subs in the front apart from the rear.</font>

<font color='#000000'>Just as a matter of interest, with the Linn Classik Movie system, when using the Classik HT speakers (Uniks + Afekt sub), Linn recommend setting the rears to 'Large' because they are considered to be 'full range' at 80Hz-20KHz +-3dB. Obviously they can't reproduce the lower bass effectively, hence the Afekt sub fill-in, but presumably it is thought that the Uniks' performance will not be significantly impaired by handling full range input. Conversely, there will be little low bass interference distortion from the single sub (recommended to be placed near a front speaker). The amp outputs and the sub can support pass-through from sub to rears, but it isn't recommended, and in my experience the relatively limited low bass performance of the Uniks is still sufficient to be superior in the recommended configuration without severe standing wave problems. However, I am using Katans as a front pair, which do contribute more bass than the Uniks... Even so, I find that room configuration (doors open/shut, curtains open/closed, etc) has far more audible effects in the low bass than switching from the 'Large' rear configuration to the 'Small' one...</font>

[Yamahaluver]

<font color='#0000FF'>Just wanted to add that the past week I have gone through ten movies with a mix of Pro Logic and DTS and can tell you that they put significant amount of bass on the rear channels. However when there is bass component in the rear, there is usualy nothing in the front or at least there is a delay of sorts. In my case, the results have been more than satisfactory and I for one have had no bass wave collison problems. Now I can hear the thunder or gunshot in the rear or in the front. The directionality has improved greatly when the rear sub is enabled and the rear speakers are set to LARGE.

Sorry for bringing the ghost back but had to post my observations.</font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE"> I for one have had no bass wave collison problems</td></tr></table>

Just an observation:

The only true way to verify this would be to perform a frequency analysis. *The ear simply isn't going to be able to accuractly tell you which frequencies are getting constructive reinforcement and which frequencies are getting destructive reinforcemnt.

It may sound OK to you, but that still doesn't mean standing waves aren't causing bass wave collisons which are heard as bass peaks and dips at very specific frequencies at specific locations in the listening room.</font>

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Bruce : <font color='#000000'>.

It may sound OK to you, but that still doesn't mean standing waves aren't causing bass wave collisons which are heard as bass peaks and dips at very specific frequencies at specific locations in the listening room.</font>
<font color='#000000'>Hi Bruce,

As I mentioned, standing waves are broken up by carefuly placed wave breakers and I dont think that DTS/Pro Logic gives bass to both front and rear channels at the same time.</font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">As I mentioned, standing waves are broken up by carefuly placed wave breakers *</td></tr></table>
Could you tell me a little more about &quot;wave breakers&quot;, as I'm unfamiliar with them? *Are these what are commercially referred to as bass traps? &nbsp;Do you use more than 4, one in each corner?

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">. . . I dont think that DTS/Pro Logic gives bass to both front and rear channels at the same time. *</td></tr></table>
By definition, DTS (and DD5.1) are full range in all 5 speakers plus a 0.1 LFE channel.

Are you speaking about Dolby PrologicI or Dolby PrologicII?
Essentially both are forms of matrix decoding used on 2-channel sources to simulate 5.1, but I thought the surrounds in PrologicI were bandwidth limited.</font>

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Bruce : <font color='#000000'>Could you tell me a little more about &quot;wave breakers&quot;, as I'm unfamiliar with them? &nbsp;Are these what are commercially referred to as bass traps? &nbsp;Do you use more than 4, one in each corner?


By definition, DTS (and DD5.1) are full range in all 5 speakers plus a 0.1 LFE channel.

Are you speaking about Dolby PrologicI or Dolby PrologicII?
Essentially both are forms of matrix decoding used on 2-channel sources to simulate 5.1, but I thought the surrounds in PrologicI were bandwidth limited.</font>
<font color='#000000'>Bruce,

As I mentioned before, I am using heavy sofas as my home made wave breakers or bass traps, whichever way you would call them.

I mentioned DTS as well as Dolby Pro Logic, my observation is that at no time do the recoding engineers feed simeltaneous bass signals in all the five channels so the delay helps offset the bass collison.</font>

[Clint DeBoer]

<font color='#008080'>Guess I'll jump in...

I notice a couple of observations:

1 - I believe Yamahaluver is explaining that there is no perceived standing wave problems in his room, not that he's calculated this with frequency analysis

2 - As a (former) recording engineer, you can really never tell what will end up in all five channels, because the way TV and movies are mixed, sounds are merely panned wherever they need to be, occasionally, in an overlapping sweep from fronts to rears, and visa versa. This results in low frequency information being routed to more than just the fronts or rears simultaneously. Bass management on the receiver will then take these frequencies and route them according to your particular settings. I have seen an explosion sent to all five channels, with differing sweeteners on each - but all well within the sub range.

3- with the number of variables in each person's room, and with the propensity for large rears (however uncommon in a setup) to put out low frequency regardless of the presence of a subwoofer, standing wave collisions would have to be measured (or perceived) and evaluated (and/or acted upon) on a instance-to-instance basis.</font>

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">with the number of variables in each person's room, and with the propensity for large rears (however uncommon in a setup) to put out low frequency regardless of the presence of a subwoofer, standing wave collisions would have to be measured (or perceived) and evaluated (and/or acted upon) on a instance-to-instance basis. *</td></tr></table>

I certainly agree with this statement. *My only observation is that I have never been in a room yet that doesn't have standing wave problems with multiple bass drivers in the room. *They may be somewhat disguised but they are still there. *The only way to know for sure is to measure.

Everyone is free to use their own tastes for sound preferences, but when it comes to standing waves the laws of physics prevail.</font>

[Yamahaluver]

<font color='#0000FF'>hawke has certainly put words of wisdom here. I am aware of the laws of physics and being a mathematician, I have had the occasion to teach it quite a few times at prestigious universities including my alma matter Rutgers. To end it all, I would say that sound is a pleasure concept, much like food and art and therefore, not subject to the rigid parameters. One cant make mathematicaly perfect recipe. My mother, for example, never used measurment, yet, her cooking is applauded even by five star chefs who regularly come to her for learning new recipes.

I had thought of the bass collison problems but decided to let my ears be the judge of HT sound. Had to do what made me and others who participated in my HT feel good. One sub was OK, but when I added the rears, there was a look of glee and satisfaction on everyone's face in the room. Even those who came in later said that watching movies was more fun than before. They all liked the fact that the bass had way more depth than before and now movie sound had much more directionality. This to me was my goal of getting the HT. HT never stood for audiophille sound. For that as I have mentioned before, I have appropriate stereo only equipment. I bought HT to view movies only and had to get close or even better the sound found in local movie theaters. With my current setup, it seems that I have been able to acheive exactly that. For me, making myself and others feel good is what sound is all about. Never said my method is all about perfection, it is about what sounds good and isnt music and sound all about that.

Thank you hawke for your insight and Bruce, being a man of science myself, I will never deny the laws of physics, which certainly doesnt mean that I cant challenge them or experiment with them. The exsistence of laws and theorems are there because people challenged the conventional thinking of them. Medical science still has a lot to deduct on the concept of human hearing and the brain's perception of sound. New grounds are boken every now and then and old theories are challenged and ammended. <img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'></font>

<font color='#000000'>hawke,

I very much agree with gene's basic premise when he makes the following statement in his cable face-off article, as gene says, &quot;We believe and cherish objective measurements and feel they are the first step in developing and/or analyzing a high fidelity product.&quot;

This same methodology applies to the physical propagation of bass frequencies (from single or multiple drivers) in an exclosed listening room. *Standing wave phenomena is easily measureable and quantifiable, while the human ear is easily fooled unless trained to recognize specific bass anomolies. *In fact, some users mistakingly equate standing wave peaks at specific frequencies as &quot;better bass impact&quot;, but of course that is their perogative. *<img src="http://www.audioholics.com/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'></font>

<font color='#000000'>I have towers, sub in the front full range center, and towers, sub in the rear with bookshelf rear backs. DVD Audio DTS still amazes me it sounds so great.</font>

<font color='#000000'>austin552,

Do you use a Radio Shack SPL meter and an AVIA or VE DVD to calibrate all those speakers?

If you have, then it's also quite simple to use the same SPL meter with the same DVD (like AVIA) to do a frequency sweep of your system for low frequency response characteristics.

Want to know what bass frequencies really stand-out in your room? *You'd be surpised how some specific frequencies can be 20dB higher than others.

What are your room's dimensions (L, W, H) and I call tell you which frequencies will likely be boosted.</font>

[Yamahaluver]

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Guest : <font color='#000000'>I have towers, sub in the front full range center, and towers, sub in the rear with bookshelf rear backs. DVD Audio DTS still amazes me it sounds so great.</font>
<font color='#0000FF'>Hi Austin,

Is your rear sub smaller than your front subs. What is the crossover point for your front subs when you are listening to music in stereo mode?</font>