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>

 

[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. &nbsp;Believe me, this is the least understood issue for most HT enthusiasts.</font>

 

[Yamahaluver]

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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>

 

[Guest]

<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>

 

[Guest]

<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>

 

[Guest]

<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>

 

[Guest]

<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>

 

[Guest]

<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]

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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>

 

[Guest]

<font color='#000000'>I see you left when everyone questioned your knowledge about acoustics and bass propagation in this thread
here

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>

 

[Audioholics]

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

 

[Guest]

<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>

 

[Guest]

<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>

 

[Guest]

<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.

</font>

 

[Guest]

<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 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.

</font>