# Rear Sub



## Guest (Nov 9, 2006)

Since more and more movies now come with considerable rear bass material, how many of you are into using a rear sub, I use three subs on my HT system, two in front and a smaller one in rear and set my rear speakers to LARGE in the speaker management of my receiver.


----------



## brucek (Apr 11, 2006)

> two in front and a smaller one in rear


How do you equalize three subs?

brucek


----------



## Guest (Nov 9, 2006)

Keep equal levels on all three with calibration disk and a SPL meter, the phase on the rear sub is in reverse and its diagonally placed.


----------



## Bruce (Sep 14, 2006)

Always been and still subscribe to the "multiple subs" in different locations is just not the way to go.

It's a rats nest of equalization problems, and something I won't recommend to anyone.

Everyone has their own opinions and listening preferences, but too many users agree multiple subs in different locations is not the best option.


----------



## norpus (Oct 11, 2006)

Bruce said:


> Always been and still subscribe to the "multiple subs" in different locations is just not the way to go.
> 
> It's a rats nest of equalization problems, and something I won't recommend to anyone.
> 
> Everyone has their own opinions and listening preferences, but too many users agree multiple subs in different locations is not the best option.


We'll have to agree to disagree then
It minimises a rats nest of room nodes and sounds great, especially on movies. Is also quite enveloping in 2ch


----------



## brucek (Apr 11, 2006)

> Keep equal levels on all three with calibration disk and a SPL meter


That's level adjustments. I was wondering if you checked their frequency responses (both individually and in concert) as room resonances tend to create humps and dips at some frequencies. The tool most of us use is Room EQ Wizard. 

brucek


----------



## Bruce (Sep 14, 2006)

norpus said:


> We'll have to agree to disagree then
> It minimises a rats nest of room nodes and sounds great, especially on movies. Is also quite enveloping in 2ch


My answer to that is to get a BFD !!! A much better solution with a much better result.

Trying to adjust room modes with multiple sources of low frequency (mutiple subs) is mostly an excercise in futility, IMO and many others, but to each his own.


----------



## Guest (Nov 10, 2006)

brucek said:


> That's level adjustments. I was wondering if you checked their frequency responses (both individually and in concert) as room resonances tend to create humps and dips at some frequencies. The tool most of us use is Room EQ Wizard.
> 
> brucek



The front two subs are pair of YST SW 800 attached to the Z9 which has two sub outs, since I keep the LFE setting on my receiver to BOTH, the subs and my main speakers get equal LFE signals, the rear sub is considerably smaller, the contention here being that its like putting a full range tower for your rears, so far I hear no humps or dips, if I use YPAO, the rears get set as LARGE as it should be. I watched Gangs of New York with the rears on and off, with the rears on, the scene where they shoot cannons from the ship, one could distinctively hear them coming from your back as opposed to with the rears off and all the LFE out in front where the same effect was just not there.


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

> We'll have to agree to disagree then
> It minimises a rats nest of room nodes and sounds great, especially on movies. Is also quite enveloping in 2ch


 Have you graphed combined response of your subs? If you haven’t you might be surprised at the results. Some argue that single corner placement best overcomes room modes, others argue that multiple subs around the room do it. Assuming the latter is correct, having subs in multiple locations can cause a whole new set of problems if they are not symmetrically placed. The sound arriving to the seating position at different times can cause ragged “sawtooth” response.

Like Bruce, my experiences with double separated subs hasn’t been good either. I liked the “enveloping” sound you mentioned, but suffered from the problem that our Moderator brucek rightly describes as “dumbed-down” response, which is an extension penalty due to one sub being less substantial than the other. In my case it was due to the fact that one was in a corner, and the other by an open hallway. 

You probably have the same situation with your smaller rear sub. This old post of mine explains the situation further, with graphs to show what happens to overall response when small subs are used with large ones.

Every room is different, and I have seen some people claim to have excellent response with multiple subs placed all over the room. (Haven’t seen them post any graphs, though.) Nevertheless, it would be a good idea to plot your response so you can see if your performance is as good as it seems to sound.

Regards,
Wayne


----------



## Guest (Nov 10, 2006)

Wayne is absolutely correct, multiple subs need proper adjustment and room acoustics, far more so than single subs, I forgot to mention, I have a rectangular 25'x14' room with concave ceiling and the room has no rear wall as it opens to another room, in my case, I have achieved the sound to my utmost satisfaction, my levels are equal and if there were dips and humps, till date no one including my musician brother and his friends have noticed it.


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

Hey, if you’re happy, that’s all that matters.  Don’t think I’d rely on your musician friends though, unless their systems are better than yours - know what I mean? :bigsmile: 

Regards,
Wayne


----------



## Guest (Nov 10, 2006)

Correct you are Wayne, musicians are least concerned when it comes to systems, they are too busy creating music.


----------



## Bruce (Sep 14, 2006)

Yamahaluver said:


> Wayne is absolutely correct, multiple subs need proper adjustment and room acoustics, far more so than single subs, I forgot to mention, I have a rectangular 25'x14' room with concave ceiling and the room has no rear wall as it opens to another room, in my case, I have achieved the sound to my utmost satisfaction, my levels are equal and if there were dips and humps, till date no one including my musician brother and his friends have noticed it.


While I agree you can like what you hear, like Wayne said without graph results to back-up your results, I wouldn't be recommending that others implement multiple subs.

Too many of us have years of experience with sub integration, and multiple subs is not on our recommended lists.

This is especially important for newer users who don't want to waste money with multiple subs which they are likely never to get to work correctly.


----------



## Sonnie (Apr 11, 2006)

Arup... have you tried REW yet?

Maybe you could give it a try and entertain us with a graph of your subs. It might surprise you as to what your ears are hearing. And being the computer guy you are, REW should be a rather simple for you to install, load up and use. You have an SPL meter, cables and few computers... should be elementary for ya. :R


----------



## brucek (Apr 11, 2006)

> It might surprise you as to what your ears are hearing.


You may well have room resonances that raises the level of signals that are from 40Hz to 80Hz. The SPL meter would be using that area as its level and you would be using that reading to set your sub level. You, nor anyone else would notice any difference. But, if you used a parametric equalizer (BFD) to reduce that hump from 40Hz to 80Hz, all of a sudden the frequencies from 40Hz down to 20Hz that you have been missing would be revealed..... You can find out what your room response is with REW as suggested.

brucek


----------



## Sonnie (Apr 11, 2006)

Maybe I should have said "...what your ears are NOT hearing." :dontknow:

You could also run 1/6 octave test tones with the SPL meter and use the Excel Workbook to log those... if you didn't want to tackle REW right away.


----------



## terry j (Jul 31, 2006)

hi guys

I know from over here in Aus what Norpus set his IB's to, 

http://www.harman.com/wp/pdf/multsubs.pdf

If I've misrepresented you Norps please forgive me.

I found the read interesting, but as my only interest is in music I can be selfish and only worry about the sweet spot!

Glad I found this, was wondering how you'd be able to properly EQ two subs - even with REW! Had already decided that it wasn't worth the hassle, and considering I only really want a sub up to 50 - 60 hz, the ability to place a single one anywhere and not be locatable suits me to the ground.

lots of love

terry


----------



## khellandros66 (Jun 7, 2006)

I agree with Arup, multiple subs makes for great impact in movies. It wasn't untill I added my 12in DIY till I had some really tactile responses. With my Yamaha receiver I have the bass set to BOTH and my main have 8in subs with 300w RMS amps in each. I must say that my recent sitting of Band of Brothers: Battle of The Bulge episode was astonishing more real.

I now had impact bass that I could discern from left to right. This I think is what Arup is trying to explain. He is by no means arguing that there isn't flaws in multiple subs but the correct subs and placement makes a ferocious system and experience.

BTW

My towers have the main powered subs facing inwards and the towers are toed in 15 degrees. My DIY sub is adjacent to them and in along the opposite wall. The phase is set as to not cancel out the towers.

~Bob


----------



## Guest (Nov 12, 2006)

Bob,

You are absolutely correct, multiple sub is not to everyone's taste or needs, they are hard to setup, but one set up right, they reward the user with sound that can't be matched by single subs.


----------



## Otto (May 18, 2006)

khellandros66 said:


> I agree with Arup, multiple subs makes for great impact in movies. It wasn't untill I added my 12in DIY till I had some really tactile responses. With my Yamaha receiver I have the bass set to BOTH and my main have 8in subs with 300w RMS amps in each. I must say that my recent sitting of Band of Brothers: Battle of The Bulge episode was astonishing more real.
> 
> I now had impact bass that I could discern from left to right. This I think is what Arup is trying to explain. He is by no means arguing that there isn't flaws in multiple subs but the correct subs and placement makes a ferocious system and experience.


How are your subs in your DTs hooked up? Speaker level in? Line level in using the sub out? Line level in using preamp L/R out?



> BTW
> 
> My towers have the main powered subs facing inwards and the towers are toed in 15 degrees. My DIY sub is adjacent to them and in along the opposite wall. The phase is set as to not cancel out the towers.
> 
> ~Bob


How does your response look with REW?


----------



## Sonnie (Apr 11, 2006)

I agree also that a properly setup set of subs can be rewarding... but the question is are they properly setup? It's nearly impossible to know without measuring the response. 

Think about how many thousands of recording engineers have downloaded Room EQ Wizard so that they can get the response of their studios setup properly. Professionals they are, but it's just impossible for them to do it by ear... they need help. 

Personally I'd say you'd have to be someone very special with a special ability that probably no one else has to be able to know your response is perfectly flat by ear alone. It would be even a greater challenge with mulitple subs... this is why we would very much like to see some response graphs. It's not hard to take measurements... why wouldn't you want to know and make sure... unless maybe you are worried of what you might discover... :yikes: a-ha.... now we know... :yes: heeheehee


----------



## Bruce (Sep 14, 2006)

I have to agree with Sonny.

Many of us oldtimers have seen this same statement (thread topic) hundreds of times in the past (that multiple subs are great!).

But when it really comes down to the rubber meeting the road, all we hear is statements from people saying it sounds great!

Come on people, show us your graphs (do we already know what they will show???).:bigsmile: :bigsmile: 


There is nothing wrong with liking what you like, but on a forum like this where people provide assistance to others, I think it's disingenuous to recommend multiple subs (big extra expense in $$$) without providing some proof that is right here at your fingertips on the website (REW).

If you have an RS SPL meter, (doesn't everyone?) you can use the REW software with the RS meter's RCA Line-out port and the computer you are using to post here.

Come on Yamahaluver, as a moderator I'm sure you can do it justice


----------



## Guest (Nov 12, 2006)

The final proof is in your ears, not in any graph or measuring equipment, specs don't make music, instruments and the people playing them do, so is recreation, so many times I have come across amps and speakers with perfect specs sounding junk, when ordinary spec systems manage to sound way better, Bruce I am familiar with SPL meter and REW, I have a B&K 2250 SPL meter at home, point is I ain't just plain interested, specs will tell me nothing about the pleasure I have from my system, only my brain and my ears do. I leave it to the people, let them test it out and come to their own conclusion, some go by pre-conceived opinion of specs, charts etc, some leave it to the audition to make their final judgment, point is why prejudice them anyways with dictum.

Btw, Yamaha at Las Vegas demoed their system with two subs, one at front and other one at back, I am sure Yamaha did all the measurements before setting it up like it they did.


----------



## Bruce (Sep 14, 2006)

Yamahaluver said:


> The final proof is in your ears, not in any graph or measuring equipment, . . . .


Same old tired answers, but that's OK, I knew it was coming.:bigsmile: :bigsmile: 

It's certainly OK to speculate how rear/multiple subs sound, but without scientific sound analysis (which is not speculation) and as a moderator, please DO NOT recommend that newbies follow your lead. I would find that irresponsible.

Most of us here are quite comfortable with the scientific analysis and how that represents what our ears actually hear. If you don't want to go down that road, I understand. :bigsmile:


----------



## Sonnie (Apr 11, 2006)

I think what happens in many situations is we get the sub, whether it be one, two or more in a room, and it seems to sound really great, especially to someone who has never had one, but in many cases it can happen to those who have had subs for a long time... we think it sounds perfect. The problem though, in many cases, is our ears just aren't perfect. I can't even begin to count the endless number of enthusiasts who have measured their sub response and had no idea it was as far off as it was... then when they equalized it... "wow, what a difference it made, I had no idea what I was missing" type of response. This from many that you might not expect it from. Then there are those who wouldn't admit it for the world... heeheehee. We understand though, pride can get the best of us. :sarcastic:


----------



## khellandros66 (Jun 7, 2006)

I will grab a RCA to 1/8 in mini phone jack cabl e long enough to run from my PC to use with my dad's RS Meter (Digital)

Gonna download REW tonight and play around with it.

~Bob


----------



## brucek (Apr 11, 2006)

> RCA to 1/8 in mini phone jack cabl e


Don't forget the stereo adapter that has to plug into.....


----------



## Bruce (Sep 14, 2006)

The RS SPL meter's output port is mono, you can use either the left or right channel.

Actually, I think the I used a stereo adapter (1/8" male phone plug to 2 RCA female) on the Line-In to my notebook (not the Mic-In). I only used one of the female RCA inputs on the adapter (either left or right) for a standard RCA male to male cable from the SPL meter's female port.


----------



## Guest (Nov 13, 2006)

Bruce said:


> Same old tired answers, but that's OK, I knew it was coming.:bigsmile: :bigsmile:
> 
> It's certainly OK to speculate how rear/multiple subs sound, but without scientific sound analysis (which is not speculation) and as a moderator, please DO NOT recommend that newbies follow your lead. I would find that irresponsible.
> 
> Most of us here are quite comfortable with the scientific analysis and how that represents what our ears actually hear. If you don't want to go down that road, I understand. :bigsmile:


And what makes you think that the current science of measurement is accurate, maybe there would be more findings as human physiology of hearing is further debunked, at current, sound perceptions of the human brain is yet to be deciphered fully. Please don't tell me what I should do as a mod, I have the right to leave this to a person's choice, numbers be damned. No one has the right to dictate and don't make this a religious post, leave it to choice, last time I checked, freedom of choice still existed, if a newbie has the money, let him or her spend it and find out if multiple subs are to their liking or not, don't give your so called scientific dictum and bind them to your theories, you don't believe into multiple sub theory, fine, thats your choice, don't impose on others as I am not imposing on you or anyone else, my original question was how many of you are into using multiple subs, if you can read simple English, then you see that all I meant was to get a consensus, not telling anyone to go get multiple subs:whew: 

And of same old tired answers, maybe they are to you as is your so called pseudo scientific notions on human hearing by a gauge is, you keep repeating your tired line of measure with gauge, guess you are of the type to whom, equipment matters more than music, everything to you represents a curve in a screen, thats all, music is secondary, seen many like you and the list doesn't end.:no:


----------



## Sonnie (Apr 11, 2006)

Okay guys... let's leave it alone and play nice... :bigsmile:


----------



## Guest (Nov 13, 2006)

Yep, I am all for it, we beg to differ, thats all.


----------



## F1 fan (Jul 6, 2006)

I plan on having dual subs operational soon.I am curious to find out how well my planned set up will actually work.I intend to put them in opposite corners(left front ,right rear) and they will be approximately equal distance from the listening position.
They will have the same output capabilities and share the same crossover/controller but each will have it's own amplifier.
I know that with the corner placement a nasty room mode at 50hz shows it's ugly head,but I can reduce much of its effect with EQ.I would expect both to need the same correction because they are both in a corner.

Anyway when I get it setup I will post my results.


----------



## Guest (Nov 13, 2006)

F1 make sure to set the phase of the rear sub to Rev, good luck, placed diametrically opposite that is antipodal, you get good results.


----------



## Sonnie (Apr 11, 2006)

Actually that may not be necessary, but you can try it. I have both my subs at zero phase and this was certainly the best setup for me. The listening location may have something to do with it.


----------



## bobgpsr (Apr 20, 2006)

I would think that with proper use of REW, a tripod mounted RS SPL meter, and linear adjustable phase on at least on of the two subs that you are working to integrate -- that you could get a proper, phase fit/sub blend, at the listening position. Maybe only the mid-bass region. This is very measureable.

An advantage of two subs, is that if you have a big room null at a particular bass frequency, you should be able to move one of the subs position to fill the null somewhat.

Bob


----------



## Otto (May 18, 2006)

Yamahaluver said:


> F1 make sure to set the phase of the rear sub to Rev, good luck, placed diametrically opposite that is antipodal, you get good results.


I don't mean to throw fuel on this fire, but how can you make such a statement after just gave Bruce the smackdown for suggesting that the REW/BFD combo is a legitimate method for setting up subs. So here you suggest a few simple steps to get "good" results. How would you measure "good"? Note that the next post by Sonnie indicates that he didn't need to go 180 degrees out of phase to get measurably good results.

You've also stated that the methods frequently and successfully used around here are "pseudo-scientific". That's patently untrue, as pseudo-science couches itself in mysterious sounding terminology designed to confuse the uninitiated, and to make it appear as scientific. I just don't see that going on here.

Furthermore, I don't think that anyone around here claims to understand everything about the human brain, human hearing and psychoacoustics, so that's just a straw man.

Audio measurements in general are used to give a representation of the frequency response of a given speaker or sub. These are, or at least should be, repeatable, testable, and modifiable. I don't believe that a frequency response plot shows the entire story of a speaker or sub. However, it represents a piece of the puzzle, and I believe it's very relevant in getting a sub set up. Subs are so very dependent on the room they are in, and we have the power to adjust funky room nodes easily and cheaply. Many of us have done this with some measure of success.

Now, if we assume that we can get the frequency response flat, it may turn out that we don't like the sound, right? Indeed, it can sound very lifeless in the low end if FR is flat to <20Hz. That's where the discussion on house curves comes in. This gives us the ability to shape the frequency response to taste. Of course, many movies and recordings have greatly varying levels of bass in their mixes, that I frequently play with the LFE level control on my preamp. I do this to taste, without taking any measurements in the middle of the movie.

I guess what all this boils down to is that the FR plots and the equalization and such gives us a known point at which to start. If we measure flat and we don't like it, we can change it. It really all does come down to "what you like." Hey, I thought my bass sounded pretty good until I started tweaking with it using REW and a BFD. It's now a lot better. It sounds better. To me. Because I was able to clean it up. If you were to actually take the time to do a few sweeps and found that you had big humps and dips here and there, and you were able to EQ them out, you might change your tune...

Having an open mind helps. "I ain't just plain interested" doesn't.


----------



## basementjack (Sep 18, 2006)

Yamahaluver - I feel your forum pain here.

I think a MAJOR point everone is missing, is that you have your rear sub being fed by your rear speakers - This is NOT the same as splitting a bunch of subs off the LFE channel!

It is really No Different than if you had Full range speakers for your surrounds.

I'm sure if you posted and said you had just bought 5 full range speakers to use in your home theater, you'd be getting cheers and congratulations...



Acoustic measuring tools like REW are great for a number of things, so I don't mean to downplay the request for measurements here, but I think your application is just fine, and wouldn't be too concerned with how the rear bass integrates with the front bass - because in your case, they should not be going off for the same material.


----------



## brucek (Apr 11, 2006)

> It is really No Different than if you had Full range speakers for your surrounds.


Generally subwoofers will extend lower than full range speakers, which enhances the chance of room resonances. Best to run surrounds as small and let the sub handle the low frequencies off the LFE channel, allowing equalization at line level...

brucek


----------



## Otto (May 18, 2006)

khellandros66 said:


> Hey not everyone on this forum is clueless


What's the implication here?



> I wanted to sit back and see peoples opinions about the multiple subs part, I guess that people get so up tight defending their beliefs that they get lost in the OP....


Just for the record, I'm not blindly defending something stupid or for no reason. It's not just a "belief". Frequency response is one useful measurement of a subwoofer. The poo-poo-ing of it is strange. Kinda like how Bose doesn't publish specs while stating that they're not important (not trying to turn this into a Bose thread, we can do that elsewhere).



> Its shame that so many here didn't give him a fuller chance to explain the situation first.


There was ample opportunity.



> And personally I can see or comprehend how a machine can register changed in visual or auditory environments as well as a human can...


I'm not really sure what that means.

Did you get a chance to measure your sub response? Oh, and you never answered my question about how you had things hooked up. I suppose that's because I'm clueless?


----------



## F1 fan (Jul 6, 2006)

basementjack said:


> I think a MAJOR point everone is missing, is that you have your rear sub being fed by your rear speakers - This is NOT the same as splitting a bunch of subs off the LFE channel!
> 
> It is really No Different than if you had Full range speakers for your surrounds.


OK this thread is getting a bit hot so I will say a few things then bail.

I did miss the part that YL was using the sub to extend the bass of his surrounds.I thought the discussion was about multiple sub's for use on the LFE channel.Sorry I confused this.
I completely agree with bj's quote above and I actually use a third sub :holycow:in the front right corner that augments the bass of the front left and right speakers and does not carry any of the LFE info.
I see no conflict here as the LR and LFE subs will be reproducing different bass signals.

Because both of my LFE subs will be the same distance from the listening position and they both have the same frequency response and crossover they should be operated in phase with each other. 

Fred


----------



## Bruce (Sep 14, 2006)

I have no problem with people describing what they like.

But, how can anyone dis a scientific perspective without even trying it ? 

Especially since this forum was founded on just that principle of bass optimization, REW.

Yes, I and many others have already been down the other side and actually tried it, and measured it to get a better handle on what our ears were actually being exposed to.

Oh well, enjoy whatever you have, as that is the objective.


----------



## khellandros66 (Jun 7, 2006)

:huh: I don't remember anyone directly dissing scientific measurements, we just merely stated that, you shouldn't rely or perhaps choose products based on it alone. And we certainly did not say that the REW can't help and thet we are happy the way things are. If you don't like that fact then walk away and not interogate us about our equipment.

That was the point we were trying to get across, it also doesn't help when you go after the OP automatically dissing them from the start. Arup has been buying audio products longer then most people on the forum.... I personally used to play percussion in high school so yeah when I hear something that sounds like the real thing why mess with it?? 

So I apologize to anyone whom I've insulted with *my * opinions.

~Bob


----------



## Sonnie (Apr 11, 2006)

Okay... I'm gonna close this thread since it seems to be really going nowhere. Let's please not let this carry over to any other threads. Thanks!


----------

