Rear Sub

**Yamahaluver** · **11-08-06, 10:31 PM**

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** · **11-08-06, 11:15 PM**

Quote:

two in front and a smaller one in rear

How do you equalize three subs?

brucek

**Yamahaluver** · **11-08-06, 11:18 PM**

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** · **11-09-06, 06:23 AM**

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** · **11-09-06, 07:09 AM**

Quote:

Bruce wrote:

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** · **11-09-06, 07:11 AM**

Quote:

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** · **11-09-06, 07:21 PM**

Quote:

norpus wrote:

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.

**Yamahaluver** · **11-09-06, 10:40 PM**

Quote:

brucek wrote:

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** · **11-09-06, 10:42 PM**

Quote:

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

**Yamahaluver** · **11-09-06, 10:48 PM**

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** · **11-09-06, 11:41 PM**

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?

Regards,
Wayne

**Yamahaluver** · **11-09-06, 11:46 PM**

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

**Bruce** · **11-10-06, 05:14 AM**

Quote:

Yamahaluver wrote:

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** · **11-10-06, 10:04 AM**

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.

**brucek** · **11-10-06, 10:28 AM**

Quote:

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** · **11-10-06, 11:46 AM**

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

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** · **11-11-06, 12:44 AM**

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** · **11-11-06, 08:52 PM**

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

**Yamahaluver** · **11-11-06, 09:22 PM**

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** · **11-11-06, 10:06 PM**

Quote:

khellandros66 wrote:

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?

Quote:

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** · **11-11-06, 11:22 PM**

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...

a-ha.... now we know...

heeheehee

Advertisement