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Topic: Subwoofer set up (Read 26148 times) previous topic - next topic
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Subwoofer set up

Reply #25 –
Quote from: mzil on
Quote from: ajinfla on
Audyssey may average the measured responses, but it cannot spatially apply those (to each position).


I'm not getting your use of the word "spatially". :confusion: Please explain.


We're getting back to the topic of the discussion - the uniformity of the field of bass energy in the room. If you don't have this problem, great! But people who have this problem seem to abound.

First lets look at the simpler problem of smooth bass response at just a preferred listening location. Not all or even many of the instances of the problem of rough response at the preferred listening location should or can be fixed with just equalization. As a rule equalization should never be used to correct situations where the bass is deeply nulled at one or more frequencies which happens quite a bit. 

Case in point - I have a close friend with a large Infinite Baffle subwoofer based on 8 18" subwoofer drivers with 30+ mm Xmax each, driven by 4 1250 wpc power amps on their own 230 volt circuit. A subwoofer this large isn't something that you move around your listening room until it sounds best. It is an architectural feature of the house. He also has a very serious null in response @ 60 Hz at exactly his preferred listening location. So, he has great response @ 8 Hz, but it is not so good at 60 Hz. What to do? 

The problem with nulls is that they can be very deep and can absorb massive amounts of power without being improved very much. One relatively easy solution is to add a fairly small subwoofer that has good dynamic range at 60 Hz in order to fill in the null. Of course it should be equalized by means that don't interact with the main system. Now, just find me an AVR that has two or more independently equalized subwoofer outputs.

When attempting to enlarge the sweet spot and produce good bass response at more than just one location, solving this problem only gets more complex.

Here are some references and links to highly regarded papers in this area:

http://www.harman.com/EN-US/OurCompany/Inn...rs/multsubs.pdf  (please check the footnotes and references at the end of the paper)

https://docs.google.com/file/d/0BxgUOGOB5Hb...yUms/edit?pli=1

https://docs.google.com/file/d/0BxgUOGOB5Hb...UtHX09aTzA/edit


Subwoofer set up

Reply #26 –
Quote from: ajinfla on
Even inexpensive receivers (eg Pioneer VSX-824K $350-400) have dual sub outs (may not be "stereo", not sure)


It may be "dual" but its mono, as is every other *current* production AVR*, despite it being inexpensive to implement as stereo had they wanted to. Yamaha, perhaps one of the last to offer a stereo sub out option, did away with that silliness and although their multiple sub outs may still be colored red and white, there is no option for L/R stereo any longer.

On this particular Pioneer the "dual" sub outs are merely an internal Y-cord. There is no provisions for controlling level or delay on them independently, as there is on some units, for instance with SubEQ HT.

*some prepros which cater to audiophile woo may offer it, I'm not sure.

Subwoofer set up

Reply #27 –
Quote from: mzil on
It may be "dual" but its mono, as is every other *current* production AVR*, despite it being inexpensive to implement as stereo had they wanted to. Yamaha, perhaps one of the last to offer a stereo sub out option, did away with that silliness and although their multiple sub outs may still be colored red and white, there is no option for L/R stereo any longer.


Some receivers like the Denon X4000 definitely have independent outputs, they use Audyssey MultEQ-XT32 and Audyssey LFC. They're not stereo, just independently controlled. But you're right the bottom end tend not to.

Subwoofer set up

Reply #28 –
Quote from: probedb on
Quote from: mzil on
It may be "dual" but its mono, as is every other *current* production AVR*, despite it being inexpensive to implement as stereo had they wanted to. Yamaha, perhaps one of the last to offer a stereo sub out option, did away with that silliness and although their multiple sub outs may still be colored red and white, there is no option for L/R stereo any longer.
  Some receivers like the Denon X4000 definitely have independent outputs, they use Audyssey MultEQ-XT32 and Audyssey LFC.
  I know, I named in that post what dual, independently  controlled sub outs are called (on Audyssey based units): "SubEQ HT"*. The topic was if the mentioned Pioneer had stereo sub outs (as opposed to dual mono). Not only does it not have stereo sub outs but no other current AVRs on the market does either. That's none from any brand, at any cost, with or without Audyssey circuits, however some brands such as Yamaha has had it in the not too distant past, such as the discontinued RX-A3020 and RX-A2020.

*[SubEq HT allows independent level and delay for the two, mono subs outs but just one EQ for their combined, measured output, which is actually the right way to do it.]

Subwoofer set up

Reply #29 –
Quote from: mzil on
I know, I named in that post what dual, independently  controlled sub outs are called (on Audyssey based units): "SubEQ HT"*. The topic was if the mentioned Pioneer had stereo sub outs (as opposed to dual mono). Not only does it not have stereo sub outs but no other current AVRs on the market does either. That's none from any brand, at any cost, with or without Audyssey circuits, however some brands such as Yamaha has had it in the not too distant past, such as the discontinued RX-A3020 and RX-A2020.


I understand  I guess it'd have to be more stereo focused to go for stereo sub outs.

Subwoofer set up

Reply #30 –
Quote from: mzil on
It may be "dual" but its mono, as is every other *current* production AVR*, despite it being inexpensive to implement as stereo had they wanted to. Yamaha, perhaps one of the last to offer a stereo sub out option, did away with that silliness and although their multiple sub outs may still be colored red and white, there is no option for L/R stereo any longer.

On this particular Pioneer the "dual" sub outs are merely an internal Y-cord. There is no provisions for controlling level or delay on them independently, as there is on some units, for instance with SubEQ HT.

*some prepros which cater to audiophile woo may offer it, I'm not sure.

Yes, I have publicly lamented the fact that Preouts ACH, which were standard on my circa 2005 VSX-815 (which I bought for <$300 IIRC), are now only available on near top of the line AVRs (for way more than $300! new).
Luckily all 3 of my AVRs (HK DPR-2001, the above Pioneer and Yamaha RX-A800) have preouts all channels. I would not buy an AVR without that feature.
So the bad news is you either pay >$600 new....or buy used for ACH preouts. Which gives you the ability to run stereo subs by utilizing the LR main preouts (full ranged signal too, which I prefer for post filtering). The outputs (line/speaker) are simultaneously active, so the mains can still be driven by the internal amps, if desired, but of course, with no high pass (which I also desire).

cheers,

AJ
Loudspeaker manufacturer

Subwoofer set up

Reply #31 –
Quote from: probedb on
I understand  I guess it'd have to be more stereo focused to go for stereo sub outs.

Quite so. I fully acknowledge my ilk would represent a tiny fringe of the market, 99.99% need only mono outs for subs, for both music and HT. Supply vs demand.

cheers,

AJ
Loudspeaker manufacturer
 

Subwoofer set up

Reply #32 –
Jumping in here with a simple question:
Given a stand mount speaker pair that goes down to about 75 hz, -3dB, what is a good XO frequency as a starting point for music play? Is there any benefit in going as high as the Sub can, 110hz, if the single forward firing sub can be placed in the center, between the speakers? Does doing this take some load off a 55wpc amp, and at the same time allow for better midrange output quality from the speaker pair?

Subwoofer set up

Reply #33 –
Quote from: KumarK on
Jumping in here with a simple question:

No such thing....in my world. 

Quote from: KumarK on
Given a stand mount speaker pair that goes down to about 75 hz, -3dB, what is a good XO frequency as a starting point for music play? Is there any benefit in going as high as the Sub can, 110hz, if the single forward firing sub can be placed in the center, between the speakers? Does doing this take some load off a 55wpc amp, and at the same time allow for better midrange output quality from the speaker pair?

What speaker? 8" 2 way? 3" fullrange? Both can be "rated" 75Hz -3db.
Yes, it can be beneficial to raise XO as high as possible to alleviate the woofer/midrange....and at the same time detrimental, that the sub will be more localized, i.e. "heard"/located. But with it centered with mono bass, that would pretty much be the case anyway, bass somewhere in the middle. So maybe no big deal. Simple, eh? 

cheers,

AJ
Loudspeaker manufacturer

Subwoofer set up

Reply #34 –
Quote from: ajinfla on
Quote from: KumarK on
Given a stand mount speaker pair that goes down to about 75 hz, -3dB, what is a good XO frequency as a starting point for music play? Is there any benefit in going as high as the Sub can, 110hz, if the single forward firing sub can be placed in the center, between the speakers? Does doing this take some load off a 55wpc amp, and at the same time allow for better midrange output quality from the speaker pair?

What speaker? 8" 2 way? 3" fullrange? Both can be "rated" 75Hz -3db.
Yes, it can be beneficial to raise XO as high as possible to alleviate the woofer/midrange....and at the same time detrimental, that the sub will be more localized, i.e. "heard"/located. But with it centered with mono bass, that would pretty much be the case anyway, bass somewhere in the middle. So maybe no big deal. Simple, eh? 

cheers,

AJ

Yes, quite straightforward! Referred speaker is a two way with a 5.5 inch cone. And I understand the localisation thing, but with the sub close to the center of the speaker pair, and listening distance more than than between the speakers, it seems to work fine for me as it ought to based on the above response. It also means that rear wall distance to the rear firing ports becomes a non issue. Thanks.

Subwoofer set up

Reply #35 –
Quote from: KumarK on
Jumping in here with a simple question:
Given a stand mount speaker pair that goes down to about 75 hz, -3dB, what is a good XO frequency as a starting point for music play? Is there any benefit in going as high as the Sub can, 110hz, if the single forward firing sub can be placed in the center, between the speakers? Does doing this take some load off a 55wpc amp, and at the same time allow for better midrange output quality from the speaker pair?


IME the top priority consideration for subwoofer placement, configuation and tuning should always relate to bass imaging.  I see no information about the location of the subwoofers and the listener in the above post.

For example if you put the upper range speakers on top of the subwoofers, then there is a lot of flexibility for choosing high crossover frequencies. The benefits you mention will then accrue.

OTOH if you put the upper range speakers some distance from the subwoofers, then there may not a lot of flexibility for choosing high crossover frequencies without disrupting imaging. The benefits you mention may be difficult or impossible to obtain.

Subwoofer set up

Reply #36 –
For those unsatisfied by "mono bass in middle" with sterophonic acoustic recordings and not afraid of experimentation/wife : http://www.davidgriesinger.com/multichan.pdf
This stuff has been around for a long time but apparently might be news here, could not find in searches (maybe entering wrong terms).

cheers,

AJ
Loudspeaker manufacturer

Subwoofer set up

Reply #37 –
I see very little reason to be worried about multiple bass channels (for <75 Hz at that) until the elephant in the room modes hasn't been addressed reasonably well. Something not easy to do without a cute little bass array and some absorbers at least. Enthusiast-level stuff, not really anything I'd have the space for here, but still.

Subwoofer set up

Reply #38 –
Quote from: stephan_g on
I see very little reason to be worried about multiple bass channels (for <75 Hz at that) until the elephant in the room modes hasn't been addressed reasonably well. Something not easy to do without a cute little bass array and some absorbers at least. Enthusiast-level stuff, not really anything I'd have the space for here, but still.

And I see reason to look at it all. 
Like Griesinger, I believe bass SQ extends beyond pressure domain only. Yes, pressure response free of peaks in perceptually preferable. So yes, what you speak of is indeed important.
Btw, we've covered much of this before. Note jj's comments in that thread regarding looking past just pressure response.

cheers,

AJ
Loudspeaker manufacturer