| Subwoofer position with Seven Pi corner horns? [message #60785] |
Mon, 07 September 2009 14:55  |
Norris Wilson
Messages: 361
Registered: May 2009
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Grand Master |
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Have you used subwoofers with your Seven Pi corner horns?
Obviously, if stereo subwoofers are desired. The space between the corner horns would be the logical choice.
But, would this be the only choice, especially if you use four subwoofers in a distributed arrangement?
Are there any problems with this subwoofers between the mains arrangement in an average sized living / listening room? Problems like reduced stereo imaging in the bass region?
Are there any subwoofer placement alternatives over being placed between the corner horns, like ahead of the mains along the wall?
Or, would that create a timing issue?
Thanks
Norris
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| Re: Multisubs with Seven Pi corner horns [message #60789 is a reply to message #60785] |
Mon, 07 September 2009 21:23  |
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Wayne Parham
Messages: 18783
Registered: January 2001
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Illuminati (33rd Degree) |
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Yes, I've used subs (actually multisubs) with cornerhorns. This is the best sound system I've ever heard, but you have to have a room with the right corners to do it.
With my DI-matched two-ways, I usually run what I call "flanking subs" so I can lift the mains up on stands. The idea is to have subs close enough to run at fairly high frequency without localization problems. This smooths floor bounce.
You don't need flanking subs with cornerhorns because the bass bin and midhorn are blended in the lower vocal range. This blending does the same thing as the flanking subs - it smooths the modes in the upper modal range, the last ones up near the Schroeder frequency, before they become so tightly spaced as to become indistinguishable. This frees your placement choices somewhat. Subs don't need to be placed close to the mains, and in fact, are probably better when placed further away and low-passed lower.
I don't think there is a good rule of thumb that can be used for identifying the best placement for subs, except one: More is better. The more subs you have, the less important it is where each one is placed. If you have just one, there is no real good placement. With two or three, I would use CARA to find the best positions to put them in, and then fine tune with measurements. With four or more, put them anywhere convenient (except grouped together) and you can expect good results.
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| Re: Multisubs with Seven Pi corner horns [message #60813 is a reply to message #60802] |
Wed, 09 September 2009 21:40 |
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Wayne Parham
Messages: 18783
Registered: January 2001
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Illuminati (33rd Degree) |
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Without the right corners, I'd go with the three π or four π models. That's what they're designed for.
Of course, I'd suggest the optional JBL or AE woofers. I think you've seen from the measurements that there's no breakup up high with them and response is nice and smooth. Respectfully, I think you expect breakup and this makes a sort of psychoacoustic situation for you. Measurements clearly show there is no anomalous behavior in the passband, which is all that matters.
The midhorn is a nice subsystem to use, but it is sized for corners. It can be used outside corners, after all, just being inside provides some boundary reinforcement. This gives the right acoustic loading and keeps response flat but it does not give the same benefit in terms of directivity. You could use false walls, but I can't imagine a situation where that would work in terms of aesthetics or decor.
Give the three π or four π speakers with the higher quality driver options a serious listening evaluation. Augment them with flanking subs, just like I have. I love this setup and I think you would too.
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| Re: Multisubs with Seven Pi corner horns [message #60818 is a reply to message #60814] |
Thu, 10 September 2009 08:03 |
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Wayne Parham
Messages: 18783
Registered: January 2001
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Illuminati (33rd Degree) |
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Measurements show the speakers are very smooth in this range so it must be something else. There are definitely a lot of speakers with cone cry in the overtone region, sometimes pretty severe. It's common. But the JBL 2226 and the TD12S are smooth as silk in the midrange through the crossover point.
One thing I find very common is people think they can hear breakup in a large driver simply because they expect it should be there. This is probably due to the fact that some (perhaps most) large drivers have terrible breakup, causing people that are exposed to them a lot to form a Pavlovian reaction to all large drivers. It's a conditioned response. Whenever they see a large driver, their expectation of it to sound bad at high frequencies is more than just a simple preconceived notion, it is an actual physical reaction.
This is a real phenomenon that is repeatable and can be shown by demonstration or experiement. When a person hears or sees something repeatedly, it is sort of "burned" into their brains and they will always expect it. They will have physical reactions to what is actually an expectation. So you can quite literally have a reaction by just seeing a large woofer, because of others in the past, even if the one you are listening to is flawless. However, if I put the speaker behind a curtain, you will no longer experience the reaction because you cannot see it.
The JBL 2226 and AE TD12S woofers have smoother response between 500Hz and 1.5kHz than many 8" and 10" drivers. There are many 8" and 10" drivers that have good midrange response but my point is that there are also some 8's and 10's that don't. For that matter there are some 5" and 6" drivers that don't either, especially those with polypropylene or metal cones. Breakup is largely determined by diaphragm material and shape, not just size. If you were to measure a lot of drivers, you would see what I mean.
The thing is, like I said, it is very common for people to expect breakup in larger woofers in a very real psychoacoustic sense. It isn't that they have bad hearing, in fact, it is their good hearing that setup the Pavlovian reaction in the first place. But when they encounter a good woofer, they then do not recognize it as such. If you were to see measurement data and listen to the sounds that correlated with the charts, you would begin to develop a different set of responses eventually, essentially changing your conditioned responses to more closely correlate with what you hear.
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