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| Re: 4 Pi and 7 Pi bass response- More similar or different? [message #62116 is a reply to message #62115] |
Tue, 16 March 2010 21:15   |
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Wayne Parham
Messages: 18675
Registered: January 2001
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Illuminati (33rd Degree) |
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Without corners there is much less advantage going with something like the seven π cornerhorn or a similar three-way speaker having the same midhorn and a front-firing woofer. The midhorn was really designed to be used in a corner, and while it doesn't lose all directivity control outside a corner, it can't maintain the horizontal below about 500Hz. It actually starts losing control around 750Hz and by 400Hz, the pattern has doubled in width, basically acting pretty much like a large flat baffle at that frequency. That's still decent control, over an octave lower than without the midhorn, and there is the matter of distributed sound sources in the upper modal region. So there are some benefits, even when used outside corners.
But it's a more complicated speaker than the four π. The simplicity of a DI-matched two-way loudspeaker is pretty attractive, having its own set of merits. For the difference in cost, you can get some subs and I would prefer four π's with subs to seven π's without. Of course, the cat's meow is seven π's with multisubs but that requires a very specific room layout, having relatively unobstructed corners and distance between them that allows their forward axes to cross in front of the listening position. That's the only problem with the cornerhorns - you need a specific room layout to use them, and not every room has that.
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| Re: 4 Pi and 7 Pi bass response- More similar or different? [message #63076 is a reply to message #61567] |
Sun, 06 June 2010 06:25 |
Psychoacoustic
Messages: 75
Registered: May 2009
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Viscount |
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Well, FINALLY got the Pi 7 bass cabs built. Have been using JBL 4507 cabs since December last year- quite satisfactorily, I must say. Not knowing too much about acoustics, I was somewhat anxious that the reduction in cabinet volume would result in less extension or 'punch'. But, if both are tuned to the same frequency, then performance must be similar in that regard, right?
So, I did the experiment. Used two window braces above and below the woofer, port was simple and I was able to finish both (MDF was cut at the hardware store), in a day. Initial impression was the the bass had tightened up and was as smooth and full as with the 5 cubic feet cabs. Most notable was an improvement in midrange balance- NICE! Won't ramble on too much until I've become accustomed to the change.
In summary, I think the most accurate statement that I can make is that I share a similar taste in speaker voicing to Wayne. I also run two Pi 3 subwoofers using the adapted car subwoofer crossover suggested by Wayne on the forum. Have used a valve amp with the Pi 7 but am preferring a Yamaha pro-amp now.
A big thanks to Mr Parham!
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| Re: 4 Pi and 7 Pi bass response- More similar or different? [message #78467 is a reply to message #62116] |
Wed, 27 November 2013 20:16 |
Psychoacoustic
Messages: 75
Registered: May 2009
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Viscount |
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| Wayne Parham wrote on Tue, 16 March 2010 21:15 |
Without corners there is much less advantage going with something like the seven π cornerhorn or a similar three-way speaker having the same midhorn and a front-firing woofer. The midhorn was really designed to be used in a corner, and while it doesn't lose all directivity control outside a corner, it can't maintain the horizontal below about 500Hz. It actually starts losing control around 750Hz and by 400Hz, the pattern has doubled in width, basically acting pretty much like a large flat baffle at that frequency. That's still decent control, over an octave lower than without the midhorn, and there is the matter of distributed sound sources in the upper modal region. So there are some benefits, even when used outside corners.
But it's a more complicated speaker than the four π. The simplicity of a DI-matched two-way loudspeaker is pretty attractive, having its own set of merits. For the difference in cost, you can get some subs and I would prefer four π's with subs to seven π's without. Of course, the cat's meow is seven π's with multisubs but that requires a very specific room layout, having relatively unobstructed corners and distance between them that allows their forward axes to cross in front of the listening position. That's the only problem with the cornerhorns - you need a specific room layout to use them, and not every room has that.
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Adding on to this older thread so that the Pi journey is documented.
Wayne, would you mind explaining a little more about how to compliment/augment 7Pi with 2X 3Pi subs as in the quote above? For example, (obviously) the subs cannot be placed behind the 7Pi as they could the 4Pi. And you have written that the 7Pi mid-woofer is fine on its own due the nature of its corner bass reinforcement, so that means that the two subs act as flanking subs that help smooth the overall room acoustics? Basically correct? Specifically, I wish to fill in the lower-end of bass response that the JBL mid-woofer doesn't cover. More rumble and bass-slam from subs in a remote, flanking context possible? I've tried many configurations but would appreciate your thoughts, please.
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I'm sure I will be super happy with Pi4's anyway. 
