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Old 22nd December 2004, 02:00 PM   #11
morbo is offline morbo  Canada
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In your initial post you suggest using the new Aura 3" driver. Then further down you reject the TB 871, which is almost identical, for being 'too bulky'.... and certainly the other aura 3 incher + a tweeter, as you later suggest, would be even more bulky than an 871. I guess I don't really understand your criteria for driver selection... it seems like either you really want to use Aura drivers (which is fine), or you really want to use something you chose yourself (which is also fine). In either case, go for it.
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Old 22nd December 2004, 04:42 PM   #12
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I wan't light drivers - not ones with big magnets.
You put 9+ drivers in a single array and you start getting some weight.

The Bose come apart and are quite portable, but I like the idea of having the sub the base for the array.
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Old 23rd December 2004, 01:58 PM   #13
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If weight is an issue build them in modules that will stack into an array and clip together. Probably better than basing your choice of driver on the weight of the magnet. I say get the driver that well perform and give you bang for buck, then find out how to make it a suitable weight. Those TB drivers are tiny and very light. If you use an idea like Darren's in the link I showed, they will have a very light box - curving makes this possible.
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Old 23rd December 2004, 02:57 PM   #14
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Default Full Range Line Array

Before you jump off the bridge with a line array using full range drivers you should read and look at the graphs that Darren Kuzma took on his array. The link and photo are above this post. Notice the equalization that Darren had to use to accomodate the roll off in the treble and the lack of bass/midrange response. Darren was using the 2"
Tang Band drivers for his array.

If you use larger drivers you can get a little more bass than what Darren was able to achieve, but the high end will roll off even lower and more. The issue with the high end is that the spacing between drivers is too great so comb lining takes place (see my white paper). The directivity suffers so the frequency response starts to fall from flat over the upper octave (10-20 kHz). Hence, you need the equalization to flatten out the response. If you want average sound, you can get there from here but even that will take equalization to prevent ear bleed.

I like the TB W3-871S but even it will need a tweeter for the high end as I did with my Needles array (the skinny array in the photo).

http://home.earthlink.net/~selahaudi...ges/LineUp.jpg

Jim
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Old 23rd December 2004, 04:09 PM   #15
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The space from driver centre to centre is most likely considerably less even with the 871 than in a typical hifi speaker. This is even better with the 2" driver.

Also consider that this is for PA use. Some of the finer points of hifi speaker design are not really critical and I don't see that the rolloff of the fullranger at the top end is going to be missed. Many use it and are happy with it even for hifi use.

Jim,

as far as lobing is concerned, and possibly a few other issues, isn't it worse to put a tweeter in the centre? I would have thought a series of small fullrangers would be better, except that a dedicated tweeter may have a more extended and flat response and have lower IMD, etc.
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Old 23rd December 2004, 07:01 PM   #16
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Paul, the way my Needles array was designed to be more of extended M's in a MTM. These arrays are intended to be used in a room wherein the listening distance would be within an 8-14 feet range. Hence, you get the line array effect for the low end of the band where it is most noticeable but the tweeter fills in where the listener is seated. Power tapering is used to better anchor the sound to the center of the array and to match to the tweeter.

For a PA application you would need a true tweeter line to achieve sound balance throughout a larger room as you suggest.

The center to center spacing for the W3-871S (mounted with frames touching) would be about 3.63". The c-t-c for the smaller W2 drivers that Darren used is about 2.25" with their frames touching. In my mind--as proven by Darren--you would need equalization to make either array sound OK. EQ is not a dirty word for pro sound applications.

Jim
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Old 23rd December 2004, 11:32 PM   #17
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Quote:
Hence, you get the line array effect for the low end of the band where it is most noticeable
I'm not entirely sure what effect you are talking about - the big soundstage? I would have thought that was more a mid and upper thing? Or perhaps you are talking about something else ....

Quote:
Power tapering is used to better anchor the sound to the center of the array and to match to the tweeter.
What exactly is this power tapering? Is it more power to the drivers closer to the centre?
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