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Old 3rd May 2003, 10:16 PM   #1
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Default Phase correct drivers

What companies make phase correct drivers? I'd like to start a DIY speaker and want a drive that is inherently phase correct.

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Old 4th May 2003, 04:35 AM   #2
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what crossover design are you thinking of using? Sealed or ported? 2Way or 3Way? Nearfield or farfield?
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Old 4th May 2003, 09:39 AM   #3
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Default Re: Phase correct drivers

Quote:
Originally posted by EternaLightWith
What companies make phase correct drivers? I'd like to start a DIY speaker and want a drive that is inherently phase correct.

Eternalightwithin
AFAIK no one makes a phase correct driver. Phase correct when used to describe loudspeakers has more to do with crossover construction, driver placement and enclosure issues.
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Old 4th May 2003, 03:26 PM   #4
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Default Maybe I took the guy wrong...

Richard Hardesty says there are only a few manufactors that make phase coherant speakers. Looking back I think he was referring to the speaker as a whole, not just the driver.

I feel kinda stupid now.

Well, I'm looking at a three-way, I think. With a 1st order crossover.

The one thing I know for sure, it's going to be either a TL or a TQWT.

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Old 4th May 2003, 04:35 PM   #5
mcp is offline mcp  United States
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Maybe not. But you may want to check out co-axials. A co-ax TL, very tempting.
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Old 4th May 2003, 05:29 PM   #6
SY is offline SY  United States
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Be careful in your design. Most designs optimized to keep the phase linear (something of very questionable audibility) end up sacrificing polar pattern smoothness, freedom from excess diffraction, power handling, and distortion (all very audible). If you're doing this from scratch and you have a lot of experience in speaker construction, design, and measurement, you've got a chance of pulling it off. If not, you may want to rethink priorities.

If you want to get a handle on the audibility of phase shift, you can build a unity gain all-pass filter with a turnover frequency at 2 kHz (a common xover point for 2-ways), and switch it in and out of a circuit while listening on headphones. You may be surprised to find that, although the circuit scrambles up square waves horribly, you can't hear its presence.
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Old 4th May 2003, 05:56 PM   #7
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You may want to try and find some Tannoy Dual Concentric drivers, and put them in a transmission line. They are wonderful drivers, and the tweeters are located right in the center of the woofer, giving them an inherently phase correct position. Then, use an active crossover and bi-amp the arrangement. This should give you pretty good results.
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Old 4th May 2003, 06:01 PM   #8
Bricolo is offline Bricolo  France
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Quote:
Originally posted by SY
Be careful in your design. Most designs optimized to keep the phase linear (something of very questionable audibility) end up sacrificing polar pattern smoothness, freedom from excess diffraction, power handling, and distortion (all very audible). If you're doing this from scratch and you have a lot of experience in speaker construction, design, and measurement, you've got a chance of pulling it off. If not, you may want to rethink priorities.

If you want to get a handle on the audibility of phase shift, you can build a unity gain all-pass filter with a turnover frequency at 2 kHz (a common xover point for 2-ways), and switch it in and out of a circuit while listening on headphones. You may be surprised to find that, although the circuit scrambles up square waves horribly, you can't hear its presence.
SPL and phase can be predicted with some simulation softwares, how do you predict those?
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Old 4th May 2003, 06:45 PM   #9
SY is offline SY  United States
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You can get an idea of polar pattern with good software like LEAP, and a somewhat cruder idea from CALSOD (which is what impecunious sorts like me use). Likewise, power handling is easily seen in software simulations. Distortion should be measured directly. There may be ways of modeling diffraction from coaxial and similar drivers, but I don't know what that is. I've done enough measurements on those drivers to get an idea of how difficult it is to prevent diffraction; the polar patterns are usually pretty awful, and getting a crossover that will, in an acoustic sense, preserve phase is a huge challenge.

I'll be back in Alsace in a week or two- how's the weather?
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Old 4th May 2003, 06:58 PM   #10
Bricolo is offline Bricolo  France
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Quote:
Originally posted by SY
You can get an idea of polar pattern with good software like LEAP, and a somewhat cruder idea from CALSOD (which is what impecunious sorts like me use). Likewise, power handling is easily seen in software simulations. Distortion should be measured directly. There may be ways of modeling diffraction from coaxial and similar drivers, but I don't know what that is. I've done enough measurements on those drivers to get an idea of how difficult it is to prevent diffraction; the polar patterns are usually pretty awful, and getting a crossover that will, in an acoustic sense, preserve phase is a huge challenge.

I'll be back in Alsace in a week or two- how's the weather?
Are you alsacian?
The weather is beautiful here, since 2 or 3 weeks! (we only had some rain friday evening)

to be short: it's like every year, the summer starts in april here
we had 27°C today, too hot for the roller skating race we had
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