Midrange drivers dips above 1Khz... - Page 2 - diyAudio
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Old 10th April 2008, 02:13 AM   #11
Jay_WJ is offline Jay_WJ  United States
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People, including me, already discussed this issue long ago. Take a look at my post:

http://www.diyaudio.com/forums/showt...62#post1236362

and Kevin Haskins' post:

http://www.diyaudio.com/forums/showt...26#post1237126

I also asked this question at PE forum, and John Kreskovsky gave an essentially the same answer.
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Old 11th April 2008, 06:17 PM   #12
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Quote:
Originally posted by Jay_WJ
People, including me, already discussed this issue long ago. Take a look at my post:

http://www.diyaudio.com/forums/showt...62#post1236362

and Kevin Haskins' post:

http://www.diyaudio.com/forums/showt...26#post1237126

I also asked this question at PE forum, and John Kreskovsky gave an essentially the same answer.
I looked at the threads some, I didn't see much discussion about how to modify speakers to reduce the dip, however.
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Old 11th April 2008, 08:08 PM   #13
Jay_WJ is offline Jay_WJ  United States
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I wouldn't bother to mod. Nearly all 6.5" drivers have a dip around that frequency. The Usher 8945P in my 2-way design has quite a bit of such a dip. With a mild correction through the xover, I don't hear any ill effects of the dip.
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Old 11th April 2008, 08:20 PM   #14
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Hi Critofur,

Midrange being part of widerange, attached Visaton responses.
Cone dia approx 6.5" ~ 2kHz. Shallow accordian edge on both.

Cheers ....... Graham.
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Old 11th April 2008, 08:31 PM   #15
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this post did not work.
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Old 11th April 2008, 08:34 PM   #16
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and another 8" driver, the Peerless 830868 with normal sized foam surround, which does sound as smooth as the traces indicate, so the dips and peaks must be down to cone shape and type.

G.
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Old 11th April 2008, 10:19 PM   #17
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I had a bias against foam surrounds because I've had speakers with the foam surrounds rot on them, but, it does seem that foam is generally superior to rubber, sonically.
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Old 12th April 2008, 04:06 AM   #18
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I found measurements ot Usher 8945P woofer,
measured in a box with 11x16 in baffle.
same 1khz dip.
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Old 12th April 2008, 12:43 PM   #19
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Quote:
Originally posted by Graham Maynard
and another 8" driver, the Peerless 830868 with normal sized foam surround, which does sound as smooth as the traces indicate, so the dips and peaks must be down to cone shape and type.
G.
Hi Graham (/others),

The 831868, formerly 830868, seems to be a Rubber surround.
http://www.madisound.com/catalog/pro...oducts_id=1610

even with the old number... (if you saw it then maybe, /or they had both?).
http://www.bmm-electronics.com/Produ...roduct_ID=4285


Quote:
Originally posted by MisterTwister
I found measurements ot Usher 8945P woofer,
measured in a box with 11x16 in baffle.
same 1khz dip
What's the length for a 1KHz wave (?)
What's the distance inside the cone between the two faces of the cone (?)
Then maybe is just an anti-phase. It can have a dustcap involved, I am just guessing here.
We had the same problem with expensive inverted dome tweeters a wile back in this forum. We need a pipe for each frequency like in the old times...
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Old 12th April 2008, 02:00 PM   #20
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Quote:
Originally posted by Inductor
[B]
What's the length for a 1KHz wave (?)

What's the distance inside the cone between the two faces of the cone (?)
Wavelength at 1Khz is approximately 340mm. I'd guess the diameter of the cone in the Usher is around 140mm.
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