Midrange drivers dips above 1Khz...

The dip I'm talking about is the one you see on manufacturer's charts, sometimes followed by a bump. This would typically be measured on-axis on a large baffle in an anechoic chamber.

When I was working with someone who designs and builds his own custom drivers for his company, I referred to it as the dipbump, with our drivers it was around 2Khz and not as severe as in some of the nice Vifa, Peerless, and Audax drivers I'd been looking at.

Having a dip right next to the bump made it less desirable to try to use a notch filter on the bump :(

I hadn't done much testing to see if the dip is audible, because, it's so hard to eliminate mechanically. When we did finally succeed in getting a flat response (by spending hours attaching bits of sticky tar in various shapes to the cone) it sounded surprisingly bad.

"cone surround dip" eh? I guess accordion cloth surrounds don't have that issue as much? Maybe the double roll rubber surrounds are little better than the single roll ones also? We even tried cutting the edge of the cone in a zig-zag pattern to see if that would help, it didn't :(
 
Jay_WJ said:
People, including me, already discussed this issue long ago. Take a look at my post:

http://www.diyaudio.com/forums/showthread.php?postid=1236362#post1236362

and Kevin Haskins' post:

http://www.diyaudio.com/forums/showthread.php?postid=1237126#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.
 
Hi Critofur,

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

Cheers ....... Graham.
 

Attachments

  • drivers.jpg
    drivers.jpg
    97.1 KB · Views: 297
Graham Maynard said:
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/product_info.php?products_id=1610

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


MisterTwister said:
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...