 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
63.87.108.184
In Reply to: Won't a simple lens help merge DDS-90 to larger woofer? posted by freddyi on February 25, 2007 at 05:20:00:
Hi Freddyi,Thanks for the shipping! That was very thoughtful of you.
I've never used a diffraction slot in front of a woofer before, so don't know first-hand what the audible pluses and minuses are. I like the pattern widening aspect, but am leery of adding diffraction - which causes coloration not by messing up the frequency response, but by adding a secondary (distorted) signal that arrives later in time than the original signal and therefore is not masked by the ear/brain system.
Frankly my inclination would be to use the 15 without the slot. Sure there's a minor radiation pattern mismatch in the crossover region, but it's not nearly as bad as most speakers have.
Now maybe a Karlson-like slot would give the best of both worlds. I think it would spread out the diffraction over time so that it doesn't present a strong, distinct impulse. Hmmmm. Seems to me somebody on this board mentioned something about Karlsons a while back...
Cheers,
Duke
Follow Ups:
hey Duke - shipping was underpaid - this driver sounds good on a Transylvania Tube.tell me roughly how to do highpass for average driver and DDS-90
Freddy
Hi Freddyi,The high pass filter I use looks like a third order filter. Next comes a small capacitor bypassed by a resistor, to equalize for the downward-sloping response characteristic of a constant directivity horn. Then I have a fixed L-pad, to level match and smooth the impedance curve (without which the highpass filter itself wouldn't work as advertised).
I also use some additional impedance-smoothing circuits (for compatibility with very low damping factor amps) as well as some response-smoothing circuits. You have to look at the off-axis response because there are on-axis phenomena that can mislead you, but really aren't audible in practice.
Duke
Hi Duke - are you working with nearly textbook capacitor ratios in that highpass?what are good ballpark values of C&R for the eq circuit with an 8 ohm pad?
I think its sometimes possible to get some of the EQ by downsizing the first cap (?)
-- trying to make a 15PZB40 half-way rattle up to DDS - is 15 to 30 degrees off good nuff for graphing and understanding whether it'd blend? - Freddy
Hi Freddyi,I'm not using textbook capacitor values at all. I model & measure & model & measure until it looks good. Then I listen to see if there's a problem - if so, I take different measurements until I can figure out where the problem lies so I can try to fix it. If in the end I can't fix it, then something drastic happens - like rejecting that driver combination and trying another. The crossover on one of my speakers took literally hundreds of hours as I tried & rejected one driver combination after another.
I'm reluctant to post crossover component values on the internet. Without the whole schematic they're not worth much, and with the whole schematic they're an invitation to an overseas manufacturer to copy & undersell or out-advertise me. One overseas manufacturer has already tried to buy a crossover from me. I offered to sell him two crossovers along with drivers and enclosures. He didn't think that was as funny as I did.
I'll shoot you an e-mail with some information in it.
Duke
Hi Duke -- any help is appreciated - pretty soon weather should be good nuff to drag stuff outdoors for roll in da mud for testing.I want to hear if DDS will mate semi-satisfactory to B&C 15 (?) - those and 15TB sound "thicker" imo than most 60g 15"
typically lowmass run 5-6dB higher than high mass im mids and a Karlson will knock that up another 3dB in midbass or so plus the goofy old K has cone-excursion reduction so high levels can be reached with very little motion while my reflex flap in the wind (not to say K doesn't have a set of problems otherwise)
after all the joking I like some things about Karlson coupler and like the little tube better in ways than the DDS wg - hahaha - we don't see overseas folks copying those phallic things nor karlson bins (other than one French K15 with new 604 coax)
I'm piddling with this stuff til the perfected coupler arrives :^)
Best,
Freddy
From an engineering standpoint it's not a very long leap from a diffraction slot to a Karlson Coupler.
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
