Al Klappenberger Posted March 19, 2004 Share Posted March 19, 2004 Cornwallers: Progress marches on! Even though I am no longer building the Cornwall crossover network, I haven't lost interest in the project. Now that I have the equipment to actually measure the complex impedance of a loudspeaker woofer, I am able to do some fancier designs. The type "B" network design that is still downloadable from my web site works fine, but I have worked up a new woofer crossover section that I think will be an improvement. The old design assumes the Cornwall woofer presents a 4 Ohms resistive load to the network. I no longer have a Cornwall to test, but extrapolating from measurements made on my "Big Heresy", may Belle woofer and on a Khorn by a friend, I have come to the conclusion that it is more like 6 Ohms in series with a 1 mHy inductor. This lets me modify the values in the Cornwall network to compensate, at least in the computer. This will also allow the impedance presented to the amp by the speaker to be changed from an uncertain 4 Ohms to a good stable 6 Ohms. This also will move the crossover from about 750Hz down to 600 Hz. At 600 Hz it is no longer compatible with the Heresy though. It's for the Cornwall (original) only! My apologies to anyone who just got done building it the old way! The schematic of the changed area is attached. Here is the changes: Old Part --> New part -------- --------- 1.3 mHy of #12 AWG --> 2.4 mHy of #14 AWG (It's about the same size). 1.3 mHy of #18 AWG --> 2.0 mHy of #18 AWG. 39 uFd to ground --> 62 uFd to ground (across the woofer driver) 39 uF in parallel with 1 uF bypass --> 30 uFd in parallel with 1 uFd. 5.6 Ohms 20W in parallel with transformer (taps 0-5) --> 10 Ohms 10W in parallel with transformer (taps 0-5) Al K. NOTE: I forgot to change the 39 uF cap to 62 uF on the schematic I uploaded. I can't seem to upload the new one over it. I am going to upload the corrected one in the next post.. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted March 19, 2004 Author Share Posted March 19, 2004 Here's the corrected schematic of the Cornwall network update. Ignore the attachment above if it's still there! Sorry, Al k. Quote Link to comment Share on other sites More sharing options...
jorjen Posted March 19, 2004 Share Posted March 19, 2004 Apology accepted Mr. Klappenberger. Quote Link to comment Share on other sites More sharing options...
Deang Posted March 19, 2004 Share Posted March 19, 2004 A simple and inexpensive fix for those who already use them. Nice work Al! Quote Link to comment Share on other sites More sharing options...
kev313 Posted April 26, 2004 Share Posted April 26, 2004 Hey Dean, now that it appears that Al is out of the crossover building game for Cornwalls, will you do any Cornwall work??? Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted April 28, 2004 Share Posted April 28, 2004 I'll do them for you if Dean bows out. It's not a big deal as far as the actual build, coming up with all the parts is sometimes slow. I live near AES in Phoenix, makes it easier. Quote Link to comment Share on other sites More sharing options...
bsacco Posted July 2, 2004 Share Posted July 2, 2004 Hi Tom, I was curious about how the AKL Cornwall x-overs sounded vs. the original x-overs. It seems you are expert in this area. Also, changing the diaphram...do they just get old? What is the best bang-for-your buck...replacing parts in the x-over or changing out diaphrams? THanks in advance, -bob sacco Quote Link to comment Share on other sites More sharing options...
Good2BHome Posted July 2, 2004 Share Posted July 2, 2004 Al, What modifications are necessary (if any) when using K-55V's (with the nested phase plug) released in March of 1980? When Klipsch began using the "new" K-55V's they soon after updated the "B" crossover to the B-2, per Dope from Hope. Thanks in advance!! Mike Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted July 2, 2004 Author Share Posted July 2, 2004 Mike, I don't think any changes are needed. The tap settings on the transformers were the same in the B, B-2 and B-3 network. This makes sense to me as most of the Klipsch squawker driver have the same sensitifity. At least all that I have tested do. I am quite sure there is no difference between the old and new K55V. Even the K55M was the same. It was the change in tweeter with the Cornwall II (K79 versus K77) that was different. The K79 is less sensitive. That is why my Cornwall design can't be used on the newer Cornwall II. AL K. Quote Link to comment Share on other sites More sharing options...
Deang Posted July 3, 2004 Share Posted July 3, 2004 Well Kevin, I do build some really nice Type B's with the Jensens PIOs for those who are hooked on the vintage flavor. I've never heard one nice thing said about the B2 or B3. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted July 4, 2004 Share Posted July 4, 2004 Well here, lemme break the ice..... The B3 network sounds fine to me. Quote Link to comment Share on other sites More sharing options...
Deang Posted July 4, 2004 Share Posted July 4, 2004 Doesn't surprise me. Trey was running the B2 in his old vertical Cornwalls in Indy last month, and those sounded pretty good to me too. Does the B3 have a high pass in it? Quote Link to comment Share on other sites More sharing options...
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