ka7niq Posted October 17, 2006 Share Posted October 17, 2006 I purchased some used 1978 Cornwalls recently, and I plan to open them up soon. The previous owner re finished them, and they sound a bit muted, and w/o much tweeter/midrange response. I presume he removed the drivers, and want to check that he re wired them correctly. And, I want to change the crossover caps, and perhaps re wire them. Can someone please provide me with a crossover/driver wiring diagram. Thanks! Chris Quote Link to comment Share on other sites More sharing options...
BEC Posted October 17, 2006 Share Posted October 17, 2006 Here it is. Bob Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 17, 2006 Share Posted October 17, 2006 bob, it didn't stick...oh...there it is. Quote Link to comment Share on other sites More sharing options...
ka7niq Posted October 17, 2006 Author Share Posted October 17, 2006 Here it is. Bob Bob, the seller said he bought the replacement tweeter diapragms from you, yet there are little highs or mids, at least compared to Forte's. I have never had Cornwalls before, but they are almost muted sounding. The schematic does not show WHICH driver terminal shall be hooked to what, plus or minus ? Is there any easier schematic ? The cap values are hard to read too. The tweeters do not sound right, very tizzy and muted sounding. Quote Link to comment Share on other sites More sharing options...
BEC Posted October 17, 2006 Share Posted October 17, 2006 I think the type B schematic is one that has not been redrawn so is not very pretty. See if this PDF version looks any better. Something must be wrong if the highs and mids are lacking compared to a Forte. Bob Crites B.pdf Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 17, 2006 Share Posted October 17, 2006 maybe this will help. don't go by the clock positons of the terminals, since these can be rotated on the mid driver. check the connections there are little 1 and 2 numbers or little t1 and t2 numbers on the mid driver terminals if they are not factory color coded. the tweeters usally have a red colored insulator where the diaphram leads are soldered for positive. the woofers usally have a + sign. Quote Link to comment Share on other sites More sharing options...
ka7niq Posted October 17, 2006 Author Share Posted October 17, 2006 I think the type B schematic is one that has not been redrawn so is not very pretty. See if this PDF version looks any better. Something must be wrong if the highs and mids are lacking compared to a Forte. Bob Crites Yes, something is not right. I hear you have different tweeters to go into a Cornwall, will they work with the stock filters ? How much are they ? I WONDER if someone used the wrong autoformer taps in these, and subdued the mids/highs I am firing them straight ahead, but even toed in, the highs/mids sound almost muffled. Do midrange diapraghms last a long time, or should they be suspected ? Quote Link to comment Share on other sites More sharing options...
ka7niq Posted October 17, 2006 Author Share Posted October 17, 2006 maybe this will help. don't go by the clock positons of the terminals, since these can be rotated on the mid driver. check the connections there are little 1 and 2 numbers or little t1 and t2 numbers on the mid driver terminals if they are not factory color coded. the tweeters usally have a red colored insulator where the diaphram leads are soldered for positive. the woofers usally have a + sign. The seller said he got the new tweeter diapraghms from Bob Crites, but how do you know he hooked em up right ? Is it possible to create an out of phase tweeter by putting the replacements in wrong ? Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 17, 2006 Share Posted October 17, 2006 lets try it again Quote Link to comment Share on other sites More sharing options...
BEC Posted October 17, 2006 Share Posted October 17, 2006 I do have different tweeters for the Cornwall, email me about price. bobcrites@centurytel.net Taps on the autotransformer should be 4 (-3db) for the Tweeter and 3 (-6 db) for the squawker. Midrange diaphragms are not usually a problem. Both of them bad in a pair of speakers would be really strange. The caps are probably bad at least as far as ESR is concerned, but that effect should be rather subtile and mostly affect the tweeter. Look the wiring over good. Bob Quote Link to comment Share on other sites More sharing options...
BEC Posted October 17, 2006 Share Posted October 17, 2006 Yes, there are a couple of places where a person could go wrong installing diaphragms in the tweeters. But I don't know who installed them or whether he had directions from me for installing them. Bob Quote Link to comment Share on other sites More sharing options...
Guest " " Posted October 17, 2006 Share Posted October 17, 2006 ka7niq Have you tested the drivers...i.e. at a modest power level...use a cardboard tube over your ear , get up close, and point it into the center of the tweeter , mid driver. What do you hear? if you have a multimeter, you can remove the back acess panel and test the drivers for dcr. The tweeters should read 6 ohms, the mids about 10 ohms, and the woofers about 3.9 ohms. Quote Link to comment Share on other sites More sharing options...
ka7niq Posted October 17, 2006 Author Share Posted October 17, 2006 ka7niq Have you tested the drivers...i.e. at a modest power level...use a cardboard tube over your ear , get up close, and point it into the center of the tweeter , mid driver. What do you hear? if you have a multimeter, you can remove the back acess panel and test the drivers for dcr. The tweeters should read 6 ohms, the mids about 10 ohms, and the woofers about 3.9 ohms. I will be removing backs shortly. The drivers all work, but tweeters sound fuzzy, and w/o extension Highs are noticeably diminished Speaker has an overly warm, almost muffled sound Quote Link to comment Share on other sites More sharing options...
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