kerkula Posted September 4, 2017 Share Posted September 4, 2017 I was recently gifted a pair of Cornwalls from some friends who were downsizing and had no space for them. From the serial numbers (which are not sequential) I can see they were manufactured in 1981. My friends were the original owners. Being curious I opened them and much to my surprise they are two different beasts. One has a type B2 crossover, K77M tweeter, K55V mid, and K33E woofer The other has a type B crossover (labeled as such) but modded to B2 configuration, K77 tweeter, K51V mid, and K33e woofer. Both mid range drivers are attached to K600 horns This leads to a couple questions. 1. Are the tweeter and mid range differences big enough to warrant matching the drivers? 2. If yes which are the superior drivers? As for the Crossover, I'm going to pull the modded one to make sure it is to spec and drivers are connected correctly. thanks in advance for your thoughts and advice, Quote Link to comment Share on other sites More sharing options...
Deang Posted September 4, 2017 Share Posted September 4, 2017 If the K-55-V has the solder lugs instead of the spring load terminals - you're good to go on the midrange. I suspect you might get lucky here because of the year. The tweeters are an issue I think. The K-77 should be replaced with a matching K-77-M. The B2 is a good network - leave in place. Quote Link to comment Share on other sites More sharing options...
kerkula Posted September 5, 2017 Author Share Posted September 5, 2017 3 hours ago, Deang said: If the K-55-V has the solder lugs instead of the spring load terminals - you're good to go on the midrange. I suspect you might get lucky here because of the year. The tweeters are an issue I think. The K-77 should be replaced with a matching K-77-M. The B2 is a good network - leave in place. Thanks for the quick reply. I don't understand your comment about the K55. Should I keep it or keep the K51? Quote Link to comment Share on other sites More sharing options...
Woofers and Tweeters Posted September 5, 2017 Share Posted September 5, 2017 You have an ideal setup. Is one side louder; is one side clearer / cleaner; have you switched cables L to R; have you tried different power sources and or have you tried them in other rooms? I have seller's remorse on some things. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted September 5, 2017 Share Posted September 5, 2017 Keep the K55. Quote Link to comment Share on other sites More sharing options...
kerkula Posted September 5, 2017 Author Share Posted September 5, 2017 Thanks for your concise answer! Now i am ISO another k55. Quote Link to comment Share on other sites More sharing options...
kerkula Posted September 5, 2017 Author Share Posted September 5, 2017 I am listening to them in a pretty good room. The left speaker (k51 and k77) seems quieter. Will a K55 and K77-M sound louder? Quote Link to comment Share on other sites More sharing options...
Deang Posted September 5, 2017 Share Posted September 5, 2017 In my experience, the K-77 is slightly less efficient than the K-77-M. If I had to guess - this is what you're hearing. The K-51-V is a dual phase plug design, and has a frequency response that extends to 6kHz. It is the ceramic magnet version of the AlNiCo magnet K-55-V with the soldered lugs (also a dual phase plug design). The most common version of the K-55-V is a single phase plug design, which is easily identified by its spring loaded terminals (the things on the driver that you push down to expose the hole you feed the wire through). This driver has a frequency response that falls off at around 4.5kHz, and then climbs again due to the action of the horn itself. Response is a little haggard between 4.5 and 6kHz. So, if you have a single phase plug design in one speaker, and a dual phase plug design in the other ... I'm thinking that might not be ideal. Picture is the K-55-V with two piece phase plug - identified by the use of soldered lugs. Quote Link to comment Share on other sites More sharing options...
kerkula Posted September 5, 2017 Author Share Posted September 5, 2017 Thanks for the explanation. Next time I open the back of the speakers I will look for the solder lugs. Quote Link to comment Share on other sites More sharing options...
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