BEC Posted August 10, 2007 Share Posted August 10, 2007 Here is an interesting one. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190139196526 This appears to be a Type A crossover from a very early Lascala. The guy mentions he has the cabinet available also. I have a pair of 1967 LaScalas that have the same type A crossover. The crossover is built on the woofer access cover which is under the squawker horn on early LaScalas. Mine don't have the transformer on the left though. I guess this one is set up for a 70 volt system. Bob Crites Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted August 10, 2007 Share Posted August 10, 2007 Here is an interesting one. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=190139196526 This appears to be a Type A crossover from a very early Lascala. The guy mentions he has the cabinet available also. I have a pair of 1967 LaScalas that have the same type A crossover. The crossover is built on the woofer access cover which is under the squawker horn on early LaScalas. Mine don't have the transformer on the left though. I guess this one is set up for a 70 volt system. Bob Crites Is that a Klipsch network? Looks like they used the better part of a rain forrest for the board. Must have been a scrap from the cuts of another speaker run. (?) tc Quote Link to comment Share on other sites More sharing options...
BEC Posted August 10, 2007 Author Share Posted August 10, 2007 Just like the Type A crossovers in my 1967 LaScalas. That large board is access to the woofer from the top. Not that I am sure anyone could really get a woofer out of that hole like that. I can barely manage to even touch the woofer in my 1967s through that hole. In 1968, they went to the more familiar bottom of the cabinet access for the woofer. Bob Quote Link to comment Share on other sites More sharing options...
IB Slammin Posted August 10, 2007 Share Posted August 10, 2007 Just like the Type A crossovers in my 1967 LaScalas. That large board is access to the woofer from the top. Not that I am sure anyone could really get a woofer out of that hole like that. I can barely manage to even touch the woofer in my 1967s through that hole. In 1968, they went to the more familiar bottom of the cabinet access for the woofer. Bob If the network board is the hatch cover, (I think that is what you are saying) then that would explain the size of it. Quote Link to comment Share on other sites More sharing options...
BEC Posted August 10, 2007 Author Share Posted August 10, 2007 Your got it. That is exactly what it is. PWK must have said, "Well, we have to cover up that hole with a board, so why not just build the crossover on it and save one piece of plywood." Bob Quote Link to comment Share on other sites More sharing options...
Guest " " Posted August 10, 2007 Share Posted August 10, 2007 Who/What needs rescuing? Quote Link to comment Share on other sites More sharing options...
BEC Posted August 10, 2007 Author Share Posted August 10, 2007 The 1967 or older LaScala the guy is parting out. First ones were built in 1963. Bob Quote Link to comment Share on other sites More sharing options...
Islander Posted August 11, 2007 Share Posted August 11, 2007 In my 1974 La Scala, with the handy removable top, you can see the woofer compartment cover board, with the AA crossover on a separate board. This picture shows the original caps and K-77 tweeter, since replaced with Bob Crites's Sonicaps and CT125 tweet. Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted August 16, 2007 Share Posted August 16, 2007 Well, I rescued the Xover, Bob, and got the empty LaScala cab for $10. The whole thing required a major sponge bath, but it lives. I will upload pictures. Quote Link to comment Share on other sites More sharing options...
whamo Posted August 16, 2007 Share Posted August 16, 2007 Well, I rescued the Xover, Bob, and got the empty LaScala cab for $10. The whole thing required a major sponge bath, but it lives. I will upload pictures. Awesome! can't wait to see it. Mark Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted August 16, 2007 Share Posted August 16, 2007 Got a great deal today for sure ($35). Gave it a sponge bath inside and out to get rid of dust and dog hair. It's Fir plywood, not birch, like my 1977 center channel La Scala. This one will make the 6th channel in my 6.1 setup (presently 5.1). Thanks for pointing this out, Bob. Co-incidentally, I had to pick up a couch for my college daughter only 3 miles from this guy's house. I'll have to pull my K33 E from the Peavey FH-1 and plug in my Klipsch K5J horn with the JBL LE85 and use a spare JBL 2404. I just need to get a fine threaded screw (one missing) from the hardware store to mount the woofer. Anyone know what year this cab was built? I enlarged the Ser. #. It also came with a Peerless 70 Volt Xformer, which I removed. We'll see how it plays tomrrow. I have a boatload of film capacitors, so I will listen to these first before I upgrade them. Bob, can I run the tweeter and the midrange off separate taps on the autoformer? Pretty the JBL stuff is way more efficient than the Atlas stuff and the drivers don't match each other in efficiency. Quote Link to comment Share on other sites More sharing options...
BEC Posted August 16, 2007 Author Share Posted August 16, 2007 The "E" in the serial number should indicate 1966, one year older than my pair built like that one. Glad you rescued that old 'Scala. You can use two of the taps, but you will need to do some calculating of the cap values based on the impedance of the drivers you are using to keep the crossover points at 400 and 6000. Bob Crites Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted August 17, 2007 Share Posted August 17, 2007 The "E" in the serial number should indicate 1966, one year older than my pair built like that one. Glad you rescued that old 'Scala. You can use two of the taps, but you will need to do some calculating of the cap values based on the impedance of the drivers you are using to keep the crossover points at 400 and 6000. Bob Crites I have a digital meter, so I can only measure the DC ohms of a voice coil, which is about 13 ohms for the JBL mid driver and about 6 ohms for the tweeter. Both appear to be close to a K55V and a K77 in terms of nominal rating, but I'm not sure. Quote Link to comment Share on other sites More sharing options...
BEC Posted August 17, 2007 Author Share Posted August 17, 2007 Yes, those readings sound like a 16 ohm midrange and an 8 ohm tweeter. If you intend to attenuate them more than the standard "A" crossover does by using different taps, that would require different values for the caps to keep the crossover points the same. Bob Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted August 17, 2007 Share Posted August 17, 2007 Yes, those readings sound like a 16 ohm midrange and an 8 ohm tweeter. If you intend to attenuate them more than the standard "A" crossover does by using different taps, that would require different values for the caps to keep the crossover points the same. Bob OK, so I'm assuming that the Autoformer taps are, in effect in series/parallel with the cap value feeding the coil of each respective driver, so I need to consider the inductances of the Autoformer as part of the Xover point? Quote Link to comment Share on other sites More sharing options...
BEC Posted August 17, 2007 Author Share Posted August 17, 2007 Really it is impedance you have to consider. When you take a 16 ohm driver and connect it to the -3db tap on the autotransformer it becomes equivalent to a 32 ohm driver. Go down one more tap to -6 db and it becomes equivalent to a 64 ohm driver. So think of the autotransformer as being an impedance multiplier. Bob Quote Link to comment Share on other sites More sharing options...
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