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Help identifying parts for rebuilt crossovers Type AA


easyone

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No, we are talking about the screw in the center of the inductor located in the upper left corner. Check it with a magnet and if it is attracted to the magnet, replace it with either a brass or stainless screw that is not attracted to a magnet.

Bob Crites

It definitely is metal according to the magnet. Do you happen to know what size screw that should be?

All you will find will be metal. The important thing is that the metal be non-magnetic. Take the screw out and take it to a hardware store to find one the same size made of brass or stainless steel. Take a magnet with you to test the screw.

Bob Crites

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.105?:) Hey, that's 40% out of tolerance. A person may or may not be able to hear the difference, and even though the microphone in the chamber doesn't show much, people routinely hear differences in things they supposedly shouldn't. The schematic calls out a .245 air core, not a .350 steel core, and since the fix involves nothing more than grabbing a screwdriver, he might as well make it right. The network has other issues too; caps supported by their leads, the steel zener bracket up against the windings of the LP coil, and what looks to be about 1/4 pound of solder holding everything together. Anyways, I get what you're saying, it's nothing worth having a stroke over, and hey, it might even be an improvement. :)

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"The important thing is that the metal be non-magnetic. Take the screw out and take it to a hardware store to find one the same size made of brass or stainless steel. Take a magnet with you to test the screw."

With those networks, I'd be inclined to just remove the screws and use some chewing gum.

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It definitely is metal according to the magnet. Do you happen to know what size screw that should be?

small enough to go through the hole in the masonite hold-down thingie, long enough to fasten the dealie down to the whatchamathing board

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245-350, what's the diff?

42.9 percent more inductance than specified on the schematic.

It didn't matter one bit in frequency response. Can you hear inductance?

Once again, I have been provoked to the point of having to set up a test.

Conditions:

The red trace is with a standard type AA tweeter circuit the inductor is 248 uH.

The blue trace is with all exactly the same except that a steel screw is inside the inductor. That changed its measured inductance to 355 uH.

The initial tweeter output is about 4 db higher with the non-magnetic screw compared to the output with the magnetic screw.

Bob Crites

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post-9312-1381939303698_thumb.jpg

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No, that is just electronic response. You know, I think PWK may have engineered in that bump in the tweeter response to compensate for the falling response of the K-55V.

Bob

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