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Only mid is working on both Cornwalls


jimjimbo

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Hi all,

Today I wanted to verify what I had heard yesterday when I picked up the very rough pair of Cornwalls, just to make sure I hadn't made some dumb connection mistake. However, I did verify that only the mid range driver is working on both. Checked all the wiring to and from the crossovers to each of the three drivers in each cabinet, everything looks good. So, my dreadfully uniformed deduction is that each crossover is bad (which is not a big surprise). However, don't have a multimeter (which I should invest in....), and I wouldn't know where to read, or what the values should be if they are faulty. Is this a proper supposition, and can someone tell me what I should be seeing at a specific terminal point when I do get a multimeter? (ordering one tonight from my friends at Amazon....) Thanks.

I was planning on replacing the crossovers anyway, but this is another in a series of many learning experiences for me....

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Good to hear from you.

My guess is that it is not the crossover. Components therein seldom fail.

However, there is some chance that the woofer and tweeters are blown out and that is why the units got sold.

Buying a mulitmeter is a very good investment. It will elevate your level of knowledge from guessing to knowing.

Do make notes and take pictures of what connections go where on the crossover board. It pays to use some masking tape to mark the leads including what goes to plus and minus screw terminals.

You will have to read the instructions on the mulitmeter to learn how to measure resistance aka "ohms." Closely related to this a simple "continuity" test. A buzzer sounds when the tested device has a resistance less than some predetermined level of ohms. But I don't know what that threshold is.

You will have to disconnect the speaker from any amp.

The classic way of measuring the resistance of the drivers is to disconnect them from the crossover and then hook the leads of the multimeter (set to ohms) up to the terminals of the drivers or wires leading to them. A good driver for the mid (I know, it is working) is about 10 ohms. The tweeter should be about the same. The woofer will be about 4 ohms.

One thing is that digital multimeter set to "ohm" typically read out something like "OL" when the test leads are connected to nothing. This is equivalent to infinite ohms or no resistance (Edit: Thanks to my brother in Klipsch for the correction, I should have said infinite resistance). This is what you get as a reading (instead of 4 or 8 or 10, etc. -- indicators of a good driver voice coil) when the voice coil of the driver has failed.

Let us know your progress and results.

WMcD

Edited by William F. Gil McDermott
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Go buy the meter.

Check the drivers.

Replace the tweeter diaphragms (if needed).

If the woofer does not have continuity, remove the dustcsap with an exacto knife, leave an 1/8" ridge. Check for continuity at the ferrules. Replace the tinsel leads as required.

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Guest David H
I am very hesitant to cut open the dust cap.

If the woofers are open will need to be re-coned anyway, so will not hurt to cut open for inspection.

If you push on the woofer cone, and the voice coil is scratchy will need to be re-coned or replaced.

Looks like Parts Express will re-cone for $73 each, if you want to keep the original parts.

Dave

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