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Cornwall I "Blaring" Midrange?


craigtone

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I just picked up a set of original Cornwalls in a trade. The crossovers have the Crites capacitor upgrade and I am told it also has the Crites tweeter diaphragms but I have not verified that yet.

As I have been listening, I am getting some harshness in the midrange so I did some cricitial listening yesterday with a few test CDs. The pink noise test shows a volume increase in the one speaker over the other but not so much in white noise which points me to the midrange horn. I also listened to an orchestral piece and then isolated each horn with an album cover. The tweeters both have equal volume and are clear. The midranges do not have equal volume and the louder of the 2 is "blaring" and not clear.

All drivers appear original with the square magnet K-33, Atlas K-55-V's and EV K-77's. Crossover is Type-B.

Anyone have any ideas?

On an unrelated note, the motor board is flush with the cabinet sides ... is this normal? I seems there is no provision for a grill (speakers did not include grills)?

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You' ll love these when you tame the trouble maker. Photos would help. It sounds like you have decorator Cornwalls.

I'd try switching the K55/Atlas drivers side to side. If the problem follows the driver, it all but rules out the balancing network, connections, etc. as the problem. If the problem doesn't follow the driver, the reverse is likely.

Please keep us posted. Good luck.

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original Cornwalls

Congrats!

The crossovers have the Crites capacitor upgrade and I am told it also has the Crites tweeter diaphragms but I have not verified that yet.

Well now, that wouldn't be "original" would it? [:P]

Anyone have any ideas?

Make sure to measure the voltage present at the terminals. The idea is to be certain it's the same on the L&R channels. Even if the voltage measures the same, you'll have piece of mind knowing that the problem indeed lies within the speaker cabinet and not outside of it, before spending money or time investigating the matter any further.

With that out of the way...

See my posts in this thread: http://community.klipsch.com/index.php?/topic/143229-my-newold-pair-of-la-scala/#entry1634397

I had exactly the same audible issues with my speakers. Developed a harsh mid range first. Fixed that only to have the tweeters follow suit shortly thereafter.

Give Bob Crites a call for the gaskets. Basic horn maintenance that'll go a long way towards good sound. [Y]

*edit* Fixed broken link

Edited by Quiet_Hollow
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The gaskets need to be replaced, but I don't think that's what's causing the problem. A bad gasket isn't going to cause an increase in SPL. Start by simply reversing the speaker wires to see if the problem moves to the the other Cornwall. If it does, then it's not a speaker problem. If it doesn't, I would compare the two crossovers to make sure they are wired identically. If they are, you might want to consider sending your drivers to Bob for testing.

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You could get new gaskets from Bob or you could do what I did. I went to hardware store got O-ring exact same size as the driver opening glued them on with a little super glue put a small amout of vasaline on for lube when tighting them down.

Your problem could be just bad connection on one or more of the crossover screws not just the ones going to mid-range. Rick

PS I think those look better than with grills. Those are awwwweeessooomme lol

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A bad gasket isn't going to cause an increase in SPL.

Sure it can. Any air leaks will shift the tuning of the affected horn upwards and allow it to resonate where it normally wouldn't.

If there is a leak, there will be a loss in pressure, and the driver will not load properly. There will be a drop in SPL and an increase in distortion. I suppose it's possible that it might sound louder because the bad sound is drawing attention to itself, but that doesn't mean it is. What is most likely is that the "blaring driver" is the one that is working fine, since that's how a perfectly working Cornwall midrange sounds. :)

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again loss of air is a problem - but you can do a lot of testing yourself and get back to us with your results

- I can suggest a few ways to test the midrange drivers -here is a small list - the k55v on CW1 are the push pin type - so all you have to do is push the pins -remove the wiring and unscrew to swap the BLARING midrange driver from speaker to speaker and from the 2 crossovers and the 2 horns -

A) You can unscrew one midrange driver at a time and test it on each of the 2 crossovers - that will give you the crossover test - basically you are testing to see if the driver sounds different on each crossover or not -

B) swapping each midrange driver on the 2 midrange horns - will handle the horn testing and the gaskets - this will allow you to see if the gaskets are causing the issue -

C) there are 6 screws on each k55V - make sure these are tight - do not overtighten -

D) if you end up not seeing any problems with the crossovers - the gaskets - the horns - then the 4th step is to remove the 6 screws on the k55V and open the midrange driver to take a look at the diaphragm of the K55V that has the issue - nothing like seeing the internals of the diaphragm -take some time and clean the inside from dust -

these 4 tests should enable you to troubleshoot the cause of the problem - again only one of the 2 drivers has an issue -so you can simply concentrate on the one that is doing the BLARING -sound -

E) You can also take an ohmmeter and check the DCR - 10ohms is about right -

F) make sure that all screws on the midrange horn are tight - as long as you are at it - go through all the screws of the tweeter driver and horn - midrange driver and horn - woofer screws - these speakers are 30 plus years old so that will not hurt at all to get to know the overall condition of your speakers -

good luck -

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