how do I diagnose my muffled speakers...

[midlifecrisis]

Hi all, after some years' absence.. I've had a pair of Mission M53s on a second system for some years and always enjoyed them, but they haven't been used much since moving house. Couple of months ago I noticed they suddenly sounded very muffled - now having just sold off my main speakers and promoted these to front the main system, I need to deal with that. Sound the same on both systems, so it's definitely the speakers not elsewhere in the chain. Have unplugged in turn the low and high frequencies - all drivers produce sound, though frankly when they're not working all together drivers on their own always sound odd to me so I can't really tell if they're working right. There's no crackling, just a really recessed, muffled sound from both speakers. I have no technical skills for measuring voltages and so forth - any views on how to proceed?

 

[Tenson]

It sounds like they have been played too loud or simply received a thump from the amp and got damaged.

Most likely I think is tweeter damage and you can not do a lot about that other than replacing them with identical units. If you pull them out you might find a part number on the back. Mission used to like Vifa parts.

Also possible is crossover damage. Pull out the binding post plate on the back and you should see the electronics. You are most likely looking for a blown capacitor. Unless visually damaged there is no easy way to test caps with a standard meter.

 

[midlifecrisis]

thanks Tenson - the tweeters still make a sound, I presume 'blowing' a tweeter is binary, so likely the crossovers

 

[Tenson]

Not always, you can just damage the voice coils by shorting a couple of turns. It seems unlikely that both would be exactly the same though. One thing you could do is stick a multi-meter on 'Ohms' across each tweeter (if you take them out). They should be the same to within about 0.1ohm. Usually measure around 6 ohms.