Mission 753 speaker fault

[rmatthew]

One of my beloved Mission 753 Freedom speakers has developed a fault. The mid-range frequencies are missing. All the cones feel like they are moving the same on both sides which makes me guess that it could be the crossover. I've physically checked the wires and they all seem ok.

Just wondered if anyone had any ideas on cause/resolution. I have a multimeter but only use it to test DC batteries, however with guidance I would be able to do some tests.

Thanks in advance for any help.

 

[Jota180]

Strange, I'd have thought if the cone was moving the same both sides it wouldn't point to crossover fault.

 

[rmatthew]

Initially I was going to swap the cones over but they are soldered in so thought I would check for ideas first.

 

[Jota180]

One thing to try is switching the cables from right to left and left to right. See if the missing mid frequencies stay missing from the same speaker or move to the other one. If it's the latter it's the amp.

 

[rmatthew]

Definitely not the amp as it has the same issue using different amps.

 

[Jota180]

Was this a sudden loss of frequncies or has it been losing it over time? If the cones are moving the same on both speakers and it doesn't matter what amp you connect then that either leaves the x-over or your source. Have you tries different srources just to eliminate that?

 

[rmatthew]

My source is Spotify so no issues there. To be honest I don't know for sure whether it has deteriorated over time or not. They have been moved twice by car recently to audition new amps and the 2nd time the guy in the showroom pointed out the issue as soon as the music started which makes me think that something happened during the 2nd move.

 

[Thompsonuxb]

The cones moving but making no sound?

Disconnect the LF/HF links and just drive the HF.

Do the cones still move?

If the cone has died (not uncommon with that era of Mission) you may need to look around for a replacement. It may be worth contacting your local hifi dealer who may have decent contacts ref replacement drive units or there is eBay. Recommend you buy replacements in pairs.

 

[TrevC]

One of my beloved Mission 753 Freedom speakers has developed a fault. The mid-range frequencies are missing. All the cones feel like they are moving the same on both sides which makes me guess that it could be the crossover. I've physically checked the wires and they all seem ok.

Just wondered if anyone had any ideas on cause/resolution. I have a multimeter but only use it to test DC batteries, however with guidance I would be able to do some tests.

Thanks in advance for any help.

Presuming that sound is coming from the tweeter you need to remove the top two series connected midrange drivers one at a time and check them for continuity on the low ohms range. They should click and move slightly with a moving coil multimeter. The cone movement may be a red herring if all the drivers share the same cabinet space.

It could be the capacitors or coil in the crossover or simply a dry joint.

 

[rmatthew]

Thanks for all your comments. The 753 has 4 woofers and a tweeter in each speaker, the upper 2 woofers being driven by the same crossover. I connected my amp directly to each speaker to isolate them and found that one sounded different to the rest. It has much less mid/lower range. I found a replacement on eBay and it should be delivered by the end of the week.

Stay tuned for the results.