mission 780se

[Bizzie]

I have a pair of Mission 780se that I let my daughter use with her Denon udm31 mini system and they have been ok for the last two years.
Suddenly they lost all the bass and all that can be heard is the treble with the base cutting in occasionaly then going off agian, at first I thought that the amp was to blame but it works ok with other speakers and the Missions are the same in my system.

I have had a look inside thinking that there was probably a wire come adrift somewhere but cannot find anything obvious.

I now don't know what to look for and I'm not sure if the problem is in the cross overs or the bass driver, how can I test the driver without causing anymore damage.

I think its really odd that both speakers are affected as I would expect a component failure to happen only to one speaker.

[john & Jake the dog]

Hi,
you should be able to connect the bass driver directly to your amp without a crossover. Don't do the same with a tweeter though
If it works ok the fault lies before the driver, could be a dry joint on the crossover in that case.
A bit puzzleing that it affects both channels though.

[andrew ivimey]

If you trust the amp, then get into the speaker box and disconnect the suspect bass driver, connect it straight to the amp with some cable you can trust and see if it plays smooth (if a little bassy) music. Then its time to look for a dry joint on the crossover!

There you see, it has to be that - we both said so, at the same time and in almost the same way. :-)

[Bizzie]

Thanks for that, I'll give it a go tommorow.

[john & Jake the dog]

Hi Andrew,
SNAP

[andrew ivimey]

Yeah, but we both could be wrong!

[Bizzie]

Bad news, I have disconnected the bass units from the cross over and connected them straight to the amp as advised and one side is completely dead and the other side just cuts in now and again with the volume up quite high

I'm not sure what could have caused the drivers to fail like that as my daughter doesn't play her music particularly loud (certainly not as loud as me)so I wouldn't think her amp would be clipping as its rated at 22 watt per channel and didn't seem to struggle at all.

Not sure where to go from here as she now is quite happy using the TDL's I've installed for her and the Missions are now redundant, but it seems a waste to discard what were a nice sounding and not particularly cheap pair of speakers.

Does anyone know if Mission will sell the drivers seperately or would the speakers have to go back for repair if thats what I decide to do.

[john & Jake the dog]

Hi Bizzie,
http://cgi.ebay.co.uk/Mission-780-Sp...QQcmdZViewItem
or there are drive units there that would probably fit, or there are other drive units that would fit and suprise you just as the Kef B200's I fitted to Mission cabs suprised me
before1.jpg

after.jpg

[Bizzie]

I've just found some drivers on epay but not sure if they're the same as the SE version so I've sent the seller a question asking if he knows.

http://cgi.ebay.co.uk/Mission-speake...QQcmdZViewItem

PS Wow that was quick got an instant reply from the seller while typing this question!! and they are the same.

[Shane]

All the 780 series were prone to failure of this unit. My 782s (which use the same unit for mid-range) failed after less than a year. Originally, Mission used an Audax unit with a Keraform cone. These were the ones that failed and were replaced by an Aerogel-coned unit when Audax stopped making the original one. This was much more reliable. Sound was slightly more forward; personally I thought the replacements were better than the originals, but others (including Peter who designed the thing) disagree. Either way the difference is not large.

The SE versions of the 780 & 782 used a better tweeter and upgraded crossover components, but the same bass unit.

Incidentally, the units on Ebay look like the later Aerogel ones, which were slightly shiny. The Keraform ones had a mottled matt grey appearance.