I see you list your occupation as engineer... this suggests you will breeze through this! 
What car engineers do is look under the bonnet of a broken car, and figure out that all cars are much the same and use their experience to fix it.
The same with loudspeakers. This is a Monitor Audio speaker that was quite broken when I got it. As it goes, the oily tweeter ferrofluid had dried out, so I replaced it. Blue Aran in Swaythling near Southampton sell it.
The crossover was this originally:
You can see I used my experience to do something much better:
I am not quite sure what a Mission 730 is. Some photos and measurements of the drivers behind the plastic cosmetic mouldings will help. Are the woofers plastic or paper? It is good to look at the crossover to see how much wriggle room we have on resistors for tweeter level. I am sure we can then find some even better substitute drivers at SEAS, Vifa, Peerless or SB Acoustics.
Thing is, commercial manufacturers skimp on drivers and crossovers and cabinet damping to keep costs down. Us hobbyists are willing to spend more on components that work superbly well, rather than achieving mere adequacy. I can only explain this weird obsession by saying we love music reproduced to the highest level of illusion of the original sound and acoustic. A really good loudspeaker is a window on musical artistry. We are in the business of building something as good as a Steinway piano or Stradivarius Violin or a National guitar.
What car engineers do is look under the bonnet of a broken car, and figure out that all cars are much the same and use their experience to fix it.
The same with loudspeakers. This is a Monitor Audio speaker that was quite broken when I got it. As it goes, the oily tweeter ferrofluid had dried out, so I replaced it. Blue Aran in Swaythling near Southampton sell it.
The crossover was this originally:
You can see I used my experience to do something much better:
I am not quite sure what a Mission 730 is. Some photos and measurements of the drivers behind the plastic cosmetic mouldings will help. Are the woofers plastic or paper? It is good to look at the crossover to see how much wriggle room we have on resistors for tweeter level. I am sure we can then find some even better substitute drivers at SEAS, Vifa, Peerless or SB Acoustics.
Thing is, commercial manufacturers skimp on drivers and crossovers and cabinet damping to keep costs down. Us hobbyists are willing to spend more on components that work superbly well, rather than achieving mere adequacy. I can only explain this weird obsession by saying we love music reproduced to the highest level of illusion of the original sound and acoustic. A really good loudspeaker is a window on musical artistry. We are in the business of building something as good as a Steinway piano or Stradivarius Violin or a National guitar.
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Thanks for all the comments so far...
Love the 'car bonnet' analogy: I don't own 'the car', being the original Mission 730 beasts and not the later bookshelf units with the same name (why did they do that??). So I can't look under the bonnet. Information sent to me was that they were 8" drivers whereas other info. pointed to 11" or 255mm drivers.
Confusingly there's also legacy 730 Mark/Series 2 and 3 with what looks like differing driver arangements.
As my tag suggests, I have a set of Mission 720 originals so was interested in refurbishing the 730 units but there's no bass drivers with it. I presume foam disintegrated and they got trashed, which is a real shame.
Mission used a lot of Peerless (Denmark) drivers but archive material suggest these are made in Taiwan with polymer cones.
Other drivers are present, tweeter is soft-dome and they usually survive intact. Mid usually takes far longer to deteriorate the foam surround but I will rebuild if necessary.
Experience is that crossover components are long-living with minimal drift: I will measure all anyway.
Any other info. appreciated. Thanks again for help so far
Love the 'car bonnet' analogy: I don't own 'the car', being the original Mission 730 beasts and not the later bookshelf units with the same name (why did they do that??). So I can't look under the bonnet. Information sent to me was that they were 8" drivers whereas other info. pointed to 11" or 255mm drivers.
Confusingly there's also legacy 730 Mark/Series 2 and 3 with what looks like differing driver arangements.
As my tag suggests, I have a set of Mission 720 originals so was interested in refurbishing the 730 units but there's no bass drivers with it. I presume foam disintegrated and they got trashed, which is a real shame.
Mission used a lot of Peerless (Denmark) drivers but archive material suggest these are made in Taiwan with polymer cones.
Other drivers are present, tweeter is soft-dome and they usually survive intact. Mid usually takes far longer to deteriorate the foam surround but I will rebuild if necessary.
Experience is that crossover components are long-living with minimal drift: I will measure all anyway.
Any other info. appreciated. Thanks again for help so far
Hi. I have a set of these that I inherited recently and as yet have done nothing with. It is not a polymer bass driver, it very much looks like a paper cone to me, Mine have suffered the complete failure of the foam that you mention.
I think they might be a SEAS unit from distant memory from when I looked into them at the time my father bought them almost 40 years ago. I will take them out in due course and see if I can find any further info for us both.
I think they might be a SEAS unit from distant memory from when I looked into them at the time my father bought them almost 40 years ago. I will take them out in due course and see if I can find any further info for us both.
Hi Julianbm,
Thanks for the very useful info. Looking up the spec. on SEAS website they quote those units as 10" with a flange OD of 261mm. That matches the rebate cut underneath the standalone steel retention ring used in the Mission 730 construction.
The units I bought as replacement "original" bass drivers will not fit as they have a flange OD of 280mm, therefore it's back to tracking down some drivers of the correct size.
Again, thanks for the info. If I find anything else I'll also let you know.
Thanks for the very useful info. Looking up the spec. on SEAS website they quote those units as 10" with a flange OD of 261mm. That matches the rebate cut underneath the standalone steel retention ring used in the Mission 730 construction.
The units I bought as replacement "original" bass drivers will not fit as they have a flange OD of 280mm, therefore it's back to tracking down some drivers of the correct size.
Again, thanks for the info. If I find anything else I'll also let you know.
Quick update... I just started searching and came upon a post I've previously read about analysis / restoration of a "Clarion by SEAS" pair of speakers Clarion by SEAS
Does that look familiar!! Visually it's the same set of drivers as Mission 730 in a different cabinet....??
Does that look familiar!! Visually it's the same set of drivers as Mission 730 in a different cabinet....??
Special foam ring for Mission 730 woofers
FYI - look the same as for Mission 720. I bought others from EBay for peanuts and they were perfect...
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