I bought bad Mission 753's, T's and x-overs fried, worth fixing? - Page 2 - diyAudio
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Multi-Way Conventional loudspeakers with crossovers

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Old 29th August 2007, 10:35 AM   #11
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boy that looks like a quality crossover - just love those polarised electrolytic capacitors.......
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Old 29th August 2007, 10:41 AM   #12
sreten is online now sreten  United Kingdom
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Click the image to open in full size.

Hi,

you may be able to persuade another tweeter into the faceplate
depending on how the tweeter is made. Photos of a disassembled
tweeter would help. You never know - a diaphragm from another
tweeter may fit also - depends on missions source. e.g. :

Click the image to open in full size.

/sreten.
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Old 29th August 2007, 04:17 PM   #13
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Quote:
Originally posted by timbert
Yes, looks like tweeters are shot at well,
You are going to have to redo the XO too...

dave
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Old 29th August 2007, 04:41 PM   #14
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Looking at it the crossover look as as if it may be saved. The resistors are fried sure, but other than that the rest looks OK.

I love the Mission 753's. I have a pair that I have tried a few mods on. Funny enough I was thinking along the lines of replacing the tweeters at some point.

Are your tweeters the metal dome or the silk (ie freedom model)

I have a schematic for the crossover from my non freedoms if that helps any. My crossover board is of a different layout. I understand that there were a few revisions.

Click the image to open in full size.

Quote:
you may be able to persuade another tweeter into the faceplate
depending on how the tweeter is made. Photos of a disassembled
tweeter would help. You never know - a diaphragm from another
tweeter may fit also - depends on missions source. e.g. :
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.

Here are a few piccies of the tweeter assembly.

I dont have one with the dome disassembled. However to describe briefly

The dome is not attached to the magnet assembly with screws or anything. The rectangular faceplate has a set of four clips. You just prise them apart and the assembly disassembles in your hand. The clips of the faceplate match the lugs that you can see in my last picture.

The whole that is left on the cabinate is a recessed rectangle with a circular hole routed out of it. The circular hole has a flat bottom however, extra space has been routed for the cables to the tweeter.

You might get replacement parts from mission themselves if you e-mail them.

If you have the non freedom version with the metal dome you could enquire about getting the silk dome as an exchange. I would think that you would not require a new magnet assembly, but I am unsure wether the magnet is different between versions. The metal dome version is sharper than the freedom. The freedoms are to my ears a little soft. The metals are quite harsh but can be improved upon for 0 outlay.

If you are using the metal dome version, when you have the tweeter apart, pop out the metal grill "guard" that covers the metal dome. The sound of the tweeter improves quite a bit without it. Replacing the cap that protects and filters the tweeter with a nice one like a sonicap or similar is also recommended in my books. The sound on the standard one can be improved thought you may have to add more resistance to the tweeter to tone it down after (I did)

I do have some kiwame resistors that I intend trying in my mission crossovers. But time is never on my side. I may get them fitted mid september. They might improve the sound further.

Other things you really must try in these once you get them going is to damp/strengthen the big drivers pressed metal baskets. Lovely improvements can be had there for very little money.

My vote would be stick with it. A couple of resistors, and tweeters and you have a pretty good set of speakers for very little money.

Feel free to pm/e-mail me if I can help.
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Old 29th August 2007, 04:49 PM   #15
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Quote:
Originally posted by ashok
Here the resistor appears to belong to the tweeter and that end is burnt ! .
FYI The top board does not control the tweeter. Thats the low pass filter for the bass assist woofers.

Timbert. If you have an inductance meter, could you produce a schematic for your version of the crossover... Just out of interest for myself.
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Old 29th August 2007, 05:41 PM   #16
timbert is offline timbert  United States
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justblair, I've looked at your other helpful posts. I do not have an inductance meter, and was thinking of just replacing the resistors and checking the caps and hoping for the best. I saw your schematic in the other post and will look to see if it appears the same, but I'm no expert.

For the tweeters, they are the same as yours and I believe they are Vifa but could not find a current model that looks like this. Here are some pics. Looks like the coil is fused to the magnet because when I pulled it off it started to come unwound. Also, the outer metal shell looks like it was in contact with the outer dome screen, and you can see what appear to be abrasions on the outside surface of it. Is that oil that leaked out of the magnet?

So I guess I need a source for the tweeters, but don't know the original model or its specs so if I have to substitute a more current model and make it fit physically I'd like to not have to mess with the crossover. I guess I'll contact Mission as I doubt I would be able to find tweeters that would just fit right in.
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Old 29th August 2007, 05:43 PM   #17
timbert is offline timbert  United States
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Old 29th August 2007, 05:46 PM   #18
timbert is offline timbert  United States
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The diameter is 2 1/8", or 57mm, and the height is 1" or 25mm.
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Old 29th August 2007, 05:50 PM   #19
timbert is offline timbert  United States
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Old 29th August 2007, 06:01 PM   #20
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You should contact Mission first.
When my 780's had problems I contacted them. They offered to replace the woofers for free under warranty but I was the second owner and the warranty was not transferrable. However they sold me two woofers for a very reasonable sum.

Try contacting them.
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