MIssion 75C - Lost HF

[winkie]

Hi Guys

This is my first post on this forum, and I hope very much that someone can help me.

I have a 5.1 System running Mission Speakers that I purchases, ooh, 10+ years ago!

I've lost the High Frequency on the Centre Speaker.

Therefore I beleive that either the crossover or the tweeter is a gonna.

I don't really know much about what I am talking (as you will soon find out!). Bu tI've opened the speaker, through the binding post cover at the rear and looked at the crossover.

Personally, I think that the crossover is at fault (don't really know why, but there you are).

The LF side is fine, and have the speaker bi-amped. I've swapped amp channels and cables and hte problems still remain - so for sure it is crossover ot tweeter.

Wihile I am at this, I thought that I may as well try to upgrade the crossover (at least the HF side anyway).

So, on the HF side (here you'll see my true technical limitations), I have 2 shite rectangular things!!!

1 x Micropride 7W 3.9Ohm J
1 x 685K 100V

So I guess its one or both of those little fellas!

So, to replace them, what would you suggest? Something that will give me a better crossoever.

Then..... the wires from the crossover to the tweeter and mid-range, looks nothing more than bell wire - I guess it would help to replace this at the same time.

Suggestions are extremely welcome.

Finally, I am living in Bangkok, so if any other posters are from Bangkok also, if you have any clues where to purchase such items would be a real bonus (or Singapore, as I visit frequently)

Thanks very much guys, and looking forward to your suggestions and help

Winkie

[sreten]

Hi, fried tweeters are far more common than crossover failure, /sreten.

[andrew01]

The first one :

A "resister" to lower the level.

Micropride = Brandname
7W = 7 watts power rating
3.9 ohm = it's resistance value in ohms

second one:
"BiPolar capacitor" to filter/block low freq from getting to Tweeter
100V working voltage rating
685K is it's capacitance value = 6.8uF

[watchdog777]

Hi,

Good news is that I can give you a list of places to check in Singapore that sells a whole array of stuff to upgrade your crossover unit.

Bad news is that I second sreten's analysis - a broken crossover is highly unlike to be the problem. I think your tweeter unit is dead.

Let me know if you need the places to get stuff in Singapore.

[winkie]

Dear All

Thank you very much for posting quick replies.

So far, looks like I need to approach the Tweeter as my first stop.

Watchdog, Yes, please, I'm going to Singapore on Wednesday adn would love to be able to resolve this issue at the same time, do you know of places where I could get a suitable tweeter also? Do you or any others have any recommendations on how I can at least match the present perfomance? Or better it? The current tweeter is 10 years old, so I am sure better is available, but will it match with what I currently have in my other speakers, and would it be a good idea to think about upgrading some or all of the crossover components/wiring at the same time.

Thanks very much to you for the advice, very much appreciated

Winkie

[watchdog777]

Hi Winkie,

A main limiting factor would be the cut out dimensions in your baffle. Not to mention that I did a quick google and can't find any information on the 75C tweeter unit.

Without being able to get an exact replacement tweeter, I wouldn't spend too much on trying to improve the crossover.

Best place for you to visit is Burlington Square which is just next to Sim Lim Square. Two important shops there, both on the first floor, Martin Electronics and Well Audio Lab.

Martin is the place to be for speaker repair and parts. Besides drivers, they sell crossover parts. For capacitor choice, you have Solen, Jensen and Auricap (up to 2.2 mFD only).

Well Audio Lab is NOS tube heaven. More important for you, he stocks capacitors from Solen, Wima, Mundorf (small values only), Multicap and Hovland.

For resistors, cement sandcast is easy to find. MOX is difficult but carried by one of two people. Popular enthusiast resistors for speakers like Mills do not have local distribution unfortunately.

Let me know if you need help in sourcing any particular brand or part.

[winkie]

Watchdog

Thanks very much for the recommendations

Am in Singapore tomorrow, and am not sure if I have time to visit, but will try. If not will be there next month for longer period and will have more time to go shopping.

Thanks again

Winkie