Posted on Monday, 2nd January 2012 by Auw Jimmy
My wife knows and supports my hobby in audio. I think she even knows almost all of my expenses. Well, ‘almost’ means maybe there are some that she doesn’t care or aware of – not my intention to hide from her .
Once upon a time, when we were on her mother’s living room, I stumbled upon an audio system used there. It was quite old and sounded ‘ultimately’ bad. She jokingly asked me how do I rate this system. Honestly I said, maybe around 20 from 100 scale. Well, it’s true. Even maybe 20 was still slightly over rated. Then she challenged to improve it. After checking them for few minutes, I decided to give further examination as the condition was ‘terrible’. OK, I could bring this home for some new year’s fun. Then the adventure begun…
Now, let’s start with the speaker. The speaker is Mission 762. Quite good on its era (20 years back). But now, it sounds so bad. The woofer seems fine, but the tweeter I think already running out of his life. Too much noises and ‘too smooth’ (means no treble or detail) .
Then the second issue is the receiver. It’s an old Marantz PM400AVK. I check elsewhere that this should be for Japanese market. First suspect is the volume control problem which produces some breaking voice. But will see.
Inside the Mission tweeter. Dusty for sure, but that’s not the problem.
The original crossover. Some bipolar capacitor, Tesla resistor, and two inductors. They form 2nd order for the high pass and 1st order for the low pass. As simple as you can be.
Will see what I can improve from this. Making them higher score over 50 would be an amazing job (as currently I rate them only 20).
One note to be taken is, we will not see expensive stuff on this upgrade (something which is unlikely for my project). So the target is economical spending, but reasonable result. Quite challenging, huh?