Yesterday evening, a water leaking in the basement hurt a pair of MB-Quart 350s. (Mb Quart 350s Speakers Pass The Test Of Sensitive Ears - Chicago Tribune)
A minor problem but when I've finished to dry the external of the boxes. I decided to remove the connector pannel to check if the boxes inside was ok...
Nothing has happend.
Then I noticed the crossover filter and it left me a bit puzzled....
It has a second order filter.
On the one on the tweeter there are two caps in series (before the parallel beetween the the driver and the inductor) the two caps are a polyester 6.8uF 5% rated for 100V (and this is fine) the other one is a ceramic! (?!)
This is written on it: "-110, on the second line: 809M", on the rear "Mexico".
If the cut frequency is around 2KHz, the ceramic should be around 10uF.
Why use a ceramic in a crossover?
I decided to short the ceramic, leaving the single 6.8uF, just to hear the difference without it.
And WOW! The result amazes me! the titanium tweeter start to sing!
Anyone out there can confirm me the correct value of the ceramic?
I really want to replace it with a serious cap, I can't leave the only around 6.8uF this is too large in value and the cut off frequency too low is a bit fatiguing in long listening session...
A minor problem but when I've finished to dry the external of the boxes. I decided to remove the connector pannel to check if the boxes inside was ok...
Nothing has happend.
Then I noticed the crossover filter and it left me a bit puzzled....
It has a second order filter.
On the one on the tweeter there are two caps in series (before the parallel beetween the the driver and the inductor) the two caps are a polyester 6.8uF 5% rated for 100V (and this is fine) the other one is a ceramic! (?!)
This is written on it: "-110, on the second line: 809M", on the rear "Mexico".
If the cut frequency is around 2KHz, the ceramic should be around 10uF.
Why use a ceramic in a crossover?
I decided to short the ceramic, leaving the single 6.8uF, just to hear the difference without it.
And WOW! The result amazes me! the titanium tweeter start to sing!
Anyone out there can confirm me the correct value of the ceramic?
I really want to replace it with a serious cap, I can't leave the only around 6.8uF this is too large in value and the cut off frequency too low is a bit fatiguing in long listening session...
Hi,
Series capacitors in that position are extremely unlikely.
Most certainly the "ceramic" looking thingy is a polyfuse.
Resettable fuse - Wikipedia, the free encyclopedia
Its DC resistance will be factored into the speaker
balance so bypassing it will brighten up treble.
Probably best to just put it back in place.
rgds, sreten.
Any idea how big a 10uF ceramic would be ?
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THANK YOU SRETEN!
Since the 10uF ceramic sounds very strange (and large) to me I've decided to ask you.
This really must be a polyfuse, never heard of it before.
But it really sounds bad in the crossover.
:-S
I understand that probably the tweeter is extremely sensible to overcurrent but with those things in those speakers sound 100 times worse...
Any suggestion to remove those without risk?
Since the 10uF ceramic sounds very strange (and large) to me I've decided to ask you.
This really must be a polyfuse, never heard of it before.
But it really sounds bad in the crossover.
:-S
I understand that probably the tweeter is extremely sensible to overcurrent but with those things in those speakers sound 100 times worse...
Any suggestion to remove those without risk?
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