On Mon, 1 Mar 2010 18:49:04 -0800, Frank wrote
(in article <(E-Mail Removed)>):
> In article <(E-Mail Removed)>, (E-Mail Removed)
says...
>>
>> On Fri, 26 Feb 2010 17:48:02 -0800, Frank wrote
>> (in article <(E-Mail Removed)>):
>>
>>> Hi all.
>>>
>>> I've decided to replace the 20 year old filter caps in my Kinergetics
>>> SW200
>>> subwoofer amp/crossover. Currently, there are two (2) screw terminal
>>> Phillips
>>> 10,000uf 75V caps measuring 3.5" high with a radius of 2".
>>>
>>> Any recs on a current, fast replacement cap would be appreciated.
>>>
>>> Also, would there be any advantages to going with a higher capacitance
>>> rating
>>
>>> or
>>> should I stick with 10K? Thanks.
>>>
>>
>> Generally, the component values chosen in a crossover determine that
>> crossover's characteristics. Installing larger caps will likely (I don't
>> know
>> this for sure, not having seen the schematic), if they are crossover caps,
>> change the frequency at which the crossover occurs. On the other hand, it
>> is
>> more likely that these caps are electrolytics used in the subwoofer
>> amplifier's power supply as filters. Are you changing them because the amp
>> is
>> humming or misbehaving in some other way? Because if the subs are working
>> normally, there is no reason to change them. If it ain't broke, don't fix
>> it.
>
> The bass is not as tight as it used to be but still sounds very good and a
> hum has
> developed, but you need to be very close to the drivers to hear it. The hum
> was
> never there before and considering the 20 year old age, I just think it's
> time to
> refresh the caps. I find it hard to believe that 20 year old electro caps
> are still
> performing up to spec. Thanks.
>
Well, it's possible. But my experience is that old electrolytics dry out with
disuse, not while being used all the time. OTOH, if the hum is caused by
leaky caps, replacing them CAN solve the problem (assuming it's not something
else). Yes, you can use larger value ones than are called for without much
problem. Theoretically, you are supposed to put multiple, parallel filter
caps with a resistor between them to form a classic "pi" filter with the
filter frequency as some multiple of 50-60 Hz (depending on whether a
half-wave of full-wave rectifier is used in the circuit ,IIRC), but I have
found it to not be that critical.