[sdiy] Hand-matching capacitors for filter stages

[Tom Wiltshire]

Harry,

Ok, I understand that there's a difference in the dielectric.  
Polystyrene is still 'top cap'.
My thought was just that mostly we're not comparing like with like. A  
typical Polystyrene cap is 1% tolerance, and a typical polypropylene  
is 5% or 10%. So it's no surprise if your filter sounds better when  
you replace one with the other, even if the dielectric was identical.

If I had 1% caps of both types, I suspect I'd be more than happy with  
polypropylene (or one of the other plastic film caps probably), even  
if polystyrene is still marginally superior in all but soldering temp.

You pays your money and you takes your choice...

T.





On 9 Feb 2010, at 18:04, Harry Bissell wrote:

> Yes, the difference is in the dielectric. Polystyrene needs to be  
> thicker,
> forcing the plates apart and the capacitance down, so you need more  
> area.
>
> Polystyrene also has a lousy soldering temperature range, use is  
> only 85C.
> Polypropolene is MUCH better temperature-wise
>
> H^) harry
>