Whoopysnorp said:
What's so bad about Illinois caps? I recently replaced the new Sprague Atoms in my Studio .22 with a new set of equivalents from Illinois Capacitors--the reason why is convoluted but irrelevant--and it sounds just as good now as it did before.
The Illinois Caps have a bad rap because their quality control sank when they went overseas in 2002. Electrolytic caps were literally exploding in amps left and right. They immediately stabilized production and currently their caps are excellent. The damage was done and folks are still scared to use em'. They are just as good as Sprague and in some instances superior to Sprague.
Significant tests have been conducted by the cats over at alt.guitar.....
Here's the blurb from them:
"When I measured "dialectric absorption" (a measurement related to the ability of a cap to recharge itself on its own...after discharge and removal of supply), ALL caps measured a healthy scant 4%.
In general, the Illinois caps are made to tighter tolerances. Read and weep! Illinois caps generally had lower S/Ds. Values were closer to their rated values. Still, both mfr's caps are HUGELY more precise than what was available 35 years ago where a tolerance of -50%/+75% was not uncommon. Illinois' average tested at an amazing 1% for the 100uF and 12% for the 22uF, Sprague's was 8% for the 100uF and 16% for the 20uF.
ESR for the 100uF was significantly lower for the Illinois, but Sprague had the edge for the 22 (20) uF cap. In all cases, the values fell within acceptable limits.
These tests are obviously non-musical. I didn't listen to 24 filter caps, just took some reliable and relevant numbers. Also, there's no indication on what will happen after 10 years in service (anybody want to do THAT test?)
But hopefully, this will put to rest the myth that Illinois caps are unsuitable crap. At least according to what I can measure, they're as good if not better than the Spragues (at least at the 100uf/350V value). Admittedly, ESR and leakage were higher for the Illinois than Sprague at 22uF, but they're still within normal limits of acceptability.
That said, I still prefer the Spragues for applications where lead length and strength are important, and Illinois where space is at a premium."