I knew.
My amp-sifu presented me with this concept in the form of a listening test.
It was discernible, just.
I agree with Cybercow, I would say it makes a difference in high-voltage environs — and will add that it makes a difference in hi-fi systems belonging to cork-sniffers.
In a distortion pedal, whatever. Nonetheless, I might go to the trouble of lining up the Film-caps in an EQ or compressor build for myself where I want the cleanest fidelity possible, but ... that'd be mostly to address my obsessive compulsive behaviours than for any real audible difference.
At least I'd KNOW all the caps were lined up properly front to back.
Still, the best chefs use the freshest ingredients — they don't use frozen peas and powdered milk.
A lot of people will say you'll never hear the 2% "x-factor" in a live-band context — no, but if you make every 2% the best possible ingredient it can be, then when all added up to the 100%, I know which meal/sound is going to taste/sound best. One or two caps, not much difference. Many 10s of caps, the difference starts to add up.
Bulk-bin Muffins made with fillers vs a high-end bakery's muffins.
Like how an amp can feel to the player — the audience can't tell the difference, but if the amp's feel inspires the player to perform better — well why suffer mediocrity when greatness can be achieved?
Why ride a bike made out of Titanium when a pot-metal frame does the same job (albeit more heavy)?
hackaday.com
