Bypassing Caps - what is it really about?

. For crossovers, this bypassing of a large capacitor with a small one, from what I have read, often very small, sounds like an urban myth that became real.

That's your problem right there.  Research without experience.  $40 in parts and a weekend is worth more than all of the Internet.

See that’s your problem right there. You confuse $40 in parts and a weekend with experience. I have been designing speakers for professional applications for the better part of 2 decades. When you lack experience, you may be able to convince yourself with $40 in parts and a weekend that bypassing a capacitor that is ideal up to nearly a MHz provides some benefit other than just changing the total value. I don’t have such a luxury.

Pick a large respectable high end speaker manufacturer. Magico, B&W (high end), Wilson. Do they bypass their large capacitors with much smaller ones? No. Could they afford it? At those margins, of course, small capacitors are inexpensive. Why don’t they? It will have no benefit. Do you honestly believe these companies don’t know any better?

My comment is specifically about crossovers. I will leave power supplies to those that know better, and the same for capacitors passing audio signals in amplifiers and other electronics.

That’s your problem right there. Research without experience. $40 in parts and a weekend is worth more than all of the Internet.

I can see a stuffy sounding vintage cap with poor high frequency transparency being bypassed by one that does to create some layering (?).

But that could create some weird situations - imagine caps which image poorly with a very mono sound, being bypassed in the high freq with a high fidelity cap. So the high frequencies image 3d dimensionally on top of an old low fi midrange? Or is that effect the goal? It could be interesting....?? 

When you lack experience, you may be able to convince yourself with $40 in parts and a weekend that bypassing a capacitor that is ideal up to nearly a MHz provides some bene

When you lack an open mind you may be able to convince yourself your measurements and models are always adequate.

Takes an open mind and discerning ear to realize when one or the other has fallen short, and this topic is impossible to argue online.  That's why I make suggestions to audiogoners to experiment inexpensively and come to their own conclusions.  Or they can listen to you stroke your beard and tell us nothing is left to be learned.

@clustrocasual ,

If you means capacitors passing signals in electronics maybe there are some effects. In speakers though, you have to look at the combined effect of the capacitor and driver. If I bypass a 100uF (was mentioned above) electrolytic with a 1uF, there is no benefit because where the 1uF starts to provide any benefit, the driver has no output.