Where exactly is it? So much conflicting information from a google search. Here it's a circle radiating from just above the middle Here it's a horizontal oval radiating from the top third of the racket Here it's a vertical oval radiating from dead center This video shows it can be found by hitting the racket with the palm to find the most repulsive area. The racket he demonstrates with shows it to be just above the center, at about the 10th string from the top. This seems true for both my rackets by his logic. That feels a little too low though. I brought this up with my coach though and he insisted it's higher up, around about the 4th, 5th and 6th string from the top. In this video from Lee Jae Bok he implicitly indicates it as more or less center. The video isn't about sweet spot so perhaps he wasn't focusing on where he touches the shuttle to the racket.
It varies from racket to racket as well as the stringing method used. Best way to find out is to hit with it, usually it's either the center or slightly above it like you said
To a limited degree, it might depend on other things than the head shape, but I think that's neglectable. Note that I am referring to where the cork hits the strings, not the feathers. The third link shows an oval racket and I'd roughly agree with that, maybe I would have put it a bit higher. Isometric rackets are a bit wider at the top, so it will move up a bit. That's what the first link shows. The second link cannot really refer to where the cork hits the strings, because if it was there, the feathers would be hit by the frame. However, it might refer to where the strings are likely to break when you hit the sweet spot, because the feathers will move the strings a lot and put additional stress on it - and they'll hit the strings in the area, when the cork hits the strings like shown in the first links. The typical compact frame shape is more narrow in the lower half compared to the isometric head shape. That means, it will feel like the sweet spot moves up a bit more, but it's probably just more narrow at the bottom, while the top half is comparable to that of an isometric racket. That's my thoughts on it. Does it matter? Not really, you should be able to feel it you hit the sweet spot or not.
For me at least it helps to visualise where exactly I should be aiming for. I'm going through a phase where I'm doubting a lot of things in my technique. Sure, I'm hitting the the sweet spot but I'm not always sure it's the SWEETEST spot lol.
If it helps, great, that's why I wrote it down. Overthinking doesn't help when you're trying to get your body to perform, though. Think about it while not on court, focus on the shuttle when on court.
