> If a single ferrite bead is used it is not usually necessary to also have the separate beads as shown in Figure 8
Yup, it's probably cheaper to put a few small ferrite beads on the board than to put a big one on the cable.
Being a differential signal, I never understood why USB cables would _need_ them, but seeing it on a premium cable inspires the feeling that you bought a better product? I also think reduced 900MHz interference from cordless phones (remember those?) made homes quiet enough that the bead became more of a value-add for most applications. Just guessing...
Anecdotal, but back when I was playing with spark gaps, my housemate's USB game controller would disconnect from the host every time I shot a spark. It would refuse to reconnect until they unplugged and replugged the cable back in. They switched to a better cable (with a bead), and it stopped happening.
I don't have any noise or scratching when I work on my Lenovo. I don't have any noise or scratching when I work on my desktop without having the connection from Samsung monitor to speakers connected. However, when I have everything connected I get a slight noise and scratching sound which gets more pronounced when I start to load my GPU more, for instance when running a game.
At first I thought this was a ground loop, but the noise isn't constant, and isn't directly coming from my computer or sound card but indirectly via the Samsung monitor when I start to game and my computer draws more power.
Interesting, I have a similar issue when I work with CAD models. If I rotate a particular model in a certain way, I can almost hear a 'scratching' noise coming from my GPU as the frames draw. If the GPU is already loaded, it seems like the noise escapes to my powered sound monitors? I think it is some sort of 01010101 color rowhammering the memory at 144Hz...
> If a single ferrite bead is used it is not usually necessary to also have the separate beads as shown in Figure 8
Yup, it's probably cheaper to put a few small ferrite beads on the board than to put a big one on the cable.
Being a differential signal, I never understood why USB cables would _need_ them, but seeing it on a premium cable inspires the feeling that you bought a better product? I also think reduced 900MHz interference from cordless phones (remember those?) made homes quiet enough that the bead became more of a value-add for most applications. Just guessing...
I have my setup as follows:
I don't have any noise or scratching when I work on my Lenovo. I don't have any noise or scratching when I work on my desktop without having the connection from Samsung monitor to speakers connected. However, when I have everything connected I get a slight noise and scratching sound which gets more pronounced when I start to load my GPU more, for instance when running a game.At first I thought this was a ground loop, but the noise isn't constant, and isn't directly coming from my computer or sound card but indirectly via the Samsung monitor when I start to game and my computer draws more power.