I'm confused. Isn't 8030c rated for 5dbA at 1m yet there are quite a few people complaining about the noise? If it's at all comparable, 15dba sounds like a total nighmare.
If 5dbA becomes zero dBa at 1.8M as calculated by
@Curvature (thanks for that!), then generally speaking you'll hear a low-level sound when listening nearfield but not farfield. Given that the 8030c and 8351b both are rated for 5dBA at 1M, I would presume that most 8030c users can hear the self-hiss while most (or at least many) 8351b users can't, since the former is more often used nearfield and the latter is often used farfield. Also, 5dBA is detectable but pretty quiet, so depending on the level and frequency spectrum of one's ambient room noise, some folks might not hear 5dBa at all if they're sitting 1M away on a decent-sized desk, or if the 8030 tweeters are below ear level (as is often the case with a desktop computer-monitor setup). And if they do hear it, 5dBA simply is not bothersome to some people (though it would drive me crazy) - so they hear it but don't mind it, or because it's not bothersome they technically hear it but they don't notice it for the most part; their brain filters it out or doesn't pay much attention to it.
As for the 15dBA of those subs, as I've commented above, yes, I think that's unacceptable and I'd never get them myself. If the 1M self-noise dBA spec is such that the noise at the intended listening position is higher than 0dBA, it's a non-starter for me.
I recently got Genelec 8351b's, and I'm really loving them. But I'm not thrilled with their low 5dBA noise level, low as that sounds. But in that case it's more a matter of principle and my own OCD tendencies, because I admit that in order to hear their self-noise, I have to get up out of my listening seat, walk to within about a meter of one of them and bend down a little so my head is closer to the vertical tweeter axis. And the spectrum of the noise sounds, for lack of a more precise term, "soft" and not grating.
In fact, I'd love to hear from our more knowledgable members about exactly what causes this kind of self-noise. I would think that even if they're using Class D plate amps that don't perform as well as Hypex and similar plate amps, that still would not explain the audible tweeter noise. I would assume it's about internal gain-staging, yes?
In general, I think self-noise is the most underemphasized and overlooked problem with all audio gear, whether it's tweeter hiss from actives, tweeter hiss in passives fro the amp and/or other downstream components, hiss and hum from ground loops, mechanical transformer hum from toroidals, or coil whine from internal PSUs (I'm looking at you, MiniDSP). The levels of noise and distortion measured in most of the equipment Amir tests are orders of magnitude lower and far less likely to intrude upon our listening experience. And aside from reporting on self-hiss he might hear from actives, there's really Amir can do to test for this stuff, since it's all about multiple components connected together, individual room noice and listening distance, and individual sensitivity level to these phenomena.
