When I set the level of the reciever to read 75db at listening position using the RS meter I get about 65db noise ( static and hissing). The sound card is SB Live 24. When I unhook the sound card from the reciever the noise goes away. Tommy D
Same thing here. If I run off the power adapter there is tons of noise. I use pink noise more often when using the adapter because it mask the noise and I can adjust the subwoofers/mic in real-time. My laptop runs off alot of power also. If I don't use the adapter it does not run my graphics card the best (I have read) but the noise does go away with the battery. I toasted a universal car adapter with my laptop that I was told would work by the store. They replaced it with another one. For very complex measurments I don't always have the luxury of noise free testing, unless I take a break while the battery charges.
I didn't use the calculate SPL routine on my last post. :whistling: That is not what I wanted to get at though. Since we have rewired the electical in the HT I now have a hum from the subwoofers when using my laptop battery but not with the AC power adapter. It is now complete silence using the adapter. A 60Hz and the fundamental 120Hz show up in my measurements most of the time still, even though I have checked the ground plugs and they are perfectly fine. Wierd huh?
I had troubles posting the graphs on the lap top. The attachment section doesn't show even after signing out and logging back on. Any ideas?
OK, I got everything set up and running. The first graph is the subwoofers responce. The second is with the mains in the mix. Don't know what to think of the dip at 63hz. The xo is set at 80hz in the receiver and xo set max on the sub. Tom