|
Computer Audio Asylum Music servers and other computer based digital audio technologies. |
|
|
|
Computer Audio Asylum Music servers and other computer based digital audio technologies. |
|
In Reply to: 28KHz anomaly, different album downloads. No 28KHz blip digitizing my own L.P. posted by AbeCollins on July 12, 2014 at 20:40:02:
Abe as an example here is about a 20 second peak hold capture of my Asus Essence STX line input hooked up to my turntable and through my powered down phono preamps. I'm using Oscillometer free version to do the capture. I leave the preamps turned off during my noise hunts so as not to obscure the problems with preamp electronic noise.You can see my own setups noise imperfections quite clearly as I seem to have a similar spike at around 25kHz and what is likely to be it's second harmonic at around 50kHz. I'm pretty sure this is caused by my PC power supply but haven't had time to really figure it out. Since this gain is about what I'd use to capture and my particular noise problem is pretty small I might not worry about it so much considering the spike peak itself is somewhere around -115dB.
Edit: By the way in case you can't see the text this is with 2^14 points averaging and Blackman Harris window and with all weighting filtering shut off.
Second edit: I found it interesting that at 1:15 AM this morning my measurements with what I bellieve to be the same setting look quite different . Please see below. Perhaps theere is a power quality difference that explains it. It leads me to want to try some line filters. I don't believe I've noticed a drastic change like this before. Again only difference seems to be time. Notice how much lower than the apparent noise floor is with respect to the picture above. The noise spikes seem to be more or less the same but some new ones have been uncovered. such as at 1kHz which was buried in the noise before. Odd. Definitely going to need to dig into this effect deeper.
Edits: 07/12/14 07/12/14 07/12/14 07/14/14
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- RE: 28KHz anomaly, different album downloads. No 28KHz blip digitizing my own L.P. - Ugly 22:06:44 07/12/14 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
