Some more test results
I was fooling around the other day, still messing with this SBLive card, and noticed that in CoolEdit Pro 2.0, I'm able to record at 16-bits, 96kHz. Yet in Sonar XL 2.0, the max it will let me do is 16/48. In any case, I know that recording in CoolEdit at 16/96 does make a difference, as I tested the noise floor with blank tracks at both 16/44 and 16/96 and it was slightly lower at 16/96. This led me to a barrage of various test setups this morning trying to isolate exactly what was causing the noise floor.
Here's the setup...
Equipment:
SBLive
Behringer UB1204Pro mixer
Hosa double mono 1/4" to single stereo 1/8" phono cable
Hosa double RCA to single stereo 1/8" phono cable
Signal chain:
Mixer -> cable -> SBLive Line-in
Warning: if you're not interested in alot of numbers, simply read the executive summary below and stop.
Executive Summary
------------------------
Sample screen shot of test 1a/1b showing noise floor drop when unplugging cable from line in of sound card:
http://www.eng.uwaterloo.ca/~pjhollow/run1-pic.jpg
-Hosa RCA to 1/8" cable raised noise floor by 4dB (compare test 2b to 2a)
-Mixer "control room out" combined with 1/4" to 1/8" Hosa cable had a noise floor 4dB lower than "tape out" with Hosa RCA to 1/8" cable (compare tests 1a/2a to 3a/4a)
-Recording at 16/96 as opposed to 16/44 lowered the noise floor by about 6.5dB (compare test 6b to 1b)
-Mixer is poorly isolated, adding 60Hz noise whether ON or OFF (notice that 60Hz noise disappears in 1b and 6b), and by plugging it in when powered off adds 11.6dB (see 4a and 4b)
-Hosa cables act as antennae, adding 60Hz signal even when not connected to mixer (see 2b and 3b)
-Noise floor on the SBLive, without any connections, is around -80dB (see 1b, 4b, 6b)
Now, since the mixer/cables are new to me (all within the last month), and therefore never having used anything but a Behringer mixer and Hosa cables (although I do have a Planet Waves XLR from my mic), I can't make any comparitive statements to say that Behringer or Hosa make noisy, poor quality components, although many of you will probably say that for me
. But I can say that, since these are the results that I got, its beginning to make sense that there are far more expensive mixers and cables available. The fact that an equivalently equipped Mackie is 3 times the price of the Behringer, and Planet Waves or Monster cable is 3-10 times the price, while maybe not justified, can at least be explained. I would like to think that the cables I use, in short enough lengths (most of mine are 15' or less), won't pick up 60Hz noise when not plugged into anything. I would also like to think that my mixer wouldn't add as much as 10-12 dB of noise floor when plugged in but not powered on.
Am I wrong? I realize that every single connection and component will add noise, thats a given. But are these sorts of numbers typical? I'm afraid about going out and buying an expensive replacement sound card for my Sound Blaster only to find out it doesn't make a lick of difference because the quality of my other components is the bottleneck.
Comments are welcome!
(Stop here if numbers make you sleepy)
Test runs (mixer is powered ON only in run 5):
1a. Mixer tape out -> RCA cable -> SBLive line in (16/44)
1b. (pulled out cable at "line in" of SBLive)
Note: testing for noise induced by cable and mixer combined
2a. Mixer tape out -> RCA to 1/8" cable -> SBLive line in (16/44)
2b. (pulled out cable at "tape out" of mixer)
Note: testing for noise induced only by mixer
3a. Mixer control room out -> 1/4" to 1/8" cable -> SBLive line in (16/44)
3b. (pulled out cable at "control room out" of mixer)
Note: testing for difference between "tape out" and "control room" outputs by comparing to results of Test 2
4a. Mixer control room out -> 1/4" to 1/8" cable -> SBLive line in (16/44)
4b. (pulled out power plug from mixer)
Note: testing for noise induced by mixer when plugged into wall (poor isolation)
5a. Mixer (powered ON) control room out -> 1/4" to 1/8" cable -> SBLive line in (16/44)
5b. (turned mixer power OFF)
Note: testing for difference in noise induced by mixer when powered ON compared to OFF
6a. Mixer tape out -> RCA cable -> SBLive line in (16/96)
6b. (pulled out cable at "line in" of SBLive)
Note: testing for difference between 96kHz sampling rate and 44kHz)
Results using Analysis/Statistics in CoolEdit:
-------------------------------------------------------
Run 1a:
Left Right
Min Sample Value: -83 -80
Max Sample Value: 76 70
Peak Amplitude: -51.44 dB -51.74 dB
Possibly Clipped: 0 0
DC Offset: -.015 -.015
Minimum RMS Power: -60.47 dB -60.82 dB
Maximum RMS Power: -59.26 dB -59.79 dB
Average RMS Power: -60.19 dB -60.59 dB
Total RMS Power: -60.18 dB -60.58 dB
Note: 60Hz noise on both channels
Run 1b:
Left Right
Min Sample Value: -32 -29
Max Sample Value: 21 16
Peak Amplitude: -59.05 dB -59.8 dB
Possibly Clipped: 0 0
DC Offset: -.014 -.014
Minimum RMS Power: -76 dB -78.03 dB
Maximum RMS Power: -73.94 dB -75.48 dB
Average RMS Power: -75.46 dB -77.34 dB
Total RMS Power: -75.45 dB -77.32 dB
Note: white noise visible only
Run 2a:
Left Right
Min Sample Value: -85 -83
Max Sample Value: 74 67
Peak Amplitude: -51.25 dB -51.44 dB
Possibly Clipped: 0 0
DC Offset: -.015 -.015
Minimum RMS Power: -60.52 dB -60.91 dB
Maximum RMS Power: -59.8 dB -60.26 dB
Average RMS Power: -60.22 dB -60.67 dB
Total RMS Power: -60.22 dB -60.68 dB
Note: 60Hz noise on both channels
Run 2b:
Left Right
Min Sample Value: -29 -38
Max Sample Value: 36 24
Peak Amplitude: -58.15 dB -57.67 dB
Possibly Clipped: 0 0
DC Offset: -.014 -.015
Minimum RMS Power: -76.25 dB -70.21 dB
Maximum RMS Power: -74.48 dB -69.31 dB
Average RMS Power: -75.53 dB -69.85 dB
Total RMS Power: -75.52 dB -69.84 dB
Note: 60Hz noise on right channel, white noise on left
Run 3a:
Left Right
Min Sample Value: -70 -60
Max Sample Value: 55 46
Peak Amplitude: -52.84 dB -54.08 dB
Possibly Clipped: 0 0
DC Offset: -.014 -.014
Minimum RMS Power: -63.75 dB -65.72 dB
Maximum RMS Power: -62.79 dB -64.64 dB
Average RMS Power: -63.45 dB -65.36 dB
Total RMS Power: -63.43 dB -65.34 dB
Note: 60Hz noise on both channels
Run 3b:
Left Right
Min Sample Value: -33 -29
Max Sample Value: 23 18
Peak Amplitude: -58.79 dB -59.78 dB
Possibly Clipped: 0 0
DC Offset: -.014 -.014
Minimum RMS Power: -74.75 dB -76.95 dB
Maximum RMS Power: -72 dB -74.88 dB
Average RMS Power: -73.75 dB -76.2 dB
Total RMS Power: -73.75 dB -76.2 dB
Note: 60Hz noise and white noise on both channels
Run 4a:
Left Right
Min Sample Value: -73 -57
Max Sample Value: 54 43
Peak Amplitude: -52.5 dB -54.5 dB
Possibly Clipped: 0 0
DC Offset: -.014 -.014
Minimum RMS Power: -64.24 dB -66.18 dB
Maximum RMS Power: -62.94 dB -64.89 dB
Average RMS Power: -63.68 dB -65.59 dB
Total RMS Power: -63.67 dB -65.58 dB
Note: 60Hz noise on both channels
Run 4b:
Left Right
Min Sample Value: -27 -25
Max Sample Value: 17 14
Peak Amplitude: -60.33 dB -60.9 dB
Possibly Clipped: 0 0
DC Offset: -.014 -.014
Minimum RMS Power: -75.79 dB -77.81 dB
Maximum RMS Power: -73.98 dB -75.85 dB
Average RMS Power: -75.3 dB -77.24 dB
Total RMS Power: -75.3 dB -77.24 dB
Note: 60Hz noise and white noise on both channels
Run 5a:
Left Right
Min Sample Value: -125 -102
Max Sample Value: 111 94
Peak Amplitude: -48.04 dB -49.73 dB
Possibly Clipped: 0 0
DC Offset: -.015 -.015
Minimum RMS Power: -56.6 dB -58.56 dB
Maximum RMS Power: -56.16 dB -58.04 dB
Average RMS Power: -56.39 dB -58.31 dB
Total RMS Power: -56.39 dB -58.31 dB
Note: 60Hz noise on both channels
Run 5b:
Left Right
Min Sample Value: -67 -52
Max Sample Value: 51 40
Peak Amplitude: -53.22 dB -55.25 dB
Possibly Clipped: 0 0
DC Offset: -.014 -.014
Minimum RMS Power: -64.1 dB -66.06 dB
Maximum RMS Power: -63.66 dB -65.53 dB
Average RMS Power: -63.85 dB -65.76 dB
Total RMS Power: -63.85 dB -65.75 dB
Note: 60Hz noise on both channels
Run 6a:
Left Right
Min Sample Value: -66 -67
Max Sample Value: 61 60
Peak Amplitude: -53.68 dB -53.55 dB
Possibly Clipped: 0 0
DC Offset: -.006 -.006
Minimum RMS Power: -61.84 dB -62.17 dB
Maximum RMS Power: -60.69 dB -61.11 dB
Average RMS Power: -61.35 dB -61.66 dB
Total RMS Power: -61.35 dB -61.66 dB
Note: 60Hz noise on both channels
Run 6b:
Left Right
Min Sample Value: -16 -15
Max Sample Value: 7 5
Peak Amplitude: -65.26 dB -65.76 dB
Possibly Clipped: 0 0
DC Offset: -.006 -.006
Minimum RMS Power: -84.24 dB -85.38 dB
Maximum RMS Power: -77.86 dB -78.92 dB
Average RMS Power: -82.47 dB -83.67 dB
Total RMS Power: -82.24 dB -83.44 dB
Note: white noise visible only