Hmm but then why would the level of noise change between the two different cables...
The cables im sure will transmit nearly identical copies of the signal, its just how much additional noise they pick up... unless perhaps the keyboard itself produces -63 decibals of noise and with an unbalanced cable it picks up an additional 3db...
hmm how can i find out for sure???
I suppose I could compare listening to headphones from the keyboards outputs versus the computer, what if I went throughmy SPDIF output? would that contain any self noise?
I just listened with headphones at different spots. First i listened with headphones via the keyboards output i am using, dead silent, then I listened via the deltas outputs, and the only time i heard noise was from output 1 or 2 when the preamp was plugged into 1/3 or 2/4 respectively...
otherwise there was no noise from the delta.
then i tested from my HP4 headphone amp and it made noise regardless, the same kind my monitors were making. and when i plugged the keyboard into the delta, the noise rose juuuuust slightly for each output, mabye like a max of 1 db total, so slight that i had to check plug and unplug multiple times to confirm that the noise was increasing.
so so far the only thing that adds significant noise was my preamp when plugged into the delta, otherwise the delta was silent by itself and the keyboard was silent by itself (when i plugged headphones into their outputs)
I then unplugged the monitors from the HP4 and plugged them directly into the Delta to see if the monitors would cease making noise, but they made the same nosie regardless of what they were plugged into (and even if they werent plugged into anything they still made this noise that i recorded with my condensor mic.
The clicking you hear at the end is my spacebar to give you a sense of relative volume, the mic was 1 inch away from the tweeter.
Monitor Noise Sound Clip
then I turned off the monitors completely and in adobe audition the volume was now hovering at -66dB with my balanced cables, i unplugged the HP4 from everything and pulled the wall wart out of the surge protector and that didnt help at all... so all i have now is my computer - delta - keyboard
i even unplugged my mouse and keyboard to see if they were causing noise and they were not, but interestingly, i found that when I UNPLUGGed the USB cable that connected my keyboard and computer, the level of the noise went up to -63dB.
I think the USB cable is grounding the keyboard or SOMEthing, because it accounts for a -3dB change in noise volume. unplugging it causes the noise volume to increase.
i then changed the input ports on the delta and the volume stayed the same.
judging by the monitors ability to continue providing noise even when they werent plugged into anything makes me think that their noise was different than that of the noise i am seeing in audition. so that will be a seperate issue.
anyways, the noise is genereated between the keyboard, cables, delta, and computer.
when I unplug the keyboard, the noise dissapears from the decible meter in my software, so I suppose that rules out that the computer is making noise in the program...
so whats left for me to check????
next thing i am going to do is send the signal via digital SPDIF and see if there is any noise, because I am pretty sure that it shouldnt pick up any interference noise, and it should rule out the delta being the problem
I am still confused as to why the USB cable accounts for a 3dB drop in volume of noise when it is plugged in. sounds like it is somehow helping to ground maybe..
the volume on the keyboard also had no effect on the noise level.
-66dB is the lowest I have got it so far.
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