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Is there a tutorial for using RMAA?

post #1 of 8
Thread Starter 
I tried Google and I couldn't find a proper tutorial on how I can use RMAA to analyse my computer audio. I have a X-Fi Titanium HD card, which I read has a pretty good ADC, and a E-MU Tracker Pre USB Interface, and I would like to know basic things, like the Noise of both units.

I just read about Ground Looping issues with USB, and I have a ODAC on the way, so I wanted to be able to test if I'm being affected by any of these issues or not.

How do I make the connections to use RMAA? Is it just a cable from Line Out of one interface into the Line In of the other?

Please let me know!

Thanks
post #2 of 8
Quote:
Originally Posted by Alec246 View Post

I just read about Ground Looping issues with USB, and I have a ODAC on the way, so I wanted to be able to test if I'm being affected by any of these issues or not.

 

If you test the ODAC with a simple loopback to a sound card in the same machine, your measurements will likely be affected by grounding issues, even if the ODAC alone would work fine in its intended way of being used. See this thread for some examples on how the measured performance can be degraded; a common effect is significantly increased noise level.

 

Quote:

Originally Posted by Alec246 View Post

How do I make the connections to use RMAA? Is it just a cable from Line Out of one interface into the Line In of the other?

 

Yes. Of course, do not forget to check the mixer settings for playback and recording (I have seen people publishing RMAA results with obvious problems like clipping).

post #3 of 8
Thread Starter 
But my question is, will the Loopback issue affect the sound output of the ODAC when I'm listening to music? Or only when I measure it with another Sound Card?

I just did some testing with my E-MU interface, around 80dbA of Noise. The X-Fi Titanium HD was much better, I think 110 or better.
post #4 of 8
Thread Starter 
What I lack is proper Cable to do the testing. I have some really bad RCA cables and good quality 1/4 ones, but that's it.
post #5 of 8
Quote:
Originally Posted by Alec246 View Post

But my question is, will the Loopback issue affect the sound output of the ODAC when I'm listening to music?

 

When you are listening to music, there is no loopback, and with a non-grounded amplifier, like the O2, no ground loop.

 

Quote:
Originally Posted by Alec246 View Post

I just did some testing with my E-MU interface, around 80dbA of Noise. The X-Fi Titanium HD was much better, I think 110 or better.

 

Do you mean testing the ODAC with the E-Mu and the X-Fi ? 110 dBA is about right for the ODAC. Or is it a simple loopback of the Titanium HD itself ? From the lack of cables, I would guess the latter. 80 dB looks wrong for anything other than onboard audio.


Edited by stv014 - 9/3/12 at 10:27am
post #6 of 8
Thread Starter 
I don't understand because it said dBA, not dB. Is there a difference?

Yes, I did the testing of both using a Loopback on the same device. What I should do is use the Titanium HD Input, which I read has a really good quality ADC, to test the other sound interface, but since the Input is RCA I need cable adapters for that.
post #7 of 8

The "A" in dBA means A-weighting, the application of a filter to the noise that simulates (approximately) the ear's lower sensitivity to low and high frequency sounds, so that the overall level corresponds more closely to the perceived loudness of the noise. Typically, if the noise has a close to white spectrum, A-weighting reduces the level by a few dB, but if there is a significant amount of low frequency noise (e.g. AC hum), then the difference is greater.

post #8 of 8
Thread Starter 
I will get proper cables before I try using RMAA again, and then I will copy here the results!

Thanks for helping me so far!
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