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Comparing outputs

post #1 of 5
4/22/10 at 3:54pm
Thread Starter 
Hi all

I wondered how easy it would be to visually compare the output waveform of any given song in lossless via the line out of my ipod classic/Arcam irdock against a cd version of the same song via the output from my Rotel cd player?

What would I need to do this? I have access to an oscilloscope at work but not sure if something pc based would be better?

Its more a curiosity thing more than anything else, I have no doubts at all that the Rotel is in another galaxy in terms of quality and shows more of the potential in my HD650's, but I would like to be able to visually inspect the differences.

Any ideas?
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post #2 of 5
4/23/10 at 8:32am
Visual inspection of the waveform won't give anyhting interesting. The differences are extremely small, and you'd have to zoom in until the waveform is hundreds of times bigger than your screen.

Using the freeware RMAA, on the other hand, can give you interesting graphs and numbers. If you zoom in the central peak of the spectral view of the harmonic distortion, you should be able to see a difference between your sources. With the CD player, the bottom of the peak should be cleaner.
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post #3 of 5
4/23/10 at 9:47am
If you have a decent line-in you could do an RMAA measurement. You just need to burn the test track on a CD and record the CD player's output, RMAA will then analyze the file and give you nice results to look at. Repeat the same with the ipod (no CD needed here, obviously).

If the ipod cannot play WAV an option would be to convert the test track to mp3 (320 kbit/s constant bit rate) and use that as test track for both devices.

Should do for a comparison.
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post #4 of 5
4/23/10 at 3:44pm
Thread Starter 
Thanks I hadn't heard of RMAA and it looks ideal.

I will hopefully be testing the original track on a cd vs the ripped lossless file on the ipod/dock to see what differences there are in the waveforms.
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post #5 of 5
4/23/10 at 5:54pm
RMAA uses a test track that will be generated as reference. Based on this reference it can calculate harmonic or IM distortion, etc.
For ideal recording results you might need to use a recording software that supports ASIO (like Audition) to bypass the Windows Mixer, good luck.

As for recording your track I agree with Pio2001, a wave editor won't show you much.
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