From something I posted on ALDJ:
Ok, here goes. I tested Live 7.1 versus Logic 8.0. As we are talking about overall sound quality and not timing issues (and not saying there are any), I ran the test using three audio loops all at the same tempo of 120 BPM. I also tried this test using projects that contained up to 10 audio loops, but the results were identical, so I'm going to discuss the 3 loops test in order to save my bandwidth, as I'm making all files available for DL:
http://tarekith.com/assets/Live7VsLogic8.zip
These are just random audio loops from my collection, I tried to pick loops that not only sounded decent together, but also demonstrated a lot of dynamics and frequency spread to make audible comparisons easier. All three loops are 24bit/44.1kHz wav files, and exactly 4 bars long at 120BPM. I placed each loop on it's own stereo audio track in both Live and Logic, and set the track faders to -6.0dBFS for all tracks in both apps. The following additional settings were used:
- Both apps latency set to 512 samples.
- Live 7 uses the equivalent of a 3dB pan law, so Logic was set to -3dB Compensated.
- Both projects set to 24bit/44.1kHz default.
- Files in Live were not warped, and did not have Fade on.
Here is the Live Project screenshot:
Here is the Logic Project screenshot:
At this point playback of both projects sounded identical to my ears, at numerous volume tests, using both Mackie HR824 speakers, and my Shure E3c and Sony MDR v700DJ headphones. So I next rendered (Live) and bounced (Logic) the projects down, in both cases choosing the output format to be 24bit/44.1kHz wav files, non-normalized, with no dither. These were then loaded into Logic 8 on seperate tracks, as you can see they look identical:
Listening comparison once again made the two files sound 100% identical, having my wife randomly solo each track while listening through my Sony headphones with my back turned, I was unable to tell any difference in audio quality no matter which was solo'd.
HOWEVER...
As I started to get more scientific in my comparisons, I discovered that there WERE differences between the files. I flipped the phase of the Logic waveform and played the two files back simultaneously. This resulted in audible (err... or not) silence, I could not hear anything as the two files were cancelling. BUT, looking at the master meter in Logic, I could see that some signal was playing back, albeit VERY quietly. As you can see in the screen shot below, using the Inspector XL spectrum analyzer, there are some very low level differences in the files:
It's important to look at the dB scale in the plug in before jumping to conclusions. In the main audible range of human hearing, the difference between the two signals is almost at -90dB, which is only 6dB above the absolute noise floor of your standard CD quality (i.e. 16bit) wav file. This is also below the dither level that would be in the file, had we applied any (and dither is almost always applied to the files you will hear in the real world). So, while there IS a difference between the renders of Live 7 and Logic 8 now, that difference is:
- For all intents inaudible, being well below the average music signal in todays music.
- Likely obscured by dither, had we applied any.
- Primarily in the low end of the audio spectrum, well below 250Hz, where the ear is least sensitive.
Anyway, the main conclusion I would draw based on these tests, is that there is no audible difference in sound quality between Live 7 and Logic 8, though they are not producing bit for bit identical copies. So, have fun arguing about the test I ran, I'm off to go pick up some friend at the airport, then snowboarding for a few days
