throw those 2 terms at google and within seconds you'll find yourself in the middle of one of the many wars on the intertoobz. on one side you'll find people who claim that live's summing bus sounds crap compared to for instance apple logic's. on the other side are people who claim that this is simply not true. or that, if it is true, it doesn't matter. for those who don't know what this is all about: summing happens when 2 or more signals are mixed together. the master channel of your daw is the most obvious example. if your summing bus is bad, every track you do suffers from it.

i'm serious about mixing and want the best possible sound. within my budget of course. currently i mix in live, but i also own logic and if logic's summing bus indeed sounds better, i'd switch immediately. so yesterday i ran a little test.

i exported every channel of one of my tracks to a separate audio file, imported all those audio files into both live and logic and bounced both to a stereo mix. listening to the bounces didn't reveal any differences. but i have far from the best ears in the industry, so i used the infamous null test to objectively compare the outputs of live and logic. i loaded both bounces into wavelab, inverted the phase on the logic bounce and mixed them together. the theory is that the signal that both bounces have in common will cancel out, be 'nulled'. the difference doesn't get nulled, and that's what you're left with.

this is a generally accepted way to see whether 2 signals are the same or not. if you find difference though, that doesn't mean one signal is worse. it just means it's different. but if you find no difference, any claim that one of the signals is better or worse has no factual basis.

so i mixed the live bounce with the phase-inverted logic bounce and i heard... absolutely nothing. human hearing has it's limits, so i grabbed the excellent free voxengo span spectrum analyzer. nothing. not even with the amplitude scale going down to -130db. luckily live has a built-in spectrum analyzer that can go even further. and that showed the following with the amplitude going down to -160db:

the test results (click to enlarge)

i ran the test again with a different track and got similar results.

so there is a difference. let's assume it's not due to fft metering limitations, and that it is really there. fine. but is it significant? i'm well aware that seemingly inaudible subtleties can influence audio quality. but i don't think this subtle difference is proportionate to the certainty with which some claim live's summing bus is made of fail. we're talking about a maximum value of -140db here.

to give you an idea: the softest possible sound on a cd is at -96db. due to how the decibel scale works, -140db is about 10000 times softer. and it is -140db at 50hz, where the human ear is at its most insensitive. as robert henke said in a lecture about live's sound quality, this is purely academic.

so are those who claim live's summing bus sucks talking out of their ass? nope. i have no doubt people hear a difference between live and logic. but the reason is almost certainly not the summing bus. so what is it?

the placebo effect is always a good one. you'll hear what you think you should hear. funny thing about the placebo effect is that more expensive placebo works better. maybe doubling the price of apple logic will make it sound even better.

then there's peer pressure. if you follow some of the discussions, you'll quickly discover that among real professionals™ it's quite common to consider live a toy, not suited for real professional work™. if you want to be one of the boys, you'd better hear that live indeed sounds bad. and have some revealing personal experience to back it up. and if you don't have that, any hearsay will do.

all irony aside, i do think there is also a real difference in sound between live and logic. i worked in logic for about 7 years and have been using live for 4 years now. due to how both programs are organized, it's clear to me that you'll make music differently in live. with sonic consequences.

to prevent this post from getting too long, i'll post a more detailed explanation of that in a few days.

update: the follow-up.