So, I just did this mix the other day on my usual studio mixing gear (CMX-3000 into DJM-3000 into Steinberg's WaveLab on my stand-alone PC). Decent enough mix EXCEPT while transitioning from one house tune to the other, I blended the mix for like 3 minutes with very gradual EQing on the lows (and some on the highs and mids).

But when I played back the mix through my bigger system, I could tell that the bass kick on one song was cancelling the other one out while both low EQs were at about 9 o'clock (i.e. half way through the process of gradually EQing the mix).

So, my question is this: Does any one know of any mixer (or other hardware or software device) that can invert the phase on one track ON THE FLY (as in while playing the song and not in advance or after the fact)? In my 17+ years of DJing, I've only come across a handful of songs that when mixed together with no EQ filtering on either channel, the sum of both bass kicks DOES NOT add up to increase the total db level (like when you mix 2 identical songs) but instead, cancels the other out. The result is made worse if the mixing is spot on, thus an extremely effective phase cancellation incident on said frequency.

Theoretically, I know this could be solved by inverting the polarities of the in-put signal of the channel in question (not the left and the right RCAs but the actual (+) & (-) terminals on each RCA). But I'm not sure I want to be switching that stuff up my self on my decks or my mixer. Any shared wisdom greatly appreciated!

This message has been edited. Last edited by: EricVISA,

I can't think of any DJ mixers which can do this, only larger or studio-grade consoles (usually it's for microphone / instrument polarity).

I know it sucks when you find a mix which does that... you could go as far as reversing it in your program (Soundforge has a function to do it easily) and re-burn it.

Actually, that's an excellent idea. I just ripped the entire song and opened the waveform on WaveLab. Then I selected the whole song and inverted the phase, saved it and burnt the track on to another CD. Perfecto! Thanx for the idea. Will probably do that for the other handful of songs...

I havent run into phase cancellation very often personally but I have heard it happen many times.

It's an interesting yet frustrating phenomenon.

In certain styles of music there's a tendancy to use the same type of kick drum, even the exact same kick drum sample, in numerous records... I've hit this problem quite frequently. I usually spot it during the mix and there's two options, either kill the bass on one of the tracks so that there's a single kick carrying both, or push them apart very slightly. Either way your 3-minute crossfade plan is history, sweep it over asap and move on.

It does strike me that times like this are when it'd great to have some FX on hand... Kick drum gone awol? Doesn't matter, slap the phaser on!

I have heard on mixes from big stars djs (mainly house djs) that they don't mix in exact beat or phase, one of the songs is a little bit delayed. So on this way you avoid cancellation while playing alive.