maybe it's because of the dj compensating on the low frequencies (bass). i always do this, having the tune coming in with no low freq, then slowly increasing the low freqs on the incoming tune while decreasing on the other.

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sempre contra a corrente do jogo

No it’s not intentional at all. What happens is that through the wonders of physics, the kicks cancel each other out. Roughly speaking, if you have a two wave forms and the peak of one matches the trough of the other they cancel one another. This is why some of the beats seem to disappear. The reason why they’ll suddenly come back is because the wave forms don’t perfectly match so you don’t quite get a peak against a trough. Despite the fact that it sounds horrible, it’s surprisingly hard to duplicate intentionally when DJ’ing, it just kinda happens now and then.

Yeah, usually if I hear the beat getting a slight bit off and I compensate, the beats get closer together, and right when they match they cancel, until its imperceptively off one way or the other.

I consider that to be a pretty useful tool in mixing even though I mix 4/4 tracks very rarely. Even on breakbeat songs it's still there, but obviously harder to spot. It's great hearing that canceled out sound in your headphones and you know you can concentrate on eq's rather than platter adjustments.

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"I feel like Elton John in this muthafucka." -Ol' Dirty Bastard, to the audience of his first show since being released from prison