Low Cut Filter

Low bass is good. What's lower than that isn't. In the octaves below 75Hz lurk all sorts of low-frequency grunge. Caused by stage or room rumble, wind noise and mic thumps, it can muddy your sound on stage or in the studio, drain PA amplifier power, or worse, actually cause speaker damage.

1. Mackie 18dB/oct. Low Cut filter.

2. Shallow Low Cut filters.

3. Theirs vs. Ours.

mixers inserts a 75Hz low cut (high-pass) filter into the channel's signal path (fig. 1). Why did we pick 75Hz? Well, the very finest microphones have a switch that lets you roll off their response below 75Hz, the very lowest fundamental frequency of the male voice. When you use this filter you notice that it doesn't have any audible effect on the human voice... but it cuts off mic thumps and room rumble. Our Low Cut filter emulates this bandwidth.

Beware of imitations.

Don't confuse our sharp 18dB/octave filter with the shallower 6 or 12dB/octave "Low Cut" circuits found on some other compact mixers (fig. 2). Not only do they sacrifice audible bass, they don't effectively cut subsonic rumble either. Figure 3 shows the difference between Theirs and Ours.
Mackie's true Low Cut Filter is handy for minimizing traffic noise, popping, and other unwanted low frequency sounds. In fact we suggest you leave it permanently switched in on all of your mic channels. But don't go away. There's more.

4. Mackie Low EQ boost with Low Cut filter.

Put your Lo EQ back to work.

Without our Low Cut Filter, using any amount of Lo EQ boost on mic channels is impossible – stage rumble and mic thumps become destructively exaggerated. Kick in the Low Cut Filter and the audible bass range is boosted, but unwanted frequencies below 75Hz are chopped off. Now you can use Lo EQ without risk – and use midrange for, well... midrange!

Sweepable Low Cut Filter (SR408 only)

Our large-format