Our microphones have a very flat and extended low frequency response. In some cases, particularly where the hall has an emphasized bass frequency response ("hall boom"), you are recording near a room boundary, the air conditioning system rumbles, traffic noise filters in from outside, or the room's sound system is equalized strongly toward the bass, it is desirable to roll off the low bass frequency response.

To address this we offer two battery boxes with bass roll-off filters. One has a fixed-response bass roll-off filter. The other offers a switchable filter.

The switchable box has a very high quality, locking mini-toggle switch mounted on the outside of the box under the mini-XLR jack. It is switched between flat response and the bass filter response very easily, but the locking toggle lever must be pulled outward to switch filter positions, and so can't be accidentally switched.

When used with recorders like the Sony PCM-M1 and TCD-D8, the bass roll-off filter rolls off frequencies below 120 Hertz at 6 dB/octave.

In general, we don't recommend that you have only the bass roll-off filter unless you regularly note too much bass in your recordings. If you want to be able to select between a flat and a rolled-off response, we recommend having the switchable box, or two fixed-response battery boxes on hand: one that's flat and one that has the roll-off filter.

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