Frequency response of the Brimar circuit. The vertical scale goes from 10 to 50 dB in steps of 5 dB. The frequency is from 10 cycles to 100 kc. In this one the thin part of the hourglass is stretched and a little bent. The third, tone flat line, starts out at 33 dB. It starts to fall at 300 cycles and by 4 kc it is down to 30 dB. It departs from the 30 dB line at 30 kc and is at 28 dB at 100 kc. Values for the lines will be given in the following order. Full boost, half boost, flat, half cut, and full cut. At 50 cycles the values are, 48 dB, 40 dB, 33 dB, 27 dB, and 17 dB. The two full boost and cut lines converge at the tone flat line at 600 cycles and the two half boost and cut lines converge at the tone flat line at 500 cycles. At about 1100 cycles all boost and cut lines diverge. Between these points they actually cross over, boost becomes a small cut and cut becomes a small boost. This is no more than 1 dB which is symmetrical about the tone flat line. At 10 kc the values are 45 dB, 37.5 dB, 30 dB, 22 dB, and 15 dB. Curve 5 does not shelve, but falls off the graph at 15 kc. Except for the 3 dB drop, this family of curves is very symmetrical both horizontally and vertically. End verbal description.
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