Frequency response of the RCA Tube Manual Circuit. This graph has its vertical scale marked off in dB from minus 20 to plus 30 with marks every 5 dB. The frequency goes from 10 cycles to 100 kc as in previous graphs. The tone flat line, number 3, is at plus 10 dB and runs along that line until it starts to roll-off at the high end, to be described later. Lines 1 and 5 start out at plus 28 dB and minus 20 respectively and converge at 10 dB at about 550 cycles. They spread apart again and are at 25 and minus 7.5 at 10 kc. Curves 2 and 4 start out at 19 and 2 dB and converge to the 10 dB line at about 150 cycles. They run in a tangle close to 10 dB until diverging to 11 and 9 dB at about 800 cycles. By 2 kc they have diverged to 15 and 5 dB. Until rolling off as described next. Curves 2, 3, and 4, fall noticeably from their values at about 6 kc. They have fallen by 1 dB at 10 kc and 3 dB at 20 kc. They are down by 14 dB at 100 kc. End verbal description.