Overview. The line for boost shows a higher impedance than the line for cut. The tone flat line is in between as you might expect. The bass end shows a much wider impedance spread between cut and boost than it does for treble. The highest impedance for treble is less than the lowest impedance for bass. All the lines merge into a single line at 1 kHz.

Specifics for max boost. The lowest impedance for the bass region is 64 k ohms between 10 and 20 Hz. At that frequency it begins to rise reaching a maximum at about 250 Hz and 100 k ohms. It falls again reaching 72 k ohms at 1 kHz. It continues to fall passing through 23 k ohms at 10 kHz. It continues to fall passing through 20 k ohms at about 13 kHz. It reaches a minimum of 16 k ohms at 35 kHz, rising again to a value of 21 k ohms at 100 kHz.

For tone flat. The tone flat line starts out at 185 k ohms at 10 Hz. It passes through 180 k ohms at 75 Hz. There is no peak as with the boost line. It falls passing through 72 k ohms at 1 kHz. It passes through 44 k ohms at 10 kHz. It falls to a minimum of 42 k ohms at 25 kHz. It rises slightly reaching 45 k ohms at 100 kHz.

For max cut. The max cut line starts out at 310 k ohms at 10 Hz. It passes through 275 k ohms at 100 Hz and descends rapidly passing through 72 k ohms at 1 kHz. It reaches a minimum of 61 k ohms at about 2.2 kHz. It rises slightly passing through 68 k ohms at 10 kHz and reaching 70 k ohms at 100 kHz.

It should be noted that because the passive part of the circuit is symmetrical The load seen by the feedback amplifier is the mirror image in the impedance axis. That is the lowest impedance is for the cut and the highest impedance is for the boost. End verbal description.
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