It's just too bad that in the era of 10+ bands they tend to put the lowest frequency at 100Hz. Would've been great to have more options for bass fine tuning. Hitachis have "63Hz" but I think it affects on higher frequencies than that. Though the Q-value surely is very low too (effects on a wider range, lower number means wider curve, higher=steeper).
But if you are a fiddler, you may want to check out the chips that are used for the EQ. It shouldn't be massive work to alter the frequencies, I found the datasheet for the ICS 5 band EQ and the frequency is set with two small caps per band.