93 bits is the width of the LFSR. Take a look at the SID random noise. It is only an 8 bit output dac, but they use a 23bit LFSR so that the generated noise will achieve all possible numbers over time. Read the linked WIKI. Take a look at their example and follow the logic in your head. That 16bit example will not achieve the 65536 states they claim if you just run the thing indefinitely. Unfortunately, they will hit a smaller repetitive loop of numbers well below 65536. But if you only use the bottom 8 bit out as an 8 bit random number generator, then you will possibly achieve a pattern with 256 steps, but only a few thousand possibilities before it repeats. This is why the 8bit SID uses 23 bits for it's random number generator as the pattern it generates is large enough to not create an audible repetitive sub-tone. An 8 bit LFSR just wouldn't be enough. Even using 8 bits out of a 16bit LFSR might have generated an acoustic sub-tone as that counter would repeat every few k clock cycles, and if your sample playback is 10 or 20 Khz, buried repetitious pattern may generate something you may be able to hear.