yea, built in, but not typically user accessable, so still a mod...
if they put a knob on it and stuck it out the case, then yea, an adjustment...
Not sure if the 'information' is inthe 'users' manual or not, but that would help out a lot of folks also...
not many folks would open a unit up, and explaining how easy it is and how the mfg supports it, may make it more desirable for those that are less 'hands on' to undertake...