Q: low battery mod for kpr77

[scott]

As the subject suggests, I'm looking to alter my kpr77
so that it'll act as though the batteries are nearly dead,
even when the batteries are new. Why? Well because about
ten minutes before the batteries die (I've been through
two sets in a week) the bass drum gets real low and buzzy,
but the rest of the machine acts normal. I prefer this 
sound to the normal sound.

Is this sort of thing possible? I was thinking maybe it'd
be as simple as placing a resister or trimpot off the negative
end of the battery. That's just me guessing though.

Thanks in advance,
scott