I just got a Bartolini NTBTG-918 preamp new (eBay) and it came with a small brown paper envelope in the box that contained a piece of cardboard with five resistors and four capacitors taped to it. Nowhere on the included schematic or anywhere I could find on Bartolini's website was there any information on what these parts might be used for. They are (in order): 1) 2Kohm 1) 6.8 Kohm 1) 10Kohm 1) 27 Kohm 2) .022 uF 2) .047 uF 1) 2.7 Kohm There *was* a web schematic for Bartolini's 1970s TBT preamp that showed adding capacitors across the legs of the tone controls to change the affected frequency somewhat. No info on if this is in any way relevant to the NTBTG-918 or a reason for doing that. Since these preamps are sold for use for bass or guitar, doesn't it make sense that you might add a couple of caps to set the frequency bands to be optimal for one instrument or the other? Bartolini is famously difficult to get an answer out of though, supposedly even worse than Ken Smith is. They don't have an email address or phone number posted on their website, just a FAX number. I'll send them a FAX on this, but since these are such widely used preamps, maybe someone here on TB knows what the extra parts are for? Thanks!