Thanks - I have some Tru-Oil on the way and have sources in Finland now. I might try rolling my own when I have the luxury of being able to experiment with recipes, however for this build I would rather stick to things tried and tested within my experience. Still, sounds like a fun idea....perhaps I might do this on the guitar stand I really really need to be building....!
In other news, the bass was brought home for autumn break. A nut has been cut plus the bass was strung up with an old set to check geometry, etc. The neck pocket could have done with being a couple of mm deeper yet. I didn't have a long enough template cutter available this week and I made a personal promise to myself to have the neck fitted so I could move on with the proper build when I return to study. This has meant that the pickup sits too low when rammed to the body as originally intended so the rubber strips have been fitted underneath. No big deal. The bridge also needed raising a couple of mm or so rather than it being rammed against the body also. Again, no big deal since the original plan was designed to put these items at their minimum fitment heights to get the maximum use of their adjustment ranges.
The bass plays very well despite not having been given any kind of proper setup or fret levelling as of yet. Just basic intonation and string height. The pickup is wired directly to the recessed barrel jack so will sound far better when not loaded in this manner. Pre-amp PCBs are not here yet, but no problem. Forgot to bring the cavity cover and truss rod cover home so I am unable to install them right now, but since the Tru-Oil isn't here either the bass will be on hold for a while.
I learnt exactly what I wanted to learn from this prototype which I will take forward onto the proper "Night Rainbow". That is, that the super-thin 30mm body could be taken down up to another 5mm or so however it would leave major issues with locating a jack socket (perhaps not a barrel jack), batteries, etc. The neck joint could easily work with a 25mm thick body. On that basis I will keep the 30mm thickness for the final build. Very pleased with that bit.
The location of the bridge and recessed tailpiece work very well feels good to me and my playing style. There is plenty of room to dig in if I want, plus the pickup works nicely as an anchoring point. I'd like to experiment with using a ramp between the neck and the pickup on the NR build, whether it be secured using recessed Nd mags or whatever.
Not 100% sure about the stainless steel fretwire. The bass in its unfinished state plays with some strange overtones through the pickup, so whether that is anything to do with the pickup, fretwire or whatever I am not sure. I'll fault find this out when the pre-amp is here and I do the full fret dress and setup. Taming the treble will easily smooth this out. SS is a PITA on many levels despite being better than nickel-silver stuff so I will likely stick to EVO and equivalents. From hereonin if it indeed causes these strange sound overtones. The usual "tonewood" non-discussion can be blown straight out of the water too; despite this bass having been built with "warm" woods the sound is still bright acoustically and amped up. The propagation of sound is slow however, which is in line with Mahogany-like woods such as Sapele and is pretty much what I expected.
I pulled a couple of really nice flamed Birch boards out yesterday which I think will work really nicely when hollowed. The original idea of a straight gloss black finish on the NR is likely to be changed to trans black or some finish that will leave the back and neck black with the front inky black with the movement of the flaming still visible. The formation of the figuring is quite wild and "cloud-y" which suits my idea well. I wonder if there is such a thing as trans black paint that looks like petrol on water....? Allan?