Spiro Weich test results
The Spiro Weich:s arrived yesterday so I decided to give them a spin since I have the bass for a couple of more days. The results are puzzling (keep in mind I run the EADGC tuning):
The E-string is absolutely dead. The volume is significantly lower, the sustain is lower, and the timbre duller compared to the Spiro Medium. Sure, some sacrifice in tone is expected, but not to this extent AFAIK.
The A, D, and G sound nice on open strings, and the tension is just right -- but the response is uneven, depending on where the strings are stopped, in particular on the A-string. E.g. the Bb and (to a lesser extent) the B on the A-string are dead. This wasn't the case with the Obligatos (although the D overall didn't sing as much as the others). A dead Bb just isn't acceptable in jazz...
Apparently this bass is quite sensitive to string selection. Maybe this is caused by the suspect saddle crack / bass bar repair?
Anyway, the Spiro Medium E is a keeper and in fact it sounds very good; plenty of volume and a lot more bottom than the typical 3/4 bass. The luthier, who sells the bass on commission, recommended Evah Pirazzi Weich, so that would be next string to try out for A, D and G. Unfortunately the high C isn't available in the lighter gauge, so this needs to be sourced elsewhere. Perhaps from Corelli?
Further observations on string length and setup
If I keep my index finger on F on the E-string I can stretch the G about 15 cents sharp at the current 44" SL. The poor setup is more limiting. The relief on the D-string is almost 3 mm at max, and the string height is 8 mm at the octave, 9 mm at the max (about 10 cm from the end of the fingerboard!), and about 8.7 mm at the end of the fingerboard. I'm now quite confident that with a perfect setup, and a modest shortening of the SL to 43.3" I'd be fine.
Conclusions
This has been a valuable learning experience. The instrument has lots of charm: The arco tone is great, and it shows promise as a jazz bass, too. However, further string experiments are called for, and a better setup is mandatory in order to really assess the qualities. It's too risky to buy the bass without knowing the results, so I'm still going to heed your advice and give the bass back and try a bunch of basses in Frankfurt next week. That said, I haven't completely ruled out a purchase of this instrument. If I don't find what I'm looking for in Frankfurt, and the seller is willing to do a basic setup (reglue and dress the fingerboard and install height adjusters) I'd be interested in a new try.
It could very well be a nice instrument, but it's far from home.
