The Spruce looks to be part of the Rib construction and not a later addition. The Lining I believe is over this but like I mentioned before, I wasn't looking at it carefully being my mind was on more interesting things like the Top.
As far as the Back goes, we haven't looked inside that close at the Back center strip but it does look like it is original. The strip is actually cross grain like the Ribs are and for some reason, I cannot ID the wood used there. This is something else to look more closely at when we get the chance.
When the Block area gets cut for the mensur shortening, we will get a real good look at the cross section of that center section. Perhaps this will tell us something as to the origin or method used. This is one of the features that point to Spain but might be short sighted because many of the Spanish makers either learned in Italy or followed the Italian style. Hence, much of the Spanish work we see is actually early Italian. The Italians made many Guitars and Mandolins so I think it's a little hasty to jump across the Mediterranean every time we see something 'Guitarish' looking.
The Varnish on the Back and Ribs is just stunning. The Top has been over-varnished at some point.
I tried several times to reach a guy in Spain named RAMON PINTO COMAS whose shop is
CASA PARRAMON. I was told he was the
expert on Spanish makers. He never returned my emails. Maybe one of you out there reading this will have more luck with him than I have and find out if he knows of a maker in Spain that could of made
this Bass. Recently I saw an old Italian Bass that had
a similar Scroll like mine with that same center line. Still, it feels and sounds Italian to me from what I have seen, heard and played whatever that means.