So I assume that means that you have not seen the "thinning" that Martin was talking about on basses as a whole. I think we can safely speculate that the makers of old did not use their best quality wood for basses simply because they could make much more money by making a dozen violins out of a piece of prime quality piece of wood instead of just one bass. Perhaps they also did not consider it worth their time to carefully graduate a bass to the degree that they would have on a more profitable violins and even cellos.
Actually, I was not referring to basses, but to a specific cello that I had made. I was showing it to an owner of an "important" shop. She loved the instrument, but then asked her repair guy to check the thicknesses. That's when she told me mine was too thin and suggested the 7mm mark. She might have even mentioned as high as 9mm!
Regarding the regraduation of old violins and making them too thin; Sacconi said in his book that when he first started making violins he was taught to make them about 5mm thick.
When he examined his first two or three Stradivari violins he assumed they had been regraduated down to under 3mm. But he said that after seeing dozens, and by his own count, working on some 350 of them during his lifetime, he concluded that Stradivari had indeed made them to those thicknesses and they had generally not been altered in their thicknesses.
Count Cozio Salabue is noted for being the first great violin collector and he kept copious notes on his violins. Much of his work has been published in a book. He says something to the effect that in Cremona there is another violin maker, though not so good, who worked along the lines of Stradivari; one of the Guarneris, the one they call Del Gesu. And then goes on to say that the Montegaza brothers who were working for him had successfully improved the tone of the Guarneris by reducing the thicknesses of the tops.
I'm skeptical about the idea of thinning out tops to help them now but ruin them later. Dozens of pictures and drawings of great old violins have been published in the Strad Magazine and elswhere and I am continually amazed at the thinness and inconsistencies in the thicknesses. I also own a copy of the Gurarneri book that has detailed pictures, drawings and thickness of some 28 Guarneri del Gesu violins. The vast majority having tops some would say have been regraduated and ruined, yet they are still the preferred instruments of some of the greatest musicians in the world.
I agree that generally either assistants or others made many of the great Italian basses that are attributed to the big name makers. Generally I have specialized in basses but I have examined enough violins by noted makers to say that I see no similarity between the work done on their violins and those of the basses even when they bear original labels. In fact, I can only think of one possible exception. Even back to Salabue's day (early 19th century), there were already people collecting labels, and some of those labels ended up in other's instruments. Also, many of the makers of that period didn't feel compelled to label their instruments at all, but aquired "name labels" later on either by those who were misinformed or misguided by greed.
One of the earliest court records on date involving violin fraud was filed by the buyer of a violin he thought was an Amati, but as it turned out it was a Rogeri "a maker of much less repute". Even today most collectors would rather own a violin from any of the makers of the Amati family, but Rogeri's fetch very high prices indeed.
I think the reason many of the early and great Italian basses were made from slab cut wood instead of quarter cut spruce simply had to do with what the player could afford, so generally the early Italian basses have slab cut tops and backs and sides of plain maple, willow or even mahogany. The workmanship by today's standards is not very good, but they have an incredible beauty just the same.
I have personally not seen an early bass that had been regraduated, although I worked on one that had wood added in the top bout!
