39 inch scale bass, 1/2 or 5/8?

That's a common string length for 5/8 size basses.

 

That's pretty much on target. You can get 3/4 basses at a 41 inch string length. IMO, any shorter than 39 and it's not going to sound much like a double bass no matter what you call it. I play a modified 3/4 bass with a 39.75 inch string length. My experience has been that 101 centimeter string length is about as short as you want to go and still get a double bass sound and feel.

 

Oh I dunno Chuck, when I was at Beserklee, John Neves (who I was studying with) had a half size old German bass (carved) in his office that sounded at least as big as the Kay I was playing at the time. Of course, I wasn't getting a very big sound then....

 

"Beserklee." That explains it. Yeah Ed. But, I think most good 1/2 sizers are around 39 to 40 inch string length. I personally like a smaller bass. I don't think there is much correlation as to quality, volume and string length. It seemed that double bass players inferred that their extra length and size was some kind of badge of honor. But the more I listen to experienced players it seems that's not the case. I was reading an older thread where Ken Smith talks about his Loveri being at 3 different string lengths: 43, 42 and 41.5 respectively. He said that in it's present state at 41.5 with a Eb neck the Loveri sounds and plays it's best. That intrigues me. I was under the impression that longer was better. I was just telling the OP that basses under 39 are lacking in IMO. I could be wrong but from the basses I've played, it sounds like that's the threshold or shortest one would go without sacrificing quality and volume. Silvio Dalla Torre, on his website, has an interesting detailed progression of the process of designing his "Bassetto" solo bass. I know it's tuned in 5ths (G D A E). He talks about how he came to the conclusion that 100 centimeters was superior to the shorter lengths he had previously used in design starting with 85 centimeters. His assertion is that it is easier to get a balance between the strings with the longer string length. His personal string maker Gensler, may have played a part in that conclusion. He also came to the conclusion that rib depth has little to do with volume. Larger was not superior with regard to rib depth in his final design.