Pirastro's popular Obligato strings have a solid synthetic core with a very thin metal wrap. They were designed to emulate gut strings, and they did a darn good job of creating such a string. Their attack is "old school" with that more blunt and thicker, warmer hit, with a little less sustain than more modern jazz strings. Their very smooth surface is kind to the fingers and they are a dream to bow. If you want your sound to be "traditional", whether for bluegrass, old school jazz and blues, or other styles that calls for that sound, you will enjoy the Obligatos. I had a set on my Kay for quite a while, for my own bluegrass, jazz and blues gigs, and I really enjoyed them. (I had planned to put a set on it again, and only removed them as I needed my laminated bass for more modern jazz sounds , as my carved Juzek underwent repairs. I just like the articulation of the Corellis for that- my high frequency hearing is just going bad! ;-) I am enjoying the gut strings on it now; see below) I am very fond of how well they emulate gut and the traditional bass sound, yet without mud or imprecision. They may look like metal strings, but they sure don't feel or sound like them-- the thin coating fools you! Not for use with magnetic pickups.
Pirastro does not list gauges on their packages, but I have taken the time to gauge all the strings using a digital caliper and present the following unofficial measurements of the standard 3/4 size Obligatos for your reference:
I haven't measured the new ¼ and ½ size Obligatos yet.
They offer them in 3/4 size, and ¼ and ½ sizes, too. All strings have red with black spiral thread at the tailpiece, and the following colors at the headstock:
- Extended E=green
- Low B=yellow
The color code ring at peg end for ½ size is yellow, and light blue for ¼ size.