Dear Ralf, I had the same experience and snapped two .42's learning that New Nylgut won't always replace the old Nylgut of the same diameter (the second course did fine). My only difference being that my mensur is 60cm. I ordered .39 NNG and that solved it. I only use nng for the 1st course, 4th 8ve and occasionally for the 2nd course (and the rest gut) so don't have experience in using it elsewhere.
My guess is that in winding the old .42 ng to tension it stretched enough to actually become .39 in diameter. Nng apparantly won't stretch that long in finer diameters. Or alternately, the abrupt bend as the string leaves bridge hole may be too much for the small diameter. Old/white ng does like its stretch: It's the only string I've found that, after about 7 months as a chanterelle, that goes flat in the upper frets --leading me to believe it loses a bit more diameter in the center of its length over time. After a year of using nng I have yet to observe any intonation problems. Those older nylguts would ocassionally be tricky. I sometimes had success by winding to a 4th below pitch and waiting a while, say, an hour and then winding to a 2nd below pitch and waiting again in the theory that it needs time to adjust internally and/or in the knots. It's certainly not as forgiving as a nylon chanterelle but neither does have the nylon's sound, thankfully. Btw, I have a lute buddy whose 63cm lute has a difficult time supporting gut to that pitch and uses a .39 (or less) old ng. You might have to go back to whatever had been successful. I hope this helps. Sean On Jun 13, 2013, at 6:36 AM, R. Mattes wrote: Dear collected lute list wisdom, I just tried to switch my (late) medieval lute from all gut to all nylgut, everything fine, except: the top strings (63cm / g' @ 440 Hz - using 0.42mm) can't be put up to full tension. Both strings imediately break directly at the bridge. Strangely the aren't even close to their breaking point (at least they still feel quite elsatic). Bridge design can't be the problem - the bridge is rather soft and well worn out (and I never had a broken top at the bridge, even in much thinner gut). Is this a known problem. Did I get samples from a bad batch? TIA Ralf Mattes P.S.: off course this always happens the day before an important rehearsal ... -- R. Mattes - Hochschule fuer Musik Freiburg r...@inm.mh-freiburg.de To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html