CD basses installed on theorbo/Chitarrone: why do they sometime break on the 5th?

Why do CD basses installed on theorbo/Chitarrone sometime break (mostly on the 5^th course), even if there are no sharp edges and they were installed properly?

 

The CD strings (from 110 CD up to 220 CD) are designed for renaissance & d minor Lute basses only.

For the long diapasons of medium extensions, the CDL type strings are available.

The thinner CD strings instead (82CD up to 105CD), are designed for 5^th courses and octaves on very lower bass strings of renaissance & d-minor lutes.

On theorbo/chitarrone these rules sometime do not work: why?

While on the traditional lute/archlute the 1^st string works with the higher FL product (220-230 Hz.m), any kind of theorbo/chitarrone works with an exceptional, longer vibrating string length, far longer than what was calculated for lute, hence the fact that the 1^st and 2^nd strings are forced to be tuned an octave lower.
For example, while a renaissance lute tuned in A at modern pitch has a scale around 57 cm, a theorbo in A at the same standard pitch has a scale of 85-88 cm (the FL product of the 3^rd string b note -that actually is the canterelle- is 220 Hz.m).

In these conditions, the range of the FL products typical of a 5^th course of a renaissance Lute (79-81 Hz.m) or the 6^th course of a d minor lute (71-74 Hz.m) allows the use of CD strings of the thinner range with no problems, while on a theorbo instead, the FL product raises up to 109-115 Hz-m, and it is too high for strings designed as basses.

In practice, the FL product of a 5^th course on a theorbo is the same of a 4^th course on a renaissance lute.

This is the explanation of why a CD string installed on the 5^th course of a theorbo can sometimes break: the FL product is too high (it’s not a matter of tension; tension has no influence in the FL product).

For more information regarding the FL product, please refer to the following article on our blog.

In conclusion, the proper place for the CD strings is – in the higher position – the 5^th course of the renaissance lute, or the 6^th , 7^th  and 8^th fretted theorbo basses. For the 5^th course of a theorbo/chitarrone, the right strings to use are NNG or CDL type.

 

Vivi felice