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CELLO BRIDGE HEIGHT

(1) The relation of bridge height to string type.
Cello full size:
	String 1 fingerboard clearance, gut 	5.5 mm
	String 1 fingerboard clearance, steel	4.0 mm
	String 4 fingerboard clearance, gut	8.0 mm
	String 4 fingerboard clearance, steel	6.5 mm
The newer steel strings (Helicore) have a wider vibrating amplitude. 
Their string clearance needs to be a bit more than 4.0 mm but not quite
that of gut.  The Dominant strings have the same vibrating amplitude as
gut therefore their clearance should be the same as gut.
The amount of scoop in the fingerboard underneath the strings is very
important.  The general rule is 1/2 the string diameter in a very smooth
curve with no bumps or valleys.
> (2) Whether the bridge height affects the ease with which the cello speaks?
I
> have recently bought a much heavier bow, which solves some of the problems,
> but it seemsto sacrifice some of the creaminess of the tone. Or is the
> 'speakingness' just an inherent and unalterable characteristic of each
> instrument?
Bridge height is very important.  As you know, cellos are very sensative
to heat and even more so humidity.  
Do the following in the winder and summer seasons to check the
"fingerboard projection" height at the bridge. Keep a written record to
be given to the luthier when repairs are made.  Fingerboard projection
is the point on the bridge which would correspond when a long straight
edge is held on the fingerboard between the D and G strings and extended
past the end until it hits the front of the bridge.  Mark this point on
the bridge with a pencil point.  This point should be 81 mm above the
cello top directly under the bridge.  With this fingerboard projection
and the string clearance as stated above, the pressure which the strings
exert upon the cello top are ideal.  If the instrument does not respond
to your expectations there can be many things wrong.  ie.  Sound post
position, tightness or looseness; Old or bad strings, wrong guage, etc.;
Bass bar is overly stiff, overly weak, wrong position, tuned incorrectly
in relation to the top graduations;  The cello top may be overly stiff,
overly weak;  The bridge may be in the wrong position;  The tail piece
may be overly heavy or light (most are much to heavy);  The fingerboard
may be to long, to short, to stiff, to weak;  ribs may be overly thick
and stiff, or they are overly tall or short;  The back graduations may
be overly stiff or weak;  The arching of the top and back may be wrong.
As you can see, it takes a very experienced luthier to diagnose these
problems.  It takes and even more experienced and talented luthier to
correct them!!!
Good luck.
Dennis Braun, Bowmaker, Luthier
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ICS Staff
Tim Janof, ICS Director
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