Bridge pressure bar

[Alan Forsyth]

Greg wrote

       >  " In my view the only thing that you can assure with this pressure
bar is string termination. At some point , though, you will simply crush the
string into the bridge body and wind up with poor termination. "

No! The string does not come into contact with the wood at all. There are
bridge inserts on either side of the pressure bar, same as on a guitar, or
similar to the rods inserted at the top bridge. The string is threaded over
the front insert, then under the bar and over the rear insert.

         > "I still don't understand what this has to do with downbearing
unless you are somehow adjusting the height of the strings with this bar,
although I don't see how. Is the bridge body somehow height adjustable? "

You can adjust the pressure of the bar same as on a normal top bridge.
It does not affect string height.

            >"The second point you have is about a soundboard being able to
be made perfectly flat as long as sufficient downbearing exists. The two are
interrelated and depend upon each other for good piano tone."


         >"If you had a piano with poor downbearing but plenty of crown the
tone would suffer. In like manner if you had a piano with plenty of
downbearing but poor crown you would, again, have poor tone."

Correct me if I'm wrong but crown in a soundboard is a method of resisting
the pressure of the strings i.e an arched object is much stronger than a
flat beam.  String pressure is used as a means of ensuring good contact with
the bridge so the string vibrations can be transmitted to the soundboard. As
far as I know it is this string pressure that is known as downbearing. If
you use downbearing as a method of bridge contact then you need crown in the
soundboard to resist or counteract the pressure (otherwise the soundboard
would simply go concave and negate the downbearing). If you used a different
method of string contact with the bridge,(i.e. not use string pressure) then
you would no longer need a crown in the soundboard.

      >"Please rethink what was supposed to be the benefit here and if
possible could you provide a clearer, larger picture?"

Picture on it's way soon but at the moment I have to churn out 4 quotes to
the local university, the usual 100 year old pianos that only get serviced
every 10 years, you know!........and look at the time!

Regards
Alan Forsyth
Edinburgh