Hex core bass strings are often considered inferior in tone compared
with properly calculated strings with a round core.  This is usually
apparent when "universal bass strings" (with a hex core) are used to
replace broken original bass strings.

Nonetheless, more than one piano manufacturer used hex core strings
successfully in their instruments.  One notable example are Berdux
pianos from Munich, Germany.  The head of the company, Ferdinand
Berdux, was a great innovator.  One anecdote about him tells that he
dictated further piano improvements to his heirs from his deathbed.

Berdux pianos are chock-a-block full of superb and sometimes perhaps
crazy features, and a lot of patents were taken out by the company.
For example, the grands feature a low-aspect plate, with a bar running
below the strings, above the soundboard and through a hole in the
bridge, if memory serves me correctly.  This was done in an effort to
counteract the string tension at string level to cut down the cross
section of the struts.  The tallest upright I ever saw was a Berdux,
a big black beauty around 152 cm tall (60 inches)!

Berdux used hex core wire on the complete bass section.  These instru-
ments sound great.  Berdux was one of the few pianos that the T-100
(red) Welte mechanism was installed into, right there with Steinway,
Bechstein, Bluethner and Feurich -- talk about an endorsement!

I have just peeked inside my wife's 1980, 109 cm (43 in.) Schimmel:
the bi-chord bass strings have hex cores, the singles have round cores.

Hex cores have the advantage that the winding will not come loose and
buzz.  However, they produce a different spectrum of harmonics than
round cores, and are usually perceived as inferior in tone.  And we now
find that two very good makes of pianos utilize them.

Can anyone comment on the pros and cons?

Jurgen Goering

 [ Why speculate?  Harmonic spectra is easily analyzed with modern
 [ computer programs for editing WAV audio files.  Make recordings
 [ of different pianos and strings and we can have concrete numerical
 [ data.  (Naturally, the customer's ears are still important!  ;)
 [ Perhaps MMDer Warren Trachtman can assist by making available for
 [ comparison the WAV file sounds of his nice Steinway.  -- Robbie