Both points of view are correct!  The sound of an organ is determined
both by the types of pipes used and the pitch ranges in which they are
played, but also the scaling and voicing of the individual pipes is very
important.

For any given pipe type (e.g., bourdon or violin or diapason), its tonal
quality can vary over a wide range depending on its scale(*), its wind
pressure, and other "voicing" factors.

(* "Scale" is a heavily overloaded musical term.  Here it refers to the
"skinniness" of the pipe, its ratio of length to width.  A flute is wide
scaled, a string pipe is narrow scaled, and a diapason ("principal") is
in between).

Some bourdons and flutes are wide-scaled and very "tubby" or dull in
tone.  These would sound poor in a street organ, being too dull in the
melody and too "muddy" in accompaniment -- although good for the bottom
bass to lend weight.

String-toned pipes, when not too narrow-scaled and on moderate wind
pressure, sound very smooth and easy to listen to for long periods of
time.  But when narrowed in scale or blown with higher pressure, they may
be harsh and tiring to the ear.  Some American piano orchestrions have
string pipes like this.

Generally, moderate scales -- meaning flutes and bourdons not too wide,
and strings not too narrow -- are best.

I have played pipe organs with a good list of stops, but which did not
sound well due to poor pipe scaling and voicing.  And then organs with a
dull-reading stop-list that sounded very lively because the flutes were
bright and the strings not too harsh.

Much of an organ builder's skill lies in choosing the right types of pipe
ranks to work together.  But if the individual pipes do not each produce
a lovely sound, there are limits to what can be done to make a good
ensemble.

Finally, it is up to the music arranger to play each set of pipes in the
pitch range that best shows its natural "talents."  Transposing a piece up
or down a little can work wonders.

Mike Knudsen