[ Ref. Bob Oppenheim in 140517 MMDigest --
KT Special #160,598 was made in 1925, when Seeburg was just making the
change from "soft-loud" to "soft-medium-loud" volume control switch and
mechanisms. KT Specials made in this era typically have a one-channel
multiplex switch. I've never seen one in which I could verify that all
the percussion tubing was correct. The switch is actuated by the soft
pedal hole in the roll.
The somewhat later two-channel switch, also controlled by the soft pedal
hole, switches the bass drum and cymbal to single-stroke tambourine and
castanet, and the reiterating snare drum to reiterating wood block.
The triangle plays from the triangle hole in the roll, and each tympani
plays from one tympani hole.
In later KT Specials (circa 1927-28) one tympani beater also controls
the triangle and castanet valve(s). They all play together from two
tracker bar holes that are also teed together: the triangle hole and
one tympani hole. An output from that tympani beater valve is tubed to
the input(s) for the triangle and castanet reverse valve(s).
When the tympani valve is off, its output conducts atmospheric pressure
to the tympani beater pneumatic and to the pouch(es) for the triangle
and castanet valve(s), leaving them off. When the tympani plays, the
valve puts out vacuum, which causes the triangle/castanet to play.
Those KT Specials also have a 2-channel multiplex switch that works as
in the previous paragraph for the other instruments.
A lot of information on the mechanisms found in Seeburg instruments
is contained in the Seeburg registry at
If anyone else needs a drawing of the 3-way switch tubing, please
contact me directly.