Summit Audio TD-100 Instrument Preamplifier and D.I. - Manual (Page 10)

Circuit Explanation
10 Summit Audio, Inc.
Circuit Explanation
The Instrument Input to the TD-100 is directly connected to
the Direct Output. The Impedance control sets the input
impedance of the first stage input. The Impedance control
can be used to match the impedance of the instrument and
to provide subtle tonal coloration.
The TD-100 features a vacuum tube amplifier driving an elec-
tronically balanced output stage. All the signal amplification in
the audio path takes place in the tube circuit. The balanced
output drivers provide a low output impedance for driving
cables and 600
Ω loads.
12AX7A
AMPLIFIER
GAIN
IMPEDANCE
INSTRUMENT
INPUT
DIRECT
OUTPUT
DIFFERENTIAL
OUTPUT
Tip
Signal
Present
Peak
Hold