Tube Tech CM1A Comp - Manual

Lydkraft ApS
Mose Allé 20, DK 2610 Rødovre
Denmark
TUBE-TECH PM 1A
Microphone pre-amplifier Module
Description
The TUBE-TECH microphone preamplifier PM 1A is a combined microphone and
DI preamplifier.
The amplifier consists of a microphone input transformer (with a static screen) with
a step-up of +10 dB, a dual tube preamplifier with a coarse stepped gain 20-60dB
(10dB/step), a fine stepped gain +/- 10dB (2dB/step) giving a total gain range of
+10-70dB, an output amplifier with two dual tubes in push-pull and an output
transformer (with a static screen).
The microphone inputs are provided with a switchable -20dB attenuation PAD, a
selectable input impedance 600/1200/2400 Ohms, a switchable phase reverse and
switchable +48 V phantom-power.
The microphone input is capable of accepting levels of up to +6 dBU (1.55V) at 40
Hz without the PAD and +26 dBU (15.5V) at 40 Hz with the PAD, so the
microphone input can be used as a unity gain line amplifier.
The high impedance DI input is unbalanced and placed in the circuit directly after
the input transformer. The gain range for this input is +10dB to +60dB. When in use,
the microphone input is disabled.
A high pass filter for the microphone and the DI input is switchable between off, 20
Hz and 40 Hz. It is advisable to use this filter in environments with high levels of
very low frequency disturbances.
(
071221 JGP)