Fredenstein F601A - Manual (Page 3)

Fredenstein F601A Microphone Preamplifier
Gain Control:
Microphone Preamplifier Gain Control, maximum +78dB when input transformer is activated,
+58 dB in transformerless mode.
Input Transformer:
When lit, the input transformer (Lundahl LL1578XL) is inserted in the signal path, if not lit, the
F601A work in the transformerless input mode. Any resulting change in gain is automatically
compensated by the internal CPU.
Output Transformer:
When lit, the output transformer (Lundahl LL1517) is inserted in the signal path, if not lit, the
F601A work in the transformerless output mode.
POL – Polarity Control:
Setting the signal polarity, when turned on (LED lit) the signal is inverted.
Low Cut – High Pass Filter:
when turned on (LED lit), the 60 Hz High Pass Filter is activated to suppress unwanted low
frequencies.
P48 Phantom Power:
Most FET condenser microphones as well as some other microphones with built-in amplifiers
require +48V Phantom Power. Setting the P48 switch to the right enables +48V through the
balanced microphone line. Please check your microphone documentation if you are not 100% sure.
Enabling P48 on microphones not designed for P48 might cause severe damage.
Please note, if the rack does not supply +48V, the LED in the button will not turn on.
LOW-Z:
To avoid impedance mismatches between the F601A and connected dynamic and ribbon
microphones, the input impedance can be lowered to 300 Ohms independent of the input
transformer setting.
DI – Direct Input:
The most common use for the DI input is to connect instruments like guitars directly to the F601A.
The input impedance is greater than 500 KOhm to insure compatibility with most instrument
pickups. After inserting a balanced (TRS, Tip-Ring-Sleeve) or an unbalanced (TS, Tip-Sleeve) plug,
the balanced microphone input through the box or rack is automatically disabled.
All parameters are internally stored in a non-volatile memory and are automatically recalled at
power-up. The F601A is powered by a 32bit ARM CPU.
Fredenstein F601A Manual V1.2 July 18, 2014 Page 2