The TM102 discrete Mic Pre TM102 has no input transformer but an electronically balanced input amplifier with hand picked transistors with very high CMRR, massive headroom and outstanding noise performance, even with low gain settings. The gain range from 12 dB to 70 dB can handle line level microphones as well as ribbon microphones with very low output levels. At low gain settings of 12 dB, the input can handle a maximum input level of + 18 dBu.
The discrete input amplifier of the TM102 Mic Pre uses handpicked transistors in a fully balanced circuitry with high base currents that result in a huge gain control range of almost 60 dB. Almost all specifications are identical to the transformer balanced mic pre TM101 but due to the electronically balanced input stage, the input impedance is a lot higher. The TM102 offers neutral sound performance without colorization. The high input impedance allows adding resistive and capacitive loads to modify the performance of the microphone.
The maximum gain of the discrete mic pre is 70 dB. The minimum gain is 12 dB. The P48 switch activates the internal phantom power.
The noise performance of the TM102 is identical to the TM101
mic pre. At 70 dB gain the noise figure is lower than 1.6 dB. Even with low gain
settings the noise figure remains below 3 dB.
Two additional switches allow loading the microphone by resistors
and capacitors. The resistor load can be switched to 600 ohms or 200 ohms; the
load capacitor can be either 1.5 nF or 4.7 nF. These components are switched
in parallel to the input and have no influence on the behavior of the amplifier;
however, the performance of the microphone can be modified by this additional
load. Actually, any effects depend entirely on the microphone.
The CMRR is better than 65 dB at 15 kHz and increases to more than 90 dB at low frequencies. The input impedance in the 20 Hz to 20 kHz band is more than 10 kOhms. The bandwidth of more than 150 kHz is limited by a very soft RF filter that protects the amplifier from RF interferences but maintains a very flat phase response. The frequency response is flat from 30 Hz to 20 kHz with any gain setting. The low frequency phase response is extremely linear and remains below 10 ° down to 30 Hz. A very soft subsonic filter protects the input stage from subsonic disturbances and impact sound.
The additional, electronically balanced Line Input is completely independent from the microphone amplifier and has its own gain control with a control range of +/- 20 dB. The input impedance is higher than 10 kOhms. The line input can handle levels of + 30 dBu. The LINE switch selects this input.
The Phase Reversal operates on
the microphone and the line input.
The high-pass low-pass Filter is
the same filter that is used in the TM101 transformer mic pre and the TM103 active
DI amp. It is inserted by the FILT switch. The low pass filter ranges from more
than 30 kHz to 1.5 kHz and has a steepness of 12 dB/oct. The sweep range of the
high-pass filter is form lower than 20 Hz to 600 Hz. The steepness is 24 dB/oct.
Both filters are active, 'maximum flat' RC-filters.
The Level Indicator is a multicolor
LED that displays output levels of more than - 20 dB with green color. If the
level exceeds 0 dB the color turns to yellow. Above 0 dB, the color changes to
orange and red. The remaining headroom with red color is still 5 dB.
The electronically balanced output can handle levels of more than + 30 dBu. The source resistance is lower than 50 ohms in the audio band. THD remains below 0.1 % up to output levels of more than + 28 dBu.
The TM102 discrete Mic Pre is a 2U ToolMod Unit that can be used in all ToolMod Frames. Vertical and horizontal versions are available.