BC1 Small Format Broadcast Consoles

Mono Input Module
BC1-IM

The BC1-IM, broadcast mono input module, is the most important channel strip of the small format mixing console system BC1. Even though the top plate size of the module is only 400 x 33 mm, the BC1-IM includes professional audio circuitry at the highest quality level. An ultra low noise, pristine sounding, transformer balanced microphone preamp with very high CMRR, versatile 4 band EQ with 2 fully parametric mid bands, and sweeped hi-pass filter are only some of the main features of this module. Like the entire BC1 small format mixer system, the BC1-IM offers ultimate + 30 dBu headroom throughout the entire signal chain and a switched insert section that operates at nominal level, also with headroom of + 30 dBu.

The Features in Detail:

The Input Section contains a transformer balanced Microphone Pre-amp with maximum gain of 70 dB, phantom power and input pad. The high quality, oversized input transformer, brand Haufe, Germany, offers more than 70 dB CMRR up to frequencies of 15 kHz. With an input level of 0 dBu at 40 Hz without input pad, the distortion is far below 1 %. With the standard input pad the microphone input can handle levels of up to + 30 dBu. The gain control ranges from 25 dB to 70 dB. The standard pad of 30 dB can be modified to any value on request. Separate switches on each module activate the 48 Volt phantom power.

The microphone preamplifier offers outstanding noise performance of less than input referred -116 dBqp, which is less than 2 dB more than the 200 ohm resistor noise. However, even more important is that the noise performance remains low also with low gains settings. With 40 dB gain, the noise figure is still better than 3 dB. Oversized coupling capacitors with high frequency bypass precision capacitors and sophisticated, hand selected input amplifiers in adt-audio's 'double balanced' technique make possible to keep the phase response in a range of below 8 degrees at 40 Hz and below 18 degrees at 20 kHz with the standard RF filters.

The Line Input can be implemented electronically balanced or transformer balanced. With both versions, the input impedance is > 10 k ohms in the transmission band. The separate gain control for the line input has a precisely trimmed center detent. The control range is +/- 20 dB. The LINE switch selects this input.

Pressing PAD and LINE at a time selects the GROUP INPUT with priority over Mic and Line. With this setting, the modules operates as an audio sub group master. The output of the internal group bus amp that is included with the BC-IM1, feeds the main input of the channel. The line gain control works also with input set to group. More details about the internal group amp are here.

The Phase Reversal is active with all inputs. It operates as usual and reverses the phase of the selected input.

The Processing Section combines a high pass filter, an adt-audio 4-band EQ and a switched, buffered insert section.

The High Pass Filter is inserted by the HPF switch. It is implemented as 'maximum flat' Filter with a steepness of 25 dB/oct. The sweep range is from below 20 Hz to 600 Hz.

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