Tube-Tech MEC 1A Recording Channel

The Tube-Tech recording channel MEC 1A is a combined microphone and DI preamplifier, equalizer and optical compressor intended for recording directly to any recording media.

Microphone preamp:

The microphone preamplifier consists of a microphone input transformer (with a static screen) with a step-up of +10 dB, two dual tube preamplifiers with two stepped gain switches, one with 10dB/step (coarse) and one 1dB/step (fine) giving a total gain range of +20dB to +70dB. The microphone input is provided with a switchable -20dB attenuation (PAD), switchable +48 V phantom-power and phase reverse. A highpass filter for the microphone and the DI input is switchable between off, 20 Hz and 40 Hz.

The microphone input is capable of accepting levels of up to +6 dBU (1.55V) at 40 Hz without the PAD. With the PAD switched into the circuit, the MEC 1A can be used as a unity gain line amplifier accepting levels up to +26 dBU (15.5V) at 40 Hz. 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.

Equalizer:

The equalizer has low and high shelving filter with a gain range of +/- 15dB, each with 6 switchable frequencies and a band filter with a gain range of +/- 20dB, 12 switchable frequencies and a bandwidth control. The shelving and the bell filters are designed around a dual tube operational amplifier. The equalizer has a separate in /out switch.

Compressor:

The compressor is of the optical device type. It has controls for ratio, threshold, attack and release. A switch selects between manual attack and release and fixed attack and release. With the link switch it is possible to link several units together on two independent bi- directional buses. The compressor has a separate in /out switch. In normal operation the equalizer is in front of the compressor, but a switch enables the compressor to be in front of the equalizer.