TL Audio Ivory 5050

The 5050 Preamplifier combines a single preamp and compressor, and has a front end based on that of the 5001, except that it adds line and instrument input options. The Instrument input jack is on the front panel, while the unbalanced line out jack is on the rear panel next to the mic XLR socket. On this model the output is on a line‑level, balanced jack only. Again, the circuit is a hybrid design featuring a solid‑state front end followed by a valve buffer, but this time it seems that only one stage of the ECC83 is used. The other resides in the compressor amplifier block. There's no mic‑level metering at all on this model, and no phase switch, though the 90Hz low‑cut filter and phantom power switching have been retained from the 5001. A single Input Gain knob sets the mic gain, up to 60dB, though the Output Fader following the compressor can add a further 15dB to this figure, with yet more gain available from the compressor's Gain Makeup control if required.

Most compressors monitor either their own input or output to derive the side‑chain control signal, but this design appears to do both. Threshold and Ratio are fully variable, as is the Gain Makeup control (+20dB max) with attack and release independently switched between fast and slow. To prevent distortion when compressing low‑frequency sounds at the Fast release setting, the circuit has a built‑in hold time that prevents the compressor from attempting to go into release mode after each cycle of the incoming signal. Gain reduction is shown by a meter above the mic/line amp, and a green LED above the compressor shows the Bypass switch status. A further bargraph level meter is fitted above the Output Fader knob to indicate output level.

Though the compressor has a conventional Ratio control, with a range from 1:1.5 right up to 1:30, the voltage‑controlled circuit has been designed with a soft‑knee response, so the compression ratio actually increases towards the target value as the signal level approaches the threshold. Overall, the technical specification for the unit is similar to that for the 5001 preamplifier.