Tube-based dual-mono mic/line & DI pre-amp with EQ and distortion section.
The Thermionic Culture Rooster is a tube-based mic/line & DI pre-amp with EQ and a distortion section based around the same 5725 valve used in the ever-popular Culture Vulture Mastering Plus.
The input is balanced, via an attenuator in Line In mode, with a custom Sowter transformer. There is 48V phantom power selected by a locking toggle, and phase reverse. A DI jack input (unbalanced) comes between the transformer and the Input Level control. Gain is provide by a twin triode 12AT7/ECC81 valve which also powers the active boost controls in the EQ section.
The neatly laid out EQ section has all the active boost controls on the left, with Thermmionic Culture's unique “Varislope” bass-lift control, peaking at 60Hz, and a selectable mid/high lift peaking at 2.5k/4kHz (“bell” shaped) and 7kHz (“Varislope”). The Cut controls are in the centre. The mid operates at 700Hz, the 6-position Bass Cut is combines a high-pass filter with shelving, depending on the setting (see curves in manual). There is also a switchable low-pass filter (labelled LPF) to remove unwanted harsh high frequencies.
"ATTITUDE" DISTORTION SECTION
The same 5725-distortion tube employed in the Culture Vulture is used in the new Rooster. It offers a subtle distortion characteristic in the triode position, moreso than a Culture Vulture, due to the higher HT voltage, plus the use of negative feedback. As such, it has a very low (about 0.01%) distortion when the Attitude control is set to 1. In the pentode mode it generates more 3rd harmonic distortion. Distortion can be pretty radical when the Attitude control is to Max and the input is high.
The output valves are 2 triode/pentode PCF80s which combine high output with low impedance, controlled by the Output Level control. The output is transformer balanced. The Output level is indicated by 3 LEDs.