Thermionic Culture Swift Two-Channel Tube EQ

The Thermionic Culture Swift is a two channel equalizer had been designed to be as much at home in tracking individual instruments or sitting across a stereo mix buss to equalize the final mix. All controls are clearly labelled and setting up the EQ is quick and easy, so it's been named after Britain’s fastest bird in level flight.

The Swift utilizes influences of 2 classic designs of the “golden days” of all valve recording with improvements to bring the specs up-to-date for today’s pro use.

The main electronics are based around a 1950s EMI desk but with extended top and bass response. It had a BAXANDALL type active eq which is still there with an added Presence switch to give a broad band lift to mid/hi frequencies. This is based on one invented by Vic Keary in 1963 and used in his own mixing desks.

The mid lift controls are based on the Pultec design and are passive. For speedy operation and economy it has just 4 frequencies, with 3 “Q” settings.

Special features are Hi Pass Filter, Mid Cut and “Air” (all passive). An interesting (Pultec type) effect can be obtained by setting the High Pass Filter at its last setting which combines a shelving bass cut with a filter at very low frequency, then using plenty of bass lift at either 50 or 100 Hz.

All pots are continuously variable.

Gain is on switches, for comparison purposes. BYPASS switch disconnects the electronics so you hear the unadulterated original signal. No metering is provided as it was deemed to be just a distraction. The Swift can output + 20 dBu without noticeable distortion and it’s practically noiseless.

Although The Swift is influenced by old designs, the electronic design is a great improvement on the old ones. There are only two valves per channel to keep coloration minimal. TC uses modern, specially designed, Sowter transformers and valves (tubes) not used before in this type of circuit. They simply sound better and the technical spec is outstanding.

Features

• All-valve signal path using NOS and new production valves;
• Combines features of the best USA and UK equalizers with Thermionic magic;
• Quick and easy to operate, clearly labelled front panel
• Shelving Bass and Treble lift /cut Controls at 2 frequencies each;
• Mid Cut and Lift at 4 Frequencies each with Three ‘Q’ combinations;
• Presence and Air Controls;
• A Switchable High Pass Filter with a Special last position which used in conjunction with the Bass lift can be a very interesting combination;
• Adjustable gain in .75 dB steps;
• Frequency response from below to well above human hearing with minuscule phase shift;
• Virtually no distortion unless driven beyond DAW capability and practically noiseless;
• Typical Thermionic Culture warm, natural sound;
• Equally superb as mix buss eq and for individual instruments/tracks;
• Lovingly hand-made and tested in Harlow, England.