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Thermionic Culture Swift EQ - Two Channel EQ

Thermionic Culture Swift EQ - Two Channel EQ

This two channel equaliser has been designed to be as much at home in tracking individual instruments or sitting across a stereo mix buss to equalise the final mix. As with other Thermionic Culture units, such as The Phoenix, all controls are clearly labelled and setting up the eq is quick and easy, so it’s named after Britain’s fastest bird in level flight.

The Swift utilises 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, plus added features of Thermionic Culture's own designs.

The main electronics are based around a 1950s EMI desk but with extended top and bass response. It has a BAXANDALL type active eq and an added a 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 we have chosen just 4 frequencies, with 3 “Q” settings.

Special features of The Swift 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. The Swift does not use indented ones for subtlety and reliability reasons.

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, its electronic design is a great improvement on the old ones. There are only two valves per channel to keep colouration minimal. It 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. In all fairness to the original designers, these valves were probably not then available at the design stage so this gives a little advantage!


  • All-valve signal path using NOS and new production valves
  • Combines features of the best USA and UK equalisers 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
  • Our own 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 miniscule 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;

Made in England.