TBS - Tracking Bias Supply Kit for Fixed-Bias


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The TBS provides an easy installation of a tracking bias supply for fixed-biased amplifiers. The proportion of bias voltage to tracked voltage is easily adjusted changing one resistor on the TBS card, but this is only neceassary for use with EL-84s.


Includes a bias pot to set the bias voltage to the output stage. For individual bias pots per tube, simply parallel more bias pots and split their output feed.

TBS works best with a low-impedance raw bias supply. This can be a winding on the existing power transformer, or through use of our RBX Raw Bias Auxiliary Supply Kit. Also, see the article "Raw Bias Supply Modifications" on this site in the Technical Articles section.

Our books TUT2, TUT4 and TUT6 explain how to use regulated bias supplies and the special performance capabilities this can add to an amp.

If your stock amp is cathode-biased, add our RBX and TBS kits to have fixed-bias. You can still switch between cathode bias and fixed-bias using one of the methods outlined in the TUT-series. Use the TBS to "convert" an SV2 into an SV1.

PCB dimensions: 1.15 x 0.8", 29 x 20mm

Kit requires assembly.

Kit includes notes with installation tips + layout and schematic diagrams of the kit.

For more info, see "Selecting a Power Scaling Kit".

About London Power

London Power was founded in 1990 by Kevin O'Connor, after two decades of research into innovative audio amplification techniques. Kevin is an audio designer, author and speaker, known for his proprietary methodology called Power Scaling, and for his eleven books on audio subjects. Whether you seek amps, kits or information, you'll find useful answers here on not just the "how" but the "why" of audio amplifier design. Please enjoy the information on this site, and don't hesitate to contact us with questions.

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