A3-500 300B Amplifier

The A3-500 amplifier is the first Electra-Fidelity amplifier to use Jack Elliano's proprietary Class A3 design with Low IMD circuit. The amplifier is a 300B single ended triode amp resulting in a robust 10 watts per channel. The amp is supplied with Sovtek 6A3 tubes that is the exact specification and plate size as an original 300B, but using the smaller 6A3 bottle. The driver tubes are 6ER5 or 12AT7 (customer choice).

The circuit design of this amplifier has a new and different set of rules than others. The bias for the A3-500 is preset for the tubes specified for use with the amplifier. In addition, the circuit is a low IMD two-stage amplifier that uses an algebraic summing loop. This lowers IMD, or mixing of low and high frequencies commonly heard with other amplifiers as amplitude distortion present at high music levels. A circuit with a fixed tuning process keeps this loop operating at the optimal level. As such, keeping the tubes near optimum operation is needed to assure top performance.

This circuit, unlike others, will produce a noticeable increase in power level that is not due to the power output. The sound will not distort until clipping occurs. Greater separation of voices and instruments will be maintained and not congest, up to full recorded levels. In addition, speaker and amplifier matching also contribute significantly to excellent sound reproduction. With properly matched speakers the first few watts of the A3-500 will develop the best reproduction even with very high peaks.

Specifications & Details

  • Power Output at clipping (1.4V input): 10 watts.
  • Bandwidth (1 watt): -1 dB 18 Hz to 36k Hz
  • THD (1 watt): 0.2%
  • THD (midpower): 0.4%
  • IMD (1 watt): 1%
  • IMD (midpower): 3%

Tubes: 2 x 300B (supplied with Sovtek 6A3) and 2 x 6ER5 or 12AT7 (customer choice) per channel.


$9,995 - Monoblocks that include steel chassis with choice of automotive paint finishes. Includes partial silver secondary output transformers.

The following are photos of a one-of-a-kind custom set of monoblocks, as well as our A3-500 in automotive finish. This custom set is available for $9995 and features chrome plated top plate, 24k gold plated transformer bell ends, and solid wood walnut chassis. In addition, the output transformers feature solid silver primary and secondary windings. The driver tubes in this set uses the 6ER5.