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Tube Amp Doctor - 7025S Premium - Preamplifier Tube

SKU: RT011


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Mullard style, delivers rich, harmonically complex tone

The new TAD 7025-S is a faithful reproduction of the legendary original Mullard ECC83 valve which was made in England until the late 1960s. This tube is regarded as the holy grail among the double-triode preamp valves. The extra thick mica spacers support the rugged mechanical construction and the careful TAD quality control proceedure ensures performance stability and low microphonics.

The TAD 7025S delivers a rich, harmonically complex tone and mid-range warmth that is just outstanding compared to any other currently manufactured tube today. Great warm and clean tones and creamy overdrive.

We recommend this tube for classic British style amps (rather than for modern high-gain amps) as well as for vintage-style open-back combos to achieve a stunning complex tone with silky smooth but rich tone.

The TAD 7025 S can replace any ECC83, E83CC, 12AX7, 12AX7A, 12AX7M, 12AX7WA/WB/WC/LPS/EH, 5751 or 7025.Upgrades 12AX7A and ECC83 tubes. Replaces E83CC especially recommended in second positions or tone stacks in vintage British amps.


Q: When does a preamp tube become a Premium Selected tube?

A: All preamp tubes labeled Premium Selected have passed the following tests:

    • Low Noise Test
    • Microphonic Test
    • Gain Test
    • Sonic Tests
    • Shock Tests
    • Listening Tests
    • Balanced Output Test

Matching and Selecting Options for Preamp Tubes

Matching in Pairs for preamp tubes means that two tubes show identical gain, hence, four characteristically identical systems. This matching method includes our Balance-Selection. We highly recommend this matching method for hi-fi systems.

TAD Premium Selected/Highgrade tubes are guaranteed for a period of 6 months (according to terms of warranties) for the quality criteria mentioned above.

RohS Compliant





      • Voltage (AC or DC) - 12.6V +/- 1.0 (Series), 6.3 +/- 0.5 (Parallel)
      • Current - 0.15(Series), 0.3 (Parallel)

Heating - Indirect

Cathode-to-heater potential, max - 150V

Direct interelectrode capacitances, max***

      • Grid to plate - 1.8pF
      • Grid to cathode - 1.9pF
      • Grid to heater - 0.4pF
      • Plate to cathode - 0.7pF


      • Operating position - Any
      • Base - E9-1, small button 9-pin
      • Dimensions - 57mm(height), 50mm(seated height), 22.5mm(diameter)
      • Cooling - Conventional
      • Approximate net weight - 13g

AF Power Amplifier

Maximum Ratings

    • DC plate voltage - 330V
    • Positive DC grid voltage - 0V
    • Negative DC grid voltage - -55V
    • DC cathode current - 8mA
    • Plate dissipation - 1.2W
    • Bulb temperature (surface hottest point) - 160 degrees celcius