Tube Amp Doctor (TAD) KT66 Power Tube

Brand: Tube Amp Doctor
Product Code: TAD-RT821
Warranty: 6 Months
Premium Matching: *

$99.00 - $396.00
Tube Amp Doctor
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The Legendary Old-School Tone!

The TAD KT66 is our remake of the great British KT66 by MOV (MO Valve), GEC, Genalex and Gold Lion. This tube is THE REAL THING. It has a large curved glass envelope and a rounded brown base. It made the Marshall JTM45 Plexi amps famous in the 60's and the Quad Hi-Fi amps a legend.

Speaking of legends: SRV used the KT66 in his Fender Amps for his outrageous, gigantic guitar sound.

For a full bodied thick tone with larger headroom, smooth but detailed top end, single channel amps, dynamic playing, vintage British Rock and Roll as well as for the new modern vintage amps 2266 and 2466.

It can also replace the 6L6GC and 5881 tubes.

TAD Premium Selection

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

A: All power tubes labelled Premium Selected have passed the following tests:

  • Plate Current (PC) and Amplification (TC)
  • Low Noise Test
  • Microphonic Test
  • Sonic Test
  • Shock Test
  • Listening Test
  • Shorts & Leakage Test

Premium RT-Matching of Power Tubes

Our Premium Matching is an exact matching of power tubes with identical Plate Current (PC) and Transconductance (TC).

Electrical Characteristics
Heater Voltage (AC or DC) Minimum: 5.8 V, Nominal: 6.3 V, Maxium: 6.8 V
Heater Current 1.27 A
Cathode Oxide-Coated, Unipotential
Cathode-to-Heater Potential, Max. 150 V
Direct Interelectrode Capacitance, Max.* Grid No. 1 to Cathode and Grid No. 3, Grid No. 2, Base Sleeve and Heater: <16.0 pF / Plate to Cathode and Grid No. 3, Grid No. 2, Base sleeve and Heater: <11.5 pF / Grid No. 1 to Plate: <1.1 pF

* Without external shielding, nominal values.

Operating Position Vertical
Base Octal, 8-Pin
Dimensions - Height 129 mm (5.078”)
Dimensions - Seated Height 116 mm (4.566”)
Dimensions - Diameter 51 mm (1.00”)
Cooling Convection
Approximate Net Weight 72 g (2.54 oz.)
AF Power Amplifier Maximum Ratings
DC Plate Voltage 500 V
Grid No. 2 DC (Screen) Voltage 400 V
Grid No. 1 DC (Control) Voltage -300 V
DC Cathode Current 100 mA
Plate Dissipation 25 W
Transconductance (Nominal) 8,500 mS
Grid No. 2 DC (Screen) Dissipation 3.5 W
Typical Operatation - AF Power Amplifier, Class A1 (Single Tube)
Plate Voltage 250 V
Grid 2 Screen Voltage 250 V
Grid 1 Control Voltage** -15 V
Plate Current 82 mA
Grid 2 Current 5 mA
Peak Input Grid 1 Voltage 15 V
Load Resistance 2.2 kΩ
Output Power at 9% Distortion 7.25 W

** Approximate value (set to zero signal plate current).

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