Vacuum Tube - 12BH7A-STR, Tube Amp Doctor, Premium Selected

Tube Amp Doctor (TAD)
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Vacuum Tube - 12BH7A-STR, Tube Amp Doctor, Premium Selected

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Maximum of Reliability - Outstanding Tonal Quality!

The all-new TAD 12BH7A-STR combines the best sonic and mechanical performance of the NOS RCA black plate with advantages of the GE version. A maximum of reliability with outstanding tonal quality makes the new balanced selected TAD 12BH7A-STR the first choice for Ampeg SVTs, the Blackstar HT-5 and high-end applications.

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

Item ID:
Tube Amp Doctor (TAD)
Product Measurements
Amplification Factor, Class A17
Body Height66 mm
Cathode Bias Resistance1 MΩ
Cathode Current (Ik)20 mA
Cathode to Heater Voltage≤ 100 V
D.C. Grid Voltage, negative-50 V
D.C. Grid Voltage, positive, AF Power Amp0 V
D.C. Plate Voltage, AF Power Amplifier330 V
D.C. Plate Voltage, Class A250 V
D.C.Plate Voltage On Vertical Deflection Amplifier500 V
Fixed Bias Resistor250 kΩ
Grid Voltage, class A (Ug)-10.5 V
Grid to Cathode Capacitance (cg/k)2.9 pF
Grid to Heater Capacitance (cg/h)2.9 pF
Grid to Plate Capacitance (ca/g)2.5 pF
Heater Current0.3 / 0.6 A
Heater Voltage6.3 / 12.6 V
Item Diameter22.5 mm
Item Height73 mm
Plate Current, class A (Ia)11 mA
Plate Dissipation, AF power amplifier (Wa)3.5 W
Plate Resistance, class A (Ra)5.4 kΩ
Plate to Cathode Capacitance0.5 pF
Transconductance, Class A (S)3.1 mA/V
Packaging Information
Packaging Dimensions0.878 in. × 0.878 in. × 2.688 in.
Weight (Packaging)0.04 lbs.

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Specifications, Files, and Documents

PDF: Specification Sheet Specification Sheet320.48 KB

Questions and Answers

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Asked by Anonymous on October 24th, 2018.
October 24th, 2018
Staff Member
This is not an acceptable replacement for 12AX7s or 12AU7s. These are used in some Ampeg SVTs from the 80s and 90s, but unless your amp calls for 12BH7s, it is not recommended that you use these in your amp.

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