12AY7EH 6072 EHX tube V1+low mic+lownoise Röhren Set

Electro-Harmonix 12AY7EH / 6072A – low-noise V1 set of two

The Electro-Harmonix 12AY7EH/6072A is an indirectly heated medium-mu dual triode with a nine-pin B9A Noval base. It is suitable for compatible input, preamplifier and driver stages requiring substantially less gain than an ECC83 or 12AX7.

This BTB set contains two valves selected for low microphony, low hum and low noise in sensitive V1 positions. The optional matched / balanced grade additionally selects all four triode systems in the two valves for closely corresponding electrical values.

Suitable applications

• V1 input stages in compatible guitar and bass amplifiers
• Tweed-style preamplifiers whose circuits specify a 12AY7 or 6072A
• Compatible 12AX7 stages requiring a substantial reduction in gain
• Hi-fi, line-level and studio preamplifiers with a suitable operating point
• Stereo, differential and driver stages when the matched / balanced option is selected
• New builds with a Noval socket and an adequately rated heater supply

BTB selection and options

Package contents

Two Electro-Harmonix 12AY7EH/6072A valves

Standard selection

Checked for low microphony, low hum and low noise in V1 applications

Matched / balanced option

Additional electrical selection of all four triode systems for closely corresponding values

Factory matching

The manufacturer does not offer Platinum Matching for the individual type; the shop option refers to BTB selection

Production type

Current production

Country of origin

Russia according to the current BTB product page

Technical data

Valve type

Indirectly heated medium-mu audio dual triode

Type designations

12AY7EH and 6072A

Base

Nine-pin B9A Noval

Parallel heater voltage

Nominally 6.3 V; permitted range 6.0 to 6.6 V

Heater current at 6.3 V

340 to 370 mA per valve

Series heater voltage

Nominally 12.6 V; permitted range 12.0 to 13.2 V

Heater current at 12.6 V

170 to 185 mA per valve

Data-sheet test point per triode

250 V plate voltage and -4.0 V grid bias

Plate current at the test point

2.2 to 3.75 mA

Transconductance at the test point

1.3 to 2.1 mA/V

Amplification factor

35 minimum

Permitted section-current difference in the production sheet

Up to ±40% at the test point; optional BTB balancing is therefore technically relevant in symmetrical circuits

Maximum plate voltage

300 V

Maximum heater-to-cathode voltage

±100 V

Maximum cathode current

10 mA per system

Maximum plate dissipation

1.5 W per system

Maximum grid-leak resistance with fixed bias

1.0 MΩ

Maximum grid-leak resistance with cathode bias

2.0 MΩ

Dimensions

Maximum diameter approx. 22.5 mm and overall height approx. 56.5 mm

Pinout and heater wiring

Pin 1

Plate of triode system 2

Pin 2

Control grid of triode system 2

Pin 3

Cathode of triode system 2

Pins 4, 5 and 9

Connections of the split heater

Pin 6

Plate of triode system 1

Pin 7

Control grid of triode system 1

Pin 8

Cathode of triode system 1

6.3 V heater connection

Join pins 4 and 5 and apply the supply between this connection and pin 9

12.6 V heater connection

Apply the supply between pins 4 and 5; pin 9 is not used for the heater

Comparison with 12AX7 and 5751

12AY7EH / 6072A

Amplification factor of at least 35 and comparatively high plate current at the stated operating point

ECC83 or 12AX7

Typical amplification factor around 100 and substantially greater gain in the same compatible stage

5751

Typical amplification factor around 70, placing its gain reduction between the 12AX7 and 12AY7

6072 and 6072A

Historical quality grades can differ; 12AY7EH/6072A is the official designation of the current Electro-Harmonix product

Selection and application notes

The 12AY7EH shares the basic base and heater-voltage arrangement of the ECC83 or 12AX7 but draws approximately 340 to 370 mA at 6.3 V rather than the typical 300 mA. Add the extra heater load when replacing several valves.

The actual gain reduction depends on the plate resistor, cathode resistor, feedback and load. The type should therefore not be selected from a percentage figure alone.

The optional matched / balanced grade is particularly relevant to stereo, differential and phase-inverter stages. In a simple V1 input stage, the included microphony and noise selection is usually the more important feature.

Hazardous plate voltages and stored charge may remain inside the equipment. Disconnect the mains supply, discharge the circuit and allow the valve to cool before replacement.

Questions about selection and use

Is the Electro-Harmonix 12AY7EH/6072A V1 set suitable for a compatible 12AX7 stage requiring substantially less gain?

Yes, the Electro-Harmonix 12AY7EH/6072A V1 set is suitable for compatible 12AX7 or ECC83 input stages where a substantial gain reduction is required. The operating point, circuit function and higher heater demand of up to 370 mA per valve at 6.3 V must be considered.

Can the Electro-Harmonix 12AY7EH/6072A be used in an existing 12AX7 V1 position?

Yes, the Electro-Harmonix 12AY7EH/6072A can be used in many compatible 12AX7 V1 positions because the base and heater connections match. The substantially lower gain, different operating point and additional heater load must suit the particular circuit.

Is the matched / balanced option useful for stereo and differential stages?

Yes, the matched / balanced option is useful when both valves and all four triode systems should have closely corresponding values, for example in stereo, differential or symmetrical driver stages. For a simple V1 position, the included acoustic selection is often sufficient.