ZX-6SN7 Linlai Audio Triode factory matched Pair

Linlai ZX-6SN7 – factory-matched dual-triode pair for audio driver stages

The Linlai ZX-6SN7 set contains two current-production indirectly heated dual triodes. Each valve combines two electrically separate medium-mu triode systems in one eight-pin octal envelope and is suitable for compatible preamplifier, driver, buffer and phase-inverter stages.

BTB offers the article as a factory-matched pair with gold-plated base pins and gold-plated grids. Pair matching describes the relationship between the two valves; the pair page does not explicitly guarantee additional internal balance between the two triode systems in each valve.

Suitable applications

• Stereo line-level and hi-fi preamplifiers using one 6SN7 per channel
• Driver stages for compatible valve power amplifiers
• Long-tail-pair, differential and phase-inverter stages using two 6SN7 valves
• Valve headphone amplifiers and buffer stages with a correctly calculated operating point
• Service and replacement in equipment that explicitly specifies 6SN7 or 6SN7GT valves

Pair selection and product configuration

Package contents

Two Linlai ZX-6SN7 valves supplied as a factory-matched pair

Matching

Factory-selected pair; the visible product information does not publish the test point or permitted spread

Internal section balance

Separate from pair matching; the pair page does not explicitly state that the two triode systems within each valve are additionally balanced

Base

Eight-pin octal base, identified by BTB as K8A

Pin finish

Gold-plated base pins according to the current BTB product version

Grid construction

Gold-plated grids according to the current BTB product description

Maximum envelope diameter stated by BTB

Approx. 53 mm; check the equipment's available height and spacing to the cover and adjacent valves

Country of origin

China according to the current BTB product page

Technical 6SN7 reference data

Valve type

Indirectly heated medium-mu dual triode

System construction

Two separate triode systems, each with its own plate, control grid and cathode

Heater voltage

6.3 V AC or DC

Heater current

600 mA per valve; the pair draws a total of 1.2 A from the heater supply

Typical reference operating point per system

250 V plate voltage, approximately -8 V grid bias and approximately 9 mA plate current

Amplification factor

Approximately 20

Transconductance

Approximately 2.6 mA/V at the reference operating point

Plate resistance

Approximately 7.7 kΩ at the reference operating point

Limiting values

The publicly visible ZX-6SN7 product information does not provide a complete Linlai-specific set of limits. The equipment circuit and documentation for the actual supplied version therefore remain decisive

Pinout

Pin 1

Control grid of triode system 2

Pin 2

Plate of triode system 2

Pin 3

Cathode of triode system 2

Pin 4

Control grid of triode system 1

Pin 5

Plate of triode system 1

Pin 6

Cathode of triode system 1

Pins 7 and 8

Heater; the pinout follows the conventional underside view of the base

Comparison with related valve types

6SN7GT, 6SN7GTA and 6SN7GTB

These belong to the same basic family but can differ in limiting values, envelope shape and warm-up requirements. The equipment specification takes precedence

6SL7

Eight-pin dual triode with substantially higher gain and lower heater current; not an unchecked direct substitute despite the same socket format

CV181

Historical and current versions are not specified uniformly. Verify heater demand, dimensions, pinout and limits before substitution

6N8S or 6H8C

Related designations from other production sources; compare the exact version with its data sheet and the equipment circuit

Selection and application notes

A pair with closely corresponding valve values can support channel consistency in stereo equipment or symmetry between two identical driver stages. Where the two sections within one dual triode must be especially close, an explicitly balanced selection or separate measurement is also required.

BTB subjectively positions the ZX-6SN7 as warmer than the Linlai E series and with more punch than the D series. The audible result also depends on the operating point, load, coupling capacitors, power supply, feedback and complete audio system.

The approximately 53 mm envelope diameter is greater than that of many classic GT versions. Check socket spacing, enclosure height, shields and adjacent components before ordering.

Hazardous plate voltages and stored charge may remain inside the equipment. Disconnect the mains supply, allow the valves to cool and leave internal servicing to suitably qualified personnel.

Questions about selection and use

Is the Linlai ZX-6SN7 factory-matched pair suitable for stereo preamplifier and driver stages?

Yes, the Linlai ZX-6SN7 factory-matched pair is suitable for compatible stereo preamplifier, driver and phase-inverter stages using two 6SN7 valves. Heater demand, operating point, socket wiring, height and diameter must match the equipment.

Can the Linlai ZX-6SN7 pair replace two existing 6SN7 or 6SN7GT valves?

Yes, the Linlai ZX-6SN7 pair can replace two 6SN7 or 6SN7GT valves in compatible circuits when the 6.3 V heater, octal base, pinout and operating limits match. The 6SL7, historical CV181 versions and other related dual triodes are not unchecked direct equivalents.

Is a factory-matched pair useful even though each 6SN7 contains two triode systems?

Yes, a factory-matched pair supports closely corresponding values between the two valves and therefore between stereo channels or balanced stages. The designation does not automatically guarantee that the two triode systems within each individual valve are also internally balanced.