12AX7 / ECC83 NOS MULLARD Blackburn 1964 – Short Gray Plates – Halo Getter – Low Noise & Mic

12AX7 / ECC83 NOS MULLARD – Blackburn (Great Britain) 1964
Short Gray Plates – Halo Getter – Balanced Sections – Low Noise & Microphonics

Description

This NOS MULLARD 12AX7 / ECC83 was produced in the historic Blackburn factory (Great Britain) in 1964 and belongs to the mature phase of Mullard production of the early 1960s, recognizable by the restyled branding.

The configuration with short gray plates and halo getter identifies a technically advanced version, appreciated for its electrical stability, operational silence and great tonal coherence.

The example is in authentic NOS condition , tested on AMPLITREX AT-1000 with VERY STRONG result, it features balanced sections and low noise and contained microphonics. A reliable tube, musically balanced and perfectly suited to both hi-fi and quality instrumental applications.

Sound Characteristics

Bass: Compact, controlled, and well-structured. The low range is precise and defined, with excellent articulation and no tendency toward excess.

Mids: The typical Mullard character is fully present: warm, natural, and three-dimensional. Vocals are fluid and believable, with a balanced and engaging harmonic texture.

Highs: Refined, well-extended, and integrated. The highs are airy yet controlled, allowing for long, never-fatiguing listening sessions.

Dynamics: Smooth and stable. Excellent microdynamics and responsive yet composed transient response, with great overall musicality.

Soundstage: Wide and well-focused. The soundstage is stable and coherent, with natural separation of musical lines.

🎧 Use in Hi-Fi Amplifiers

Ideal for:

• input and pre-amplification stages,
• integrated and pre-hi-fi where silence and stability are required,
• medium-high level systems that benefit from tonal balance and naturalness.

Particularly suitable for jazz, classical, vocal and acoustic music.

🎸 Use in Music Applications

Also highly appreciated in:

• vintage and boutique guitar amplifiers,
• V1 position, thanks to low noise & low microphonics and well-balanced sections.

It offers controlled harmonic response, good definition and the classic British Mullard character in a mature and stable version.

🎯 Note for audiophiles

• VERY STRONG issue,
• balanced sections,
• AMPLITREX professional test,
• original Blackburn production with restyled logo.

A valve designed for those who want the authentic Mullard sound in a more recent, reliable version that can be perfectly used in hi-fi and music systems, with the usual Vacuum Tubes Treasures quality standard.

Test Results:

Valve tested on AMPLITREX AT-1000 Tube Tester:

• Test Conditions: Va = 250V ; Vg = -2V
• Average 100%: Gm = 1600 ; Ia = 1.2 mA
• Test Result: VERY STRONG

Valve:

• Section 1: Gm = 1500 ; Ia = 0.9 mA
• Section 2: Gm = 1500 ; Ia = 1.1 mA

• Microphonics: Low. Tested and approved for use in hi-fi, including phono stages and guitar amplifiers. Also suitable for V1.
• Noise: Low and well-controlled. Silent operation in hi-fi and music amplifiers in the intended positions.
• Balance: The sections are coherent and well aligned, making the valve also suitable for use as a phase inverter in hi-fi and instrumental applications.
• Output Quality: Excellent – ​​Very strong and stable output, no fluctuations.
• Short circuits and GAS: Absent.

Conditions:

• Condition: NOS - New Old Stock - Tested and working - Supplied in our custom box for optimal protection.
  
• Functionality: Fully functional.
  
• Cosmetic condition: Excellent – ​​Excellently preserved lettering, minimal signs of wear. See photos for details.
  
• Manufacturing Code: I63 B4D5 → I6x indicates an ECC83 with the sequential progression of x, where the increment of x indicates the manufacturing changes - B4D5 B → Mullard, Blackburn - 4 (out of four digits) → 1964 - D → April - 5 → 5th week of the month
  

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