Set of 3 Ultron EF86 Tubes – Mesh Shield (Tested Good)

German Heritage & Selection 🇩🇪
These Ultron EF86 Tubes represent the golden age of vacuum tube electronics. Ultron-Elektronik, based in Munich, was renowned not for manufacturing, but for premium selection. They sourced valves from the finest European factories (such as Siemens, RFT, or Philips) and branded only those that met their strict quality standards. Buying Ultron means buying a component that passed a rigorous German quality control process.

Technical Construction: The Mesh Advantage
What sets these specific specimens apart is their internal architecture. Unlike standard solid-plate versions, these Ultron EF86 Tubes feature a fine metal mesh shield.

Superior Shielding: This mesh acts as a Faraday cage, drastically reducing electrostatic interference and “hum.” This is critical for the EF86, which is often used in the first stage of amplification where signals are most vulnerable to noise.
Low Microphonics: The robust construction minimizes mechanical vibration pickup, ensuring that sound from your speakers doesn’t feedback into the tube€”a common issue in lesser EF86s.

Condition & Testing Report
Reliability is paramount. This set has been tested for emission on a calibrated Kyoritsu K-119 Tube Tester.

Test Results: As shown in the gallery, the needle registers firmly in the high “GOOD” (Green) zone. This indicates a strong electron emission, equivalent to NOS (New Old Stock) performance.
Physical State: While the original boxes show signs of vintage shelf wear, the tubes themselves are pristine. The glass is clear, pins are straight, and the getter flash (silver coating) is healthy and tight.

Recommended Applications
These pentodes are a direct high-performance replacement for the 6267 standard. They are highly recommended for:

Guitar Amplifiers: Essential for the “EF86 Channel” in VOX AC15, AC30, Dr. Z Z-28, and Matchless DC-30 amplifiers.
Hi-Fi Audio: Perfect for vintage Quad II preamps, Leak components, and phono stages requiring an absolute silent background.
Studio Microphones: Suitable for circuits based on the Neumann U67, where low noise floor is non-negotiable.

Technical Datasheet Summary:

Type: Sharp-cutoff Pentode / Audio Preamplifier.
Base: 9-Pin Miniature (Noval B9A).
Filament: 6.3V / 0.2A.
Plate Voltage: 250V (Typical).
Classification: Low Noise / Low Microphony.
Origin: Germany (Ultron Selection).

Frequently Asked Questions (FAQ)

1. Are these tubes brand new?
Based on the Kyoritsu K-119 test results showing emission near 100%, these tubes perform as NOS (New Old Stock). While the packaging shows age, the tubes function electrically as if they just left the factory.

2. What is the benefit of the “Mesh Shield”?
The internal mesh structure provides superior shielding against electromagnetic interference compared to solid plates. This makes Ultron EF86 Tubes exceptionally quiet, offering a cleaner sound with more detail and less background hum.

3. Can I swap this tube with a 12AX7 / ECC83?
No. The EF86 is a pentode, while the 12AX7 is a dual triode. They have different pinouts and electrical characteristics. Only use these in sockets specifically designed for EF86 or 6267 tubes.

4. Do I need to bias my amp when installing these?
In most audio preamp circuits, the EF86 is “cathode biased” (self-biasing). This means they are generally “Plug & Play.” However, for vintage equipment, having a technician verify voltages is always a good practice.