The **6Z1-R** (often written as **6Z1P-EV** in Western transliteration from the Cyrillic **6Ж1П-ЕВ**) is a miniature 7-pin pentode vacuum tube. It was primarily manufactured in the Soviet Union and is widely used today in vintage radio restoration and low-cost vacuum tube headphone amplifiers. --- ### 1. Technical Specifications The "EV" (or -R) suffix denotes a "Special Quality" version, meaning it is designed for high reliability, long life (typically >2000 hours), and low microphonics compared to the standard 6Z1. | Parameter | Value | | :--- | :--- | | **Type** | Sharp-cutoff Pentode | | **Heater Voltage** | 6.3 Volts | | **Heater Current** | 170 mA | | **Plate Voltage (Max)** | 200 V | | **Transconductance** | 3.9 to 5.1 mA/V | | **Base Type** | 7-Pin Miniature (B7G) | --- ### 2. Pinout Configuration The 6Z1-R follows the standard 7-pin pentode layout: | Pin Number | Function | | :--- | :--- | | **1** | Control Grid (G1) | | **2** | Cathode | | **3** | Heater | | **4** | Heater | | **5** | Plate (Anode) | | **6** | Screen Grid (G2) | | **7** | Suppressor Grid (G3) | --- ### 3. Equivalents and Substitutes If you are looking for replacements or equivalents for the 6Z1-R, the following tubes are compatible (though minor sonic differences may exist): * **EF95:** The standard European equivalent. * **6AK5:** The American equivalent (widely used in military gear). * **5654 / 403B:** Premium, high-reliability versions of the 6AK5. * **6J1:** The Chinese version (commonly found in budget Nobsound or FX-Audio amps). --- ### 4. Common Applications Due to its high frequency capabilities and low noise, the 6Z1-R is used in several specific areas: 1. **RF/IF Amplification:** Originally designed for wideband high-frequency amplification in radio receivers. 2. **Audio Pre-amplifiers:** Frequently used in the "buffer" stage of modern hybrid tube amplifiers to add "warmth" to the sound. 3. **Military Equipment:** The "-R" or "-EV" versions were built to withstand high vibration and shocks in Soviet military hardware. --- ### 5. Sample Schematic (Simple Preamp Stage) In a typical audio application, the 6Z1-R might be wired as follows: ```text Input Signal -> [Capacitor] -> Pin 1 (Grid) Pin 2 (Cathode) -> [Resistor + Bypass Cap] -> Ground Pin 5 (Plate) -> [Load Resistor] -> B+ (High Voltage) Pin 7 (G3) -> Connected to Cathode (Pin 2) Output Signal taken from Pin 5 via a Coupling Capacitor ```