Genalex
Features
Gold-plated grid wire for superior conductivity and tonal purity
Carbonized screen grids for enhanced durability and longevity
Tri-alloy clad plate structure for exceptional performance
6550 equivalent providing versatile amplifier compatibility
Exceptional sound quality with rich harmonics and low distortion
Designed for Hi-Fi audio output stages in premium tube amplifiers
What's in the Box?
Warranty
The Genalex Gold Lion KT88 is a world-class beam tetrode power tube, widely celebrated as the "King of Power Tubes" for its massive headroom and legendary British tone. This premium reissue faithfully recreates the original 1957 Marconi-Osram design, utilizing a sophisticated tri-alloy clad plate structure and carbonized screen grids to deliver high power output with remarkably low distortion. Audiophiles frequently choose the Gold Lion KT88 to revitalize both classic and modern amplifiers, as it provides a vast, deep soundstage characterized by tight, authoritative bass, creamy mids, and sparkling, detailed highs that remain non-fatiguing even during extended listening sessions.
Engineered for maximum reliability in high-voltage applications, these tubes feature gold-plated grid wires that ensure superior electrical conductivity and exceptional thermal stability. This robust construction makes them a preferred choice for demanding systems like the McIntosh MC275 or Audio Research amplifiers, offering a significant performance upgrade over standard 6550 or generic KT88 varieties. By providing ultra-clean headroom and a transparent, lifelike presentation, the Genalex Gold Lion KT88 stands as a top-tier investment for listeners seeking to achieve the ultimate in analog fidelity and dynamic range without the extreme cost of elusive vintage stock.
| Parameter | Specification |
|---|---|
| Physical Specifications | |
| Model | 6550ЕН, KT88EH, KT88SV, KT88 Genalex |
| Type | Beam Tetrode |
| Construction | Glass bulb with octal base, equipotential cathode |
| Application | Low frequency power amplification in output stages of HI-FI audio |
| Envelope Diameter | Ø52 mm (-2) |
| Overall Height | 117 mm (-2.5, +3.5) |
| Pin Configuration | 1: Heater 2, 7: Plate 3: Grid 2 4: Grid 1 5: Cathode, beam-forming screen 6: Outer metal screen 8: Heater |
| Heater Specifications | |
| Filament Voltage (Nominal) | 6.3 V |
| Filament Voltage (Min) | 5.7 V |
| Filament Voltage (Max) | 6.9 V |
| Heater Current (Nominal) | 1.5 - 1.7 A |
| Operating Conditions Limits | |
| Plate Voltage | 400 V (typical operating), 300 - 500 V (range) |
| Second Grid Voltage | 225 V (typical), 200 - 300 V (range) |
| First Grid Voltage (Negative, Max) | -300 V |
| First Grid Voltage (Positive, Max) | 0 V |
| Cathode-Heater Voltage (Pulse) | +300 V |
| Power Dissipation at Plate (Max) | 42 W |
| Power Dissipation at Second Grid (Max) | 6.6 W |
| Temperature at Most Heated Part of Envelope (Max) | 523 K° |
| First Grid Circuit Resistance (Max) | 0.051 MΩ (fixed bias) 0.1 MΩ (self-bias, triode/tetrode connection) |
| Electrical Parameters | |
| At: Filament voltage 6.3 V, Plate voltage 400 V, First grid voltage -16.5 V, Second grid voltage 225 V | |
| Cathode Current (Nominal) | 75 - 125 mA |
| Plate Current (Nominal) | 58 mA |
| Second Grid Current (Nominal) | 9.5 - 14 mA |
| First Grid Reverse Current | 0.7 µA |
| First Grid Cut-off Voltage (Negative) | -192.5 V (at plate voltage 400 V, second grid voltage 225 V) |
| Cathode-Heater Insulation Resistance | 44 MΩ (at cathode-heater voltage +300 V) |
| Performance Characteristics | |
| At: Filament voltage 6.3 V, Plate voltage 400 V, First grid voltage -16.5 V, Second grid voltage 225 V, Plate circuit resistance 3.0 kΩ, First grid alternating voltage (efficacious) 11.7 V | |
| Output Power (Nominal) | 18.0 - 230 W |
| Slope of Characteristic (Nominal) | 8.2 - 10.0 mA/V |
| Distortion Factor | 5.7 - 6.9% |
| Additional Information | |
| Compatible Models | 6550ЕН, KT88EH, KT88SV, KT88 Genalex |
| Characteristic Curves | Plate current vs. Grid voltage and Plate voltage curves available at various operating conditions (Ep=Eg2 at 300V, 400V, and 500V with multiple grid voltages) |