Vacuum Tubes

Part Number	Description / PDF	Quantity
NOS-211 TubeDepot	211 / VT4C GE	0
245STANDARD_TUBE_SET TubeDepot	VAC. TUBE SET FENDER BASSMAN 70	0
73STANDARD_TUBE_SET TubeDepot	VACUUM TUBE SET AMPEG GVT52112	0
425STANDARD_TUBE_SET TubeDepot	VACUUM TUBE SET MARSHALL TSL100	0
GROUPING_PAIR_GL-KT77 TubeDepot	GENALEX GLD LN KT77 PWR TUBE	17
GROUPING_PAIR_GL-B739 TubeDepot	GENALEX GLD ECC8112AT7 PREAMP TB	11
GL-B739 TubeDepot	GLD LN ECC81/12AT7 PREAMP TB	22
394STANDARD_TUBE_SET TubeDepot	VACTUBESET MARSHALL DSL 40 COMBO	0
110STANDARD_TUBE_SET TubeDepot	VAC. TUBE SET BOGNER METROPOLIS	0
NOS-12AX7-JANRAY TubeDepot	JAN RAYTHEON 12AX7	23
545STANDARD_TUBE_SET TubeDepot	VAC. TUBE SET TWO ROCK CORAL 50	0
GROUPING_THREE_PACK_JJ-ECC82 TubeDepot	JJ ECC82/12AU7 PREAMP TB	0
NOS-6922-AMPEREX TubeDepot	6922 AMPEREX	0
GROUPING_PAIR_SI-6L6WGS TubeDepot	TUBE PAIR 6L6WGS BLK PLATE PWR	3
555-0113-545 TubeDepot	GROOVE TUBES GTE34LS MED DUET	0
GROUPING_PAIR_SO-6SL7GT TubeDepot	SOVTEK 6SL7GT PREAMP TUBE	9
253STANDARD_TUBE_SET TubeDepot	VACUUM TUBE SET FOR FENDER CHAMP	0
NOS-5R4WGB TubeDepot	5R4WGB JAN CETRON	0
NOS-VT229 TubeDepot	WWII ERA VT229 / 6SL7GT	75
39STANDARD_TUBE_SET TubeDepot	TUBESET MASTERSOUND COMPACT 300B	0

Vacuum Tubes

1. Overview

Vacuum tubes (electron tubes) are sealed glass/ceramic devices containing electrodes in a vacuum environment to control electron flow. While largely replaced by solid-state electronics, they remain critical in high-fidelity audio equipment, high-power RF transmitters, and niche applications requiring unique tonal characteristics. Their importance lies in superior sound quality perception in audio amplification and robust high-voltage handling capabilities.

2. Major Types and Functional Classification

Type	Functional Characteristics	Applications
Triode	Three-electrode structure with high linearity and low distortion	Pre-amplifiers, guitar amplifiers (e.g., 12AX7)
Pentode	Five-electrode design with added screen/grid for higher gain	Power amplifiers, broadcast transmitters (e.g., EL34)
Beam Tetrode	Focuses electron beam to reduce space charge	High-efficiency power amplifiers (e.g., 6L6GC)
Cold Cathode Diode	Non-heated cathode for rectification	Voltage regulation, early radio circuits
Gas-Filled Tubes	Gas ionization for voltage stabilization	Thyratrons in high-power switching

3. Structure and Components

Typical vacuum tube construction includes:

Envelope: Borosilicate glass/metal-ceramic housing
Electrodes: Cathode (electron emitter), Control Grid (current modulator), Screen Grid (pentoide), Plate/Anode (electron collector)
Filament: Tungsten/rhenium heater for thermionic emission
Getter: Barium coating to maintain vacuum integrity
Bases: Octal/Noval pin configurations for electrical connection

4. Key Technical Specifications

Parameter	Description	Importance
Max Plate Voltage	Up to 1500V for power tubes	Determines breakdown resistance
Transconductance (Gm)	5-20 mA/V range	Impacts gain and dynamic response
Amplification Factor ( )	10-100	Defines voltage gain potential
Noise Figure	0.5-3 dB	Audio signal purity
MTBF	2000-10,000 hours	Reliability prediction

5. Application Fields

Major application areas include:

High-end audio: Pre-amps (e.g., Manley Reference), Guitar amps (Fender Twin Reverb)
Medical imaging: X-ray generators (Siemens Megalop)
Broadcast: AM/FM transmitters (Continental Electronics 816C)
Industrial: RF heating (Inductotherm units)

6. Leading Manufacturers and Products

Manufacturer	Headquarters	Representative Product
Euro Audio Team	Slovenia	45 Single-Ended Triode
Mullard	UK	EL34B-M matched quad
Svetlana	Russia	6N3S-W tube
Tung-Sol	USA	5881WXT power tube
JJ Electronic	Slovakia	EL84M-STR matched pair

7. Selection Recommendations

Key considerations:

Application Type: Audio vs. RF vs. industrial
Operating Voltage/Current: Match with power supply capabilities
Microphonics: Critical for pre-amp stages
Bias Requirements: Fixed vs. cathode bias configurations
Availability: NOS (New Old Stock) vs. current production

8. Industry Trends Analysis

Current trends show:

Audio Renaissance: 12% CAGR in high-end tube amplifier market (2023-2028)
Miniaturization: Development of subminiature tubes for portable devices
Hybrid Designs: Integration with solid-state components in modern equipment
Material Innovation: Carbon nanotube field emission research
Environmental Compliance: RoHS exemptions for audio tubes maintained until 2029