Vacuum Tubes

Part Number	Description / PDF	Quantity
GROUPING_PAIR_SI-5881 TubeDepot	PAIR OF SINO 5881 PWR VAC. TUBE	3
TS-KT66 TubeDepot	KT66 NEW PRODUCTION PWR TUBE	15
553STANDARD_TUBE_SET TubeDepot	TUBE SET PRO PLUS 22	11
GROUPING_PAIR_EH-12AX7GP TubeDepot	ELECTROHARMONIX GLDPIN PREAMP TB	7
GROUPING_PAIR_MU-6V6GT TubeDepot	MULLARD 6V6GT NEW PRD PWR TUBE	1
390STANDARD_TUBE_SET TubeDepot	VACUUM TUBE SET MARSHALL 6100	0
NOS-EL84-TELE TubeDepot	TELEFUNKEN EL84 / 6BQ5	0
GROUPING_QUAD_TS-KT120 TubeDepot	4 OF TUNGSOL KT120 PWR VAC TUBE	0
GROUPING_PAIR_TS-6L6STR TubeDepot	TUNGSOL 6L6 STR NEW PRD PWR TUBE	0
NOS-5751 TubeDepot	5751 U.S. MADE VARIOUS BRANDS	71
GROUPING_QUAD_JJ-E34L TubeDepot	4 OF JJ E34L / EL34 PWR VAC TUBE	0
NOS-01A TubeDepot	01A UX LONG PIN ST SHAPE	0
270STANDARD_TUBE_SET TubeDepot	VAC. TUBE SET FENDER PRO REVERB	0
89STANDARD_TUBE_SET TubeDepot	VACUUM TUBE SET B52 AT112 COMBO	0
SO-6C41C TubeDepot	SOVTEK 6C41C PWR VACUUM TUBE	2
GROUPING_PAIR_TS-7591A TubeDepot	TUNGSOL 7591A NEW PRD PWR TUBE	8
TS-7591A TubeDepot	TUNGSOL 7591A NEW PRD PWR TUBE	16
600STANDARD_TUBE_SET TubeDepot	VACUUM TUBE SET FOR VOX AC30HW2	0
GROUPING_QUAD_TK-6L6GC TubeDepot	4 TELEFUNKEN BLK DIAMOND 6L6GC	2
SO-6L6WXT TubeDepot	SOVTEK 6L6WXT+ PWR VACUUM TUBE	14

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