Choosing and Using Vacuum Tubes Includes information on replacement tubes for hundreds of amplifiers! 4th Edition • $14.
About Groove Tubes® For over 30 years, Groove Tubes have been trusted and demanded by touring professionals and their techs around the world. Groove Tubes started in southern California, and through innovative design, rigorous selection and testing, GT-powered amps have rocked the world in some of the most famous rigs ever played from studio to stage.
Introduction to Vacuum Tubes Electric guitar and bass players over the past 50 years have been linked by a single critical piece of equipment: The tube amp. With all of the advances in transistor and digital technology, professionals still prefer tube amps as part of their musical arsenal from studio to stage. There are many reasons for this, and we will explore many of these factors in plain language, throughout in this guide.
What is “biasing”? Bias refers to the adjustment (generally in the power tube section) that controls the voltage of the grid of a tube. When the grid bias is properly set, the tubes are balanced in the circuit and produce a clean, powerful signal. It is like matching the engine RPM to the proper gear in a race car to achieve optimum performance for the desired speed. If the bias is not set correctly, the amp may not perform properly, or the tubes may wear out more quickly.
Tube Replacement? When, Why and How? Glass, metal, lots of little parts... tubes are subject to mechanical problems and are not meant to last a lifetime. The harder you work your tubes, the faster they wear out. Plus, there are a number of other factors that make tubes one of the easiest and least expensive “fixes” for your tube amp. 1. Tubes are subject to vibration damage.
Preamp Tubes These pass every Groove Tubes premium certification for microphonics, hum, physical characteristics and function. Quite simply the best preamp tubes you can buy — specifically designed and tested for musical instrument amplification and standard equipment on Fender amps. Outstanding and consistent performance for mixing and matching to get a signature tone from your amp.
Preamp Tubes (Continued) GT-ECC83-S Preamp Tube GT-12AU7 Preamp Tube GT-12AT7 (ECC81) Preamp Tube GT-12AY7 Preamp Tube Our highest-gain preamp tube, this tube has a huge amount of gain, with terrific output that makes it a great choice for driving modern, complex high-gain circuits.
Rectifier/Specialty Tubes These pass every Groove Tubes premium certification for microphonics, hum, noise floor, physical operation and characteristics. Includes rectifier tubes, phase inverters and specialty kits specifically designed and tested for musical instrument amplification applications as noted. GT-5AR4-R Rectifier Tube GT-5U4 Rectifier Tube Our highest-output rectifier tube. Originally used in early higherpowered Fender amps (40 watts or more) with tube rectifiers; also used in the Vox AC30.
6V6 Power Tubes The 6V6 is a low-output power tube (12-18 watts) often used in Fender amplifiers, including the Champ, Deluxe, Dual Professional, Vibro-King, Princeton, Vibrolux and others. It has a very warm, round and soft response with rich harmonics, and distorts easily. One of the best choices ever produced for rehearsal and recording amplifiers. Available as singles, pairs and quartets; stocked in “medium” power ratings.
EL34 Power Tubes The original power platform behind most high-powered British guitar stacks from the ’60s onward. Output is generally between 20 and 25 watts, with pronounced midrange punch, tight low end and crisp top end that breaks up relatively smoothly and gets a little crunchy when pushed hard. It provides a great voice that stands out in a band mix as the mids tend to power their way through an overall mix. Big brother to the EL84.
6550 / KT88 Power Tubes One of the highest-output pentodes available. Originally manufactured in the United States by G.E., it delivers 35 to 50 watts per tube and was original equipment in Ampeg SVT and Marshall amps during the ’70s and early ’80s. A big, clean, tight tube with amazing headroom and performance and great power and dynamics. A similar tubes is the KT88 (used by Sunn and others). The highest-output power tube in this family.
SILVER Series In a world of “Good, Better, Best” choices, Silver Series tubes are the “Better” choice. They are excellent workhorses in many amplifier circuits in reverb driver, phase inverter or other applications, and can also be an excellent choice in the audio chain in most positions. Silver Series tubes are fully functional and pass many of the same exhaustive tests of premium Groove Tubes.
TUBE/AMPLIFIER REFERENCE To use this guide, locate the manufacturer of your amplifier or other tube-based audio product (listed in alphabetical order),and then search for the model. The full complement of Groove Tubes replacement tubes will be listed next to the model name. if you can’t find your amplifier model in this guide, contact Groove Tubes for more information.
Ampeg (Continued) VT-22 3-12AX7, 1-6K11 1, 1-12DW7, 1-6AN8, 1-6CG7, 7027 Quartet VT-60 4-12AX7, 1-12AU7, 6L6 Duet VT-120 4-12AX7, 1-12AU7, 6L6 Quartet V-2 3-12AX7, 1-12DW7, 1-12AU7, I-6K1 1,1-6CG7, 7027 Duet V-3 4-12AX7, 1-12AT7, 6550 Duet V-4 3-12AX7, 1-12DW7, 1-12AU7, I-6K1 1,1-6CG7, 7027 Quartet V-4B 2-12AX7, 1-12DW7, 1-12AU7, I-6K1 1, 7027 Quartet V-5 3-12AX7, 6550 Quartet V-7 4-12AX7, 1-12AT7, 6550 Quartet V-9 1-12AX7, 4-12DW7, 1-6CG7, 2-12BH7, 6550 B-15 - early 2-6SL7, 1-7199, 6L6
Carr (Continued) Mercury 2 X 12AX7, 1 X 12AT7, 1 X EL34 Viceroy 3 X 12AX7, 1 X 12AT7, 2 X 6L6 Rambler 3 X 12AX7, 1 X 12AT7, 2 X 6L6 Slant 6V 4 X 12AX7, 2 X 12AT7, 4 X 6V6, 1 X 5AR4 Hammerhead 2 X 12AX7, 2 X EL34 Carvin VTR 2800 50-watt 1-12AT7, 6CA7 Duet VTR 2800 100-watt 1-12AT7, 6CA7 Quartet VTX 100 3-12AX7, 6L6 Quartet X-B12 30-watt 3-12AX7, 6L6 Duet X-T12 60-watt 3-12AX7, 6L6 Duet X-V112 100-watt 3-12AX7, 6L6 Quartet X-VI12 - later 3-12AX7, EL34 Quartet X-V212 100-watt 3-12AX7,
Crate (Continued) V100 4 X 12AX7, 4 X EL34 Demeter TGA-3 6-12AX7, 6550 Quartet TGP-3 6-12AX7 VTBP/201 6-12AX7 VTDB-2 1-12AX7 Diaz CD-100 3-12AX7, 1-12AT7, 6L6 Quartet Diezel VH4 & VH4S 4-12AX7, 4 X 6L6, KT66, KT88, 6550, EL34 HERBERT 4-12AX7, 6 X 6L6, KT66, KT88, 6550, EL34 EINSTEIN 4-12AX7, 4 X 6L6, KT66, KT88, 6550, EL34 SCHMIDT 4-12AX7, 4 X 6L6, KT66, KT88, 6550, EL34 Divided by 13 LDW 17/39 12AX7, 2 X EL34 EDT 13/29 12AX7, 12AT7, 2 X KT66, 1 X 5AR4 CJ 11 2 X 12AX7, 2 X 6V6, 1 X
Fender (Continued) Bandmaster/Reverb 4-12AX7, 2-12AT7, 6L6 Duet, 5U4 Bantam Bass 2-12AX7, 1-12AT7, 6L6 Duet, 5U4 Bassman 4x10 OS 1 1-12AY7, 2-12AX7, 6L6 Duet, 5U4 Bassman 4x10 OS 2 1-12AY7, 2-6925, 6L6 Duet, 2-5U4 Bassman 4x10 OS 3 2-12AY7, 1-12AX7, 6L6 Duet, 2-5U4 Bassman 4x10 OS VOS 1-6SC7, 1-6SL7, 6L6 Duet, 5U4 Bassman Top 50-watt 3-12AX7, 1-12AT7, 6L6 Duet, 5U4 Bassman Top 70-watt 3-12AX7, 1-12AT7, 6L6 Duet Bassman Ten 70-watt 2-12AX7, 1-12AT7, 6L6 Bassman 100 2-12AX7, 1-12AT7, 6L6 Qu
Fender (Continued) 18 Harvard 1-12AX7, 6V6, 5Y3 Harvard 1-12AX7, 1-6AT6, 6V6 Duet, 5Y3 Musicmaster Bass 1-12AX7, 6V6 Duet Princeton VOS 3-6SC7, 6L6 Duet, 5U4 Pro OS 2-12AY7, 1-12AX7, 6L6 Duet, 5U4 Pro Brown 6-12AX7, 6L6 Duet Pro 3-12AX7, 1-12AT7, 6L6 Duet, 5AR4 Pro Reverb 4-12AX7, 2-12AT7, 6L6 Duet, 5AR4 Quartet Reverb 4-12AX7, 2-12AT7, 6L6 Quartet Rack Amp RPWI 2-12AX7, 1-12AT7, 6L6 Quartet Rack Guitar Preamp 2-6C10, 4-12AX7, 2-12AT7 Rack Bass Preamp 2-6C10, 4-12AX7 Rack 200-watt
Fender (Continued) Super-Sonic 6-12AX7, 2-12AT7 6L6 Duet Super-Sonic (head) 5-12AX7, 1-12AT7 1-6550 Sextet 57 Deluxe (reissue) 2-12AX7, 6V6 Duet, 5Y3 57 Twin (reissue) 4-12AX7, 6L6 Duet, 2-5U4 Blues Deluxe 3-12AX7, 6L6 Duet Blues DeVille 3-12AX7, 6L6 Duet 64 Vibroverb Custom 4-12AX7, 2-12AT7 6L6 Duet, 5AR4 Princeton Recording Amp 3-12AX7, 1-12AT7 6V6 Duet EC Twinolux 4-12AX7, 6L6 Duet, 2-5U4 EC Tremolux 3-12AX7, 6V6 Duet, 5Y3GT EC Vibro-Champ 2-12AX7, 6V6, 5Y3GT Machete Combo & Head 5
Gibson (Continued) 20 BR-6F 1-6SJ7, 1-6SN7, 6V6 Duet, 5Y3 BR-9 1-6SN7, 6V6 Duet, 5Y3 Duo-Medalist 3-6EU7, 1-12AX7, 2-12AU7, 7591 Duet Falcon 3-6EU7, 1-12AX7, 2-12AU7, 7591 Duet Falcon 4-12AX7, EL84 Duet GA-Custom 3-6SJ7, 2-6SQ7, 2-05, 6L6 Duet, 5U4 GAART-1 1-12AX7, 1-6BM8, 5Y3 GA-IRVT 1-7100, 1-6EU7, 1-6BM8, 5Y3 GA2-RVT 4-6EU7, 1-12AU7, 6V6 Duet, 5Y3 GA-4RE 2-6EU7, 1-12AU7 GA-5 1-12AX7, 6V6, 5Y3 GA-5T 2-6EU7, 1-6AQ7, 6X4 GA-6 1-12AY7, 1-6SL7, 6V6 Duet, 5Y3 GA-6 newer 2-12AX7, 6V
Gibson (Continued) GA-70 Country-Western 1-12AX7, 1-12AY7, 1-12AU7, 6L6 Duet, 5V4 GA-75 Recording 2-6EU7, 1-6CG7, 6L6 Duet, 6C4 GA-75W 1-12AX7, 2-6SC7, 1-6W7, 6L6 Duet, 5V4 Super Medalist 2-6EU7, 2-12AU7, 1-6AU7, 1-12AX7, 7591 Duet Thor Bass Amp 2-6EU7, 1-6CA7 Duet Titan 1, 11 and 111 3-6EU7, 2-12AU7, 1-OA2, 1-6FQ7, 6L6 Quartet Titan Medalist 3-6EU7, 2-12AU7, 1-OA2, 1-6FQ7, 6L6 Quartet Hawk 3-12AX7, 1-EL84 Duet Les Paul TV or JR 1-6SJ7, 6V6, 5Y3 Skylark T 1-6X4, 2-12AX7, 1-EL84 Skylark
Hiwatt 30W 4-12AX7, EL84 Quartet 30WR 4-12AX7, EL84 Quartet 50 4-12AX7, EL34 Duet 100 4-12AX7, EL34 Quartet 200 4-12AX7, EL34 Sextet 400 5-12AX7, KT-88 (6550) Sextet C520 4-12AX7, EL84 Duet D50L 4-12AX7, EL34 Duet D50LR 4-12AX7, EL34 Duet D50LRC 4-12AX7, EL34 Duet D100L 4-12AX7, EL34 Quartet D100LR 4-12AX7, EL34 Quartet PRE-1 3-12AX7 PW50 4-12AX7, EL34 Quartet S50 4-12AX7, EL34 Duet S50LC 4-12AX7, EL34 Duet S100L 4-12AX7, EL34 Quartet Jim Kelly Single Channel 2-12AX7, 6V6
Laney A50 4-12AX7, EL34 Duet A100 4-12AX7, EL34 Quartet PT-50 4-12AX7, EL34 Duet PT-100 4-12AX7, EL34 Quartet PT-30 3-12AX7, 6V6 Duet PT-50 MV 3-12AX7, EL34 Duet PT-50 AOR 4-12AX7, EL34 Duet PT-100 MV 3-12AX7, EL34 Quartet PT-100 AOR 4-12AX7, EL34 Quartet ST-30 4-12AX7, 6V6 Duet Legend G-50 and G100 3-12AX7 with transistor amp Leslie Model 147 1-12AU7, 1-OC3, 6550 Duet Model 122 2-12AU7, 1-OC3, 6550 Duet Marantz Model 7 6-12AX7 Model 8 2-6CG7, 2-6BH6, EL34 Quartet Model 9 1-6C
Marshall (Continued) DSL 401 4 X 12AX7, 4 X EL84 DSL 201 4 X 12AX7, 2 X EL84 TSL 100 4 X 12AX7, 4 X EL34 TSL 122 4 X 12AX7, 4 X EL34 TSL 60 4 X 12AX7, 2 X EL34 TSL 601 4 X 12AX7, 2 X EL34 TSL 602 4 X 12AX7, 2 X EL34 1959 SLP, SLPX 3 X 12AX7, 4 X EL34 1959 HW 3 X 12AX7, 4 X EL34 1959 RR 3 X 12AX7, 4 X EL34 1987 X, XL 3 X 12AX7, 2 X EL34 2245 (JTM 45) 3 X 12AX7, 2 X 6L6, 1 X 5AR4 JTM45100 (40TH ANNIVERSARY) 3 X 12AX7, 4 X KT66 JTM45OS 3 X 12AX7, 2 X KT66, 1 X 5AR4 1962 3 X 12AX7, 2
Mesa/Boogie Studio 22 5-12AX7, EL84 Duet Studio Preamp 4-12AX7, 1-12AT7 Quartet Preamp 8-12AX7 MK-1 60 - early 2-12AX7, 1-12AT7, 6L6 Duet MK-1 60 Reverb - early 4-12AX7, 1-12AT7, 6L6 Duet MK-1 60 EQ - early 2-12AX7, 1-12AT7, 6L6 Duet MK-I 60 Reverb/EQ - early 3-12AX7, 2-12AT7, 6L6 Duet MK-I 10t - early 2-12AX7, 1-12AT7, 6L6 Quartet MK-I 100 Reverb - early 2-12AX7, 2-12AT7, 6L6 Quartet MK-I 100 EQ - early 2-12AX7, 1-12AT7, 6L6 Quartet MK-I 100 Reverb/EQ - early 3-12AX7, 2-12AT7, 6L6 Quar
Mesa/Boogie (Continued) SOB 60 3-12AX7, 6L6 Duet SOB 60 Reverb 4-12AX7, 6L6 Duet SOB 100 Reverb 4-12AX7, 6L6 Quartet D-180 - early 2-12AX7, 2-12AT7, 6L6 Sextet D-180 3-12AX7, 1-12AT7, 6L6 Sextet Bass-400 4-12AX7, 6L6 Sextet Bass-400 Plus 4-12AX7, 2-6L6 Sextet 50150 Power Amp 2-12AX7, 6L6 Quartet TriAxis Preamp 5-12AX7 Dual Rectifier Solo Head 5-12AX7, 2-5U4 6L6/EL34 Quartet Triple Rectifier Solo Head 5-12AX7, 3-5U4 6L6/EL34 Sextet Dual Rectifier Trem-O-Verb 6-12AX7, 2-5U4 6L6/EL34 Qua
Musicman (Continued) 150 6L6 Quartet (transistor preamp) NOTE: Early model used 6CA7, check amp.
Peavey (Continued) Triumph 120 4-12AX7, 1-12AT7, 6L6 Quartet Butcher 3-12AX7, 6L6 Quartet Vintage - early 2-6C10, 6L6 Quartet Vintage - later 6L6 Quartet (Transistor Preamp) VTA 400 3-12AX7, 1-6AN8, 6550 Quartet VTA 800 3-12AX7, 1-6AN8, 6550 Octet VTB 300 2-12AX7, 1-6AN8, 6550 Quartet VTG 300 2-12AX7, 1-6AN8, 6550 Quartet Classic 30 3-12AX7, EL84 Quartet Bravo 3-12AX7, EL84 Quartet XXX 3-12AX7, 6L6 Quartet (Option of EL-34 Quartet) 5150 5-12AX7, 6L6 Quartet (NOTE: V4 is the phase inve
Seymour Duncan 60-watt Combo/head 3-12AX7, 2-12AU7, EL34 Duet 60-watt Convertible 3-12AX7, 2-12AU7, EL34 Duet 100-watt Combo/head 6-12AX7, 2-12AU7, EL34 Quartet ,5U4 100-watt Convertible 6-12AX7, 2-12AU7, EL34 Quartet ,5U4 8440 3-12AX7, EL34 Duet KTG-1 2-12AX7, 1-12AU7 KTG-2100 2-12AX7, 2-12AU7, KT88 Quartet Silvertone 50-watt Reverb 4-12AX7, 2-6CG7, 6L6 Duet 100-watt Reverb 4-12AX7, 2-6CG7, 6L6 Quartet Sound City Bass 150 2-12AX7, 1-12AT7, 6550 Quartet Concord 3-12AX7, 2-12AT7, EL34 Qu
Sunn (Continued) Spectrum I 1-12AX7, 1-7199, 6CA7 Duet Solarus (190L) 1-12AX7, 1-12AU7, 1-6AN8, 6550 Duet 100S 1-12AX7, 1-12AU7, 1-6AN8, 6550 Duet 20OS (190B) 1-12AX7, 1-6AN8, 6550 Duet 1000S 1-12AX7, 1-12AU7, 1-6AN8, 6550 Quartet 120OS (350L) 1-12AX7, 1-12AU7, 1-6AN8, 6550 Quartet 2000S (350B) 1-12AX7, 1-6AN8, 6550 Quartet NOTE: Later models may use 7199. Earlier models may use 6CA7.
Victoria 518-T 1-12AX7, 6V6, 5Y3 20112-T 1-12AY7 or 5751, 1-12AX7, 6V6 Duet, 5Y3 DOUBLE DELUXE 1-12AY7 or 5751, 1-12AX7, 6V6 Quartet, 5Y3 or 5AR4 35210-T 2-12AY7, 1-12AX7, 6L6 Duet, 5U4 35115-T 2-12AY7, 1-12AX7, 6L6 Duet, 5U4 35310-T 2-12AY7, 1-12AX7, 6L6 Duet, 5U4 45410-T 1-12AY7, 2-12AX7, 6L6 Duet, 5AR4 80410-T 1-12AY7, 2-12AX7, 6L6 Quartet, 5AR4 50212-T 1-12AY7, 2-12AX7, 6L6 Duet, 5AR4 80212-T 3-12AX7, 6L6 Quartet, 5AR4 VICTORI-ETTE 3-12AX7, 2-12AT7, EL84 Duet, 5AR4 VICTORILUX 3-12
Groove Tubes Process Acquisition • There are very few tube factories in the world, GT only sources from the best • GT only purchases raw tubes that meet specs for low hum, noise and microphonics • Tubes are shipped to GT global facilities for further selection and grading Preamp Tubes • The first step is a burn-in period which lasts approximately 2 hours • This “settles the tubes”, burns off impurities and stabilizes components • All processes and computer programs are proprietary to Groove Tubes • “H
Groove Tubes Process Pass - GT Tube Preamp Tubes Continued • GT proprietary program tests for smooth frequency response, gain and output • Tubes are tested for hum and noise level, results are displayed in graphic form • The Kennedy Amplitrex AT-1000 Internal tube function revealed • GT proprietary program further dissects and measures tube performance • Evaluates plate resistance, current, voltage, bias draw, transconductance • Provides numeric values for gain and voltage for each triode • The Hage
Groove Tubes Process Power Tubes • Groove Tubes features proprietary matching and grading of power tubes • Tubes must meet the same rigorous manufacturing specs as preamp tubes • Tubes are placed in a fixture and “Dynamically Energized™” • Only Groove Tubes does “Dynamically Energized™” testing of power tubes • Measures cathode filament voltage, plate voltage, wide variety of other specs • The GT “Mothership” contains all coding information on unique GT testing • Tubes are graded according to distorti
Groove Tubes Display Look for this display at your local Groove Tubes retailer to find the tubes that are right for you and your amp! My amplifiers / tubes reference: (use pencil) Amplifier One Date tubes changed:______________________________ Amp Brand______________________________________ Model_________________________________________ Serial Number___________________________________ Year___________________________________________ Preamp tubes (QTY / TYPE)_________________________ Rectifier tubes(QTY / TY
My amplifiers / tubes reference: (use pencil) Amplifier Two Date tubes changed:______________________________ Amp Brand______________________________________ Model_________________________________________ Serial Number___________________________________ Year___________________________________________ Preamp tubes (QTY / TYPE)_________________________ Rectifier tubes(QTY / TYPE)_________________________ Power tubes (QTY / TYPE )__________________________ POWER RATING__________________________________ Amplifi
My amplifiers / tubes reference: (use pencil) Amplifier Four Date tubes changed:______________________________ Amp Brand______________________________________ Model_________________________________________ Serial Number___________________________________ Year___________________________________________ Preamp tubes (QTY / TYPE)_________________________ Rectifier tubes(QTY / TYPE)_________________________ Power tubes (QTY / TYPE )__________________________ POWER RATING__________________________________ Amplif
My amplifiers / tubes reference: (use pencil) Amplifier Six Date tubes changed:______________________________ Amp Brand______________________________________ Model_________________________________________ Serial Number___________________________________ Year___________________________________________ Preamp tubes (QTY / TYPE)_________________________ Rectifier tubes(QTY / TYPE)_________________________ Power tubes (QTY / TYPE )__________________________ POWER RATING__________________________________ Amplifi
For the latest information on Groove Tubes, visit our website at www.groovetubes.com GROOVE TUBES HEAR THE DIFFERENCE™ © 2012 FMIC. GROOVE TUBES is a registered trademark of Fender Musical Instruments Corporation. All rights reserved. Amplifier and model names contained herein are the property of their respective owners and are provided for reference only. Specifications subject to change without notice.
This comprehensive quick guide provides complete and accurate information on replacement tubes for hundreds of amplifiers from vintage classics through the newest and coolest models! We have also included a section on tube basics, from troubleshooting to biasing. Also included are descriptions of the performance characteristics of the most commonly used tube types and the Groove Tube versions of these tubes.
