12AX7

12AX7 preamp tubes play a remarkable, dynamic role in the creation of the final tone in your vacuum tube amplifier. 12AX7s are components, early in the circuit, that determine how clean or, how lush, layered and massive the high gain will be – not to mention all the tonal shades of grey in between like clipped, overdriven and crunch sounds. MESA® 12AX7s provide the stability AND high gain required for extraordinary distortion sounds while at the flick of a switch, deliver the sensitivity and brilliance needed for some of the world’s most detailed, crisp clean sounds as well as the subtleties of the in between gain ranges.

SPAX7

MESA® SPAX7 preamp tubes are a premium grade 12AX7 that possess an even higher standard of overall performance due to their incredibly low sensitivity to microphonic noise. This is the ultimate preamp tube to use in critical gain stage applications, particularly in first stage/input positions or other high gain stages in the preamp tube string. These tubes are selected during our rigorous 12AX7 testing process and when found to be substantially more stable and quiet in extreme high gain applications, they are fitted with a shrink-wrap shielding, further stabilizing the tube and reducing external interference and noise. MESA SPAX7s deliver the lowest noise floor for the highest gain output. While not required for optimum performance, SPAX7s are a great tube to have on hand as spares and for any applications where the absolute lowest noise floor and low-microphonic response is needed.

12AT7

The MESA® 12AT7 is a premium grade, lower gain preamp tube most often used in reverb stages and/or phase inverter positions in older amplifiers. It is used in older MESA/Boogie® designs (MESA amps built before 1991) as a reverb driver stage, but the 12AT7 can also be substituted in 12AX7 gain stages where users are seeking lower gain response from higher gain positions in the preamp string. The lower gain output of 12AT7s can expand the range of clip and overdrive potential of higher gain amps for truly authentic roots and traditional styles.

6L6 STR 440

The MESA® 6L6 STR 440 is our very best overall, premium grade, USA equivalent 6L6, and our tube of choice in the production of all new MESA 6L6 powered models. Remarkable bass definition, articulate mids and shimmering highs keep every note amazingly intelligible, with a smooth, creamy character. Leading structural quality provides exceptional consistency and reliability and is an outstanding choice for ANY 6L6 based amps and all styles of music. The STR 440 is a direct replacement for our out-of-production STR 420s and STR 430s.

5881 STR 425

The MESA® 5881 STR 425 is a military grade 6L6 designed with an emphasis on rugged durability and the capability to handle higher voltage requirements. It produces a full bass and rich midrange with tapered highs that lends itself well to styles of jazz, fusion and traditional roots and blues music… or any style where tapered high frequencies and greater longevity and reliability is desired. The STR 425 is also commonly used in older MESA all-Tube Bass Amps using 6L6s like the MESA D-180, Bass 400 and Bass 400+ models.

6v6 STR 417

The MESA® 6V6 STR 417 is the little brother to the 6L6 and exemplifies classic American tube tone from yesteryear. Extremely sweet and bubbly with a beautifully deep bass and spacious, shimmering highs, this tube defines vintage “Deluxe” styled tones and is a great substitute in Mark & Lone Star Series amplifiers when used with their Tweed Power Switch feature (consult the amplifier owner’s manual for proper use).

EL-84 / 6BQ5

The MESA® EL-84 / 6BQ5 is the little brother to the EL-34 and is the classic European-designed tube that lead the original British invasion. Our EL-84 offers tight and punchy bass, smooth and warm midrange, and an amazing chiming upper-mid and sparkling top end that is always inspiring to play!. Brilliant focus with a frequency response that always brings your guitar to the front of the mix, this EL-84 is true to its classic roots.

EL-34 STR 447

The MESA® EL-34 STR 447 is our very best overall, premium grade NOS equivalent EL-34 and our tube of choice in the production of all new MESA EL-34 powered models. It offers traditional EL-34 tone & feel – urgent and aggressive – and is an excellent choice for all styles of gain, especially classic rock, alternative rock & metal. This tube is true to it’s British origins with tight, focused low end, crushing midrange crunch and crystal-like highs. It’s one of our favorites for authentic Brit tones.

STR 450 EL-34

The MESA® STR 450 EL-34 is a German made, “A” grade NOS (New Old Stock) Siemens EL-34. This legendary European EL-34 is known for its unsurpassed “bell-tone” clarity and touch sensitive sustain & articulation. Premier German engineering provides outstanding structural quality that makes this a toneful, consistent and reliable new old stock classic. Quantities are subject to limited availability.

STR 488

The MESA® STR 488 is the premium KT-88 of choice for our all-tube Prodigy and Strategy Bass Amps. Capable of delivering incredible power and fundamental bass punch, the STR 488 also offers the perfect blend of balanced midrange and high frequency detail to compliment the outrageous low-end potential this tube serves up. Modernized structural detail combined with excellent materials and workmanship produce a premium quality KT-88 that will enhance any KT-based circuit and especially MESA’s all-tube bass line, designed specifically with this tube in mind.

5AR4

The MESA® 5AR4 Rectifier Tube produces a vintage feel with light to mild “sag”. While it produces more “sag” than Silicon Diodes, it is the least “saggy” of our tube rectifier offerings. Used in vintage MESA amps like the Heartbreaker, Blue Angel and Maverick as well as many other vintage, non-MESA amplifiers.

5Y3

The MESA® 5Y3 is a favorite among vintage aficionados and is our tube of choice in the production of the Lone Star Special. This tube produces sultry, vintage sag, creating a silky-smooth feel on the strings that is incredibly addictive to play. It provides the most sag of all of our rectifier tubes.

5U4GB

The MESA® 5U4GB Rectifier Tube is our very best overall 5U4 and our rectifier tube of choice in the production of all new MESA amps featuring this tube. This tube produces a “traditional vintage sag” with the most elastic and compressed feel of the two 5U4’s that we offer. Amazing feel and exceptional overall quality make this our factory favorite. Based on classic 1950s technology, the 5U4GB is a vastly improved 5U4 design that is extremely reliable and consistent, as well as more compact compared to original “Coke Bottle” 5U4Gs (3 3/4″ from bottom of base to top of glass). It is similar in size to a 6L6 power tube so please take special care to install them in the correct tube position(s), especially when replacing 6L6’s at the same time.

5U4G

The MESA® 5U4G Rectifier Tube is a classic 1930s “Coke Bottle” design. It produces a flexible, elastic and spongy feel that is a bit more controlled and slightly less “saggy” than our newer 5U4GB.

PLEASE NOTE:This older 5U4G is no longer the current production tube used in new MESA amps featuring this tube type and due to its tall “Coke Bottle” design, this tube may not fit in all amplifiers (4″+ from bottom of base to top of glass). Please confirm the height between your amp’s chassis and the top of your cabinet before choosing this tube. All current MESA amps using this tube type ship with the newer, compact, shorter profile 5U4GB.

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