Mesa/Boogie (also known as Mesa Engineering) is a company in Petaluma, California that makes amplifiers for guitars and basses. It has been in operation since 1969.
Mesa was started by Randall Smith as a small repair shop which modified Fender combos to give them more gain. Prominent early buyers included Carlos Santana, and Keith Richards of The Rolling Stones, helping to develop Mesa/Boogie's reputation as an amp builder.
Mr. Smith, the creator of Mesa/Boogie, began his career at Prune Music, a Chinese grocery store turned music shop. Working as a repair tech while his business partner and friend, David Kessner, ran the front, Smith quickly gained a reputation with the local San Francisco Bay Area musicians. This reputation brought him business from bands including the Grateful Dead, Big Brother and the Holding Company, and Carlos Santana.
In 1969, Smith, as a joke, modified Barry Melton's Fender Princeton amplifier. He removed the standard 10-inch speaker and modified the chassis to fit the larger transformers that were needed by the 4-10 (four 10" speakers) tweed Fender Bassman, the circuit that he had added into the tiny 12-watt Princeton. Finally, Mounting a 12-inch JBL D-120, a popular speaker of the time, Smith had created what would be the first Boogie.
Randall Smith, needing to test his creation, took the "hot-rodded" Princeton into the front store, where Carlos Santana was present. Santana "wailed through that little amp until people were blocking the sidewalk". Impressed, Santana exclaimed to Smith, "Man, that little thing really boogies!" It was this statement that brought the Boogie name to fruition.[1]
The MESA name came about through Smith's other job, rebuilding Mercedes engines and repairing houses. He needed an 'official' sounding name through which to buy Mercedes parts and building supplies, and chose MESA Engineering. It was originally spelled with all capital letters but has been written as Mesa in recent years.
In 1971, Bassist Patrick Burke approached Randall with a proposal for a custom Bass amp. Smith was persuaded and constructed the Snakeskin Mesa 450 - Smith's first bass amplifier and the first official Mesa/Boogie product.
The real breakthrough came when Smith began building a preamp project for Lee Michaels to drive his new Crown DC-300 power amplifiers. Not knowing what signal was required to drive the power amps, Smith added an extra tube gain stage to the preamp, with three variable gain controls at different points in the circuit. In adding this extra gain stage, Smith had created the first high-gain amplifier. He set about designing a guitar amplifier around the new principle, and in 1972 the Mark I was released.
He produced a number of custom variations on the Mark I through the late 1970s, with options including reverb, EQ, various speakers (most often Altec or ElectroVoice), koa wood jointed cabinets, and wicker grill. The Mark II was released in 1978.
In the 1980s, Mesa continued to produce combo and head amplifiers, and began production of rack power and pre-amps, developing power amplifiers such as the M180/190 and Strategy series, as well as pre-amps such as the Quad and Studio. Other models developed in the 1980s included the Mark III, the Son of Boogie, and the Studio .22.
In the '90s, Mesa launched the smaller Dual Caliber series and the more powerful Rectifier series.
Production of new models has continued into the 2000s, with models such as the Road King II, the Lone Star and Lone Star Special, and the Stiletto and Express lines.
The Mark Series of amplifiers was Mesa's flagship product until the introduction of the Rectifier series. It was introduced in 1971 and is still being produced today. The most recent model is the Mark V.
Introduced in the Mark II-B was the Simul-Class power amplifier stage, which combined tubes running in Class A and Class AB through the same output transformer. The Simul-Class system has been a staple in Mark Series amplifiers since then, as well as the 5-band graphic equalizer, both exclusive to the line until the introduction of the Electra Dyne, and select power amplifiers.
The Rectifier series is Mesa's flagship line.
The line-up began as the Dual Rectifier series of amps, which included the Solo, Heartbreaker, Maverick, and Blue Angel. All amps in the series, except for the Blue Angel,* had two forms of electrical rectification (conversion of power from AC to DC): silicon diodes and one or more vacuum tube(s) that the user could select via a switch located on the back panel of the amplifier. (Hence the name "Dual Rectifier".) While the Heartbreaker and Maverick used only one 5AR4 tube rectifier, the Solo employed two 5U4G tubes. This distinction engendered the misconception that the name Dual Rectifier was derived from this amp; the Solo's popularity only reinforced this misconception. Future designs would further contradict and confuse the line's namesake.
* The Blue Angel was designed with only a vacuum tube rectifier but retained the Dual Rectifier designation.
In short order, Randall Smith stopped production of the other Dual Rectifier amps and concentrated on producing different configurations of the Solo, which became the Dual Rectifier.
The Solo, with its visceral aesthetic and aggressive gain structure, soon became the most popular model of the Dual Rectifier series. The cascading gain preamp circuit is largely borrowed from high-gain amplifier designer Mike Soldano and his Super Lead Overdrive 100 amplifier(SLO 100). Equipped with five 12AX7 preamp tubes and a quartet of 6L6 power tubes, the Solo produces 70-100 watts, depending on power options chosen. A bias select switch is standard, allowing the user to switch between EL34 and 6L6 power tubes without re-biasing. Originally designed with two channels (though not true parallel channel circuits) the amp later evolved to three channels.
The earliest Dual Rectifier was a heavily modified Mark IV, or at least, was fitted in a Mark IV chassis during the prototype stage. This was one of what became known as the elusive Revision A/B amplifiers. These would only see limited production as prototypes, and were never sold to the public.
Revision C was the first to be sold. It featured two independent channels: Orange, or "Vintage," and Red, or "Modern." If the player so desired, the Orange channel could be switched via rear panel rocker to a clean channel, and the Red channel could be switched in much the same manner to "Vintage." Later revisions were produced up to Rev F, which is considered the last of the coveted "Pre-500" Dual Rectifiers, referring to their serial number being in or below the 500's. After that, many players argue that Revision G lost a certain character that the others had. Some believe it was because Mesa had switched transformer suppliers, but that theory has been debunked since some Rev G amplifiers were still equipped with the older transformers, made by Schumacher Electric.
After Revision G went out of production, the Dual Rectifier received a third dedicated clean channel, in addition to the Orange and Red channels. Later revisions added voicing switches, and minor circuit tweaks until the 3-channel went out of production in 2010.
In 2010, after the 3-channel was phased out, production began on the "Reborn" Dual Rectifier. This new revision attempted to capture the tone of the legendary Pre-500 amplifiers, while making the Orange and Red channels duplicates of each other for improved flexibility. The clean channel was re-worked to be more responsive and have a wider range of gain saturation in both voicings. Mulit-Watt capabilities were added per channel, which offered switching between 100 or 50 watts and 4 or 2 power tubes respectively. Recto-Tracking per channel was also introduced, much like the implementation on the Road King, or Roadster. An improved footswitch was also implemented, along with an integrated mute function.
As the name implies, the Single rectifier shared roughly the same preamp as the Dual, but was fitted with only a silicon diode rectifier. Power output is only 50 watts with only two 6L6GCs or EL34s in the power section. The Single Rectifier originally had two channels, much like Rev C thru G of the Dual Rectifier, but was upgraded to a three-channel design as well. The circuit in the Single Rectifier has remained much the same since it was implemented with a third channel, and was not included in the "Reborn" model refresh in 2010.
The Triple Rectifier* is equivalent to the Coliseum option for Mark Series amplifiers. It featured a more powerful output section with six power tubes, and as the name implies, three 5U4G rectifier tubes.
*The term Dual Rectifier originally referred to the two options available to rectify the high voltage current being supplied to the amplifier. However, lesser-informed players assumed it referred to the dual 5U4 tubes in the amplifier, though the Single Rectifier was clearly lacking one, as its name would be interpreted by these players. The laymen's interpretation was bestowed upon the Triple Rectifier, to the disappointment of die-hard fans, indicating triple 5U4 tubes, probably due to lack of a better name.
The Triple Rectifier was not developed along with the other Pre-500 models, and was introduced later. It has 3 channels and many of the same features as the Dual Rectifier, with the exception of a higher headroom power amplifier. The Triple Rectifier was included in the "Reborn" refresh in 2011, making it sound closer to the Pre-500 amplifiers, adding per-channel Recto-Tracking, and Multi -Watt switches for selecting 150 or 50 watts of output power.
These variants of the Single Rectifier introduced tube-driven spring reverb, and optical tremolo effect (volume modulation. Similar in operation to Fender's mislabeled Vibrato feature on blackface amplifiers, except the tube circuitry was substituted for a "555" timer circuit) respectively. These amplifiers were offered in head and 2x12 combo formats with the original two channel design of the Single Rectifier.
Mesa Boogie then produced the most feature - and option - laden iteration of the original Solo design: the Road King. It features four channels, each with two different speaker outputs, two effects loops, and Progressive Linkage, which allows five different power tube configurations (two 6L6, two EL34, two 6L6 plus two EL34, four 6L6, four 6L6 plus two EL34), indicated by different LED lights on the front of the amplifier. The amp also features Recto-Tracking, which automatically selects the appropriate rectification (single or dual 5U4s or silicon diode) depending on the power tube configuration. Even after the introduction of the Mark V, which draws many features from the Road King, the Road King Series II still remains Mesa's most versatile (and at first glance, complex) amplifier.
In response to complaints from some that the Road King was too complex, the Dual Rectifier Roadster was introduced. A scaled-down and less expensive version of the Road King that had fewer options for the power amp and speakers while retaining four independent channels.
In response to the growing demand for low-wattage and more portable amplifiers, the Mini Rectifier Twenty-Five was introduced in 2011. It is constructed in a similar manner to the Transatlantic Series, with an aluminum outer shell in lieu of the traditional vinyl-covered wooden shell of Mesa's larger amplifiers. The amplifier features two independent channels: a Green channel housing clean and pushed voicings found on the Green channel of newer Dual Rectifiers, and a Red channel containing the Vintage and Modern voicings of the corresponding channel on the new Dual Rectifier. The amplifier is equipped with multi-watt switches per channel which switch between 25 watts Class AB, and 10 watts Class AB. The switches are effectively Pentode/Triode switches, as there is no Class A or Single-Ended mode as in the TA-15. The rear of the amplifier is stripped of all jacks, knobs and switches found on its larger siblings, with the exception of an effects loop, and two speaker outputs.
The Lone Star amplifier was released in 2004 with the tag "Tone as big as Texas," and now comes in two variants, Classic and Special. The Classic can be compared to Fender's Blackface amps, while the Special is voiced more similarly to the Vox AC30.
The amplifier was designed to recreate the tones of Texas blues guitarists such as Stevie Ray Vaughan, though it also features a clean channel. Both channels are capable of switching between 50 watts and 100 watts, with the option of a tube rectifier in the 50-watt mode. In 2007 Mesa added a 10-watt Class A option to both channels.
The Lone Star Special was released in 2005. The Special featured EL84 tubes, rather than the 6L6 tubes used in the Classic. It is switchable between 5, 15, and 30 watts The 30-watt selection uses a solid-state rectifier for a cleaner tone, while the 15- and 5-watt settings use a tube rectifier for a warmer, grittier, sound. The 5-watt setting uses one power tube producing singled-ended Class A amplification (the other two settings produce push/pull Class A amplification [1]). This lowers the power, allowing the tube to saturate at lower volumes, producing overdrive. In addition, the second harmonic (an octave above) is not canceled out, resulting in a richer overtone.
The Stiletto "Stage I" was released in 2004, and is designed as a British-flavored variant of the Rectifier series. This was in response to musicians using Marshall amplifiers combined with Mesa/Boogie amplifiers. Three models were released; the Ace, the Deuce, and the Trident. All three come standard with EL34 tubes.
The Deuce is a 100w dual-rectified four EL34 powered head. The Trident is the highest output power of the Stiletto line, with a switchable 50w/150w power rating. It has six EL34 power tubes and three 5U4 rectifiers.
As of the 2006 model year, all previous models are generally referred to as "Stage I" versions, and have been replaced by the new "Stage II" versions. The Ace is the first of the "Stage II" series. It is a 50-watt amp that is available in different formats. The "Stage II" models have several features that were not available in the first series. This features are RE-voiced modes, two new clean modes named Fat and Tite, a Fluid-Drive mode and faster power supply.
As of December 2009, Mesa/Boogie no longer produces the Stiletto Trident head.
The Express line of guitar amplifiers was released in 2007, and has essentially replaced the F-Series in the Mesa Boogie line up. Although not directly descended from the F-Series, these two lines do have some features in common, some of which have been expanded upon in the Express line. This amp uses solid-state rectification like the F series.
The Express line introduced Mesa's Duo-Class technology. This technology offers the ability to run the power section of the amplifier in either true class A (single-ended) mode, or true class AB (push-pull) mode. This allows the operator to choose between running the amplifier at a reduced power output of 5 Watts (class A), or full power (class AB). When run in 5-Watt (Class A) mode, the power section is operating on only one vacuum tube.
There are two different models offered in the Express line; the 5:25, which has a maximum power output of 25 Watts; and the 5:50 which has a maximum power output of 50 Watts.
The 5:25 operates on two EL84 tubes in the power section, and produces a maximum rated power output of 25 Watts. It is available as either a Short Chassis Head (19 inches wide), or a 1x10 (Open Back) Combo unit containing one E50 Speaker, and comes with casters included. They also offer a 1x12 (Open Back) Combo unit with one V30 Speaker which offers a bigger sound over the 10" speaker.
The 5:50 operates on two 6L6 tubes in the power section, and produces a maximum rated power output of 50 Watts. It is available as a Medium Head (Width 22-7/8in), a Long Head (Width 26-1/4in), a 1x12 (Open Back) Combo unit containing one C90 Speaker, or a 2x12 (Open Back) Combo unit containing two C90 Speakers. Both Combo units come with casters included.
Common features among the models in the Express line are as follows:
The Atlantic Series was launched officially at Winter NAMM 2010 with the release of the Transatlantic TA-15. At first, this was seen as Mesa's foray into the rapidly growing "Lunchbox Amplifier" market, but with the recent introduction of the Royal Atlantic RA-100, featuring a full sized head form factor, the line has expanded outside of the aforementioned compact market segment.
The TA-15 was launched at Winter NAMM 2010 as Mesa's entry into the "Lunchbox Amplifier" Market. However, in true Mesa fashion, it was designed to bring something new to the table in the form of two discrete channels with separate two-band tone stacks, and dedicated voicing and Multi-Watt switches per channel. The "Green Channel" pays homage to the classic "chimey" sound of the Vox AC30 with switchable Normal and Top Boost settings, complete with the trademark Vox "cut" control. The cut control is located on a push/pull potentiometer, which when pulled, locks the cut control to a preset value, and allows the potentiometer to function as a master volume. The "Red Channel" contains three modes: Tweed-which ironically, resembles an unspecified Blackface-era Fender; Hi 1-which models higher gain British sounds commonly associated with Marshall, Hiwatt, and Orange; and Hi 2-which simulates the "liquid lead sound" that Mesa is famous for. Both channels have a Multi-Watt switch which adjusts the operating mode of the EL84/6BQ5 based power amplifier to the player's taste. The 25 watt mode operates in 25 watts Class AB, 15 in 15 watts Class A, and 5 in 5 watts single-ended Class A.
The TA-30 addressed the limitations of the smaller TA-15, because of its enlarged size. The wider 19" chassis includes the same preamp controls and voicings as the TA-15, but with the addition of a tube driven reverb/effects loop circuit. The "Red Channel" also removes the volume control in favor of a push/pull potentiometer which in normal operation, acts as a volume control, but when pulled, boosts the signal, thus creating more gain saturation. The TA-30 also has an upgraded power amplifier producing 40 watts of output dissipation in Class AB, 30 watts in Class A, or 15 watts in Class A. The TA-30 is also offered in a 1x12 or 2x12 combo cabinet, as well as a new rack-mounted chassis.
The RA-100 was introduced along side of the TA-30 in 2011. It only resembles the other amplifiers in the series in name, and aesthetics. The preamp was changed to a three-channel design. This included a dedicated clean channel, and a second channel with two modes. The 3-channel/mode system resembles the Electra Dyne to some extent, but Mesa insists that it is a totally different design, concentrating on the British gain sounds found on the other members of the Atlantic series. The amplifier sports an EL34/6CA7 based power section, with accommodations for a 6L6GC retrofit. Unlike the other members of the series, the RA-100 forgoes Multi-Watt capabilities in favor of a multi-step attenuation system billed as Multi-Soak. Each channel has a dedicated rotary switch used to select the amount of signal received by the speaker(s).
The Electra Dyne was introduced in 2009 along side the Mark V at that year's Winter NAMM show. While the Mark V can appear complicated with many knobs, switches, lights, and sliders, the Electra Dyne was created to be the polar opposite. It features six knobs and one switch on the front panel (not including the Power and Standby switches), the first Mesa amplifier with this few controls since the Mark 1. The Electra Dyne is a single-channel amplifier with three foot-switchable modes: Clean-a recreation of the standard clean channel found on the Mark IV, Vintage Low, and Vintage High, based on hot-rodded British designs. Stacked potentiometers, and isolated preamp circuits facilitate balanced sounds, while facilitating the simple controls. The amplifier also features a tube-driven spring reverb and effects loop, as well as several additional balancing controls on the rear panel, assuring maximum versatility from a minimum of controls. The Electra Dyne happens to be the first Mesa amplifier outside the Mark Series which employs a Simul-Class output section, which runs a Class A power amplifier and a Class AB power amplifier simultaneously through the same output transformer. The output can be switched between 90 watts and 45 watts.
A five-tube preamp built to put all of the Mark series amps into one package. The Triaxis combines the clean tones of the Mark IV and the crunch of the Mark IIc series.
The Rectifier Recording PreAmp is a Rectifier model designed for silent recording. It can also be used as the front end of a rack mounted setup.
Mesa also makes bass amps. Mesa's bass amps have been used by numerous professional bassists such as: Les Claypool, Paul McCartney, Mark Hoppus and Cliff Burton.
The current lineup of Bass Amps includes the simul-state Big Block series, M-Pulse, M9 Carbine, M6 Carbine, and Walkabout. The Big Block models, namely the Big Block 750 and the Titan V12, are powerful MOSFET-based amps that are aimed toward rock and heavy metal musicians because of their overdrive, all-tube preamp, simple control layout and extreme volume. The M-Pulse line includes the M-Pulse 600, the Walkabout, and now-discontinued M-Pulse 360. These amps offer an extremely flexible parametric equalizer as well as a strong, high-headroom clean tone. The Walkabout is a smaller, more portable version of the M-Pulse. All current M-Pulse models are offered in a combo version. The new M6 Carbine amp (formerly named the Fathom) is a basic, more affordable amp that has more of a fast, solid-state feel than the other MOSFET amps, and is geared toward bassists who prefer such an amp.
Mesa's most famous contribution to the bass world stems from its line of all-tube bass amps. The first was the D-180, which ran from 1982 until mid-1985. It utilized six 6L6GC power tubes to deliver 180-200 watts and featured an optional six-band graphic EQ. It also featured cascading-gain input channels for more "crunch". Demand for a more powerful amp led to the development of the Bass 400, which replaced the D180 in mid-1985. It used six 6550 power tubes to push out about 250 watts; however, the cascading-gain channels were replaced with two separate hi- and low-gain channels. Mesa's supply of 6550 tubes was cut short in the late 1980s and they were forced to sell the 400 with 6L6GC tubes, reducing its output to that of the D180. The solution came in early 1989 in the form of the Bass 400+. It was the same as the 400 in most respects but was powered via twelve 6L6GC tubes for nearly 360 watts of power. The 400+ was discontinued in November 2007.
At the time solid-state amplifiers were coming on the market and their sound did not match the sound of tube-driven amplifiers. His original idea was that there is a difference between the sound of a tube amp and a solid-state one. There is a small delay in the migration of electrons that must navigate the space of a tube while electrons in solid-state devices migrate quickly. Thus, in concept the Boogie amp represented a natural sound while its solid-state counterparts represented an artificial or "plastic" sound subjective—provide references
In operation since the early 1970s, Mesa Boogie has discontinued a number of products as its product lines and market change. Some of the major discontinued products are described below.
The Series 300 amplifier head was a very powerful amplifier head. It came in the Mark IIB, IIC, IIC+, and III configurations.
It possessed up to 180 watts of power, making it too powerful for practical usage. As a result, it was discontinued. However, this amplifier head is very rare and information about it is scarce. They are estimated to have a high value. Notable users of this amplifier head are Metallica, Prince, John Sykes and The Rolling Stones.
The head itself can have as many as 8 push and pull knobs with 3 volume knobs, integrated equalizer, reverb, limiter, and a 1/2 power switch that cuts the voltage in half. It utilizes 6 power amplifier tubes. It was mainly designed to play large venues. The sheer loudness of the amp was too much for even a large club. Regardless, these amps remain a coveted piece of Mesa/Boogie history and to this day are very rare pieces of equipment.
The Quad preamp is divided over two channels, the above one is modeled after a Mesa/Boogie Mark IIC and the lower channel is based on a Mark III.The preamp uses 8 NOS Tesla E83CC tubes. These were made in the 70's by Telefunken. The whole signalpath of the Quad uses tubes and no opamps like many other preamps such as the Triaxis and the JMP-1.
Mesa/Boogie designer and president Randall Smith: "The Quad (plus the Simul 295 Stereo power amp) is intended primarily for the concert-touring pro. And the idea is to offer a real alternative to the usual assemblage of two or three (or more) separate amps -usually modified- plus a custom switching system."
Some sources state that Channel 1 is based upon the IIC, however, according to Mike B. at Mesa Boogie, the IIC and IIC+ circuits are quite different, and the Quad is in fact closest to the IIC+ circuit.
Specification:
The Mesa Blue Angel was an offshoot of the Rectifier series. It sported a single channel that thrived with jazzy clean tones, but gave an aggressive sound when turned loud. The amps were available in a head, 1x12, 2x10, and 4x10. The amplifiers featured Mesa's Progressive Linkage technology, enabling the use of two 6V6 power tubes and four EL84 tubes. The amplifiers used a single GZ34 rectifier tube and 5 12AX7s. Interestingly, the Blue Angel's "Dual Rectification" did not include switching a la the Dual Rectifier, but instead used a GZ34 to supply current to the power tubes, while utilizing solid-state rectification for preamp tubes.
Mesa's Nomad series was produced from1998 until the early 2000s, and were considered a successor to the Caliber series of the 1990s. They boasted three channels with the option of a graphic equalizer on some models. It was sold in 45, 55, and 100 watt variations, and was phased out with the introduction of the F-series
The Maverick was a Class-A, channel switching amp available in a 4x10, 2x12 combo, or 1x12 combo format, as well as a 35-watt head. The 1x12 combo was discontinued after about the first half of the production lifetime of the model. The amp was aimed towards country and classic rock players, and was replaced by the Lone Star.
Pre-amplification is done with six 12ax7's divided over two channels, and power amplification is handled by four EL84's in Class A mode.
The Formula is an all tube 1u rack-mount preamp. Basically a front-end of a Nomad series amp.It has 5 12AX7 tubes 2 channels plus assignable/switchable 5 band Graphic equalizer.Touted as being a direct-to-tape recording tool,having built in mic/speaker emulation as to set the user free to record spontaneously without the hassle of speaker cabs and mic placement etc.
The preamp didn't gain acceptance most likely due to the fact that the direct recording tone wasn't optimal. Whilst sonically offering good vintage style clean tones and blues/fusion style lead tones, those looking for rock and more modern sounds felt left out.
There are third-party amateur produced modifications available that apparently improve on the circuitry to make the gain channels more usable.
Dream Theater guitarist John Petrucci remarked that he used the Formula in his rig for clean tones.
The F-Series debuted in 2002 as the spiritual successors to the early '90s Dual Caliber series. There were 3 sizes, the F30 (30 watts), the F50 (50 watts) and the F100 (100 watts). In 2007 the F-Series was replaced by the Express line of amplifiers.
The smallest amplifier in the series was the F30. Rather than 6L6 tubes, it uses two EL84s in its power section. It was available in a 'shorthead' version or as a 1x12 combo.
The F50 was the most critically acclaimed model, featuring two 6L6 tubes in the power amp and using solid-state rectification. It is available as a 'medium head' version, or a 1x12 'widebody' combo. Early 1x12 models shared the same size combo as the F30.
The F100 used a quartet of 6L6s for 100w output, with a 60/100w switch. It was available as a 2x12 combo or in a 'long head' version.
Many notable musicians have used Mesa Boogie amplifications, including Kurt Cobain, Prince and Carlos Santana.
After numerous companies' attempts to copy both circuit designs, and technologies developed by Mesa, Randall Smith began patenting every amplifier, and features unique to them. Below are technologies patented by Mesa and used in many of their amplifiers.
The addition of a distortion synthesis circuit to the signal path of the amplifier. Essentially, Channel Switching. Specifically that found in the Mark II.
The simultaneous operation of two pairs of thermionic devices, one pair in class A, and the other in class AB, through a common output transformer. Found in Mark Series amplifiers from the Mark IIB thru V, the Electra Dyne, and numerous rack mount power amplifiers.
Modification of the power amplifier's dynamic response under increased load in order to avoid the common phenomenon known as "ball sag." Found in Mesa's lower wattage amplifiers, usually employing an EL84 power section.
Over-winding of the power transformer primary coil, and the addition of a switch to select between normal and reduced voltage to simulate the use of a variac. Found in many models after and including the Mark IV.
Allows the user to select between a solid state or vacuum tube rectifier for means of high voltage operation. Found in most Rectifier Series amplifiers, as well as the Lone Star and Mark V. This technology is not to be confused with Recto-Tracking, which automatically selects the rectifier depending on power amplifier configuration. Recto-Tracking is patented and awaiting issue.
Actually applied for by Mesa employee Daniel Van Riezen, the patent outlines the means of replacing potentiometers in an amplifier with digital programmable controls. This technology is only found in the TriAxis preamp, of which Van Riezen is the inventor.
Allowing for the matching of dissimilar pairs of output tubes, e.g. EL34s and 6L6s or any combination thereof. Found exclusively in the Road King.
Allowing for outboard effects, whether in processor, or stomp box form to be implemented in an effects loop parallel to the signal path of the amplifier, allowing the user to mix the desired level of effects saturation into the "dry" signal of the preamp. The Parallel Effects Loop saw use in the many variants of the Rectifier Series, and other amplifiers, before Mesa reverted to their Series Effects Loop design, which proved more transparent in the preamp.
A proprietary method of muting the amplifier by means of shunting the preamp signal to ground at multiple points in the circuit. Found in one form or another since the Mark IV.
The ability to select a second master volume at a different signal level. The original patent calls for two potentiometers in parallel acting as the Master and Solo controls, but more recent designs put the controls in Series, with a relay connecting the first potentiometer to either ground, or to the wiper of the second, preventing the second potentiometer from establishing a volume lower than that set by the master volume. Found in amplifiers since the Dual Rectifier Solo head.
Not to be confused with Simul-class, this enables a push-pull power amplifier to be switched to single-ended operation by means of the same output transformer. Commonly found in Mesa's lower wattage amplifiers with EL84 power sections, but also in higher-powered amplifiers such as the Lone Star in both its forms, and the Mark V.
The ability to assign a power amplifier configuration with a predetermined output to each channel. First found in the Lone Star.