Mesa/Boogie 55, 100, 45 owner manual On TRIODES, Pentodes & Irishmen

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ON TRIODES, PENTODES & IRISHMEN:

 

A look into the inner workings of the Vacumm Tube

 

With apologies to Friends and Relatives from the Emerald Isle - who will make their appearance soon enough - the humor which follows is dedicated to the memories of Spec McAuliff and Fae (Rafael) McNally, two of the True Greats.

As their numerical references suggest, the terms Diode, Triode and Pentode indicate the number of elements within the vacuum tube i.e. two, three or five. All tubes also require a filament or heater which is not included in the count. Its purpose is to excite electrons from the cathode coating by raising the temperature such that they are able to boil out of the electron-rich coating material and form a cloud of free electrons in the vacuum space surrounding the cathode.

Although the term filament and heater are often used interchangeably, there are specific differences: A filament is a directly heated cathode where cathode coating is applied directly to the heating element. Examples are 5U4 twin diode rectifier and 300B triode amplifier tubes.

A heater, on the other hand, is a heating element which is separate from the cathode and is usually inserted within the tubular cathode sleeve. Examples are 12AX7 twin triode amplifier and 6V6 or EL84 beam power pentode tubes. In all cases this fundamental aspect of each tube’s construction is clearly visible, especially when the heating element is glowing red hot.

The cathode, then, would be considered the first numbered element because it is the source of the electrons. The word itself is from the Greek literally meaning completely down, which implies a sense of central origin - like the center of the earth where Tone begins. It might be said that an ecstatic audiophile experiences a positive catharsis, his soul being purified when his system transports him to Audio Nirvana. The only trouble with taking this positive imagery too far is that the cathode is, unfortunately, negative... at least electrically speaking. However this is easily remembered since virtually all musicians and audiophiles have also experienced the more common negative catharsis when they emerge from the emotional rebirth kicking and screaming in rage and frustration.

Once heated, the intrinsically negative electrons are energetic little fellows of almost no mass. Thus they may be accelerated almost instantaneously and will travel through a vacuum a nearly the speed of light. Being of like, negative charge, they tend to repel one another and thus within the electron cloud surrounding the cathode, there is much jostling and elbowing as each one tries to maintain his distance from all the others... unless there is a strong and universal attraction from an outside influence.

Visualize, if you will, a group of sub-atomic Irishmen milling about and in a repellent, negative state of mind. All are scowling and none wants to have anything to do with the other. Now introduce a strong attraction say, a public bar, and you can easily picture an orderly, if rapid movement of the lot in a single direction. This is what happens when a positively charged element called the anode or plate is introduced into the vacuum.

The plate is the large metal element most prominently visible through the glass of an electron tube. It is the outermost element of a tube’s structure and it surrounds all the others. The cathode is at the center radiating electrons outwards. As higher and higher positive voltage is applied to the plate, the attraction for the electrons surrounding the cathode is increased and with nothing standing in the way, full uninhibited flow to the plate occurs... sort of like removing the doors and offering free drinks to the crowd of

surly Irishmen milling around outside. As electrons flow to the plate, the space charge will continually be replenished by further ‘boiling’ of the hot, electron-rich cathode as you can easily imagine other Irishmen impatiently taking up the places of those who’ve gone inside - until the entire village is deserted.

Now, where do they come from and how do they emerge? Well, a grand and elegant lady once showed me how to revive flat champagne: She dropped a raisin into the glass. There was a dramatic and immediate increase in effervescence with the introduction of a cathoding surface. Thousands of tiny bubbles suddenly appeared - and continued to flow from the raisin. Of course the bubbles were made up of gas dissolved in the beverage, but the analogy makes it easy to visualize the loosely bound electrons dissolved in the rich cathode coating as they effervesce from its heated surface.

But back to the electron flow. If the electrons are strongly attracted to a positively charged plate, then it follows that they are strongly repelled by a negatively charged plate and they are. Thus, if an alternating current - such as comes from a transformer - is applied to the plate, electrons will flow only during the times when the plate is positively charged. During periods of negative plate charge, electron flow is stopped and the space charge of electrons remains compressed in the area around the cathode.

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Contents Spirit of Art in Technology Page USE Common Sense and Always Observe These Precautions Table of Contents Overview Nomad Showing all 3 ChannelsModels 45, 55 OverviewFront Panel Nomad Tips for the Desert Rear View NomadTips for the Desert Quick Demo Settings ControlsCH1 CH1 Gain Trol is set low these two controls become dominant Channel 1 Normal / Pushed Channel Modes Channel 2 Normal / ModernSounds...especially overdrive sounds Front Panel Controls OutputRest Area Rear Panel Controls & Connections Rear Panel Controls & Connections Output onlyThese steps Without having to look at them CH2CH1 Reverb Channel 1 Factory Sample Setting Channel 1 Warm & Round Channel 1 Agro Crunch Channel 2 Factory Sample Setting Channel 2- Rotundo Channel 3 Factory Sample Setting Channel 3 Flat Out Nomad 45 Tube Task Chart Nomad 55 Tube Task Chart Nomad 100 Tube Task Chart Page Page Bias Adjustment Part of a continuous series Page Cheers Randall Smith Designer & President Speaker Impedance Matching & HOOK-UP Guide Speaker Impedance Matching & HOOK-UP Guide PositiveWiring SCHEMES...Amplifier to Speaker Cabinets Wiring SCHEMES...Amplifier to Speaker Cabinets Wiring SCHEMES...Amplifier to Speaker Cabinets 16 Ohm On TRIODES, Pentodes & Irishmen On TRIODES, Pentodes & Irishmen Page ALL Knobs Rear Panel Nomad Front Panel Nomad Mesa Boogie 707 778-6565 FAX no

45, 55, 100 specifications

Mesa/Boogie, a name synonymous with innovation in the guitar amplification world, has carved out a niche in the hearts of musicians with its formidable lineup of amplifiers. Among these, the Mark series stands out, particularly with models like the Mark 100, 55, and 45. Each model brings its unique flavor and versatility, allowing players to craft their sound with precision.

The Mesa/Boogie Mark 100 is a powerhouse in the 100-watt category. It boasts multiple channels, allowing guitarists to switch between clean, crunchy, and high-gain tones effortlessly. One of its standout features is the onboard EQ, which facilitates fine-tuning for different guitars, pickups, and musical styles. The Mark 100 is engineered with Mesa's signature Dyna-Watt technology, providing a dynamic response at various volume levels without sacrificing tonal quality. This responsiveness makes it ideal for both live performance and studio recording, as it yields rich harmonic overtones and a wide dynamic range.

Moving to the Mark 55, this model offers a refined approach with 55 watts of power. It retains many features present in the Mark 100 but is more accessible for players who prefer a slightly lower wattage. The Mark 55 excels in mid-gain settings and is popular among blues and rock guitarists. Its Dual Rectifier circuitry can dial in everything from smooth, bluesy overdrive to tight, aggressive rock tones. The amp also incorporates a versatile effects loop, providing seamless integration with pedals and processors, making it a favorite among pedal enthusiasts.

The Mark 45, perhaps the most compact of the trio, brings 45 watts of power to the table, making it a versatile choice for players seeking portability without compromising tone. It retains critical features such as multiple channels and a powerful EQ section while being lighter and easier to transport. The Mark 45's sweet spot is found in its ability to deliver rich, saturated tones at manageable volume levels. Often favored for intimate gigs and home recordings, its versatility allows players to explore genres from jazz to metal with equal flair.

All three Mesa/Boogie amplifiers utilize high-quality components designed for durability and peak performance. Their construction is robust, ensuring reliability on stage or in the studio. With advanced features such as power scaling and tube rectification options, musicians can tailor their sound precisely.

In summary, the Mesa/Boogie Mark 100, 55, and 45 each present guitarists with distinctive tonal characteristics and features that enhance playability and sound. From the powerful performance of the 100 to the compact yet versatile 45, these amplifiers deliver the high-quality, rich tones that Mesa/Boogie is renowned for, catering to the diverse needs of players across genres.
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