Mesa/Boogie Vacuum Tube Audio owner manual Headphone Output, Auto Bias

Page 16

5 - 3 HEADPHONE OUTPUT: (Continued)

what to listen for when you resume listening to your speakers. If you wish to mute your main speakers not to listen to Headphones but while a second pair of speakers is active in a multi-room application via the Preamp Output, we recommend adjusting the multi-room volume with the Level Set attenuator, leaving the Master Volume control at the lowest possible setting. This avoids running the load

FRONT PANEL: TIGRIS

resistor of the Headphone circuitry unnecessarily hot. Should

REAR BAY:

TIGRIS

you own Headphones so efficient that the usable gain range is

 

 

 

 

restricted to just a few “clicks” on the Volume control, select

 

 

one of the higher stages of Feedback and/or more treble activ-

SPEAKERS

 

ity. This procedure decreases overall output and widens the

V A C U U M T U B E A U D I O

 

usable range of the Attenuator.

 

 

 

 

 

HEADPHONES

WARNING: Similar to the warning signs in your car’s review

HEADPHONE

mirror ( objects are closer than they appear ), volume levels during headphone listening are often higher than they might appear. This is especially true after prolonged listening sessions, when listener’s fatigue reduces

our sensitivity and we compensate by increasing the volume. Abnormally elevated playback levels during headphone listening can permanently damage your hearing!

5 - 4 AUTO BIAS:

The TIGRIS uses cathode biasing for its power tubes and thus no adjustments are ever required. This is one of the invisible features we mentioned in the Introduction and it is attractive because it removes the need to monitor and maintain the biasing of the power tubes. Cathode biasing is so effective it is also known as self biasing or Auto Biasing. For the technically minded who want to know more about Bias techniques, here is a brief explanation:

A tube’s operating conditions are established by striking a balance between attracting and repelling forces. Remember, unlike charges attract, like charges repel. At the center of the tube is the cathode which, when heated, emits a cloud of electrons. Possessing an inherently negative charge, these electrons are strongly attracted to the plate (or anode) which is charged to a high positive voltage from the main power supply. Located in between the cathode and the plate is a spiral of thin wire called the control grid. In order to restrict the flow of electrons from the cathode to the plate, the plate is made to be more negative than the cathode. Because like charges repel, negative electrons from the cathode are both repelled by the more negative grid and attracted by the highly positive plate. A small change in the negativity of the grid can cause a large change in the amount of electrons flowing to the plate. And that’s the essence of amplification: a small change in the grid voltage causing a large change in the plate current.

But first, a proper zero-signal, static state current flow must be established and that is accomplished by achieving the proper relation- ship of voltages between the cathode, plate and grid.

In a fixed bias system, such as the BARON, the power tube cathodes are tied directly to ground at zero Volts. A negative voltage from a separate small power supply is then applied to the control grids and that voltage ( called the Bias voltage ) is set such th at a predetermined idle current flows through the power tubes under zero-signal conditions. The more negative the grid is with respect to the cathode, the less idle current will flow through the tube to its plate.

Cathode

...........................................0

Plate

+ 450

Grid

- 50 (voltage generated by

 

separate power supply)

In a self-bias system, such as the TIGRIS, the power tube cathodes are tied to ground - not directly - but through resistors. When current flows through the tubes, a voltage drop occurs across these cathode resistors and this provides a positive voltage on the cathodes. The control grids may then be operated at a zero D.C. voltage - but they will still be negative with respect to the cathodes because the cathodes are now slightly positive.

PAGE 12

Page 15 Page 17
Image 16
Page 15 Page 17
Contents Vacuum Tube Audio Page Table of Contents Chapters Precautions USE Common Sense and Always Observe These PrecautionsOperating Instructions OverviewFront View Tigris Installation UnpackingLocation Speaker Binding PostsSpeaker Binding Posts HOOK-UP OptionsHOOK-UP Options HOOK-UP Options A.C. on / OFF Switch Detachable Power CordWarm / Operate Switches Ground Switch CongratulationsAdvanced Features About BREAK-INCongratulations Tandem State ImagingTandem State Imaging Power Tube Blend Headphone OutputHeadphone Output Auto BiasCathode resistor Class a OperationOn TRIODES, Pentodes & Irishmen Class a OperationOn TRIODES, Pentodes & Irishmen Triodes Tube Maintenance Tube Maintenance & Tube RollingPentodes Evolution of the Tigris Tube MaintenanceTube Rolling Evolution of the Tigris Customer Service Mesa/Boogie Professional HeritageTrouble Shooting Specs Versus PerformanceBasic Specs Specs Versus Performance14 1 Within the US Warranty14 2 Outside the US Warranty Registration Form From Mesa Boogie Spirit of Art in Technology

Vacuum Tube Audio specifications

Mesa/Boogie is a revered name in the world of vacuum tube audio, renowned for its high-quality amplifiers that have shaped the sound of modern music. Founded in 1969 by Randy Smith in California, Mesa/Boogie began by transforming Fender amplifiers into customized, high-gain models, ultimately gaining a reputation for producing powerful, versatile, and low-noise amplifiers. The signature sound of Mesa/Boogie is characterized by a complex harmonic richness, warmth, and clarity that resonates with guitarists and audiophiles alike.

One of the standout features of Mesa/Boogie amplifiers is their all-tube design. Utilizing vacuum tubes as the primary amplification source, these amps deliver a dynamic range and tonal complexity that solid-state amplifiers struggle to match. The quality of the tubes used, often hand-picked or specifically designed by Mesa, contributes to the unique audio characteristics of each model. The use of EL34, 6L6, and 12AX7 tubes in various configurations allows for a range of tonal options, from lush cleans to searing leads.

Mesa/Boogie amplifiers are also distinguished by their innovative technologies. The brand pioneered the dual rectifier system, which allows players to switch between tube and solid-state rectification. This feature gives musicians the ability to tailor their sound to preference, enhancing the responsiveness and feel of the amplifier. The Contour controls found on many models further exemplify Mesa’s commitment to versatility, allowing for fine-tuning of EQ settings that adapt to different musical styles.

Another hallmark of Mesa/Boogie designs is their attention to build quality. Each amplifier is crafted with robust materials, ensuring durability and reliability even in demanding performance environments. The custom cabinets and speaker selections are optimized to complement the amplified tone, providing a cohesive sound that resonates in live settings.

Mesa/Boogie’s reputation is enhanced by their extensive lineup, including the Mark series, the Rectifier series, and the Lone Star series. Each line caters to different playing preferences and styles, from jazz to metal. The versatility of these amplifiers makes them suitable for diverse genres, allowing musicians to explore their sonic identities.

In conclusion, Mesa/Boogie remains a leading force in vacuum tube audio, combining traditional craftsmanship with cutting-edge technology. Their dedication to quality, innovation, and tonal versatility ensures that they remain a favorite among guitarists seeking the ultimate sound experience. Whether in the studio or on stage, Mesa/Boogie amplifiers continue to inspire musicians to push the boundaries of creativity.
Top Page Image Contents