Mesa/Boogie Mark 5 Owner'S Manual Download Page 35

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45 WATT (EXTENDED CLASS A, PUSH-PULL):

In this setting only the middle pair of 6L6s are on, and it’s these that run in the extended Class A with their bias reduced. Thus, they

run a little hotter but also smoother, especially across the threshold into clip without sounding harsh.

This essentially half-power position is great for pushed rhythm and threshold-of-clip sounds where you want a smooth
break-up that is devoid of harshness and a slightly higher region of sparkling top end. It also excels at Blues, Roots and
Classic Rock single note solo sounds, where you don’t want to saturate the preamp too much in favor of adding some
authentic power clip to the character. At gig volumes the 45 watt setting will be well into the power band ensuring that

you are playing it old school when it comes to your overdrive.

RECTIFIER NOTE:

In Channels 1 and 2, the 45 Watt mode includes the ability to select the type of high-voltage Rectifier best suited for

your chosen musical style. (Since the Mark IIC+ and the Mark IV never used a tube rectifier, the switch location for Channel 3 is used
for selecting Pentode or Triode, which allows you to achieve the exact performance of the originals – The Mark IIC+ was wired Triode,
the Mark IV allowed you to choose via a Triode or Pentode switch.) In 90 watts, silicon diodes are automatically selected to deliver
the necessary power while the 10 watt mode auto-tracks to the 5U4 tube for lowered voltage and traditional vintage performance.

As mentioned, different musical styles will benefit from the different characteristics of silicon diodes versus vacuum tube rectifiers.

DIODES deliver the maximum headroom and punch, tracking tighter, especially in the bass region. Clean sounds, crunch sounds
and lead sounds will all be more explosive and focused and deliver the greatest articulation.

TUBE slows things down, reduces headroom, smooths things out and scoops upper midrange along with producing a more elastic,
bouncy feel on the strings. Tube rectification is great for threshold of distortion sounds on rhythm parts and vintage style single note
soloing. TUBE also re-voices the top end raising it up an octave and making it a little recessive at the same time.

10 WATT (CLASS A, SINGLE-ENDED):

This position features not only a low power version of CLASS A power, but it takes the vintage mojo even further and switches the

wiring configuration to Single-Ended! In the world of output stage wiring, Single-Ended is the holy grail of circuits. It
is the sweetest, smoothest power style you can achieve and though the power available in this type of circuit is very
limited, the sound is truly golden.

Single-ended wiring emphasizes the second harmonic-- the one that’s cancelled out by push-pull. Because the second
harmonic is one octave above the original fundamental note, it’s very consonant. It actually sweetens the note, adding

a halo of richness that is eliminated by the more modern and powerful push-pull circuits.  As amplifiers were originally developed,
push-pull was seen as a great improvement:  more power and less distortion.  But those early amps were designed for theater sound,
for the then-new “talkies”, not for musical purposes where those harmonics can become part of a magic expressive tonality.   It’s
interesting that some of the most expensive and sought-after “high-end” stereo power amps today are single-ended Class A using
the same 300B Triode tube as those old movie theater amplifiers. And they’re revered for their “musicality”!

For 10 WATT operation the two 6L6s next to the 5U4 supply the single-ended Class A audio power as they are wired in parallel, not
push-pull. Meanwhile the other two function as a “current sink” to enable the push-pull output transformer to continue to operate
properly in a single-ended configuration. This patented technique overcomes the obstacle that a single-ended output transformer
requires a “gapped core” to prevent DC saturation, while such a core would seriously degrade push-pull operation where the balanced
and opposing magnetic fields prevent saturation.

Use this setting to practice with at home as it feels amazing on the strings and sounds rich, full and gorgeous for both clean chording
and overdrive solo sounds. It begs to be pushed into clip with lower preamp gain settings to create dynamic and super expressive

frOnt panel:

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Continued

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MK II C+

EXTREME

EQ ON

EQ FS

90 W

10 W

CH 3

NORMAL