Available Now at Northeast Music Center!

MESA/Boogie Tube Replacement Set for 2:Ninety Simul-Class Stereo Power Amplifier

Bring one of MESA/Boogie's legendary stereo power amplifiers back to full strength. This complete tube replacement set provides eight MESA 6L6 power tubes and three MESA 12AX7 preamp/driver tubes—the complete 11-tube complement required for the MESA/Boogie Stereo Simul-Class 2:Ninety.

The MESA/Boogie Stereo Simul-Class 2:Ninety is a serious piece of MESA history.

Designed to deliver 90 watts per channel, the 2:Ninety combines eight 6L6 power tubes with MESA's legendary Simul-Class™ power architecture, producing the authority, harmonic richness, dynamic response, and unmistakable tube feel that made it a cornerstone of professional rack systems.

MESA's official specifications confirm that the 2:Ninety uses eight MESA 6L6 power tubes—four per channel—plus three MESA 12AX7 preamp tubes.

This complete replacement set gives the 2:Ninety owner everything needed to refresh the amplifier's entire tube complement at once.

Available from Northeast Music Center, this is the right choice for players who want to maintain one of MESA's most powerful and respected stereo tube power amplifiers with the correct tube configuration.

COMPLETE 2:NINETY REPLACEMENT SET

• Specifically configured for the MESA/Boogie Stereo Simul-Class 2:Ninety
• 8 × MESA 6L6 power tubes
• 3 × MESA 12AX7 preamp/driver tubes
• Complete 11-tube replacement set
• Four 6L6 power tubes per channel
• Correct complement for the 90-watt-per-channel 2:Ninety
• Designed for MESA's maintenance-free fixed-bias architecture
• Complete power and preamp/driver tube refresh
• Ideal for maintaining a professional 2:Ninety rack system
• Genuine MESA/Boogie replacement-tube configuration

A current dedicated 2:Ninety replacement kit confirms the standard MESA configuration as 8 × Premium STR-445 6L6 tubes plus 3 × MESA 12AX7 tubes.

EIGHT MESA 6L6 POWER TUBES

This is a serious power-tube complement:

8 × MESA 6L6

That's:

4 × 6L6 per channel.

The 2:Ninety uses those eight tubes to deliver 90 watts per channel through MESA's Simul-Class power architecture.

For players accustomed to today's compact solid-state and Class D power amplifiers, eight 6L6s may sound extravagant.

But that's exactly where much of the 2:Ninety's personality comes from.

This amplifier wasn't designed simply to make a preamp louder.

The power amplifier itself is part of the sound.

THREE MESA 12AX7 PREAMP/DRIVER TUBES

The complete complement also includes:

3 × MESA 12AX7 tubes.

These tubes are part of the 2:Ninety's front-end and driver architecture and contribute to the response and character of the complete power amplifier. MESA's official specification confirms the three-12AX7 configuration.

That means a complete re-tube isn't simply about replacing the eight large power tubes.

Refreshing the three 12AX7s gives you a known tube complement throughout the amplifier.

MESA SIMUL-CLASS POWER

This is what separates the 2:Ninety from an ordinary stereo tube power amplifier.

MESA's Simul-Class™ architecture combines operating characteristics associated with Class A and Class A/B simultaneously to produce the amplifier's rated 90 watts per channel.

The result helped give the 2:Ninety the depth, harmonic complexity, punch, and responsiveness that made these amplifiers such formidable partners for professional guitar preamps.

This wasn't intended to be a sterile amplification system.

The 2:Ninety was designed to contribute its own musical personality.

90 WATTS PER CHANNEL

The 2:Ninety provides:

90 Watts – Channel A

and:

90 Watts – Channel B

That's 180 watts of total stereo tube power available from a two-rack-space amplifier.

And it's being generated through:

Eight 6L6 power tubes.

For stereo rigs, wet/dry/wet systems, large stage setups, and professional rack systems, that gives the 2:Ninety enormous authority.

DEEP, HALF-DRIVE & MODERN

The 2:Ninety also incorporates MESA's Smart Power™ functions:

DEEP

HALF-DRIVE

MODERN

These functions can be switched remotely and change the response of the power amplifier to suit different playing situations and preamp sounds.

That makes the 2:Ninety much more than a simple stereo power source.

The power amp itself becomes another tone-shaping component in the complete rig.

WHY A COMPLETE RE-TUBE?

Power tubes are wear components.

And with eight 6L6s operating across two channels, maintaining a healthy, properly functioning power-tube complement is particularly important in an amplifier such as the 2:Ninety.

As tubes age, players may begin to notice changes in:

Punch

Clarity

Dynamics

Headroom

Low-frequency authority

High-frequency detail

and overall response.

Because deterioration can happen gradually, you may not immediately notice how much the amplifier has changed.

A complete replacement set provides a clean starting point.

Eight fresh 6L6s.

Three fresh 12AX7s.

One complete amplifier refresh.

FIXED-BIAS SIMPLICITY

The 2:Ninety uses MESA's maintenance-free fixed-bias design.

That's one reason using properly selected MESA power tubes makes sense.

MESA's amplifier and tube-selection approach was designed as a complete system rather than requiring the player to install arbitrary power tubes and then adjust the amplifier around them.

For the owner of a valuable professional MESA rack amplifier, that eliminates unnecessary guesswork.

FAN-COOLED FOR SERIOUS OPERATION

Eight 6L6 power tubes create substantial heat.

MESA therefore designed the 2:Ninety with fan cooling to help manage temperatures inside the compact two-rack-space chassis.

That's another reminder of what this amplifier actually is.

The 2:Ninety puts a tremendous amount of genuine tube power into a relatively compact professional rack format.

BUILT FOR THE GREAT MESA RACK RIGS

For many players, the 2:Ninety immediately brings to mind the golden age of serious guitar rack systems.

Pair it with a great tube preamp and you've got something fundamentally different from a conventional amplifier head.

MESA's own preamps were natural partners.

The legendary TriAxis became an especially compelling match.

But the 2:Ninety can also provide genuine tube power for other professional preamps and modern rack-based systems.

That's one reason these amplifiers continue to have value decades after their introduction.

A POWERFUL PARTNER FOR MODERN MODELERS

There's also a modern application worth considering.

Today's modelers and preamp processors can produce extraordinary sounds, but some players still prefer the response of a real tube power section driving real guitar cabinets.

That's where a properly maintained 2:Ninety becomes very interesting.

Use the processor or preamp to create the front-end sound.

Let the 2:Ninety provide:

Eight 6L6s

Simul-Class power

Stereo operation

and:

90 watts per channel

to drive the cabinets.

For the right player, that's still an extraordinary rig.

KEEP A CLASSIC MESA POWER AMP ALIVE

The Stereo Simul-Class 2:Ninety represents an era when professional guitar rack systems were built without much concern for how many tubes were required.

Eight 6L6s?

Absolutely.

Three 12AX7s?

Put those in too.

90 watts per channel?

Why not.

The result was a power amplifier with tremendous authority and personality.

That's why Northeast Music Center believes these amplifiers remain worth maintaining.

If you own a good 2:Ninety, you own a serious piece of MESA engineering.

And when its tubes have reached the end of their useful life, this complete replacement set gives you the proper complement to put it back to work.

8 × MESA 6L6.

3 × MESA 12AX7.

11 tubes total.

90 watts per channel.

One legendary MESA stereo power amplifier.