What is the WAZA Tube Amp Expander?

The WAZA Tube Amp Expander and WAZA Tube Amp Expander Core are professional solutions that fuse classic tube-based amplification with modern recording and performance benefits. BOSS’s Tube Logic approach and reactive load design retain an amp’s natural response, supported by premium signal processing that makes it simple to achieve superior results. Learn how load boxes work and why amp/speaker interaction is vital to your tube amp’s tone and feel. Then, discover how this device can help create dynamic new sounds, “sweet spot” tones at home-friendly levels, and much more.

Supreme Tube Tones at Any Volume

A tube-based guitar amp sounds and feels its best when the volume is cranked and its power section is really working. Unfortunately, the levels produced are usually unmanageable for anyone without an isolation booth or very forgiving neighbors.

WAZA Tube Amp Expander products are innovative devices that work in complete harmony with your favorite tube amps, extending and enhancing their capabilities for today’s performing and recording needs. Bringing together many unique guitar tools in one convenient package, they give you easy access to diverse creative options that used to require multiple pieces of expensive, specialized gear and many complicated connections.

At the heart of a WAZA Tube Amp Expander is a variable analog reactive load, which employs groundbreaking BOSS technologies to outperform the capabilities of any commercial load box previously available. The unique BOSS approach fully retains your amp’s tone while augmenting it with potent modern features.

The Load Box—Reining in the Roar

When everything’s in top working order, a great guitar paired with a cranked-up tube amp is a glorious thing, and every player knows that their rig sounds and feels best when it’s dialed up loud. But while you may love it, the resulting sound level is usually too intense for most practical purposes. To tackle this pesky volume issue, two commonly employed solutions are load boxes and power attenuators.

A load box is a device placed after the amp’s speaker output. It contains circuitry that mimics an actual speaker’s electronic loading properties. Once the load box captures your raw amp sound, a discrete line-level output lets you feed it to a secondary amplifier, mixing console, or recording device. Some designs also have a speaker passthrough, allowing you to simultaneously feed the amp’s full power output to a live speaker cabinet.

A power attenuator is a more specialized load box that reduces the amp’s raw output before it reaches the speaker, essentially functioning as a post-amplifier volume control.

Load boxes and attenuators have two common types of designs. Let’s look at both.

"A load box is a device placed after the amp’s speaker output. It contains circuitry that mimics an actual speaker's electronic loading properties."

Resistive Load—This uses a simple resistive network that effectively contains a tube amp’s output signal. However, it also changes the complex impedance interactions with the amp’s output transformer, which substantially alters the tone and feel, particularly as the attenuation amount increases.

Reactive Load—This type of load box contains more advanced circuitry designed to emulate the natural impedance interactions between the output transformer and speaker. As such, the amplifier “sees” the load as if it’s connected directly to a real speaker, resulting in much better sound and feel.

The downside is that most reactive loads are designed to mimic one specific speaker type, so they don’t work equally well with all amps. For example, if the load is tuned to an open-back 1×12 cab loaded with a specific speaker type, you can’t get an accurate sound when you connect a stack-style head, which wants to see a 4×12 cab for the most authentic response. If you’ve ever used a reactive load with your amp and been dissatisfied, this is a big reason why.

Impedance Response—The Key to Magical Sound and Feel

The interaction between the amp’s output transformer and the speaker is essential. It’s critical in determining how a tube amp responds and feels in the player’s hands.

As the guitarist plays, the tube amp’s output transformer communicates with the speaker in a back-and-forth fashion. When the speaker moves in reaction to the signal from the output transformer, it sends some electrical current back into the amplifier, which influences how the transformer behaves. Combined with the touch-sensitive properties of preamp and power tube distortion, this creates a complex, dynamic ecosystem that delivers the magical interactive “thing” we all love about a great tube amp.

Different speakers have unique impedance response curves, which affect how they interact with the amplifier. Going further, the cab type even influences how a speaker behaves with an amp. If you’ve ever changed a speaker or connected your amp to a different cab, you’ve probably experienced this; it usually makes a massive difference in the sound and feel, almost like you’re playing an entirely new amp.

"After your amp’s complete sound and feel have been captured and optimized with the WAZA Tube Amp Expander, you’re then able to use it in many different ways."

Variable Load—Inspiring Sound and Feel with Any Tube Amp

Backed by the refined Tube Logic approach, the innovative BOSS team has taken the reactive load concept to a new dimension. In contrast to the simple fixed designs of other reactive load boxes, the WAZA Tube Amp Expander’s load section features advanced circuitry and variable controls that allow you to dial in the appropriate impedance interaction for your amp’s output transformer. This means that your amp is not only behaving like it’s connected to a real speaker—it’s also behaving like it’s connected to the right speaker for your amp, be it a 4×12 closed-back cab, 1×12 open back, 4×10 open back, and so on. The result is natural, inspiring tone and authentic response, no matter what type of tube amp you use.

The original WAZA Tube Amp Expander model features Resonance-Z and Presence-Z panel controls that provide direct access to many different impedance curves, allowing you to choose the best interaction with your tube amp. Various options are available that represent classic cabs loaded with different speaker types. In addition to providing the tone and feel you’re used to, this variety lets you explore the effect of speaker types and configurations you wouldn’t usually use. The streamlined WAZA Tube Amp Expander Core model offers Combo and Stack impedance curve options, providing simplified operation to support the two most common amp/speaker types.

The next step? Crank your amp to its sweet spot for your perfect tone. And now the fun starts. After your amp’s complete sound and feel have been captured and optimized with the WAZA Tube Amp Expander, you’re then able to use it in many different ways.

Integrated Power Amp with Continuous Volume Control

An important technical feature of the WAZA Tube Amp Expander is its active approach to volume control, which brings numerous advantages over the more common passive designs found in other load devices. With passive attenuation, the volume reduction is split into a few fixed steps, typically with big volume jumps between each. In addition, more and more electronics are added to the circuit as the attenuation is increased, altering the impedance response and changing the tone and feel (usually in an unappealing way).

To maintain authentic tone and feel at all times, BOSS employs a more sophisticated active design. After your tube amp’s sound has been optimized with the reactive load section, it’s routed to an internal amplifier that can feed a speaker cab. The WAZA Tube Amp Expander provides 100 watts of high-headroom power that will support gigging situations, while the WAZA Tube Amp Expander Core features a 30-watt power amp that’s ideal for home practice and low-volume recording with a traditional microphone setup.

"Via a simple panel knob, you can always enjoy your amp’s 'sweet spot' tone at the right volume for your current playing situation."

Reamplifying your amp’s load through a secondary neutral power amp avoids the issues introduced with passive attenuation, giving you consistently great sound with continuous level control. Via a simple panel knob, you can always enjoy your amp’s “sweet spot” tone at the right volume for your current playing situation.

Applications

Live Performance

Adding the WAZA Tube Amp Expander model to your regular stage tube amp setup brings a new dimension of creative control to your rig, opening a world of possibilities when gigging. Here are a few of the many ways you can implement it into live performances:

Dial in the ideal tone for a high-wattage amp while matching the volume for any gig.
Boost the volume of a low-wattage amp to gig-ready levels.*
Create customized rigs to enhance your sound with effects and EQ.
Patch your own effects into the external effects loop.
Select from different rigs and control effects and volume via a MIDI device.
Send a mix-ready tone directly to the main PA via the XLR line output (no mic needed).

*Be sure to connect to a speaker that can handle the WAZA Tube Amp Expander’s output wattage.

"The WAZA Tube Amp Expander and WAZA Tube Amp Expander Core are equally powerful as studio tools, providing central command centers for capturing professional guitar tracks."

Studio Recording

The WAZA Tube Amp Expander and WAZA Tube Amp Expander Core are equally powerful as studio tools, providing central command centers for capturing professional guitar tracks with all your tube amplifiers. Explore these ways to utilize them when recording:

Mic up your favorite cabs and record with great tone at quiet volumes.
Silence the cabinet and record your amp direct to a DAW while playing through one of 22 onboard cabinet emulation types or your own speaker IRs.
Record mic’d cabs and cab-emulated tones at the same time to increase your creative choices at mixdown.
When using mic’d cab emulation or speaker IRs, adjust the Reactive Load control to fine-tune the feel for the most authentic response with the selected cab type.
Capture your amp’s tone along with the WAZA Tube Amp Expander’s stereo delay and reverb effects via the stereo line outputs or USB.

Best of All Worlds

The game-changing WAZA Tube Amp Expander and WAZA Tube Expander Core deliver the best of all worlds, merging classic tube-based amplification with modern performance and recording workflows. Compact, portable, and easy to operate, these amazingly powerful devices seamlessly blend into your rigs anywhere you play. Once you start using one, you’ll soon wonder how you ever got along without it.