WAZA TUBE AMP EXPANDER

A Deeper Look at BOSS’s Innovative
Tube Amp Command Center

Modernize
the Tube Amp Experience

Despite the fact that nearly all facets of the electronics world moved on from vacuum tube technology decades ago, the venerable tube guitar amp remains the favored choice for serious players everywhere. The electric guitar is an incredibly sensitive and expressive instrument, and the player is in direct control of everything with their hands. A tube-based amplifier is the perfect vehicle for amplifying this expression, as it responds in an equally sensitive way to every nuance that’s driven to the guitar’s output.

BOSS’s Waza Tube Amp Expander is an innovative device that works in complete harmony with your favorite tube amp, extending and enhancing its capabilities for today’s performing and recording needs. Bringing together many unique guitar tools in one convenient package, it gives you easy access to diverse creative options that used to require multiple pieces of expensive gear and lots of complicated set up.

At the heart of the 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. But it doesn’t stop there — it’s also equipped with a 100-watt power stage, deep control options, extensive effects, and versatile DI outputs, making it an immensely powerful rig command center for both stage and studio. Most importantly, the Waza Tube Amp Expander fully retains your amp’s core tone while augmenting it with all these potent modern features.

In this article, we’ll take a deeper look at the way amplifier load boxes work and discuss how the amp/speaker interaction is vital to your tube amp’s tone and feel. We’ll also explore the Waza Tube Amp Expander’s many features and spotlight how this incredibly cool device will transform your rig to new levels of versatility and practical usability.

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 just too intense for most practical purposes. It’s also not any good for your ears! To tackle this pesky volume issue, two commonly employed solutions are load boxes and power attenuators.

A load box is a device that’s placed after the amp’s speaker output, and it contains circuitry that mimics the electronic loading properties of an actual speaker. Once your raw amp sound has been captured by the load box, 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 feed the amp’s full power output to a live speaker cabinet at the same time.

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

With load boxes and attenuators, you’ll find two common types of designs: Resistive Load — This uses a simple resistive network that’s very effective at containing 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 amount of attenuation is increased.

Reactive Load — This type of load box contains more advanced circuitry that’s 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 1x12 cab loaded with a specific speaker type, you simply can’t get an accurate sound when you connect a stack-style head, which wants to see a 4x12 cab for the most authentic response. If you’ve ever used a reactive load with your amp and been a bit dissatisfied, this is a big reason why.

Impedance Response— The Key to Magical Sound and Feel

As touched on in the previous paragraph, the interaction between the amp’s output transformer and the speaker is quite an important relationship. In fact, it’s a critical factor 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 actually sends some electrical current back into the amplifier, which influences how the transformer behaves. When 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 their own unique impedance response curves, which affect the way they interact with the amplifier. Going further, the cab type even has an influence on the way 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 huge difference in the sound and feel, almost like you’re playing a completely new amp.

The BOSS Variable Load Advantage— Inspiring Sound and Feel with Any Tube Amp

Backed by our refined Tube Logic approach, the Waza Tube Amp Expander takes 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 4x12 closed-back cab, 1x12 open back, 4x10 open back, and so on. The result is natural, inspiring tone and authentic response, no matter what type of tube amp you use.

Resonance-Z and Presence-Z panel controls provide direct access to 16 different impedance curves, allowing you to choose the best interaction with any tube amp up to 150 watts. A variety of options are available, which represent classic cabs loaded with different speaker types. In addition to providing the tone and feel you’re used to with your amp, this variety also lets you explore the effect of speaker types and configurations you wouldn’t normally use. Suggested settings are right on top of the Waza Tube Amp Expander, so it’s easy to dial things in quickly.

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, and all at the same time.

Reactive Load Suggested Settings

R-FIER STACK

R-FIER STACK

MESA/Boogie
DUAL/TRIPLE RECTIFIER + 412 Recto

CAB / SPEAKER TYPE

4 x 12” Closed
Celestion Vintage 30

REACTIVE LOAD

HIGH GAIN STACK

HIGH GAIN STACK

FRIEDMAN
BE-50/100 + 412 CABINET

CAB / SPEAKER TYPE

4 x 12” Closed
Celestion Vintage 30 + Greenback

REACTIVE LOAD

BRIT STACK

BRIT STACK

Marshall
JCM 800 + 1960B

CAB / SPEAKER TYPE

4 x 12” Closed
Celestion G12T-75

REACTIVE LOAD

CLASSIC STACK

CLASSIC STACK

Marshall
1987 + 1960BX

CAB / SPEAKER TYPE

4 x 12” Closed
Celestion Greenback

REACTIVE LOAD

SUPER COMBO

SUPER COMBO

Fender Super Reverb

CAB / SPEAKER TYPE

4 x 10” Open Back
CTS Alnico Magnet

REACTIVE LOAD

TWEED COMBO

TWEED COMBO

Fender Bassman

CAB / SPEAKER TYPE

4 x 10” Open Back
Jensen P10R

REACTIVE LOAD

DIAMOND AMP

DIAMOND AMP

VOX AC30

CAB / SPEAKER TYPE

2 x 12” Open Back
Celestion Greenback

REACTIVE LOAD

TWEED DELUXE

TWEED DELUXE

Fender Tweed Deluxe

CAB / SPEAKER TYPE

1 x 12” Open Back
Jensen P12Q

REACTIVE LOAD

DELUXE COMBO

DELUXE COMBO

Fender Deluxe Reverb

CAB / SPEAKER TYPE

1 x 12” Open Back
Jensen C12K

REACTIVE LOAD

MINI COMBO

MINI COMBO

Fender Champ

CAB / SPEAKER TYPE

1 x 8” Open Back
 

REACTIVE LOAD

  • The suggested settings are just starting points. We recommend experimenting with the Reactive Load controls to find the best setting for your amp and playing needs.
  • Company names and product names appearing in this page are registered trademarks or trademarks of their respective owners. In this page, company names and product names of the respective owners are used because it is the most practical way of describing the sounds that are modeled using BOSS technology.

Integrated Power Amp with
Continuous Volume Control

Another 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 just 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, the Waza Tube Amp Expander 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 100-watt amplifier that can feed one or two speaker cabs. 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 any playing situation, whether that’s performing on stage, recording in the studio, or simply practicing at home.

Most of the time, you’ll probably use the Waza Tube Amp Expander to experience the raging tones of a high-wattage amp at a volume that won’t get you fired from the gig or evicted from your living space. But an equally great advantage of its active approach is that it lets you boost the volume of a low-wattage amp to gig-ready levels. Imagine — it’s now possible to get above a loud drummer with your favorite small amp! (A little caution is needed though: just be sure to connect to a speaker that can handle the Waza Tube Amp Expander’s robust 100-watt output.)

Advanced Rig Control with
Powerful Effects and DI Capabilities

To complement its variable reactive load circuitry and onboard power amp, the Waza Tube Amp Expander is equipped with a rig control section that brings an array of modern performance features to your tube amp. This is particularly beneficial with vintage and vintage-reissue tube amps, which typically don’t have features like master volume controls, or effects loops. And with 32-bit AD/DA and 32-bit/96 kHz internal processing, the Waza Tube Amp Expander delivers premium-grade audio performance that’s right on par with the very best studio processors available.

Top-quality BOSS reverb and delay effects are built in, and they’re placed where they perform their best, which is after any amp distortion. Multiple EQs are available for basic tone shaping or boosting the sound for solos, and there’s also a compressor for rounding out your sound with some studio-style polish. An external effects loop lets you patch in your own processing as desired, with selectable levels and series/parallel operation to interface with any type of effect. There’s also an Amp Control jack for selecting channels on multi-channel amps, plus a MIDI output for remotely controlling any MIDI devices you work with.

Balanced mono and stereo line outputs include tone shaping from onboard mic’d cab emulation or user impulse responses (IRs), providing ready-to-mix direct signals for the main PA mixer, stage monitors, and recording devices. There are 22 cab emulations available, and each includes nine different close-mic types with adjustable positioning, plus five room mics for adding more depth to your sound. In addition, 32 slots are on hand for loading up your preferred speaker IRs. Of course, the cab emulation can be defeated if needed to suit any particular application.

Cab Simulation Types

CAB TYPE EXPLANATION
4x12” STANDARD The sound of a closed-back cabinet equipped with four standard 12-inch speakers.
4x12” R-FIER The sound of a MESA/Boogie Recto cabinet (closed-back) equipped with four Celestion Vintage 30 12-inch speakers.
4x12” BRIT STACK The sound of a Marshall 1960B cabinet (closed-back) equipped with four Celestion G12T-75 12-inch speakers.
4x12” CLASSIC STACK The sound of a Marshall 1960B cabinet (closed-back) equipped with four Celestion Greenback 12-inch speakers.
4x12” GREEN / V30 The sound of a Friedman 412 cabinet (closed-back) equipped with two Celestion Greenback and two Celestion Vintage 30 12-inch speakers.
4x12” for FOH A closed-back cabinet equipped with four standard 12-inch speakers. Produces a well-defined sound that’s appropriate for a front-of-house mix.
4x10” STANDARD The sound of an open-back cabinet equipped with four standard 10-inch speakers.
4x10” SUPER COMBO The cabinet sound of a Fender Super Reverb. This is an open-back cabinet equipped with four CTS alnico 10-inch speakers.
4x10” TWEED COMBO The cabinet sound of a Fender Bassman combo. This is an open-back cabinet equipped with four Jensen P10R 10-inch speakers.
4x10” for FOH An open-back cabinet equipped with four standard 10-inch speakers. Produces a well-defined sound that’s appropriate for a front-of-house mix.
2x12” STANDARD The sound of an open-back cabinet equipped with two standard 12-inch speakers.
2x12” DIAMOND AMP The cabinet sound of a VOX AC30. This is an open-back cabinet equipped with two Celestion Greenback 12-inch speakers.
2x12” for FOH An open-back cabinet equipped with two standard 12-inch speakers. Produces a well-defined sound that’s appropriate for a front-of-house mix.
1x12” STANDARD The sound of an open-back cabinet equipped with one standard 12-inch speaker.
1x12” TWEED DELUXE The cabinet sound of a Fender Tweed Deluxe. This is an open-back cabinet equipped with one Jensen P12Q 12-inch speaker.
1x12” DELUXE COMBO The cabinet sound of a Fender Deluxe Reverb. This is an open-back cabinet equipped with one Jensen C12K 12-inch speaker.
1x12” for FOH An open-back cabinet equipped with one standard 12-inch speaker. Produces a well-defined sound that’s appropriate for a front-of-house mix.
1x10” STANDARD The sound of an open-back cabinet equipped with one standard 10-inch speaker.
1x10” for FOH An open-back cabinet equipped with one standard 10-inch speaker. Produces a well-defined sound that’s appropriate for a front-of-house mix.
1x8” STANDARD The sound of an open-back cabinet equipped with one standard 8-inch speaker.
1x8” MINI COMBO The cabinet sound of a Fender Champ.
1x8” for FOH An open-back cabinet equipped with one standard 8-inch speaker. Produces a well-defined sound that’s appropriate for a front-of-house mix.
USER 1-32 Thirty-two user locations for loading speaker impulse response (IR) data with the Waza Tube Amp Expander IR Loader software.

Microphone Types

MIC TYPE EXPLANATION
DYN57 Simulates the sound of the Shure SM57, a dynamic mic that’s one of the most popular of all time for capturing guitar cabinets.
DYN421 Simulates the sound of the Sennheiser MD 421, a dynamic mic with extended low end.
CND451 Simulates the sound of the AKG C451B, a small-diaphragm condenser mic.
CND87 Simulates the sound of the Neumann U 87, a large-diaphragm condenser mic.
RBN121 Simulates the sound of the Royer R-121, a modern ribbon mic that’s become favored for use with guitar cabinets because of its warm, natural sound.
BLEND A Simulates the blended sound of the Shure SM57 and Royer R-121, with the SM57 mixed at a higher level.
BLEND B Simulates the blended sound of the Shure SM57 and Royer R-121, with the mics mixed at equal levels.
BLEND C Simulates the blended sound of the Shure SM57 and Royer R-121, with the R-121 mixed at a higher level.
FLAT Simulates a mic with a perfectly flat frequency response. Produces a sonic image that’s similar to listening to the sound directly from the speakers on-site.

Room Microphone Types

ROOM MIC TYPE EXPLANATION
ANECHOIC No reflected room sound mixed in.
SMALL ROOM Mixes in the room sound of a small studio space.
MID ROOM A Mixes in the room sound of a medium studio space.
MID ROOM B Mixes in the room sound of a medium studio space (higher mix level than MID ROOM A).
BIG ROOM Mixes in the room sound of a large studio space.

The Waza Tube Amp Expander has a USB output as well, offering another direct feed for tracking with your preferred music production software. And with the phones output and its dedicated level control, you can practice anytime and anywhere with your rig, whether it’s late night at home or in a hotel room on the road. In addition, a Fletcher-Munson equal loudness contour can be enabled when playing through a speaker cab at bedroom volumes. Our ears are naturally less sensitive to bass and treble frequencies as the volume of a source is reduced; this cool advanced feature dynamically compensates for this effect as the Speaker Out control is adjusted, allowing you to enjoy big, inspiring tube tones at whisper-quiet levels.

The rig control section can be fully customized with the Waza Tube Amp Expander Editor on your Mac or Windows computer. You’re able to store 10 complete setups — including effects settings, amp control status, MIDI, cab parameters, and more — inside the unit for easy recall while performing. And with the simple panel controls, you can make some basic tweaks on the gig and save them with a quick button press. Better still, rig setups and various control functions can be selected and operated with an optional GA-FC foot controller, or even MIDI devices like the BOSS ES-8 and ES-5 effects switchers and GT-1000 multi-effects.

The Waza Tube Amp Expander’s compact configuration sits right on top of your amp, making it easy to integrate with your regular setup. And for touring applications and permanent studio installations, it can be mounted in a rack via the included brackets. Just be sure to leave 1U open spaces above and below (4U total including the Waza Tube Amp Expander), as the unit needs ample ventilation while it’s reining in your amp’s power load.

Applications

Live Performance

Adding the Waza Tube Amp Expander to your regular tube amp setup brings a new dimension of creative control to your rig, opening up a world of possibilities when gigging.

  • Maintain your amp’s ideal tone while matching the volume for any gig.
  • Connect up to two of your favorite speaker cabinets.
  • Create customized rigs to enhance your sound with effects and EQ.
  • Patch your own effects into the external effects loop.
  • Remotely switch between clean and lead amplifier channels via the Amp Control jack.
  • Send MIDI program and control change messages to MIDI effects and other MIDI-enabled gear.
  • Select from different rigs and control effects and volume via the GA-FC foot controller and/or MIDI devices.
  • Send a mix-ready tone directly to the main PA via the XLR line output (no mic needed).

Studio Recording

The Waza Tube Amp Expander is equally powerful as a studio tool, providing a central command center for personal music production and professional session work with all of your tube amplifiers.

  • 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 mic’d 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 Resonance-Z and Presence-Z controls 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.

Introduction Movie

Your Go-Everywhere
Tube Amp Companion

The game-changing Waza Tube Amp Expander delivers the best of all worlds, enabling you to fuse your classic tube-based amplification with numerous modern performance benefits. Compact, portable, and easy to operate, this amazingly powerful device seamlessly blends into your rig anywhere you play. Once you start using the Waza Tube Amp Expander, you’ll soon wonder how you ever got along without it!

Cautions When Using the Waza Tube Amp Expander

When used properly, the Waza Tube Amp Expander is perfectly safe for use with any tube-based guitar amplifier up to 150 watts. However, there are a few things you’ll want to keep in mind to avoid any damage to your equipment.

  • Never Run a Tube Amplifier Without a Load Connected — In contrast with most modern solid-state amplifiers, a running tube-based amplifier must always be connected to a load, whether it’s a speaker cabinet, a resistive load device, or a reactive load device like the Waza Tube Amp Expander. Operating a tube amp without a load connected — even for a very short time — can seriously damage its output transformer, and possibly other components as well.
  • Only Connect a Tube Amplifier to the Waza Tube Amp Expander — The “From Tube Amp” jack on the Waza Tube Amp Expander is specifically designed for connecting the speaker output of a tube-based guitar amplifier. Never connect the output of another type of amplifier to this jack.
  • Be Careful When Running Your Amp with Its Volume Controls Cranked — As we’ve detailed, one of the prime benefits of the Waza Tube Amp Expander is that it lets you open up your tube amp while controlling its overall volume after the speaker jack. But when cranking your amp’s volume controls to the max, you should always remain aware that it’s now running at full throttle, whether it’s directly connected to a regular speaker cab or a load device like the Waza Tube Amp Expander. As such, your amp’s tubes and other components will be taxed much harder than when running at lower settings. In addition, moving your guitar’s pickups in very close proximity to the natural magnetic field produced by your cranked amp may cause noise and feedback, particularly when working with very high-gain amplifier types.

For complete operation instructions and more info on these and other important safety considerations, please refer to the Waza Tube Amp Expander Owner’s Manual.