Boss Waza Tube Amp Expander

Published 4 years ago on January 9, 2020

By Guitar Interactive Magazine


Guitar Interactive star rating:⭐⭐⭐⭐⭐

MSRP (UK) £1143 (US) $1899


Superb quality variable reactive load box and power amp.

First of its kind, tuneable reactive load.

High-quality cab/mic simulations.

Free, easy to use software editor.

Well priced, considering all the features.


No ribbon mic...yet


Power Handling: 150W

Impedance: 4/8/16 ohms

Attenuation: Variable

The BOSS Waza Tube Amp Expander endows your cherished vintage tube amps with all the benefits of a modern digital setup. FX loop? Speaker-free reactive loading plus attenuation? Onboard cab sims AND the ability to load your own impulse responses? It's all available in the Waza Tube Amp Expander. Tom Quayle tells us more.

Boss have been knocking it out of the park over the last few years with some amazing product releases that have really shaken up various sectors of the guitar market. The Katana amp range, ES pedal switchers and 500 effects series have all been highly successful, setting new benchmarks for price to performance and innovative features. Boss’ latest product, designed to shake up the tube amp sector, is the Waza Tube Amp Expander – a highly featured, pro-level tone utility device, designed to take the versatility and practicality of your tube amp to another level entirely.

The Tube Amp Expander (TAE) is a complex product that covers a lot of different bases but, essentially it is a very high quality variable reactive load box and attenuator with a built in effects section, cab/mic simulation, active analogue power amp, IR loader and recording interface all in a single device, built like a tank. This is the first time a product like this has been released with all these features together, making this a device very much worthy of the ‘high-end’ Boss ‘Waza’ label.

Everyone knows that tube amps sound best when they’re cooking, with the volume cranked for that much sought-after power tube saturation and dynamic response. This comes with the downside of ear-splitting volume levels that are becoming less and less appropriate for live and studio environments, especially in the age of amp modelling. The TAE’s all analogue variable reactive load allows you to run any tube amp (up to 150w) at that perfect, cranked level, whilst attenuating the actual volume back down to a sensible level without losing any of the tone, feel and response that you love about that cranked sound. Attenuators have been on the market for years now and they often do a great job of the reducing the volume of your amp but introduce all sorts of artefacts and tonal compromises into the equation. By utilising a reactive load, the TAE ensures that your amp thinks it’s seeing a real speaker at all times, sounding and feeling exactly as you’d expect, allowing you to experience the awesome tone of your cranked amp at any volume level you desire.

There are a whole swathe of reactive load boxes on the market, but the TAE takes things a step (or 16 steps) further thanks to the inclusion of it’s ‘Resonance-Z’ and ‘Presence-Z’ controls. These two dials control the impedance interaction between the amps output transformer and the TAE, allowing you to tune the reactive load to match your amp - selecting between 16 different settings - making your amp feel and sound just as though it were connected to your favourite cab. Boss provide some suggested settings to get you started, allowing you to tune the load for several different 4x12, 4x10, 2x12 or 1x12 type cabs. Unlike other reactive load boxes, where the impedance characteristics are fixed, the TAE allows you to tailor its reactive load to perfectly match any amp, from a vintage combo, to a modern high gain head.

Boss have taken this concept one stage further though, with the inclusion of a built-in 100w Class AB power amplifier. This allows you to reverse the attenuator concept and make a low wattage amplifier louder. Let’s say you have a 5w combo that you adore the sound of, but it just isn’t loud enough for gigs. Plug it into the TAE and the power amp allows you to amplify it to gig volume whilst retaining all the tonal and response characteristics that you love so much. Two speaker outputs allow you to run a pair of cabs in parallel or a single cab as required.

The reactive load and power amp are just a single element of this tonal cornucopia however, as Boss have also included an external series/parallel effects loop and amp control jack, allowing you to switch amp channels from the TAE and add any effects after the power stage of your amplifier. The TAE also includes a studio quality, 32-bit, 96kHz DSP effects section with compression, four parametric/graphic EQs, delays and reverbs built-in that can be routed to the speaker outs and line-outs at the same time or individually, meaning you could conceivably leave your pedal board at home and gig/record with just the TAE and your amp. The effects are of superb quality with all the usual suspects such as plates, halls, rooms, digital, analogue and modulated delays plus studio-quality compression for that super produced guitar tone straight out of the box. All the effects run in stereo through the line outs, although the speaker outputs are mono, so no wet/dry rigs here unfortunately.

The icing on the cake is a fully integrated cabinet and mic emulation suite for the line-out section, with 22 cabinet simulations, five close-mics and three room-mics to choose from. The usual suspects are there, with 4x12, 4x10, 2x12, 1x12 in all the usual speaker flavours with a good selection of dynamic and condenser mics that all sound fantastic and highly realistic, especially when combined with the tune-able reactive load to really dial in the feel and response of your particular amp. One glaring omission is the lack of any ribbon mics, something that Boss will hopefully fix with a future firmware update. However, you can load up to four of your own impulse responses, so that problem can be mitigated somewhat, but in using an IR you lose access to the superb sounding room mics.

Any of the effects, cab sims, FX loop and amp switching features can be stored to one of ten ‘RIG’ preset locations, accessible via the front panel or the downloadable editor software, allowing you full control over any of the on-board parameters. The editor allows you to store an unlimited number of RIGS on your computer for future use. High quality front panel controls allow you to switch on or off the FX Loop, internal effects, EQ/Solo Boost and Amp Control and there is a dedicated dial for the onboard reverb. Finally, a Line Out and Headphone Level control complete the front panel section, offering a decent amount of control without using the software editor, something live performers will welcome a great deal. Using a Boss GA-FC foot controller (purchased separately) allows for even more realtime live control. Tap-tempo, switching rigs, bypassing effects, solo boost/EQ and the FX Loop can all be controlled from the floor. There is even an expression pedal input allowing you to control the volume of the entire rig and full midi-integration for control via your favourite midi controller.

The editor software is of the usual Boss, functional variety. It does the job well and is easy to use but won’t win any awards for graphical quality or good looks. Mouse operation can also be a little twitchy and imprecise at points too, but you always have the option to type in specific parameters if you need more detailed settings.

I/O is of a professional standard too thanks to balanced XLR line outs, a dedicated ‘Front of House’ mono output (both with ground life switches), headphones out and a USB port that turns the TAE into a fully fledged audio interface for your tube amp with dedicated ASIO drivers for low-latency operation.

The TAE is a totally unique product given its combination of so many different tonal tools into a single device. There are other products on the market that do similar jobs, but nothing that covers this many bases as a utility tool for Tube Amp performance on stage and in the studio. Boss have once again shaken up the market with a product that offers exceptional performance and features, professional, road ready construction and real innovation. For tube amp lovers, this might just be the most useful product out there right now for getting the most out of your beloved tone machines. Highly recommended!




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