Guitar World Verdict
The full-size Tube Amp Expander is the ultimate secret weapon for tube amp users, but the Core proves that the concept bears shrinking. It captures the essence of the original model's appeal – taming even the most feral of tube amps, giving them flexibility never previously thought possible.
Pros
- +
It truly captures the utility of the full-size Tube Amp Expander.
- +
Superbly priced for the features on offer.
- +
Small and convenient size.
Cons
- -
The power adaptor isn't as robust as the universal IEC.
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What is it?
When Boss released its Tube Amp Expander under its Waza sub-brand in 2019, there was nothing else quite like it. Far from the crude technology of older load-boxes and amp attenuators, it was a true Swiss army knife, boasting every trick in the book for ‘expanding’ a tube amp.
An advanced reactive load circuit preserved your amp's tonal characteristics while bringing the decibel level down. Direct outputs for silent recording, multiple slots for IRs, built-in effects, and an effects loop for amps without one. It'd even boost a smaller amp's output, its own integrated power amp cleanly increasing the volume of an amp that might otherwise lack sufficient headroom. Quite a thing.
Now, though, Boss has… ahem, contracted the Expander down to what it considers the essentials, calling this new model the Tube Amp Expander Core. Does the little newcomer remain a vital tool for extending the capabilities of your amp?
Specs
- Price: $769/£599/€699
- Type: Reactive load box, attenuator and power amp, IR loader
- Origin: Malaysia
- Features: 10 IR slots, reactive load and onboard 30w power amp
- Controls: Reactive Load response selector, Rig selector, Air Feel Level, Speaker Out level, Line Out level, Phones level
- Connectivity: 1/4" to speaker, 1/4" from amp (with input level selector), XLRs for Line Out left/right (with ground/lift), DC in, MIDI in, USB, 1/4"s for FX loop Send and Return (with level control), 1/4" headphone jack
- Footswitch: None
- Weight: 2.2kg (4lb 14oz)
- Dimensions: 200 x 99 x 202mm
- Contact: Boss
Build quality
Build quality rating: ★★★★☆
Like the original, its robust but relatively unassuming aesthetic will blend in with your rig - an ultra-distinctive Universal Audio OX this is not. Regardless, it's a nicely-made bit of kit, with well-damped controls and a what-you-see-is-what-you-get layout. There's a complex block diagram on the top panel, detailing how it can be integrated into various setups.
One concern is that the universal IEC power socket makes way for a smaller (perhaps flimsier) DC adapter. Other than this, the Boss seems like it'd stand up to gigging with aplomb. Sturdy, functional, and easy to understand.
Usability
Usability rating: ★★★★☆
There's still a lot to unpack, though. The Core's a small box, around half the width of the full-fat model, but crams in almost as many controls.
We've a ten-position encoder labelled 'Rig', selecting which IR to apply to the direct signal, and the Air Feel control, for a simulated room-like ambience. You'll need to open the editor app to set this up to taste, however.
Yes, you really can play your tube amp through headphones, all night if you want – what a time to be alive
There's a knob for the reactive load, for combo or stack-style response; as a mere two-way control, perhaps this could have been a switch. On the bottom row, three volume controls – one for any connected speakers, one for the direct signal, and one for headphones, alongside a 1/4" jack. Yes, you really can play your tube amp through headphones, all night if you want – what a time to be alive.
While it retains the lion's share of its bigger brother's features, some have fallen by the wayside; no onboard effects or dual speaker outputs, and no provision for footswitch control. The line out, MIDI and effects loop are also simplified a little, but are still probably enough to keep most users happy.
The attenuation circuit itself cannot be used with amps rated above 100 watts (down from the original's 150); this limitation will only trouble owners of truly enormous amps. Overall, the Core preserves much of what made the original Expander such a useful tool.
Sounds
Sounds rating: ★★★★★
I set up the Core with my 2x12 Marshall cab on one end, and my Laney VH100R on the other; that's four EL34s and 100 watts of comically oversized British thunder. It's a stadium amp, utter overkill for a home situation – it's a shame that it doesn't get to stretch its legs more. That is, until now.
To my delight, I could hear the big Laney get into its stride - turning the volume up to allow the power tubes to start doing their best work, while balancing it with the Core's Speaker Out level control to keep the volume at neighbour-friendly levels.
I repeated the trick with my '68 Custom model Fender Deluxe Reverb, taking advantage of the Core's effects loop to introduce such joys as the Boss RE-202 Space Echo and Dimension C chorus to the old Fender, which has no loop of its own.
And of course, one might set the amp's volume around its power section 'sweet spot', and then push Speaker Out to make it louder without introducing further distortion. Not to the same volume as the full-size Expander, but enough for many needs.
Both these amps were able to be easily, silently recorded too - with selectable IRs providing a choice of sonic finishing touches.
Verdict
The Core provides yet further evidence of Boss's fantastic work with the Waza line, and the Tube Amp Expander concept. It provides a very well-judged abbreviation of the same feature set – half the size and price it may be, but it's far more than half the product.
Some will need more in-depth features, justifying the stretch to the full-size model, but the Core won't leave many feeling short-changed
Some will need more in-depth features, justifying the stretch to the full-size model, but the Core won't leave many feeling short-changed at all. Considering everything it does for $769, it ought to create many new fans for the Tube Amp Expander range.
Guitar World verdict: The full-size Expander is the ultimate secret weapon for tube amp users, but the Core proves that the concept bears shrinking. It captures the essence of the original model's appeal – taming even the most feral of tube amps, giving them flexibility never previously thought possible.
Test | Results | Score |
|---|---|---|
Build quality | No complaints, other than the less durable DC adaptor replacing the trusty IEC. | ★★★★☆ |
Usability | It's full of features and the control panel is easy, but you'll need the app to get the most from it. | ★★★★☆ |
Sounds | It's a vessel for the true potential of your tube amp, and can enhance it with your chosen high quality IR. | ★★★★★ |
Overall | It is compact but there is more than meets the eye. It'll bring any amp to heel. | ★★★★½ |
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