Fender Mustang GT 40 review: A superb practice amp that’s also a Bluetooth speaker

The Mustang GT 40 is a digital modelling guitar amplifier, which promises to replicate the sounds of a wide range of classic amps. It has a good range of built-in effects too and you can program and control it from your smartphone, using the Fender Tone app for Android and iOS. On top of that, it can also serve as a stylish Bluetooth speaker.

Considering the price, it’s an impressive box of tricks but digital modelling doesn’t always sound as good as the real thing, and the amp’s small size might prompt questions about sound quality. Is the Mustang GT 40 an indispensable accessory for home musicians, or just a gimmick?

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Fender Mustang GT 40 review: Price and competition

The Fender Mustang GT 40 is the smartest guitar amp we’ve seen – and if you don’t need all its sophisticated features, you can save money by going for something a bit simpler. The Fender Champion 20, for example, costs just £100 and, while it has only half the output power of the Mustang GT 40, it gives you twelve amp simulators to choose from, with a practical selection of built-in effects including overdrive, chorus and delay. Or, for £139 you can get the Mustang LT25 – a cut-down version of the GT 40 with a simplified interface, a smaller speaker and a more limited selection of preset tones.

Another option to consider is the Line 6 AMPLIFi 30, a fully-fledged modelling amplifier that, like the Mustang GT 40, can be controlled from a smartphone app, and supports Bluetooth music streaming. It’s not as user-friendly as the Mustang, as there’s no digital display on the amp itself, and it’s also rated at a quieter 30W, but you can find it online for as little as £129 so it’s definitely an affordable alternative.

If you’re interested in sharing your music with the world, it’s also worth thinking about the Mustang GT 100 and GT 200 models, which have all the same features as the Mustang GT 40, but are rated at 100W and 200W respectively. This means they’re far louder, but they’re also a lot bulkier – and more expensive, at £289 and £429.

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Fender Mustang GT 40 review: Design

Measuring less than 40cm across, the Mustang GT 40 is clearly designed for playing at home, rather than on the Pyramid Stage and it fits that role very nicely. It’ll slot comfortably into the smallest bedsit, its aesthetics are tasteful (if unadventurous) and, while the twin 6.5in speaker cones won’t blow the doors off, they go loud enough to annoy the neighbours.

Along the top, there’s a set of physical knobs you can tweak to sculpt your sound, which I’ll get to later, and a basic but adequate array of sockets, including a 6.35mm guitar input at the left and 3.5mm line-out and headphone sockets at the right. There’s no secondary input for a backing track, but that’s no biggie as you can stream audio to it over Bluetooth.

At the back there’s also a connector for an optional footswitch control and, unexpectedly, a micro-USB socket, enabling you to plug the GT 40 into a computer and capture your performances in full, CD quality. It’s a neat addition, although you’ll probably want to invest in an extra-long USB cable to use this unless your amp lives right next to your PC.

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Fender Mustang GT 40 review: Controls

The Mustang GT 40 can be used just like any regular guitar amp: plug your instrument in, crank up the volume and tweak the knobs to adjust the gain, treble and bass.

There’s much more to the GT 40, though. Next to the master volume control, there’s a 5.5cm colour LCD screen, which you navigate using the big knob on the other side of the amp. Fender calls this the “encoder”. A quick twist lets you switch between recreations of 31 classic amplifiers, including the Fender Twin Reverb, the Vox AC30, the Marshall JCM800 and the Orange OR120, to access a vastly greater range of tones than you’d ever get from a standard amp.

To further tailor your sound, the GT 40 also includes a good selection of guitar effects, from classic overdrive to chorus, flanger, delay and reverb. These can be punched in, tweaked and even reordered as you please.

If we’re honest, editing sounds and settings using the encoder knob is a bit of a faff. Luckily, there are other ways to do it. One is using the free Fender Tone smartphone app, for Android and iOS.

This connects to the GT 40 via Bluetooth and lets you hop between presets with a single tap. You can also use it to adjust your amp and effects controls, and save your own patches in one of the 200 available slots. You can even download new presets and sounds for free, direct from Fender.

The other option is to invest in a footswitch. With Fender’s four-button MGT-4 controller, you can jump between sounds and settings at the stomp of a foot. It also enables the GT 40’s built-in looper, so you can build up cyclical soundscapes if that’s your thing. It extends the amp’s usability significantly, and it can be bought online for under £50.

Alternatively, you can go for the EXP-1, a wah-type expression pedal that can be used to dynamically adjust a specific parameter such as drive or chorus depth. You can’t use both switches at once, however, as there’s only one socket on the amp.

In all, a lot of thought has clearly gone into making the Mustang GT 40’s features practical and accessible. I only hit one puzzling problem while testing it, and that was when trying out its USB recording capabilities: when I selected the Mustang as the input source in my DAW, my regular audio interface was disabled, and my speakers went dead.

The solution turned out to be to delve into the Fender ASIO control panel and manually route the output to my existing audio interface. Once that was set up, it all worked smoothly but it might be simpler just to use an analogue connection.

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Fender Mustang GT 40 review: Sounds

Digital modelling hasn’t always had the best reputation. The models I’ve tried in the past have mostly disappointed with brash, hollow-sounding “recreations” of classic gear.

Not so the GT 40. Fender’s engineers clearly understand what musicians are looking for and, while I wouldn’t like to swear that the numerous amp sims sound perfectly identical to the real things, they all have the right character. Perhaps more importantly, they’re terrifically playable: in different and distinctive ways, they all sound great.

The value of this can’t be overstated. With some digital amps, hunting around for decent-sounding patches is a tiresome business that sucks the fun and immediacy out of playing. With the Mustang GT 40, you can spin the knob at random and almost always land on a usable and interesting sound – it’s an inspiring feeling.

Bluetooth audio quality isn’t bad either. Music sounds a little boxy and constrained but that’s hardly surprising given the size and primary purpose of the amp. What’s great is that all your amp effects and settings remain available while the amp is streaming – so the GT 40 is perfect for jamming along to your favourite albums on Spotify, or working through practice videos on YouTube.

Fender Mustang GT 40 review: Performance

As we’ve said, the Mustang GT 40 is designed for home use. But it sounds so good that you might well be tempted to take it out on the road, and it does have some gig-friendly features. One is its exceptional portability: the amp weighs an astonishingly light 6.25kg, and has a convenient carry handle set into the top of its sturdy plastic casing.

The software also has a handy Setlist function, which lets you cue up all your favourite patches in a specific order, and then conveniently step through them as needed when playing your set. Partner this with the MGT-4 footswitch and you can basically ditch your entire pedalboard.

The problem is volume. This little solid-state unit may have the same nominal power rating as a room-filling Hot Rod valve amp, but in use it’s nowhere near as loud. Trying out the Mustang GT 40 with a live band, I found I simply couldn’t hear myself over the drums – even with everything turned up to ten.

Of course, you can always mic the amp up, or put it through a PA via the 3.5mm line out socket. Sadly, balanced outputs are only available on the much bigger 100W and 200W variants. That’s a shame, as it’s surely this model that would benefit from them the most.

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Fender Mustang GT 40 review: Verdict

I can see an eager guitarist investing in the Mustang GT 40 and ending up frustrated – not because it doesn’t do everything Fender promises, but rather because it’s so good that you’ll wish you could use it for live performance. If that’s a potential concern, you should probably check out the more sizeable Mustang GT 100, which ups the power rating to 100W for a (still very affordable) £289.

But on its own terms, as a small amp for personal practice and home recording, the Mustang GT 40 is a little wonder. It sounds terrific, it’s hella versatile and, frankly, it’s a steal at the price. A stunning addition to anyone’s music room – as long as you’re happy for it to stay there.