Positive Grid Spark 40 review

With a suite of future-forward features and great tones, is the Spark the gamechanger for digital modelling amps?

  • $299
Positive Grid Spark 40 review
(Image: © Future / Olly Curtis)

MusicRadar Verdict

The Positive Grid Spark 40 might just be the ultimate at-home amp. The tones are great, and the smart tech is indeed smart. Auto Chord and Smart Jam are incredible practice and learning tools, and a lot of fun, too.


  • +

    So many features, so many tones!

  • +

    Intuitive layout.

  • +

    Smart Jam and Auto Chord are incredible practice tools.

  • +

    The amp response feels authentic.

  • +

    Value for money.


  • -

    A footswitch for channel switching would be amazing.

MusicRadar's got your back Our team of expert musicians and producers spends hours testing products to help you choose the best music-making gear for you. Find out more about how we test.

What is it?

The Positive Grid Spark 40 is a 40-watt modelling guitar amplifier that is just packed with all kinds of features. It has some 30 amp models and 40 onboard effects, and with its Smart Jam and Auto Chord functions, it might just be the future of digital guitar amplification. 

Certainly, it makes a convincing case for being the ultimate amp for the home. The Spark comes in a compact format, with a pair of 4" speakers offering stereo performance from a unit that weighs just 5.2kg.

You can stream songs from your mobile device and using the Auto Chord feature, Spark will transpose the songs into chords so that you can play along

The Spark 40 was a hit with guitarists even before it was launched. Some 25,000 people pre-ordered the amplifier, and over 100,000 own it now in the first year of its release.

We have seen Positive Grid's BIAS modelling tech elsewhere and can testify to its power. You might find it in software form or in one of their amp heads. but here it is seamlessly integrated with the Spark App, offering comprehensive control over your tone. Size-wise, it is in the desktop bracket, but we could see it being positioned anywhere in the home.

There is no shortage of tech-forward digital amplifiers on the market. The Spark feels fully integrated with today's technology; you can stream songs from your mobile device and using the Auto Chord feature, Spark will transpose the songs into chords so that you can play along. 

The Smart Jam feature is every bit as clever. Simply pick a tempo, play a few chords or a riff, select a genre and let the amplifier create a backing track for you to play over. Such tools are invaluable for improving your guitar playing.

What's more, the Spark looks like a guitar amplifier. It is finished in black vinyl. There is nothing intimidating about the front panel. The features might be next-gen but guitar players shouldn't be spooked by the design here.

Performance and verdict

There are seven amp voices, which equates to to seven channels in the language of yore. You've got two for bass and acoustic guitars then Clean, Glassy, Crunch, Hi-Gain and Metal. There is a three-band EQ, gain, master volume and output. The effects each have their own dedicated controls so you can dial them in and out of your signal on the fly.

The set up os very much plug-in-and-play. The app isn't necessary to get started. The dual 4" speakers put out an impressive amount of volume, and a deeper than expected voice. The headphones output is handy for silent practice. Modelling tech typically lives or dies on its ability to imitate a valve-amp response, and the Spark does an excellent job of this. The amp might be avowedly digital but it knows how to communicate with organic matter such we guitar players.

Perhaps the best thing we can say about the Spark 40 is that it makes you want to play more

Now, to fathom the amp's full potential, you'll want to download the Spark App. This is where you can do some deep editing and access the [deep breath] 30 different amp models, five compressor pedal models, nine overdrives and 10 modulation pedals, six delays and, for good measure, nine reverbs. 

Furthermore, you have full control over the signal chain. You can save your favourite sounds and then assign them to any of the seven amp voices across four preset banks.

While it is easy to get started, you can find yourself tweaking and tweaking, as the hours go by. That is part of the fun, though, and to have such a variety of quality tones at your disposal still feels like a luxury.

The Spark app's Smart Jam and Auto Chord features are perfect examples of future-forward features that are a piece of cake for today's player to access and use in the moment.

Also consider...

(Image credit: Yamaha)

Yamaha THR30II
The original THR introduced the concept of the ‘third’ amp in desktop-friendly dimensions. This MKII introduces refined modelling, optional battery power and bluetooth connectivity.

Blackstar ID:Core Beam
Blackstar’s 2x10W desktop amp is an overlooked gem with dedicated channels for electric, acoustic and bass, as well as bluetooth playback.

Boss Katana Air
A fully wireless 30-watt amp that includes a bluetooth transmitter for your guitar. Boss’s Tone Studio app offers 50 effects with COSM modelling and impressive amp voices.

There is a huge online database of chords and song for Auto Chord to pull from. But say you choose a song that is not on its list, Auto Chord will analyse the song and figure out the chords within minutes.

It might occasionally miss the odd chord, and it's not truly perfect yet, but it will help train your ear and make sense of what your favourite players are doing on record. That's a big part of learning guitar. 

So too is playing to an accompaniment; Smart Jam will definitely improve your time keeping, and it makes practice more fun than just playing to a metronome click.

This is a paradigm shift for the digital desktop amplifiers. The Spark 40 makes you want to play more, and it has the tools to make you better. Even without that, it offers a great-sounding and tweakable digital amp experience, with recording capabilities too.

There used to be something a little bleak about bedroom practice. But the Spark 40 brings a little life and light into practice sessions, and there is nothing more satisfying than making progress on the instrument and playing around with new sounds and new ideas. The Spark 40 delivers that experience.

MusicRadar verdict: A high-functioning digital modelling amp that looks and sounds great? Sure, but the Positive Grid Spark 40's Auto Chord and Smart Jam features make it, quite possibly, the ultimate bedroom amp right now.

Hands-on demos

Positive Grid

Sophie Burrell

Riffs, Beards & Gear


  • TYPE: Digital modelling combo for guitar, bass and acoustic with BIAS Tone Engine and app integration for jamming
  • OUTPUT: 40 watts
  • SPEAKERS: 2x4” custom designed
  • TOP CONTROLS: Amp Type, Gain, Bass, Mid, Treble, Master, Mod, Delay, Reverb, Output Volume, Music Volume, four programmable Preset buttons, Tap/Tuner button
  • ONBOARD EFFECTS: 30 Amp Models, 40 Effects
  • SOCKETS: 1/4” guitar input, 1/8” aux input, 1/8” headphone, Bluetooth audio, USB connectivity for recording 2 In x 2 Out
  • DIMENSIONS: 350mm [w] x 180mm [w] 190mm [d]
  • WEIGHT: 5.2 kg
  • CONTACT: Positive Grid 

MusicRadar is the number one website for music-makers of all kinds, be they guitarists, drummers, keyboard players, DJs or producers...

  • GEAR: We help musicians find the best gear with top-ranking gear round-ups and high-quality, authoritative reviews by a wide team of highly experienced experts.
  • TIPS: We also provide tuition, from bite-sized tips to advanced work-outs and guidance from recognised musicians and stars.
  • STARS: We talk to musicians and stars about their creative processes, and the nuts and bolts of their gear and technique. We give fans an insight into the craft of music-making that no other music website can.