Having mastered guitar amps, Positive Grid’s Spark system takes aim at the rest of your backline!
The Spark Live puts Positive Grid’s guitar amp modelling technology into a 150W, Class‑D‑amplified, four‑channel gigging PA that features a full‑spec guitar amplifier modelling channel plus a mixer that can blend in one further mic/instrument source. The mixer also has a stereo line input, as well as allowing music playback over Bluetooth. Bluetooth is also used to connect an Apple/Android app for in‑depth control over the DSP, and for pairing with the optional Spark Control X footswitch unit. For portable applications, an optional 6Ah rechargeable lithium‑ion battery will give up to eight hours of performance time at a moderate volume, with a recharge time of three hours. The Spark Live is designed to be loud enough to hold its own against drum kits in smaller venues, and in larger venues, the amplifier can feed a house PA.
Number Crunching
Given its 150W power rating (450W peak), the Spark Live is pretty compact at just 464 x 251 x 306mm, making it very portable, though it feels reassuringly substantial and weighs a hefty 12kg. Its cabinet is covered with vinyl, and has an attractive grille cloth as well as protective plastic corner pieces and carry handles.
The speaker setup comprises a pair of one‑inch compression tweeters feeding a custom angled horn, with the lows and mids handled by a pair of reflex‑loaded, 6.5‑inch custom woofers. SPLs of 118dB (121dB peak) are specified, with a frequency range of 45Hz to 20kHz (no tolerances are given). The Spark Live can be used either horizontally or vertically, and there’s a fold‑out leg on the rear in case you want it angled. For stand‑mounting, there’s a standard pole socket for horizontal use.
In all, there are three mixer channels: one on the front panel for guitar, and two more on the rear panel. Two rotary controls on the front panel adjust the overall level of channel 1 (guitar) and music (Bluetooth streamed audio or USB DAW playback). Channel 2, which has a volume control and a preset selector, is fed from a combi XLR/jack socket and has access to its own menu of amp modelling and effects, while channel 3+4 has only a pair of straightforward jack inputs and a volume control. There’s also a 3.5mm mini‑jack output for headphones.
The Spark Live can accommodate an electric guitar, a mic or other instrument, a stereo line‑level source, plus stereo Bluetooth or DAW playback simultaneously.
A pair of five‑pin DIN sockets provides MIDI In and Out. MIDI can be used to bypass the effects, to change presets, to control the levels of the individual channels and to sync a second Spark Live amp. There are also two USB‑C sockets, one for use as an audio interface or for firmware updates, the other for charging mobile devices. The Bluetooth pairing button is located just above the USB ports. The recording feed produces a 24‑bit/48kHz stereo signal, and is compatible with macOS and Windows.
Two line output jacks facilitate running the amp’s signal to a PA or further amps or speakers. A master control section offers a three‑band EQ and a volume knob.
The Engine Room
At the heart of the system is Positive Grid’s proprietary “Sonic IQ audio engine”, featuring signal processing that has been designed to take account of the acoustic engineering aspects of the amplifier so as to optimise the final sound. The amplifier can even adapt dynamically using its G‑Sensor, automatically tuning the system depending on whether it is being used horizontally or vertically. In vertical mode the amp works in mono, while in horizontal mode it switches to wide stereo. Other features include auto loudness and clarity adjustments, compression, bass enhancement and vocal enhancement.
How can all this be achieved without making the amplifier too complicated? The answer is to put a practical number of physical controls on the amp itself, whilst leaving detailed editing and preset creation to the app. The app allows amp and effects modules to be swapped out and adjusted before being saved back into the amplifier, from where they can be further controlled using the familiar amp‑style controls on the front panel. Channel 2 presets are accessed in the same way, though all adjustments have to be done from the app.
A channel 1 preset can have one amp model and up to three pre‑and three post‑amp effects, drawn from the full complement of Spark processing modules (33 amps and 43 effects). The front panel offers physical controls for Drive, three‑band EQ and volume, while up to eight presets can be saved/recalled using a push‑turn encoder accompanied by four LEDs that show either red or green. A long press of the encoder stores the current settings as a preset, while a double‑press puts the amp into tuner mode and mutes the guitar output. The LEDs show whether the note is sharp or flat relative to the closest note, but they don’t tell you what note it is.
Channel 2 offers three amp models tailored for vocals, bass or acoustic guitar, this time with 50 effects covering instrument and vocal treatments. Here the user can set up one effect before the amplifier model and two after it, and there’s a preset encoder dial exactly like the one on channel 1. A typical use for channel 2 might be for a vocal mic or acoustic guitar, with the stereo channel available for sources such as keyboards or the outputs from a small mixer.
Appy Now?
Channel 1 offers the complete set of Spark amp and effects emulations, while channel 2 offers a more limited selection that caters to electric acoustic guitar, bass and vocals.
We’ve covered the amp and effects emulations in Positive Grid’s Spark range before, but suffice to say there’s a useful range of amp types and effects from which to choose, allowing for guitar tones that run from country clean to ‘veins in your teeth’ heavy rock. There’s also an AI Jam Along feature: tap in a tempo on your phone, play a few lines, and the app will create a suitable backing in the same key. A number of ready‑made backing tracks are also included, with chords displayed on your phone, and there’s a library of presets created by other users available from Positive Grid’s Tone Cloud.
Navigating the Spark Live app is straightforward: a mixer icon takes you to a very simple faders page that lets you balance the levels of the various inputs, while tapping the Channel button toggles between channels 1 and 2. The app is clearly set out, with graphic depictions of the various amps and effects that offer strong visual clues as to which ‘real life’ amps and pedals they are inspired by. You can turn effects on or off, switch them out, swap amplifiers, adjust their controls and so on. Communication works both ways, so adjusting a dial on the app changes the value on the amp, and vice versa.
In Use
Though the amplifier comes with its preset slots filled with a variety of amp tones, I didn’t find any that were quite right for my own rock covers band, so I invoked the app and found that setting up my own amp/effect chains was very easy. Additional FX can be purchased, but for most applications the user is well served with a practical selection of each type of effect.
If there’s a function missing, it is a master preset level adjustment on the amp itself, to provide an easy way to balance the levels of the presets you wish to use live. As it is, you need to use the app and adjust the master volumes on the amp models, which is not quite so straightforward, especially if you want to make tweaks during a soundcheck at a gig.
Overall, the app is really well thought out, and the AI features are useful if you want to explore variations of tones that fit a particular genre, or jam along with an automatically generated backing. The more generic jam tracks arranged by genre are also useful, and I like the way they display the chords on a moving grid as they play. Checking out what other users have created via Tone Cloud is also a good way of homing in on tones you like, as you can see exactly what settings they have used.
The optional battery pack can power the Spark Live for up to eight hours at moderate volumes.Of course, if the amp didn’t actually sound good, then all of the above technology would be a waste of time. Fortunately, Positive Grid have been working on amp modelling for years and they’ve got it down to a fine art. As long as you give yourself time to explore the different amp models and make the necessary adjustments, you can get pretty much any guitar sound you like. The compression and reverb add a professional polish to clean sounds, while combining compression with light overdrive or a gently pushed amp will deliver those edge‑of‑breakup sounds that work well for blues or country‑rock. There’s a decent amount of touch responsiveness too, so you can control proceedings via the guitar volume control and/or playing dynamics.
When it comes to high‑gain sounds, there’s everything you could wish for, from classic rock to edgy metal. Add a bit of delay and the corner of a small pub becomes a stadium. You don’t quite get that sense of moving air that you get from an open‑backed combo — to my ears, what you hear is more like a studio recorded guitar sound, but at gigging volumes. For many players, that will be just what they want, especially if a lot of different sounds are needed during a gig. The noise gate works well for cleaning up high‑gain sounds but the default setting sometimes cuts off sustained notes a little short, so I’d advise adjusting the threshold as low as you can get it.
In a home or studio setting the amp feels right at home and it can deliver recording‑ready tones very easily...
In a home or studio setting the amp feels right at home and it can deliver recording‑ready tones very easily, either over its two‑in/two‑out USB audio interface, by taking a line feed from the back of the amp or by sticking a mic in front of it. At pub gig levels you should be fine if just using the amp for one guitar, but if mixing multiple sources and playing with a drummer, hooking up a powered extension speaker or two would be a good plan. Lastly, the optional battery would be a great option for some seriously good‑sounding busking.
Pros
- A huge range of very viable guitar tones.
- Separate presets for channel 2.
- Simple mixer built in.
- Spark Live app for tone editing and more.
- Optional battery operation.
Cons
- A way to balance the different preset levels on the amp itself would have been nice.
Summary
A flexible, great‑sounding portable PA that offers full‑fat guitar DSP, as well as options for bass, vocals, acoustic guitar and more.
Information
£529; battery £79. Prices include VAT.
$549, battery $79.
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