How to turn an iPhone into a guitar amp

I’m with the band

There are lots of iOS guitar interfaces to choose between, and the choice of app is just as varied. The one we must mention first is Apple GarageBand. At £3.99 it’s one of the cheapest amp simulators available for iOS, but that’s just one of its many functions. It’s also a multi-track recorder and comes stuffed with virtual instruments, so you can record entire songs complete with drums, bass, vocals, piano, strings and all sorts of other instruments.

^ Apple GarageBand is packed with fun music-making tools, including a decent amp simulator

To use GarageBand with an electric guitar, select the Guitar Amp instrument and tap the icon on the left that resembles a jack plug. Enable the Monitor option so you can hear what you’re playing. Move the Noise Gate slider all the way to the left, and then slowly drag it to the right until the background hiss disappears. The drawback of using this noise gate is that the ends of notes can be cut off prematurely, but if you want the amp to be silent when you’re not playing, this is the way to achieve it. Next stop is the guitar tuner, accessed via the tuning fork icon on the right. Once you’re happy with this, it’s time to fire up the amp itself.

There are 32 preset guitar sounds organised into Clean, Crunchy, Distorted and Processed categories. However, it’s more fun to mix and match components to make your own sounds. These are drawn from a choice of eight amp models, many of which closely resemble real amps from the likes of Fender, Marshall, Vox and Orange – both in tone and visual appearance. Each virtual amp has the same settings, which isn’t authentic to the original amps but makes it much easier to compare each one. Their tone varies greatly, from the gentle twang of English Combo to the full-throttle growl of Modern Stack. Up to four stomp box-style effects can be added to the chain from a choice of 10 including a compressor, overdrive, fuzz and phaser. There’s also the option to add reverb and delay using GarageBand’s mixer settings (the icon with three faders towards the top-right).

The latest version requires iOS 8.0 or later, which rules out certain older iOS devices. Otherwise, though, there’s no excuse for iPhone, iPad and iPod touch owners of a musical persuasion not to snap up this versatile, highly entertaining app.

Take the tube

AmpliTube is perhaps the best-known amp simulator app, made by the same company that produces the iRig interfaces. It’s compatible with all devices running iOS 7.0 or later. It has grown into a huge array of modules, with some included as standard and others available as in-app purchases or as special editions. It can get a bit confusing keeping track of what’s been paid for, and the regular attempts to upsell to additional modules are pretty tedious.

Then again, IK Multimedia deserves some credit for offering something for nothing. AmpliTube Free and AmpliTube Fender Free are intended as demos of the paid-for versions but they’re fully functional and offer the same high quality processing. They’re limited to one amp, one cabinet and a couple of effects but that may be all you need to be getting on with.

The main app is simply called AmpliTube. It costs £15 and includes nine virtual effects pedals, five amp models, four speaker cabinets and a choice of two microphones. Up to four effects can be used at a time, and the amps’ controls are accurately modelled on the amps on which they’re based. There are various themed versions available for £11, bearing the suffixes Fender, Orange, Slash and Jimi Hendrix. We particularly like the Fender bundle, which sounds more charismatic to our ears than the standard set. You can also buy the standard version and then add the additional content as an in-app purchase.

^ AmpliTube has some superb amps, effects and extra features, but beware of the aggressive upsell

Line 6 Mobile Pod is free to download, but it doesn’t support an audio input unless you pay a £15 in-app purchase or connect a Line 6 Sonic Port or Sonic Port VX interface. This unlocks the full suite of models, with 32 amps, 15 cabinets and 15 effects pedals to choose from. Up to eight effects can be used at a time, with four before and four after the amp in the signal chain.

Mobile Pod comes top for quantity of amp models, and to our ears it also comes top for quality. As we auditioned the various presets, amp models and effects, we found that we spent more time being inspired into playing the guitar than we did with the other apps. The effects section is surprisingly simple, with only one distortion pedal available, but there’s a huge range of tones available from the 32 amps. It’s particularly impressive that the gentler amp models are just as charismatic and interesting as the raunchier ones. Evocative names and graphics and concise descriptions for each amp all contribute to a rewarding user experience.

JamUp by Positive Grid is available as a free taster app, with the full JamUp Pro costing £15. The free version includes two amp models plus a single distortion, delay, reverb, filter and modulation effect. JamUp Pro increases this to 40 amps, 17 distortion pedals, 16 modulation effects and so on. Other features include a built-in eight-track recorder and a Jam mode that plays back songs from the iTunes library, complete with options to slow the track down and change the pitch – just the thing for mastering those tricky guitar solos.

JamUp becomes really interesting when it’s used alongside the snappily titled BIAS Guitar and Bass Amp Designer and Modeler (£15). JamUp and BIAS can be used as stand-alone apps, but with both installed, BIAS acts as an editor for JamUp’s amp models.

^ BIAS Guitar and Bass Amp Designer and Modeler lets you design your own virtual amps by mixing and matching virtual valves and other components

BIAS goes way beyond any other app in the extent to which amplifiers can be customised. While the others let you pick an amp model and adjust its settings, this one lets you design an amplifier from basic virtual components. You can choose which type of valve is used at four points in the signal chain, change the power amp topology and adjust settings such as Bias Adjust and Splitter Gain. Much of the science behind it is beyond us, but it’s enough to simply experiment and go for whatever sounds right. There’s an option to set between one and five valves at the input stage, which is a quick way to vary the tone from a gentle sizzle to searing distortion. There are no virtual effects pedals, but the Room Control page in the Settings adds some reverb to recreate the sound of an amp in a room. For a full assortment of effects, it’s a simple job to export the custom amp model to JamUp or JamUp Pro. The only downside is that it’s not possible to customise amp settings while auditioning the effects at the same time.

Amps to 11

All these apps support Audiobus for inter-app audio. That means you can use an amp simulator app to process your guitar sound and record it to GarageBand, for example. The only limitation is that you record the processed version of the performance. If you use GarageBand’s built-in amp simulator, the dry signal is recorded and the amp settings can be adjusted all the way up to the final mix.

If you’re planning to use these apps live, you’ll find an iPhone or iPad isn’t very easy to operate with your feet. Manufacturers have thought of this, though. The iRig BlueBoard by IK Multimedia is a Bluetooth controller with four footswitches for switching between sounds in AmpliTube. The controller also has two sockets to attach additional pedals for volume control and wah-wah effects. The AirTurn range of Bluetooth pedals offer similar functions and are supported by the Positive Grid apps.

^ If you need hands-free control, check out the iRig BlueBoard controller

It’ll be a while before gig-going audiences accept seeing their guitar heroes roll up to a concert with nothing more than a guitar and an iPhone or iPad. For the rest of us, though, it’s a big breakthrough for convenience and value. If nothing else it makes it easier than ever to enjoy playing the guitar, and that can only be a good thing.

Quick reactions

Latency is an important but thorny issue for music production, and never more so when playing a guitar through an amp simulator effect. The clean sound goes into the device, is processed using various effects and then comes out again. The time it takes for this to happen is called latency, and high latency can make it completely impossible to play the instrument in time.

On a Windows or Mac computer, setting latency is a dark art, with the computer’s hardware, the audio interface, the recording software, the number and complexity of plug-ins and the choice of audio driver type all having an influence. Set the latency too low and drop-outs begin to occur, introducing clicks in the audio. Thankfully, it’s a lot easier on iOS devices, insofar as there’s very little you can do about it either way.

We measured 22ms latency in Amplitube when using an iRig Pro interface and the iPad’s headphone output. However, there’s an Ultra-Low Latency option in the settings, which brought it down to 14ms. The speed of sound is 340m/s, so 14ms is equivalent to standing 5m from a guitar amp in the room. This kind of latency is perceptible but it’s not too distracting.

Line 6 Mobile Pod doesn’t have any latency settings to adjust, but 20ms when played with the iRig Pro is just on the right side of acceptable. BIAS came in at 33ms, but setting its Latency from Normal to Low reduced this to 22ms. We found that we sometimes had to toggle the Latency setting after launching the app to ensure that it was delivering the lowest setting.

Ultimately, all these latency values are manageable, but whichever app you choose, it’s worth using the lowest setting available. However, you’ll need to listen out for clicks in the audio output, particularly on slower hardware or when there are lots of effects in the chain. If clicks begin to appear, reverting to the longer latency value should remove them.