How to Use Multi-Effects Modeling Apps to Play Music with Your iPad or iPhone

By Ryan C. Williams, Mike Levine

When you have an interface on your iPad or iPhone, you’ll be ready to start making some music with your guitar or bass. If you want to get authentic-sounding amp and effects pedal sounds, you’ll want to use a guitar multi-effects app featuring digital amp and effects modeling, or a multitrack recording app like GarageBand.

You can also send your guitar signal into a multi-effects app and then into a recording app, using the Inter-App Audio feature Apple introduced in iOS 7, or the Audiobus 2 app. Both facilitate sharing audio between apps in your device.

Guitar multi-effects apps with modeling explained

Digital modeling is a process by which the circuitry and sound of a particular hardware audio device — it could be a guitar amp, speaker cabinet, effects pedal, or any unit that outputs audio — is painstakingly re-created in digital form. The basic idea is that you can duplicate the sound of the device being modeled by designing digital circuitry that mimics the behavior of the original. And it works pretty well. Is it a perfect replication? No, but it’s often very tough to tell the difference.

In iOS, many guitar multi-effects apps feature modeling technology, and these apps typically let you choose from various amp types and pick the effects in your virtual pedalboard. With an instrument plugged in through an interface to your iOS device, it can sound, in your headphones, as if you’re playing through a massive gear rig.

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All the apps give you graphic representations of the amps and effects they’re modeling, and on most, you can control the amps and effects from their virtual knobs. This is very cool for duplicating the experience of using real gear, but it’s hard to be precise when turning a virtual knob.

Amp types

Let’s look at some of the amp types typically modeled in iOS multi-effects modeling apps:

  • Fender: Fender amps have been an integral part of the guitar gear industry since the 1940s. The Deluxe Reverb, Twin Reverb, and Super Reverb are combo amps (head and speakers in one unit) that are typically modeled, as is the Bassman, a separate amp head that plugs into a speaker cabinet (this configuration is referred to generically as a “stack”). IK Multimedia even has an app totally devoted to Fender amps and effects called AmpliTube Fender, which was created in conjunction with the manufacturer.

  • Marshall: Emulations of these legendary British amps are also found in virtually every modeling product. Most of the classic Marshall amps are stacks. Two of the amps you find frequently in modeling software are the JCM800 and JCM900, and the speaker configuration of the cabinets usually modeled with them is 4×12, which means it has four 12” speakers in it.

  • Mesa/Boogie: This American amp maker is best known for its Dual Rectifier amp, which offers a smooth, high-gain sound, and for its Mark I model that’s used by Carlos Santana. Most amp-modeling products offer at least one Mesa/Boogie model, usually the Dual Rectifier.

  • Vox: The Vox AC30, a British amp with a distinctive sound, has been used by many top guitarists, including Brian May of Queen and The Edge from U2. There were many different versions of the AC30 made, but the one called AC30 Top Boost is the one you’ll find in most modeling apps and hardware.

Other amps you often see modeled are from Orange, HiWatt, Ampeg, Soldano, and Peavey, among others.

Bass players will be happy to know that some guitar multi-effects apps also include bass amp models. These might be modeled from Ampeg, Gallien-Krueger, Acoustic, or others. You can also find dedicated bass amp modeling apps such as PocketGK from PocketLabWorks, a bass amp app designed to emulate the sound of Gallien-Krueger bass amps.

Like with real guitar and bass amps, it generally sounds better for a bass to go through a virtual bass amp rather than a virtual guitar amp.

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When you choose an amp type in a modeling app, it will typically be “matched” automatically with its corresponding speaker cabinet, which allows you to instantly get a close replication of the sound associated with that particular amp.

However, one of the cool things about modeling apps is that they make it easy for you to mix and match amp components. This allows you to create hybrid setups that aren’t readily available in the real world, which can be cool for creating unique amp sounds. Positive Grid’s Bias, an amp-design app that works in conjunction with the company’s JamUp Pro apps, even lets you change components inside the amplifier to create custom setups.

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Even though a combo amp is a one-piece unit with speakers integrated into it, amp modelers usually treat a combo’s speaker section as a separate component, allowing you to mix and match its amp or speaker section with other models.

Mic models

Modeling apps not only simulate the sounds and architecture of an amp and speaker cabinet, but also the microphones placed in front of a speaker cabinet. Once again, modeling comes into play in apps that give you choice of a virtual mic type— usually either a dynamic mic, which tends to offer a fatter sound, or a condenser mic, which usually has a brighter, crisper response.

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Some apps, such as Agile Partners/Peavey Electronics AmpKit+, even let you move the mic’s position on the cabinet to change the sound. AmpKit+ gives you three choices:

  • On Axis: This setting simulates the mic pointed directly at the cabinet, and is the brightest setting.

  • Off Axis: With this setting, the virtual mic is angled a bit as it points to the cabinet, and has less high end.

  • Distant: This setting has more “air” (a term musical folks use to describe hearing more sound from the room as opposed to directly from the amp) in it, as it’s emulating a mic placed back from the amp.