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Positive Grid BIAS for iPad Review

Positive Grid BIAS for iPad Review

A great-sounding, supremely customizable amp modeler for iPad and iPhone.

Most musicians who’ve spent time with an iPad grasp what a gratifying music-making tool it can be, whether you’re just tapping out simple tunes with your thumbs, or refining guitar overdubs for your next album. The best iOS music apps provide shockingly good sound, smooth connectivity between apps and devices, and ingenious interfaces that make the most of the multi-touch screen.

One particularly successful iOS app for guitarists is Positive Grid’s JamUp, a versatile amp and stompbox modeler with added superpowers, such as an 8-track DAW and an audio file player for practicing to mp3s. JamUp XT, the free version, offers a single amp model and six stompbox simulations. The $20 JamUp Pro XT provides six virtual amps and 16 effects (and many more if you purchase additional expansion packs for five or ten bucks each).

Now Positive Grid dives even deeper into amp modeling with BIAS, a $20 app for iPhone and iPad (sold separately). While the multi-functional JamUp is no slouch in the modeling department, BIAS focuses exclusively on amp modeling, offering a large collection of fine-sounding models of almost unrivaled tweakability. There are no recording functions, no mixing, and no effects other than simple ambient reverb and noise gating—not even amp tremolo or simulated spring reverb.

The extraordinary flexibility of the preamp stage and its ability to realistically simulate the multiple preamp stages of modern, high-gain amps deliver punishing chunk tones that retain character and complexity even at extreme settings.

It’s misleading, however, to dwell on the things BIASdoesn’t do, since BIAS supports both Audiobus and Inter-App Audio, two protocols that allow iOS apps to communicate with each other. You can, for example, open the amps you create in BIAS within JamUp, or record into GarageBand for iOS via BIAS’s amp modeling. So while BIAS performs a single task, there are few limits to how you might deploy the app.

A Model Modeler
I tested BIAS on an iPad Air, connecting my guitar via an Apogee Jam interface (which connects via the iPad’s Lightning jack), and also with an IK Multimedia iRig (which plugs into thetablet’s headphone jack). Both methods yielded great results. (Positive Grid also makes two hardware interfaces, JamUp Plug and JamUp Plug HD, but BIAS works with any iOS-compatible interface.)

BIAS’s home screen browser lets you select amps from nine tone categories: clean, glassy, blues, crunch, high gain, metal, insane, acoustic, and bass, each with four factory models. When you select a model, a virtual faceplate appears, offering six controls (gain, bass, middle, treble, presence, and master.) Functions remain fixed for all 36 models. The modeling quality is excellent overall. Tones are realistic, detailed, and responsive.

But the factory sounds are only the jumping-off point. When you click the gear icon to enter edit mode, a flow-chart-like graphic appears, depicting seven tone-shaping stages. Selecting one brings up a specialized interface for adjusting its parameters. The possibilities are vast—the preamp editor, for example, includes 21 user-adjustable parameters, allowing you to choose virtual tubes, fine-tune the gain structure and simulated biasing, and micro-manage EQ leaving and entering the stage. The tone stack stage, meanwhile, offers 15 different tone models plus three bands of quasi-parametric EQ. The power amp, transformer, and cab simulation stages are equally versatile. Additionally, there are two fully parametric EQ stages you can insert anywhere within the virtual circuit.

It’s deep. Some players will get everything they need from the presets and never enter edit mode. But players who enjoy tweaking and customizing are likely to be BIAS’s biggest fans.

Yet there’s nothing off-putting about BIAS’s formidable controls. The app makes customizing virtual amps so fun and approachable that it’s hard <em>not</em> to come up with cool new models. And once you do, you can share them with other BIAS users from within the app, or download thousands of user-created patches.

Minimum system requirements: iOS 7 or higher. iPhone 4S or newer. iPad2 or newer. iPad Touch fifth generation or newer.


Excellent tones. Immensely customizable. Powerful connectivity. Lucid interface.

Vintage/clean tones not quite as engaging as modern hard rock and metal sounds.


Ease of Use:



$20 street in the Apple Store (also available for iPhone)

Positive Grid BIAS for iPad

BIAS tends to favor heavy rock and metal sounds. The extraordinary flexibility of the preamp stage and its ability to realistically simulate the multiple preamp stages of modern, high-gain amps deliver punishing chunk tones that retain character and complexity even at extreme settings. BIAS’s clean-toned, vintage-flavored sounds are perfectly pleasant and usable, but it's the high-gain realm where BIAS savages much of the competition. It’s no surprise that BIAS is rapidly becoming the modeler of choice for many shred and metal players.

Keeper Tracks?

Absolutely—and iOS makes it easy to wrangle the files. For example, I recorded this review’s demo clips (online version only) using BIAS within GarageBand, and simply emailed myself the mp3 mixes. Next, I uploaded my entire session to iCloud, and it appeared on my computer as a GarageBand file, which I could open within Logic Pro X, my usual DAW. There I could refine sounds further with Logic’s relatively sophisticated tools, but there was nothing lacking in the iPad recordings. It’s entirely plausible that a crafty player could track an entire album on an iPad using BIAS and an iOS DAW.

In fact, the Positive Grid team seems set on making iOS/desktop comparisons moot. A plug-in version of BIAS for Mac is reportedly coming soon. Meanwhile, the company just released Final Touch, a sophisticated mastering tool for iOS.

The Verdict
We find BIAS guilty of being a killer iOS amp modeler. Luddites can get good results from the factory presets, and tweakers will have a field day with a virtual amp designer whose process feels much like, well, designing an amp. High-octane distortion is BIAS’s marquee sound, though there are many nice clean-toned and bass colors as well. The UI is a joy to work with, and BIAS plays well with other iOS music software. Anyone making guitar music on an iPad should investigate this powerful and beautifully realized app.

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