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DigiTech Mosaic

Can this pedal really produce cool 12-string tones without a 12-string guitar?

by Phil O'Keefe


For many guitarists, a 12 string guitar can be a bit of a luxury. While some players (such as George Harrison, Roger McGuinn, and Leo Kottke) are closely associated with 12 strings, most players use them more sparingly; often for supportive parts and layers on recordings, or to cover well-known sounds in cover bands or other live situations. If that describes you, chances are you don't want to put a bunch of money into another guitar that you'll only use occasionally, or have to haul to gigs when you need it only for a song or two. Is there another option? Let's take a look at one possible alternative - the DigiTech Mosaic Polyphonic 12 String effect pedal, and see how close it gets to the sound of the real thing.

What You Need To Know

  • The DigiTech Mosaic is a digital pedal that works with both electric guitars and amplified acoustic guitars, and uses intelligent polyphonic pitch shifting to create a simulated 12-string-type sound, complete with doubled and octave strings and the associated shimmering, chorusing-like effect they provide.

  • The Mosaic uses 24 bit converters and a 44.1kHz sample rate.

  • Housed in a rugged metal box that weighs about a third of a pound and measures 2.875" W x 4.75" L x 1.75" H, the DigiTech Mosaic is fairly standard in size and weight and appears to be ruggedly built and road-ready.

  • The pedal is dressed in basic black powder coat, and the graphics have a celestial / zodiac-based theme.

  • The Mosaic's unbalanced 1/4" input and output jacks are side-mounted.

  • The Mosaic is one of the simplest effects you'll find in terms of controls, with just two cool-looking black metal knobs, which makes it very easy to use.


  • The Level knob acts a bit differently than it does on most pedals. Instead of turning up (or lowering) the overall output level of the pedal, it instead controls only the level of the doubling and octave effect that's added to your dry signal and provides the 12-string effect.

  • The second knob, Tone, controls the overall brightness of the 12-string effect.

  • The Mosaic is powered by an included 9V DC power adapter that uses the industry-standard 2.1mm center-negative barrel style power plug. The jack is located at the top of the pedal.

  • No battery-powered option is provided, and DigiTech has made it very difficult to open the pedal itself. Attempting to do so will absolutely void your warranty - the pedal is covered for one year, which DigiTech extends to six years if you register your purchase with them online.

  • The DigiTech Mosaic features true bypass switching. A red LED located just above the bypass footswitch illuminates to indicate when the effect is active.


  • There are some audible digital pitch shifting artifacts. They become more audible with higher settings of the knobs - particularly the Tone control.


This could prove to be a very practical and useful pedal for some players. I liked the sound best and felt it had the most realism with fairly high settings of both controls, but unfortunately the pitch shifting artifacts become audible with those settings too, which can give away the fact that you're using a simulator and not a real 12 string to golden-eared listeners. For many users and in many situations the sound is more than "close enough" and this won't be a deal-breaker; the Mosaic can definitely give you 12 string sounds that will fool most of your audience, especially for live performances.


Live use is where the Mosaic really shines, and being able to cop some of the jangle, chime and doubled/octave string effects of a 12 string with just a press of a button sure beats having to take another guitar out on the road with you - especially if you only use a 12 string on a few songs, or if you need to be able to quickly switch back and forth between 6 and 12 string type sounds on the same song. For example, if you want to be able to cover "Hotel California" or "Stairway To Heaven" and do the opening 12-string parts as well as the solos all from one single-necked guitar, this pedal's for you.


The DigiTech Mosaic can even work on recordings as long as the guitar track using the effect isn't soloed out or strongly featured - for those situations, I think I'd still rather use a "real" 12 string guitar. But as long as it's layered in the mix with other tracks, many listeners will probably never know your "12 string" wasn't a guitar, but a pedal. Best of all, you won't have to deal with the tuning hassles that come with a real 12-string guitar!  -HC-


DigiTech Mosaic polyphonic 12 string effect pedal ($187.44 MSRP, $149.95 "street")

DigiTech's product web page    

DigiTech Mosaic product manual (PDF file)    

You can purchase the DigiTech Mosaic from:


Guitar Center    

B&H Photo Video  

Musician's Friend    



Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.  

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