ToneWoodAmp pushes digital effects through an acoustic guitar's body

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The ToneWoodAmp from Ofer and Helene Webman

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Acoustic players looking to augment the natural sound of their guitars with live effects may well have to succumb to a world of cables, amps and stomps to do so. Ofer and Helene Webman out of Phoenix, AZ, have developed a smartphone-sized box called the ToneWoodAmp – or Twamp for short – that brings the kind of effects enjoyed by electric guitarists to acoustic pickers without needing to route the instrument through a big power amp.

If, like me, you bought into the little devices that claimed to turn any flat surface into a music player's speaker, you'll likely have noticed that output quality varies considerably. Though my ears simply rebel at the sound coming from glass windows and metal doors, they will at least listen to a song or two when the Soundbug is placed on a wooden table. Securing it to the back of my acoustic guitar further enhances the listening experience, while giving me the chance to strum along. The ToneWoodAmp takes that to the next stage.

"Before the ToneWoodAmp, acoustic guitarists who wanted to experience the sound of their guitar with the benefits of added effects had to own, carry and connect their instrument to external amplifiers or sound boards," Ofer Webman told Gizmag. "There was no other way for guitarists to just grab his/her guitar and play a song with effects. This dependency on external equipment hindered the natural mobility of the acoustic guitar."

Currently, the Twamp prototype attaches to some magnetic rails that are positioned using a template on the back of the acoustic guitar (with a mild adhesive that's said not to leave a mark when the rails are removed), with its transducer facing the back board. Setup is reported to take less than 5 minutes and doesn't require any specialist knowledge or tools. Players who buy a production unit will also be offered the option of a clamp-on system for more permanent installation.

The unit packs a digital signal processor (DSP) and a mini amp, and offers some built-in effects such as reverb, delay, echo and tremolo. It features a program change knob for selecting different onboard effects, three control knobs for fine adjustment of effect parameters, and gain and volume knobs. Presets can be saved to its integrated memory for quick recall.

"To get its source sound, the ToneWoodAmp requires some sort of pickup installed," Webman explained. "The most recommended types are magnetic or under saddle piezo pickups. You don't have to own a guitar with a pre-amp installed in order to supply a signal to the ToneWoodAmp and any decent static sound hole pickup will work just fine."

For electro-acoustic players, the amp syncs the effects in real time with what's being picked at the business end by way of the instrument's own pickup. The selected sound effect is then "pushed" into the body of the instrument so that the augmented tones heard by the player and audience comes from the guitar. Straight acoustic players will be offered a "technician-free" magnetic pickup to install alongside the Twamp (or a special piezo bridge pickup for nylon-stringed guitars).

"The overall sound result which you hear is a combined sound of the natural guitar sound plus the ToneWoodAmp effects vibrating through the guitar's body," said the Twamp's inventor. "Our sound philosophy is based on the idea that the natural guitar sound is at the front, and in the lead, while the ToneWoodAmp effects are supplementing it. This concept makes sure that a rich natural guitar sound is always at the core."

The unit can also be cabled to an iOS device running a digital effects app such as AmpliTube from IK Multimedia, and the numerous sonic flavors added to the acoustic canvas – meaning you can dial in some sweet distortion, or mix in some funky auto-wah, or experiment with pitch shifting. It also works with apps that support virtual MIDI, such as MIDI Guitar and GarageBand.

By default, the processed sound from an external iOS device is routed through an active Twamp DSP, but there is a switch to bypass this and allow the effects to pass through uninterrupted. Though latency when using the built-in effects is described as negligible, players may experience a small amount of lag when using an external effects source (depending on the processing capabilities of the iOS device and the app supplying the effects). Webman told us that he's currently looking at having the internal DSP and the iOS device work in parallel to allow players to use apps more efficiently.

The Twamp also includes screwdriver-adjustable filters (low cut, mid cut and phase reverse) to accommodate different instrument body shapes, and runs on three AA-sized batteries for at least 10 hours of constant use (based on in-house testing). The developers are looking at rechargeable options for the production version.

The Webmans are currently at the pre-production stage of development, but have decided to add some last minute new features to the system based on feedback received from players at Nashville's Summer NAMM back in July.

"When we presented the ToneWoodAmp at the Summer NAMM 2014, we couldn't predict that so many professional musicians would want it as a stage instrument," Ofer Webman revealed. "Almost everyone who tested it fell in love with the device, and asked for some sort of output to PA. This is going to be one of the main changes that we will apply to the device."

The Twamp is currently up for discounted pre-order When it goes up for sale in early 2015, it will be priced at around US$180. Before that, it will be the subject of a crowdfunding campaign to generate some online chatter and raise some manufacturing funds. Backers will naturally get the chance to pledge for the Twamp at significant less than the retail price.

Update Nov 14: The ToneWoodAmp Kickstarter campaign is now live. Early bird Twamps are priced at $90, with delivery estimated to start in June 2015 (if all goes to plan). Have a look at the pitch video below to see what's on offer.

Source: ToneWoodAmp

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