Sound Stone

Sunwave - Analog Optical Filter (Limited Batch of 100)

Sale price Price $139.99 Regular price Unit price  per 

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The second batch of 100 units now available!


We're extremely excited to debut our first guitar pedal. The Sunwave is a low-pass filter, which is what analog synthesizers use to shape their sound. We have always wanted an affordable low pass filter that was designed specifically for guitars and is affordable.

The sound itself is akin to plugging a guitar into a synthesizer's filter input. While it is similar to a wah (a bandpass filter), a low-pass filter is much more drastic and has a distinct sound quality that many find more pleasing than a wah. 


There are a few other low-pass filter pedals on the market, what makes this one different? 

Nearly all filter pedals use transistors, diodes, or OTAs, which work great for a synthesizer but not for a guitar due to the difference in signal levels. This leads to a filter that has a high noise floor and little headroom. In order to address this, we decided to use an optical approach, which uses photocells and light to modulate the filter's cutoff.

Inside the pedal, there is a series of LEDs, which affect the filter cutoff based on how bright they are shining. To control the brightness, you can either use the onboard knob, an expression pedal, or the built in LFO. Each unit has hand matched photocells, in order to have an even filter response. In addition, we calibrate every unit so that the resonance will be pleasing when maxed out. There is an option to remove this safeguard though, via the "Full Res" switch, which will allow the pedal to achieve self-oscillation.

Because of the variety of controls, it's also possible to use the pedal as several different effects. If the gain is turned up all the way, it functions as a distortion. When the resonance is turned down and the LFO Amount is turned up, it acts as a tremolo pedal. You may also use the expression pedal to turn the effect into a volume pedal.

We highly recommend using an expression pedal with the Sunwave, since it adds hands-off control. While most expression pedals should work, we recommend this affordable option.

Note: The LED only signifies that the power is on and the LFO rate. In a future version we will add a foot switch toggle indicator. 

Initially, we will be selling this pedal in small batches of 100. Each batch will be labelled, numbered, and signed on the inside of the pedal. Uses a standard 9V guitar power supply (center negative). Power supply not included.

If your unit is defective, please reach out and we will do a refund or a replacement. All shipments will be insured and sent via UPS GROUND. Customers will be responsible for paying any customs fees or tariffs if they are ordering internationally.