What FTT says:
The FREE THE TONE SOV-2 OVERDRIVE uses a high performance DC-DC converter for its internal power supply circuit and drives its signal circuit by supplying ±15 Vdc, providing natural amplification of guitar sound and characteristics.
The SOV-2 with ample overtones features singing overdrive tone that can express subtle picking nuances as differences in timber.
Wide dynamic range and powerful expression based on ±15 Vdc internal boosting. Incredibly high signal-to-noise ratio. Exceptional sound stability by using long-life high reliability components.
NOTE: Due to relatively large current consumption, we recommend to use an AC adapter.
The background of the SOV-2 begins with the original SOV-1. The SOV-1 used no vacuum tubes, but as a result of many years of development it successfully achieved the soft distortion and dynamics that are characteristics of the best tube amplifiers.
We received numerous requests from the SOV-1 users around the world for a smaller, lighter version that would run on batteries or an AC adapter.
In order to realize the requested modifications without compromising on sound quality it was necessary to reconsider the power supply. The original SOV-1 was AC powered and employed a precision power supply circuit of the type used in recording equipment. The sound of the original SOV-1 was to a large degree dependent on an exceptionally clean, stable power supply. It would be physically impossible to use the same power supply in a compact version, so a new circuit had to be developed from scratch.
We decided to use a high-performance (and very expensive) DC-DC converter to deliver the ±15V power required by the original SOV-1 signal circuitry. A highly efficient filter was designed and implemented to prevent the converter’s oscillator from interfering with the audio signal. The signal lines were also laid out with extreme care in order to optimize the unit’s sound. What I have just described in a few sentences actually took several years to achieve, but the results in the SOV-2 are totally satisfying.
The SOV-2 is unique. It is an ideal match for Marshall, Fender, and a wide range of high-end and boutique guitar amplifiers. We sincerely hope that players will make it a part of their music: nothing could be more gratifying for a guitar effect designer.