The SoloDallas Storm is a boost and limiter pedal that packages the voicing of the Schaffer-Vega Diversity System, the wireless unit used by Angus Young, David Gilmour, Eddie Van Halen and, in SoloDallas' words, "nearly every legendary guitarist throughout the 70s and 80s"1. Released in 2019 as a smaller, pedal-form version of the company's Schaffer Replica sound, it works as what Delicious Audio calls a "colored boost": a preamp that pushes the low-mids for punch while an analog limiter tames transients and accentuates harmonics23.
The circuit is 100% analog, and the current version on SoloDallas' store carries the limiter, overdrive, boost and line buffer from the larger EX Tower in a compact metal enclosure14.
What the Storm does to your sound
SoloDallas built the Storm around the combination of studio effects that made the original Schaffer-Vega system's reputation. The company describes the result as "the unparalleled string separation, percussive attack, copious harmonics and singing sustain heard on some of the greatest guitar tracks ever recorded"1. In practice that means a boost stage that bumps the low-mid frequencies for punch and cut in a mix, plus a limiter that smooths out peaks while adding harmonic content2.
Guitar.com's reviewer found the pedal works well as a subtle enhancer as well as a boost: with the gain low and the boost and limiter halfway, "the raw, harmonically rich amp tone is enriched" with gritty drive and a volume increase5.
The three controls
The Storm keeps it simple with three knobs, which SoloDallas says "allow you to effortlessly shape your sound"6.
| Control | What it does |
|---|---|
| Boost | Controls the gain circuit, bumping the low-mid frequencies for punch and standing out in a mix2 |
| Limiter | Controls the compression circuit, setting the threshold of the optical limiter37 |
| Output volume | Sets the level at the end of the signal path, after the output amplifier7 |
Aion FX's circuit trace also identified an input pre-gain volume control inside the pedal, used to prevent clipping with high-output instruments7.
How much clean boost?
SoloDallas rates the boost preamp at up to 31dB of clean boost1, a figure Delicious Audio repeats as "over 31db"3. Aion FX, which traced the circuit in detail, puts the output amplifier at approximately 25dB of clean boost7. The two numbers describe different stages, so both are worth knowing when comparing the Storm against other boost pedals.
The Storm runs on a power supply only, drawing 200 mA at 9 to 12 vDC, center negative1. There is no battery option, and the current draw is high enough that players on crowded pedalboards should check their power supply's capacity per output.
Compander or optical limiter?
The original Schaffer-Vega Diversity System used a compander, a compressor at the input paired with an expander at the output, and the earlier Schaffer Replica pedal carried that compander over7. The Storm does not. Aion FX's trace found that SoloDallas "replaced the compander in the original SVDS... with an optical limiter," based on a new reverse-engineering of the original unit7. The limiter uses a vactrol, an LED and light-dependent resistor pair, with a variable threshold set by the Limiter knob; Aion FX compares the design to optical units like the Flatline Compressor and Philosopher's Tone7.
Two small details from the trace matter to circuit-minded players. A 10uF capacitor (C5) sits in parallel with the vactrol LED and helps control the limiter's attack time, and a 120pF input capacitor (C1) marked "input RF filter" tames radio frequencies. On the traced unit, both jumpers were unpopulated, so both capacitors were disconnected7.
From the Schaffer-Vega to the Storm
The Storm's lineage runs through SoloDallas's recreations of the Schaffer-Vega Diversity System, the wireless unit used by Angus Young, David Gilmour, Eddie Van Halen and other players through the 70s and 80s1. The company recreated those systems in both pedal and tower form as the Schaffer Replica2, and the Storm is a smaller, more refined pedal-form version of that sound2. It was created initially as a 1:1 replica of the original Schaffer-Vega Diversity System audio circuitry and is derived directly from the 2017 Schaffer Replica EX Tower3.
SoloDallas has also said it struck a deal with the original designer of the Schaffer wireless preamp, which the company credits as the basis for its reproductions8.
- Schaffer Replica: SoloDallas's pedal and tower recreations of the Schaffer-Vega wireless system2
- 2017: Schaffer Replica EX Tower, the Storm's direct predecessor3
- Storm: a smaller, more refined version of the same sound in pedal form2
How it relates to the EX Tower
The Storm is not simply a mini EX Tower, but it is close. Pedal of the Day describes it as "a 100% analog signal path that is nearly identical to the EX Tower, perfectly capturing the signature 'Schaffer Sound'"2, and SoloDallas' own history page says the compact version "contains the limiter, overdrive, boost and line buffer from the EX Tower"4. The practical difference is format: the Tower is the full recreation of the wireless system, while the Storm puts the same core circuits on a pedalboard. Guitar.com calls the Storm "the latest stompbox version of the Replica"5.
What reviewers said
On That Pedal Show, Dan and Mick tried the Storm into a Marshall-style amp and stacked it with another pedal, and their verdict was blunt: "I think that sounds amazing it's killer"8. Guitar.com's review highlighted the build quality, noting "its metal enclosure, true-bypass footswitch, Neutrik jack sockets and 100% analog circuitry," while observing that the enclosure comes only in black5.
Videos
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Questions
What is the Schaffer sound the SoloDallas Storm is aiming for?
It is the voicing of the Schaffer-Vega Diversity System, a wireless unit used by Angus Young, Eddie Van Halen, David Gilmour and many others in the 1970s and 1980s. SoloDallas describes the result as string separation, percussive attack, rich harmonics and singing sustain, the qualities heard on the guitar tracks recorded through the original system.
How much clean boost does the SoloDallas Storm provide?
SoloDallas says the boost preamp delivers up to 31dB of clean boost. Aion FX, which traced the circuit, measured the output amplifier at approximately 25dB of clean boost. The two figures describe slightly different points in the circuit, so both are worth knowing when comparing with other boost pedals.
Is the SoloDallas Storm the same as the EX Tower?
Not quite. The Storm is a compact stompbox that contains the limiter, overdrive, boost and line buffer from the 2017 EX Tower, and Pedal of the Day describes its analog signal path as nearly identical to the Tower. The Tower is the full rack-style recreation, while the Storm packages the same core circuits in pedal form.
Does the Storm use a compander or an optical limiter?
An optical limiter. The original Schaffer-Vega system and the earlier Schaffer Replica pedal used a compander, but the Storm replaced it with an optical limiter circuit based on a fresh reverse-engineering of the original unit. Aion FX compares it to optical designs like the Flatline Compressor and Philosopher's Tone.
What chip is in the Storm's output stage?
The output amplifier is powered by an LM386, the small power-amp chip also found in many low-wattage amplifiers and DIY projects. According to Aion FX's circuit trace, it delivers approximately 25dB of clean boost and is followed by a volume control.
Sources (8)
- The Schaffer Replica® Storm, SoloDallas LLC
- SoloDallas Storm Boost Limiter, Pedal of the Day, 2019-07-24
- Solo Dallas Storm Boost + Limiter, Delicious Audio, 2020-02-27
- History of The Schaffer Replica Circuit, SoloDallas LLC
- Review: SoloDallas The Schaffer Replica Storm, Guitar.com, 2020-11-03
- Unlock Iconic Marshall Tone: The SoloDallas Marshall Tone Pedal Unleashed!, SoloDallas LLC
- Tracing Journal: SoloDallas Storm, Aion FX, 2019-10-18
- Mythos Runestone, 3 Leaf Audio Chromatron, Walrus Audio Lillian, SoloDallas Storm, That Pedal Show (YouTube), 2019-03-05
