Variac Overdrive

More than another amp in a box…

The Variac Overdrive places an entire era of rock guitar right under your foot.

  • Individual controls for preamp and power amp overdrive for vintage and modern sounds.
  • Two different phase inverter styles.
  • Vintage rock, hard rock and old school metal tones and more.
SKU: VO Category:

Rock guitar tone has long been defined by overdriven tube amplifiers. Those tones have evolved over the years as amps were intentionally designed for more gain and a more focused overdriven sound.

You want those tones all the time, but we all live in the real world. You head out to a gig not knowing how loud you can play, whether you’re amp will be mic’d or how much of an amp you can even fit on the stage. Your practice space is tiny and even the drummer thinks you are too loud.  And of course you need to practice without waking the neighbors on occasion. We get it. We’ve been there too.

The Variac Overdrive emulates both a hot-rodded tube preamp and a power amp with two phase inverter options. Chords sound huge, leads sing with clarity, and pinch harmonics come out with ease. The Variac Overdrive is an expressive overdrive pedal with the articulation and touch sensitivity of a tube amplifier. The controls are interactive along with “hidden” controls like the power supply.  Dynamics and headroom are all affected by the power supply. Powering from 7.5 to 18 VDC opens up even more possibilities. More on the “hidden” controls below.

With tones ranging from AC/DC, early Van Halen, Judas Priest to Tom Morello and even 80’s hair sounds, the Variac Overdrive is more than another amp in a box. It places an entire era of rock tone at your feet. It’s based on tests of individual tube circuits, careful listening to some of our favorite rock and old school metal, and the topology of amplifiers the artists actually used.

The “hidden” controls:

These are not internal switches or knobs. No these are hidden plain sight.

Demos and soundclips

Dennis Kayzer looping & down tuning with the Variac.

Using the Variac overdrive.

These aren’t really rules, but pointers to get started using the Variac Overdrive.

Pedal order: The Variac Overdrive loves getting pushed by other overdrives, boosts and fuzzes. For best results place the Variac as the last dirt pedal in your chain, but before modulation, delay, reverb or other time based effects, unless of course you want those effects to sound like they are going through a dirty amp.

The Cathodyne / Long tail pair switch: Cathodyne is best for smaller amps and playing at low volumes. The LTP setting works best with bigger amps, especially at stage volume levels. There will certainly be exceptions depending on overall gain and the bass response of the amp you are using.

Amp volume- Keep in mind that the actual volume level of your amp will affect the overall tone, dynamics and feel. As you turn up your amp you’ll likely find yourself decreasing the gain and tone control settings on the pedal.

The guitar- Every guitar will sound different with the Variac. Every pickup will sound different. The volume knob on your guitar is great for controlling the overall gain. The cascaded gain stages and tone stack let all the intricacies of each guitar shine though. Your Telecaster won’t turn in to a metal machine, and your pointy neon EMG equipped shred guitar probably won’t get all warm and bluesy either.

Sample settings- Consider these all starting points. Given the variables of guitars, amps, overall volume, etc. you’ll likely need to tweak things.


[one_half last=”no”]Variac Brown Sound

One of two main sounds we used for the Variac’s initial foundation. Many rumors and much mystique surrounds the tones on VH’s early work. For years there were rumors that Eddie’s main amp had been heavily modified. Voltage starved tubes? There are a few things we can be sure of. Eddie often dirtied things up with stompboxes like an EQ pedal. Many tracks on that album had his Echoplex plugged in even when not in use.

Eddie was also one of the first guitarists to really embrace the Floyd Rose bridge with his PAF equipped frankenstrat allowing some crazy sounds. (before they became a cliche) Much of his tone relied on technique and the guitars he used as well.  The Brown Sound setting should get you started. At lower volumes you’ll likely want to turn the tone controls up a little to make it sound ALIVE! Set the volume and PI switch to taste.

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The second initial inspiration for the Variac. Specifically the era of 1979-1981. Again these settings are a starting point, and these settings cover two different guitarists so tweak as necessary.

To get really authentic you’ll want an SG and a Gretsch. While they’ve both been rather single minded with their guitars, the stories behind the amps used have been inconsistent, and don’t always match what they had on stage in photos.

Overall both had bright gainy tone. Their guitars likely created as much contrast in their tone as the amps. Malcolm especially had a lot of thick harmonically rich tones compared to their earlier work.[soundcloud url=”” comments=”no” auto_play=”no” color=”CE0504″ width=”100%” height=”100%”] [/one_half] [one_half last=”no”] variac 70s

The 70’s? That’s a lot to cover in one setting.  Again this is a starting point, and specifically we’re talking”we don’t want to sound like the 60s” rock guitar here. Everyone was so over the Beatles or at least did not want to be pigeonholed by that sound.

24 track recording on 2 inch tape was becoming the norm in the 1970s opening up possibilities for thicker mixes and complicated production. Stereo FM-radio was on the rise. The old cranked amp “live” sound used to cut through the AM mono mix was on the out. Amplifiers were being designed specifically for gain and a more focused sound. A trend started a decade earlier by the JTM45, but now with even more control to fit in even thicker mixes.

Again this is a starting point. The pentodes and treble controls will be the place to start tweaking. Adjust volume and PI switch to taste.

[soundcloud url=”” comments=”no” auto_play=”no” color=”CE0504″ width=”100%” height=”100%”] [/one_half] [one_half last=”yes”] variac 80s

Painting with a wide brush again. Arguably the beginnings of 80s hair metal started with Van Halen. Not so sure they want credit for that dubious honor.  The cliche of a Flamboyant singer + Virtuoso guitarist was a corner stone of nearly every hair band. After a decade of non-stop pick scraping, pinch harmonics, whammy bar dive bombs and triplet tapping solos (not to mention the aesthetic) not everyone was lining up for ten more years of it.

In spite of the cheeseball antics and musically beating a dead horse for a decade some of it was really good and there’s certainly some choice classics. Again, guitar was completing for sonic space in recordings. In the 80s synthesizers were filling up more of the mix. Drum recordings were being super processed. Getting brighter in the 80s allowed to cut through the mix and helped pinch harmonics sing and sustain.

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The king of tasteful use of pinch harmonics, Gibbon’s sound from the mid 70s to early 80s is timeless and iconic rock guitar tone.

His Pearly Gates 59 Les Paul in to a 100 watt Super Lead were a big part of his tone

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A classy and timeless vintage tone. It’s warm and not too gainy and works well with more complicated chords.  The treble control massively changes the character and pick attack. Leave the PI switch set to cathodyne to fill out the bottom end. For best results power the pedal at 12 volts or higher.

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Lots of low end without getting muddy. Perfect for modern drop tuning tones. [/one_half] [one_half last=”yes”]  [/one_half]

Control interactivity

Preamp vs Pentodes: As you travel through rock and roll time you’ll hear distinct differences in amp design. In the early days most loud overdriven tones were primarily cranked amps pushing power tubes, transformers and speakers to the edge. Much of the cranked amp tone was never intentional. Early tube amplifier design was all about making the most volume out of the least number of tubes and smallest transformers possible. Eventually master volume and channel switching amps were designed for more versatility and overdriven tones. Typically power amp distortion is open with a vintage sound. Preamp distortion is more compressed and modern.

The Variac Overdrive gives you control of both sounds, but both knobs offer more gain than a vintage amplifier circuit. You’ll usually want to keep one of the knobs below 2:00 if the other is cranked, especially if the bass knob is cranked too.

Pentodes overdrive: Turned up past noon and you will start to hear that open overdrive sound of pushed power tubes. Turn it up more and harmonic distortion becomes less linear. It’s easy to think of this control as an emulation of a master volume on an amplifier. There’s more to it than that.
It doesn’t turn down all the way. That wouldn’t be exactly useful. It simply turns down enough to offer maximum headroom with the preamp and tone stack knobs cranked, but not so low to start sounding thin or hollow.

As the pentodes knob approaches maximum gain it cuts low end to keep things from getting muddy and flubby. Because of the subtlety and gain involved you don’t actually hear a cut in bass response, it just keeps your tone tight and focused.

Tone Stack: Employing a similar topology found in JTM/JCM amplifiers and placed at the end of the preamp and modified for use in front of an amp rather than inside it. Response of the treble and bass controls are dependent upon preamp and pentodes gain setting. With more preamp gain they shape tone. With higher pentodes settings they change the nature and articulation of the distortion.

The phase inverter: The phase inverter is like the bass player of amp design. No one thinks much about the phase inverter, but that’s no reason to belittle its importance.  At low volumes it rarely contributes much to the sound of an amplifier. When amplifiers are pushed to the edge of their capability everything makes a difference.

The cathodyne phase inverter is common in small push pull tube amplifier designs. It’s advantage is usually considered it’s simplicity. That simplicity is a big advantage in smaller amps when there are only so many tubes to go around and tight bass response is often deemed of negligible importance.
The long tail pair caught on after the introduction on the tweed Bassman and has been the mainstay phase inverter of tube amplifiers over 50 watts ever since. The long tail pair is more complicated and requires two triode stages. It allows for more fine tuning options in the design process which becomes critical as amplifiers get bigger and louder.

Large high power tube amps can be built with a cathodyne phase inverter, but since the introduction of the tweed era bassman they are quite rare.
Initially this control was added to the Variac as a “what if.” We found ourselves favoring the cathodyne setting with smaller amps, playing at lower volumes and just sounding a little more out of control when things got loud.
The LTP setting is best suited for higher power amps with 2 speakers or more. The cathodyne setting on 1×12 and smaller.

Of course this is rock and roll and rules were meant to be broken.