Review: Amptweaker Depthfinder and Curveball Junior

Allocate some space on your pedalboard for the Amptweaker Depthfinder and Curveball Junior and see what they can do for your sound.
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Amptweaker has made a name for itself as a company that builds high-quality guitar pedals based on its own unique designs. This month, we’re looking at two of its latest creations: the DepthFinder active EQ and Curveball Junior three-band EQ.


DEPTHFINDER Although he’s been known as the Amptweaker guy for many years, tone guru James Brown made his initial splash as the brains and brawn behind the legendary Peavey 5150 amplifier. What many guitarists loved about that amp — aside from its searing, high-gain tones and sweet sustain — was the resonance control, which provided awesome thump to go with the presence control’s sizzle in the power section. Now Amptweaker has packaged those two magical knobs in a bite-size box called the DepthFinder active EQ.

The DepthFinder couldn’t be easier to use. It doesn’t even have an on/off switch. You can plug it into your amp’s effect loop and enjoy a radically expanded sonic range, but the applications actually go beyond that. Brown explains that a key difference between tube amps and their solid-state or digital sisters is that the power sections in tube amps have a much lower damping factor, and that’s part of what makes them sound and react differently (and, purists would say, better). Because of this, the DepthFinder can make your digital amp sound and feel a little tubier, according to Amptweaker. I tried it with a Kemper Profiler, dialed in for an open-sounding Plexi Marshall tone, and the DepthFinder absolutely gave me more highs and more lows. Could I achieve the same sound using the Kemper’s EQ? Sort of, but I liked what the DepthFinder did to the tone and feel, making it bigger, badder and meaner.

Other uses for the DepthFinder include placing it after your distortion boxes, with the presence and resonance controls filling out the tone and making it more amp-like. I placed the pedal after an MXR EVH Overdrive and a Way Huge Green Rhino, and it definitely stepped up their respective games.

The DepthFinder is a simple, effective and musical tone-shaping tool. It would come in handy for any amp or modeling device that doesn’t have a resonance control — which is most of them — and would be a cool addition to a pedalboard, as it takes up little space.



The Curveball Junior has a different, but no less powerful, take on frequency sculpting. It’s a three-band active EQ, but, in true Amptweaker fashion, it does a ton of stuff. In addition to low, mid and high controls, there’s a mid switch, which is divided into U.S., U.K. and Thrash modes to approximate the midrange frequencies for those flavors of amps and styles. There’s also a Fat/Normal/Tight switch that can make the Curveball Junior hit the front of an amp or pedal in different ways, adding gain while tailoring the sound.

And there’s more. The Curveball Junior has a volume knob, so once you set your EQ, you can run it at unity, boost or cut. The pedal also packs a secondary boost, and you can enter Boost mode by pressing and holding the foot switch. That keeps your three-band tone on all the time and allows you to toggle up to 10dB of boost on and off. Put this in front of your amp or distortion boxes and get tons more gain, or place it in your effect loop (or after distortion boxes) and get a tear-your-head-off lead boost. Personally, I love a toneful boost in the loop. Adding gain to a solo tone won’t help it be heard, but boosting the level (with beefed-up low mids) will get everyone’s attention. I might not even use Boost mode. I think I’d dial in a sweet tone, set the volume knob for a healthy boost, and kick that in for leads.

Curveball Junior does a very cool mid-boost thing, providing Brian May–style bark and “Money for Nothing” grind. Sure, most EQs can do this, but the frequencies that it emphasizes are spot-on. To paraphrase Mark Knopfler, that’s the way you do it.

Amptweaker says that many customers use their distortion boxes right into power amps or effect loop returns. If you have an Amptweaker Pro pedal, like a Tight Rock or Fat Metal, you can put the Curveball in the SideTrak loop on those boxes and use it as your clean tone as you switch the distortion on and off.

Many players don’t take advantage of the cool ways EQs can help their tone, particularly when placed in the loop. (Hint: You can coax some of the most extreme metal tones out of polite little combo amps with an EQ in the loop set for notched mids and boosted lows and highs.) Rather than buy yet another overdrive or distortion box, maybe allocate a little space on your board for Curveball Junior and see what that can do for your sound.



PRICE $90 street

INPUTS One 1/4"
OUTPUTS One 1/4"
CONTROLS Presence, resonance

KUDOS Simple, powerful tone shaping

Curveball Junior

PRICE $190 street

INPUTS One 1/4"
OUTPUTS One 1/4"
CONTROLS Low, mid, high, volume, boost; (switches) US/UK/Thrash, Fat/Normal/Tight

KUDOS Powerful 3-band EQ. Flexible tonal options