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AmpTweaker DepthFinder Active EQ


The AmpTweaker DepthFinder Active EQ is a useful addition to your effects chain for an expanded EQ than you might normally find on your amp.

Expand your tone

The DepthFinder replicates the Presence control that you'd find on vintage tube amps, and the Resonance control featured in the 5150 amp to give you far greater control over your low and high ends. With the DepthFinder you can boost your highs to be more prominent and vibrant and you have the option to add a deeper, punchier bass to your sound.


The DepthFinder is most useful when used in the effects loop of solid state or digital amps as a way of broadening what can be a narrow tonal palette. However the DepthFinder is not limited to this purpose, its use as an active EQ means it can be paired with tube amps, put at the end of a pedal chain or even put in the effects loop of a pedal. Many AmpTweaker pedals feature a built in effects loop and pairing it up with a DepthFinder will allow you to expand the tonal options of that specific effect!

Here's What AmpTweaker Say About the DepthFinder Active EQ:

Add Resonance and Presence to the effects loop or pedalboard with the DepthFinder active EQ.

One of the key ingredients to tube amplifier tone is the fact that their power amps have much lower damping factors than their solid state or digital counterparts. Vintage tube amps used the Presence control to adjust the damping at high frequencies, to boost the extreme high end and make the sound more lively.  In the 1990’s, the 5150 amp added a Resonance control, which deploys the same technique in the lowend, boosting the bottom where the speaker and cabinet resonance happened to be, to allow the user to tailor that for his preferred tightness….especially noticeable when palm-muting and stopping notes.  Now many tube amps have these type of controls, but rarely do solid state amps include this…..and the result is that the solid state amps can sound TOO tight.

The DepthFinder is an active boost-only EQ pedal that simulates the tube amp Resonance and Presence controls, but without having to be done in the power amp. This means you can use it with an amp that doesn’t have Resonance and Presence, by patching it in the effects loop. It also works great for building a pedalboard direct signal, since that low damping factor is a key ingredient to the overall tone. It can easily make a solid state amp sound and feel more like a tube amp, and can actually widen the bandwidth since it boosts at very low and very high frequencies.

The frequency range and boost of each knob was matched to the controls on the 5150, while the amp was connected to a Vintage 30-loaded birch plywood cabinet, so the resonance matches that resonant system. The Presence also matches how the amp reacts to the inductance of the speakers. The taper of the pots were also improved, so that it’s easier to find the sweet spot of each!

The pedal has a high impedance input, so it can be used in front of the amp with a guitar into it, but the best simulation of power amp damping EQ comes from putting it further down the line, such as in the amp’s effects loop.  If no loop exists, use it after all distortion for the best results.  If using it in an amp’s effects loop, make sure not to place it above the power transformer end of the amp(usually near the power switch and line cord), otherwise it and the cables could pick up hum.

When using the DepthFinder in an Amptweaker pedal loop, you will normally get better results by setting that loop to Post…..but it could be used in front to add brilliance and/or punchy bottom to the guitar tone.  It can also be used to add more sizzle or punch to the Boost loops on the Pro pedals, to help the solo cut through, or just to make a heavier tone with the extra gain.  The DepthFinder is a simple way to tweak your pedal yourself.  And lastly, it can help simulate a typical tube clean tone if used in the SideTrak loop so it only affects the clean tone.

The DepthFinder can also be used with any pedalboard looper system, allowing it to be added into the pedalboard for certain presets that need to be more lively or punchy sounding.


  • 2 Band active Boost-only EQ
  • Resonance and Presence controls simulate power amp damping EQ
  • Inside gain boost trimpot
  • Can be used in amp effects loop or pedalboard
  • Power supply not included
  • No internal battery (too small)
  • Current:  4mA with 9V or 18V supply
  • Weight: 6 ounces, Dimensions: 3.7″W X 1.5″D X 2″H
  • Handmade in the USA
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