EHX Knockout – Review of Electro-Harmonix Knockout Attack EQ

The Electro-Harmonix Knockout Attack equalizer pedal brings surprising versatility to your guitar setup. Like any EQ pedal it allows you to boost or dampen specific frequencies of your tone, but takes a different approach with a two-pass filter system so simple even I could understand it, and I can barely spell “acoustics.” 

With just three knobs, the pedal keeps the layout simple. By simplifying the process, they allow you to switch tones on the fly easily. Depending on where you put the pedal in your signal chain, the EHX Knockout can also significantly adapt your distorted tones. 

Discerning ears may not quite buy the “Strats-to-Les-Paul” transformation, but this pedal most certainly allows single-coil tones from humbuckers. The Knockout does a beautiful job mimicking a range of guitar sounds and improving the tone on a lower-end guitar. Read on to hear more about our EHX Knockout review. 

Why would you need an equalizer pedal?

Equalizer pedals allow you to adjust your guitar’s tone with the push - or stomp - of a button. Your guitar’s tone comes from the degree to which it brings out various parts of the frequency spectrum.

By allowing you to adjust how much low, middle, or high-frequency sounds pass from your guitar to the amp, equalizer pedals give you a lot of control over exactly how your guitar sounds. If you need to mimic a specific guitar for a particular song or reduce undesirable elements like “tinny” sounds, an equalizer pedal will help. 

Consider how much control you really want over your guitar’s tone, and how often you need it. Those seeking a more fine-tuned approach may require a traditional graphic equalizer that allows adjustment to a greater range of frequencies. But simpler EQ setups - like the EHX Knockout - can provide a lot of variability with much easier controls. 






Electro - Harmonix

Knockout Attack

Electro-Harmonix Knockout Attack EQ Pedal

PRO's & CON's of Electro-Harmonix Knockout

Before we dive into our review, let's look at some of the pros and cons of the Electro-Harmonix Knockout Attack EQ Pedal:


  • Simple but incredibly effective
  • Stylish graphic with classic EHX look
  • Highly durable design that can take a hit
  • Size and plug-in placements fit easily into most pedal setups


  • Very sensitive, which can make operation challenging
  • Slightly more limited than traditional equalizers

Features and Benefits

Okay, we might get a little technical here. But rest assured, it will help you better understand just how this pedal works and why it works well.


First and foremost, the EHX Knockout alters your tone. Electro-Harmonix makes the audacious claim that the Knockout Attack pedal can, in fact, make a Les Paul sound like a Stratocaster, and a Stratocaster sound like a Les Paul. Indeed, they get pretty close. 

The pedal packs a startling versatility into three little knobs. Guitarists can brighten their beefier sound or take the bite off a twangier guitar. The EHX Knockout also works great when you need to punch up or drop back your volume without changing your tone. 

I used to play in a cover band with an old Line 6 Spider II Amp loaded with scores of presets meant to imitate everything from Enter Sandman to 50 Ways to Leave Your Lover. 

This pedal would have replaced a lot of scrolling through a tiny LCD screen, and probably sounded better than many of them by itself. 

Guitar collecting can quickly turn into an addiction and an expensive one at that. After years of being a Gibson person, you suddenly find yourself with a wandering eye. “Man, this Rickenbacker sounds cool,” you think, and before you know it, another paycheck is hanging on the wall.

A good equalizer pedal can work a little like a nicotine patch. A pedal like the EHX Knockout can feel like a whole new guitar but without the price tag.


The EHX Knockout Attack equalizer pedal comes with three knobs: low, dry, and high. The low knob adjusts the amount of “low end” coming through the pedal and out of your amp. When you crank it to the right, you get more of a humbucker sound or a more filled-out distortion tone.

Similarly, the high knob adjusts the amount of higher frequency passing through the pedal. More high end can brighten up a tone to approximate a single-coil pickup. When done to the extreme, it can give the guitar a distinctly tinny sound - maybe good, maybe not, but if you meant to do it, great. 

Between the low and high lies the dry, a knob that adjusts the degree to which the pedal alters your tone. In other words, you may want the tone of “low knob at 10 o’clock, high knob at 2 o’clock,” but that tone would pose too dramatic a departure from the sound you have without the EQ. 

The dry knob can preserve some of your guitar’s natural tone. More dry (turned to the right) means less “effect” from the pedal, while more wet (turned to the left) means your sound gets the full brunt of the Knockout’s abilities. 

Balanced on these three knobs sits a world of possibilities. However, you do need a light touch. The two filter setup means a slight turn of the knob makes a more significant difference than a slider on a traditional EQ that affects only one of nine frequency ranges.


For all its simplicity, the EHX Knockout equalizer pedal has an extraordinary ability to change the sound of your guitar. The dry knob sets this pedal apart from most others in its ability to adjust the “dosage” of your equalizer without altering the tone for which you’ve set it. 

Set up early in the signal chain, this pedal makes a huge difference to the beefiness of distortion. Our band played a lot of Incubus covers, and their guitarist the great Mike Einziger (a man who loves pedals himself) wrote a lot of parts where a distorted guitar went up a notch for one of their big arena-rock style choruses. 

A pedal like this would have done wonders to provide that separation. It makes tones a little fuller when you need it, and thinner when you don’t.

Social Proof of the Pedal

We know we only have one viewpoint thus far in our article: our own. We looked at what other users had said about the EHX Knockout to see if our opinions lined up.

EHX Knockout Review 01

This user from Musician’s Friend echoed our sentiments about the value of simplicity with this pedal and the degree to which this pedal helps users “perfect” their tone. We also sympathize with his struggle to put the pedal’s power into words: it sounds good, but it’s tough to explain why without trying it.

EHX Knockout Review 02

For those of you with guitars from the bargain bin, this user from Guitar Center makes a strong case for this pedal as a little lipstick on the pig. While he didn’t find a lot of success fixing his distorted tones, we can only assume he just didn’t experiment sufficiently. More importantly, he found like we did that the Knockout fixes the rough spots on a wide range of guitars. Or, if you want to, it can roughen up a tone that seems just a little too perfect in the context.

EHX Knockout Review 03

Finally, this Amazon reviewer breaks down all the best things about the Knockout. It allows for endless tone shaping but does have some pitfalls when you turn things too far in either direction. He also spoke to the Knockout’s unique tonal quality. Yes, you can theoretically get more fine-tuning from a traditional EQ. Still, Electro-Harmonix did an exceptional job making a pedal with its own unique sound in a crowded market.

In Conclusion

The Electro-Harmonix Knockout Attack equalizer dramatically expands the tonal possibilities on your guitar. The simple design, coupled with the beautiful sound allows it to stand out among other EQ pedals. It can get you a great sound in the studio, or an easy adjustment during a live gig. Does this sound like something you need? If so, click here to check out the EHX Knockout!

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