Build Quality:4.9 out of 5 stars
Hardware:4.8 out of 5 stars
Electronics:4.8 out of 5 stars
Sound:4.8 out of 5 stars
Value:4.9 out of 5 stars
Average:4.8 out of 5 stars

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Electro-Harmonix Knockout Attack EQ


  • Lets you be creative
  • Great value for money
  • Quite versatile


  • Too sensitive
  • Takes time to find precise adjustments

It was either 1974 or 1975. The sun was shining brightly on a cold January morning. It seemed as if nothing extraordinary would happen but that was not exactly the case. Around that time something really special took place: our beloved Electro-Harmonix Released its first Attack Equalizer. It was labeled as the most capable EQ that could transform your Fender into a Les Paul and vice versa. Many musicians tested that theory countless times with different guitars and setups. Many did not believe that claim and just explored the features of the pedal. Regardless, that was the main emphasis that Electro-Harmonix marketed quite intelligently.

Luckily, this mysterious apparatus did not stay in the past and is still produced to this day as a reissue. Today we are going to forget about the original and judge the newer version (i.e. Knockout Attack Equalizer) on its own. We are going to discuss its main features, explore the controls available and see what sonic possibilities this fella carries. We will try to scrutinize its pros and cons and figure out if it can actually live up to its advertisement. Can Knockout Attack Equalizer actually achieve the sound of any guitar with just a couple of tweaks? We shall see the answer below. Let’s begin!


Electro-Harmonix never lets us down by creating dull and boring units. Rather, their pedals are always slightly different from the rest and pack their own unique punch. That is probably one of the reasons why I love and trust this brand so much. Knockout Attack Equalizer, in particular, has a very cool layout. It features a red boxing glove on the black surface which supposedly knocks something out with cartoonish yellow lights (I am sure you can all imagine the scene). The sides and the bottom are silver to add traditional EHX character to the whole thing.

What is more, this pedal is not a typical equalizer, so do not even expect to get much performance out of it. Instead of being graphic or parametric, it is comprised with multi-pole high and low pass filters. These filters are the tools that allow you to add or cut the desired frequencies. Such configuration might seem a bit weird, but trust me, you will fall in love with it soon enough. The body of Knockout Attack Equalizer is quite sturdy and durable, which means you will not have to say farewell for a long time. It has a true bypass switching so that your tone is not compromised when the pedal is deactivated.

It has a standard EHX size, which means it will not take up your whole pedalboard. Side-mounted input and output, as well as a top-mounted DC jack make it possible to place it conveniently without any fuss. If you hate adapters, then you can always power it with a single 9V battery, just do not forget to unplug the pedal to avoid draining it quickly. That’s it, we have now covered the most essential information that you should know about the features of this bad boy.


Judging by the fact that Electro-Harmonix Knockout Attack Equalizer is neither parametric nor graphic, you can assume that its control section is comprised with encoders. All we have here are three knobs that act as bosses and take care of the whole business with clear and all-encompassing orders. Those who are used to the sliders of graphic equalizers might find such layout a bit odd, but it is very easy to get used to it, since all you have to do is twist a knob and tailor the results to your own sound.

First on the panel is the Low knob. This fella acts as a volume control for the lower frequencies. The further you turn it clockwise, the louder the bottom-end will be. It operates with the help of 7-pole Low Pass Filter, which has a fixed cut-off frequency at 85Hz. Next, we have Dry, which modifies the level of the original signal. This way you can bland dry and effective sounds together and accentuate your guitar in the whole mix. Then there is a High knob, which does the same thing as Low, but for the higher frequencies. It utilizes a 6-pole High Pass Filter with fixed cut-off frequency at 6.5kHz. All you have to do is turn these knobs left or right and modify the presence of various ranges. This baby is quite sensitive and might get crazy easily, so be careful with your adjustments and take things slow.

EHX Knockout Sound

Here is the thing, there are some pedals on the market that everybody loves and there are some that are either loved or hated. Electro-Harmonix Knockout Attack Equalizer falls in the latter category. It covers everything from subtle to extreme and that is why it might not be for everybody. Even a slight modification affects your sound a great deal and at maximum settings, things might get a bit out of hand (it still depends on your instrument). Is the claim that it can turn your Les Paul into Fender true? Almost.

What I mean is that it gets close, but it will not be an exact replica. This bad boy allows you to change the character of your sound completely and achieve different results with each tweak. It has girth and drive, which adds more depth to the whole playing. It works with guitar and bass, but you can produce cleaner and more defined sounds with your guitar. On the whole, Electro-Harmonix Knockout Attack Equalizer still shares some of its characteristics with the original, but with newer twists.


Just like every single pedal out there, Electro-Harmonix Knockout Attack Equalizer is not faultless either. However, it has many perks that make it a useful tool in any rig. It is an affordable beast that can give you amazing results. You just have to spend some time with it, tweak, explore and fiddle around in order to find the settings that work for you. Do not be lazy, my friend, and you will discover unimaginable things. Good luck!

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