JSA “Eureka” Review – Is it Time for a Compressor!


Compressor pedals aren’t something I have a lot of experience with, however, I am finding myself playing more clean “funk” sounding stuff so thought it might be time to dive into them. What better company to try than our good friends at JSA. He does a Compressor pedal called the “Eureka”. So we thought that would be worth trying and reviewing.

Been using the pedal for a while now, and getting to grips with it and what it does and have put together this review. If you don’t know what a compressor does it takes an audio signal and brings up the quiet bits and lowers the loud bits, making the sound more consistent and “flat”. However, this all depends on the settings, as we will get into. So why don’t we have a look at the Eureka and go over it a bit?

Eureka Top banner

The Eureka Pedal

JSA Eureka - Front look
Front look of the JSA Eureka compressor pedal.

The Eureka is a compressor pedal, or what I would call a simple compressor pedal, with 3 knobs and a switch! Making it easy to use and a joy to play with. My pedal came in a Black enclosure however this is not how a stock pedal would come, They are normally in a light grey housing, but JSA had too many black ones so I said he could build it into one of those (he is flexible like that).

The pedal has 3 knobs and 1 switch. On the top left, we have a “Level” knob, Which is the volume control, The top right is the “Comp” knob, Which is the amount of compression you want, and the bottom middle is a “Blend” knob. This allows you to blend the compressed signal back in with the dry signal (Allowing you to do a sort of parallel compression kind of thing). The switch is the release time for the compression. With the switch at the top position, it is a medium release, the middle is the fastest and the bottom is the slowest.

More on the JSA Eureka Pedal Pedal

If you look inside the pedal, there is a trimpot for threshold level, What this does is allows you to adjust how much signal there needs to be before the compressor kicks in. What I will say is that in my playing with this pedal, I haven’t had to adjust that trim pot at all.

The input, output and 9v supply input are all mounted at the top of the pedal meaning you can tuck this tight against any other top-loaded pedals. In the box was the pedal and a few gifts like stickers and a pin badge! Great for collectors. The pedal runs on a standard 9v power supply!

JSA Eureka - Bottom look
From this angle you can see the labels and case design.

The Sounds

Well, it’s time to hear some sounds of the JSA Eureka. When dealing with a compressor one genre and type of music comes to mind! Funk! I had to create a funk track for this pedal! So below is the sound video. This pedal is used in all the guitar work using my LT custom Strat. After the demo song, I then run through some sound clips of the pedal and what it is capable of doing.

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What are my thoughts?

JSA Eureka - Top look
Love the feel of these controls and the easy to read labels.

The packaging is great! Cardboard for everything! Highly recyclable and eco-friendly. You also get a sticker and a badge! Very nice touch! The pedal itself is very JSA in design! Easy to read, no fuss or mess! Just what a working musician wants on his board!

One thing I am surprised by is how useful the blend knob is. I didn’t think I would use it that much but having it set somewhere between 9 and 12 o clock really gives you an amazing sound. It is great for setting up an extremely smashed compressed sound and then blending the original back in. What I love about this pedal is that you can actually hear a difference, moving the controls makes a change! I have tried compressors in the past where you only really hear a difference at extreme values. However, this pedal has very nice feedback! With the help of the blue threshold LED, you can actually see what the pedal is doing and the changes you make. Great feedback!

Anything Else?

How does the pedal deal with gain? Well, let’s put it in front of an overdrive pedal and find out! In the sound sample, I put it in front of the Landscraper by Bleak District (Read Review here). What does It do to the sound? Gives you so much sustain! if you use a single coil guitar this is perfect for getting more sustain out of it!

The Eureka is £120, which for a hand built to order pedal is a crazy old deal! All his pedals are well-priced, but for a custom-made Compressor pedal, it is a steal! With that price you also get his amazing customer care, any questions or queries you can just send him an email and he will help you out.

If it hasn’t come across clearly I absolutely love this pedal! There isn’t anything negative I can say about it, the price, build quality, Design and functions are all amazing! Once the full pedalboard is built this will definitely be going on and staying on! I haven’t had much use with compressor pedals, but by using this one I have discovered why people love them! I am now one of those people! JSA has smashed it with pedal, built, price, sound and control are all top-notch!

JSA Eureka - Full Pedal look
This pedal is a great size and a welcome addition to the board!


Thanks to JSA for making this pedal! If you are after a Eureka pedal for yourself, or any of his other pedals (he does a lot of pedals and can also make pretty much anything you want) then please head over to the links below and shoot him a message! He is super friendly and knowledgeable and will be able to help you out!

We have also tried another JSA pedal out, The Dumblemost. You can read its full review here! Something to be said that it hasn’t come off my board since I received it! 

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