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JSA Harmonic Tremolo Review – It has the Wobble, it has the Vibe!
Introduction
We have another incredible pedal from JSA Pedals—the JSA Harmonic Trem! This hand-built harmonic tremolo is an absolute gem. As you might have guessed, I’ve been diving deep into tremolo effects lately, especially harmonic tremolo. We also love working with JSA Pedals, so when I found out they had released the JSA Harmonic Trem, I knew I had to give it a try! Based on their previous pedals (links at the bottom of the page), I had high expectations—and let’s just say, I wasn’t disappointed!
JSA was kind enough to send this pedal over for review, though unfortunately, I’ll have to return it. That said, could there be a custom JSA Harmonic Trem in the works for Gigs & Guitars? I won’t spoil too much, but I might need to have a chat with Simon about that!
Now, let’s dive into the JSA Harmonic Trem—exploring its features, what makes it special, and, of course, how it sounds!
JSA Harmonic Tremolo Pedal
The JSA Harmonic Trem is JSA Pedals’ take on the classic harmonic tremolo, combining two distinct circuits in a single pedal running in parallel. It features a volume modulation circuit and a phase cancellation circuit, allowing you to blend and mix between them for a truly unique tremolo effect.
The version I have comes in grey, but if you ask Simon when ordering, he can build it in almost any color you like!
The phase cancellation circuit only affects the treble frequencies, creating a smooth modulation in the upper range while keeping the mids and lows intact. This ensures a warm and dynamic tremolo effect without losing body or depth.
So, how does the JSA Harmonic Trem work? What controls does it offer? Looking at the pedal, you’ll find four knobs:
- Level: Adjusts the output volume of the pedal.
- Mix: Blends between the tremolo effect and your clean signal.
- Phase: Controls the mix between volume modulation and phase modulation. Fully left is pure volume modulation.
- Speed: Adjusts the tremolo rate.
All inputs are top-mounted, making cable management easier, and the pedal comes with stickers and Velcro for easy pedalboard mounting.
More on the JSA Harmonic Trem
Like all JSA Pedals, the JSA Harmonic Trem is built in their signature compact housing, keeping the footprint minimal while delivering maximum versatility. It runs on a standard 9V power supply, making it easy to integrate into any setup.
Every pedal is made by Simon by hand! He builds a lot of his pedals to order but even still he is able to produce a pedal fairly quickly so unless you all put an order in together, the lead time isn’t that bad!
The Sounds
For our demo, we ran my LT Custom Strat (Full Article) into a Behringer Klon (Review Here), then straight into the JSA Harmonic Trem. The amp was set fairly clean, with the Klon providing a nice clean boost—resulting in a snappy, articulate solo with amazing clarity. The JSA Harmonic Trem added beautiful movement and depth to the tone, making it feel alive and dynamic!
After the demo track, we explored the pedal’s full range of sounds. This time, we ran the JSA Harmonic Trem directly into the front end of the Revv D20 (Review Here), testing it with both clean and crunch settings. This way, you can hear exactly how the pedal reacts across different tones, from subtle shimmer to rich, textured modulation.
If you love what you hear, head over to our YouTube channel to check out more sound sample videos. Don’t forget to like, comment, and subscribe—every bit of support helps us bring you more great content!
What are my thoughts?
We’ve had the JSA Harmonic Trem for a while now, and we’ve been playing it a lot! Since we’ve reviewed plenty of JSA Pedals, we went into this with high expectations—and it completely smashed them!
Design and Looks
The design of this pedal is quintessential JSA—rugged, practical, and built to last. It has a clean layout with clearly labeled controls, making it incredibly easy to dial in. The compact size makes it a dream to fit onto a pedalboard, while the sturdy construction ensures it can handle the demands of gigging. The knobs have a solid feel and stay exactly where you set them, meaning no accidental shifts when packing and unpacking your board.
"The JSA Harmonic Trem offers a much more natural and controlled modulation. It can sit in the background, adding depth without overwhelming your sound."
The Sounds
It sounds lush. Thick and rich are the best words to describe the JSA Harmonic Trem. This pedal has so many uses beyond a traditional harmonic tremolo. You don’t have to use it in the usual way—you can keep it subtle as a thickener, or just add a touch of movement to your tone.
What stands out is how usable this pedal is. Many tremolo and harmonic tremolo effects can be too exaggerated, which is why some players avoid them. That seasick, pulsing effect isn’t for everyone. However, the JSA Harmonic Trem offers a much more natural and controlled modulation. It can sit in the background, adding depth without overwhelming your sound.
Running it through an FX Loop and tweaking the phase control creates a beautiful wash effect, adding a sense of movement that evolves over time. This makes simple chord work so much more dynamic and expressive. Dialing up the speed brings out some fantastic vibe-like textures for lead playing. Combine it with a delay, and even the simplest lead lines sound massive and complex.
The Negatives?
One thing to note is that the JSA Harmonic Trem is purely a harmonic tremolo. It doesn’t have a switch to toggle between standard and harmonic tremolo modes. For me, this is perfect, but some players might prefer that added flexibility.
Another feature some might miss is tap tempo. Many high-end harmonic tremolo pedals include it, allowing you to sync modulation to your playing. Personally, I don’t mind not having it—I prefer modulation to be a little out of sync and more natural. But if tap tempo is something you rely on, it’s worth considering.
Final Verdict
I honestly don’t think Simon from JSA Pedals advertises this pedal enough! When compared to other harmonic tremolo pedals on the market, the JSA Harmonic Trem is incredibly well-priced, hand-built, and sounds phenomenal.
If you’re looking for a high-quality harmonic tremolo that’s versatile, musical, and easy to use, this is a must-try. Don’t just take our word for it—get one for yourself and experience how good it really is!
Conclusion
A big thanks to Simon from JSA Pedals for sending this one over! It was great to put the JSA Harmonic Trem through its paces and see what it could do. This isn’t a pedal he keeps in regular stock, but if you drop him a message on Instagram, he’ll get back to you and can build one—in almost any design you want!
If you’re interested in a JSA Pedal or want to check out their other offerings, you’ll find all the links below, along with some of our previous JSA Pedals reviews. Don’t miss out on these incredible hand-built effects!
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JSA Harmoinc Trem Links:
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