The JHS 3 Series Harmonic Tremolo is a tremolo pedal from JHS Pedals that packs two tremolo circuits into one compact stompbox. With the toggle up you get what JHS calls "a great sounding amp trem," a conventional volume-based tremolo. Flip the toggle down and the pedal switches to JHS's take on the harmonic tremolo, the effect Leo Fender introduced in his Bandmaster and Vibrasonic amps in 19601.
It belongs to the JHS 3 Series, a collection of pedals the maker describes as designed to give you affordability and simplicity without compromising quality. Every pedal in the line shares the same format: three knobs, one toggle, and one footswitch12. The Harmonic Tremolo was announced in September 2022 alongside the Octave Reverb, bringing the 3 Series to 13 units3.
What a harmonic tremolo does to your sound
A standard amp tremolo, the kind built into many guitar amplifiers, raises and lowers the volume of your entire signal at a set speed. That is the toggle-up mode here, which Pedal of the Day's reviewer called "a great sounding amp tremolo"5.
The harmonic tremolo works differently. It is a modulation effect that splits the signal into high and low-frequency channels and alternately modulates the bass and treble levels against each other4. Rather than the whole signal getting louder and quieter, the low end swells while the high end dips, and then the reverse, which gives the effect a shifting, swirling motion. Delicious Audio notes that this alternation gives the harmonic tremolo characteristics reminiscent of a phaser6.
JHS describes the result as "a dreamy effect similar to the Uni-Vibe"1, and Delicious Audio's Paolo De Gregorio similarly called it "a dreamy tremolo effect reminiscent of the Uni-Vibe"4. So while it is not a Uni-Vibe clone, players chasing that slow, liquid modulation texture will find the harmonic mode lands in the same territory.
The controls: three knobs and a toggle
Like every 3 Series pedal, the Harmonic Tremolo keeps the control panel minimal: three knobs, one toggle, and one footswitch2. Delicious Audio identifies the three knobs on this model as Volume, Rate and Depth4.
| Control | What it does |
|---|---|
| Volume | Sets the overall output level of the pedal |
| Rate | Sets the speed of the tremolo sweep |
| Depth | Sets how deep the amplitude modulation goes |
| Toggle up | Amp tremolo, a conventional volume-based trem1 |
| Toggle down | Harmonic trem, JHS's take on the 1960 Fender circuit1 |
The toggle is the heart of the pedal, since it chooses between the two tremolo types rather than switching presets or adding a secondary voicing14. JHS says the three simple controls and one toggle offer a wide range of sounds, aimed at beginners and professionals alike1.
History: Leo Fender's harmonic tremolo in the 3 Series
The harmonic tremolo traces back to 1960, when Leo Fender introduced the circuit in his Bandmaster and Vibrasonic amps1. Guitar World notes that Fender, better known as a guitar maker, pioneered the effect by introducing the harmonic tremolo circuit into those two amplifiers3. Delicious Audio places the effect's first appearance slightly earlier, in Fender "brownface" amps made between 1959 and 19636.
The circuit never became a standard feature, and pedal versions of it have been rare. When JHS announced the 3 Series Harmonic Tremolo in September 2022, Gearnews' Jef wrote7:
"I believe it is the first time that JHS has made these circuits"7
The announcement came alongside the Octave Reverb, and both pedals carried the same $99 price tag and streamlined three-knob feature set as the rest of the 3 Series3. Gearnews reported the pair as two new $99 USA-made pedals that brought the 3 Series range to 13 effects328.
The 3 Series context
The 3 Series is JHS's affordable line, and the Harmonic Tremolo fits its pattern exactly. Vintage Guitar reviewed the line at $99 each9, and JHS's own Josh has described the project plainly:
"we put together a USA-made pedal series for $99"
Each 3 Series pedal is made by JHS in Kansas City, Missouri, using high-quality parts, quality control, and attention to every detail1. Pedal of the Day's reviewer summed up the line's appeal in a 2025 review of the Harmonic Trem:
"The 3 Series from JHS Pedals is a fantastic and affordable way to get into this crazy effects world we all live in"5
For players comparing tremolos, JHS has a history in the effect that reaches beyond the 3 Series, including the Honey Comb Deluxe and the Boss TR-2 Two Speed Mod. The 3 Series Harmonic Tremolo stands apart from those by pairing a conventional amp trem with the vintage Fender harmonic circuit at the line's entry price154.
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Questions
What is the difference between harmonic tremolo and amp tremolo?
Amp tremolo raises and lowers the volume of the whole signal at a set rate. Harmonic tremolo splits the signal into high and low frequency channels and alternately modulates the bass and treble levels, which gives it a character reminiscent of a phaser. The JHS 3 Series pedal has both: toggle up is amp trem, toggle down is harmonic trem.
Does the JHS Harmonic Tremolo sound like a Uni-Vibe?
JHS describes the harmonic trem mode as a dreamy effect similar to the Uni-Vibe, and Delicious Audio called it a dreamy tremolo effect reminiscent of the Uni-Vibe. It is not a copy of the Uni-Vibe circuit, but the way it shifts bass and treble against each other puts it in the same dreamy territory.
How much does the JHS 3 Series Harmonic Tremolo cost?
The list price is $99.00 USD on JHS Pedals' product page. Gearnews reported the same USD 99 MSRP when the pedal was announced in September 2022, and every pedal in the 3 Series carries the same $99 price.
Where are JHS 3 Series pedals made?
JHS Pedals states that each 3 Series pedal is made by the company in Kansas City, Missouri, using high-quality parts, quality control, and attention to every detail. JHS has described the line as a USA-made pedal series at the $99 price point.
How many pedals are in the JHS 3 Series?
When the Harmonic Tremolo and Octave Reverb were added in September 2022, Guitar World reported the total number of 3 Series units at 13. The line includes overdrive, distortion, compressor, phaser, flanger, chorus, delay and reverb pedals, all sharing the same three-knob, one-toggle format.
Sources (9)
- 3 SERIES HARMONIC TREM, JHS Pedals
- OUR SUCKIEST PEDALS YET, JHS Pedals
- JHS Pedals adds $99 Harmonic Tremolo and Octave Reverb to its 3 Series range, Guitar World, 2022-09-26
- JHS 3 Series Harmonic Tremolo, Delicious Audio, 2022-12-13
- JHS Pedals 3 Series Harmonic Trem, Pedal of the Day (www.pedal-of-the-day.com), 2025-05-25
- Source Audio True Spring Reverb, Delicious Audio, 2022-12-05
- JHS 3 Series Harmonic Tremolo and Octave Reverb revealed, www.gearnews.com, 2022-09-28
- The new JHS Series 3 pedals are priced at $99 each, gearnews.com, 2020-10-02
- JHS 3 Series, Vintage Guitar magazine, 2021-12-07
