The One Control Lemon Yellow Compressor 4K is a mini compressor pedal designed by Björn Juhl, the Swedish designer known as BJF, for One Control. It sits in the BJF Series, a line of small-format effects built in compact aluminum enclosures, and it carries three knobs plus a switch in a case roughly the footprint of a couple of effects pedals side by side12.
One Control describes it as "a particularly natural compressor" that keeps its clarity even in loud playing, with what the maker calls a great presence in slide playing1. Delicious Audio, covering the earlier Lemon Yellow Compressor, called it "a very musical compressor in a mini case" and added it to the site's roundup of best mini compressor pedals2.
Controls and how it works
The pedal keeps compression control to three knobs and a side switch, an arrangement One Control arrived at after development ran from a one-knob prototype to a two-knob prototype before the completed three-knob plus switch version was released1.
| Control | What it does |
|---|---|
| GAIN | Adjusts the strength of the compressor1 |
| RATIO | Adjusts the compression ratio1 |
| VOLUME | Adjusts the volume1 |
| Side switch | Increased release time, for more sustain2 |
The compression ratio is variable from 1:1 to 5:11. At 1:1 the pedal applies no compression, so the VOLUME knob can act on its own, while 5:1 is a moderate ratio that evens out attack without the heavy squashing of a limiter. The GAIN knob sets how hard the compressor works, and the side switch lengthens the release time for longer sustain, a feature carried over from the earlier Lemon Yellow Compressor2.
Using it as a boost
One Control gives the pedal an output of up to +18dB, enough to boost the input levels of the rest of the signal chain1. With the ratio backed off to 1:1, that headroom lets the pedal double as a clean boost in front of an overdrive or amplifier, which is a common way players use a compressor's volume stage separately from its compression.
Power, size and connections
The pedal runs at 9V with a current draw of 10mA1, low enough to share a daisy chain with other small pedals. A built-in battery is also possible, though batteries are not included1. Input impedance is 500K and output impedance is 10K1, figures that sit comfortably with typical guitar-level gear on either side.
One Control lists the Lemon Yellow Compressor 4K as sold out at its own store as of October 2026, at a regular price of $164.99 USD shown against a listed price of $206.99 USD1. Players shopping for one may need to look at retailers or the used market.
Where it came from
The 4K is the latest step in a line that began with the One Control Lemon Yellow Compressor, part of the BJF Series FX pedals designed by Björn Juhl, whom Delicious Audio called "world-renowned pedal guru and mad professor"2. That earlier version carried controls for compression ratio, amount of compression, and level, with the same side switch for increased release time, and the series pedals were built in high-quality compact aluminum enclosures weighing about 160 grams, with true-bypass switching and power from a 9V battery or standard DC supplies2. The 4K keeps that format, the aluminum mini case, and the true bypass, while One Control positions it as the company's latest compressor1.
What reviewers said
Published coverage of the line has been positive. Delicious Audio's Paolo De Gregorio wrote of the original2:
"The One Control Lemon Yellow Compressor is a simple, versatile compressor that delivers extremely high-quality tone2."
Delicious Audio, 20222
The same review noted the pedal's small footprint and solid construction, and placed it among the site's picks of best mini compressor pedals2. Coverage of the 4K itself comes from One Control's own product page, which emphasizes its natural character and clarity at volume1.
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Questions
Does the One Control Lemon Yellow Compressor 4K have true bypass?
Yes. One Control lists true bypass switching for the Lemon Yellow Compressor 4K, so with the pedal off the signal passes through without the circuit in the path. The earlier BJF Series pedals from One Control also used true-bypass switching.
Can the Lemon Yellow Compressor 4K run on a battery?
Yes. One Control states a built-in battery is possible, though batteries are not included. It also runs on 9V DC power. With a battery installed the weight rises from about 160 grams to about 200 grams.
What compression ratios does it cover?
The RATIO knob adjusts the compression ratio, which One Control says is variable from 1:1, effectively no compression, up to 5:1. That range keeps the pedal in gentle-to-moderate territory rather than heavy limiting.
Who designed the Lemon Yellow Compressor 4K?
It was designed by Björn Juhl, the Swedish designer known as BJF, for One Control. One Control describes him as a famed pedal designer who has created several classic compressor designs over the years.
How much current does the Lemon Yellow Compressor 4K draw?
One Control lists a current consumption of 10mA at 9V. That is low enough that it can share a daisy chain or a modest isolated supply with several other pedals without straining the power budget.
Can it be used as a clean boost?
Yes. One Control says the output reaches up to +18dB, enough to boost the input levels of the rest of the signal chain. With the ratio at 1:1 the pedal is effectively out of the compression path while the VOLUME knob still provides level.
Sources (2)
- LEMON YELLOW COMPRESSOR 4K (OC-LYC4Kn), One Control USA
- One Control Lemon Yellow Compressor, Delicious Audio, 2022-02-17
