SanJune GB-CP Optical Compressor Review

Two compressors bearing the SanJune brand have recently appeared on the market: The GB-CP and the smaller GB-CPX. Both are made in China at a very low price point. At the time of writing the GB-CP appears on at just $66.99 and the GB-CPX at $65.99.

Both appear to offer an impressive amount of compressor controls, nice format, and clean design. I was delighted when a forum member reached out and offered me a GB-CP for review. I must admit being skeptical simply because of the price point. How good could it really be?

On the other hand, if it was half as good as other compressors on the market offering similar functionality the GB-CP would be a killer value.

In doing my research I found little about a company called SanJune. However, after receiving the pedal and cracking it open I say this URL printed on the circuit board: This website is a property of Shenzhen Bai Leka Technology Co., Ltd, a production-oriented enterprise specializing in the production, development and sales of various musical electronic products.

Thanks to Google Translate I learned that the engineer worked for D'Addario Gibson for many years in electronic development.

The Shenzhen website says the company is

"committed to providing customers with high-quality, professional, technologically advanced, humanized, visually stylish, and excellent performance music electronic products. Better and more attentively assist customers in learning music, mastering music, and creating music."

Let's talk about the pedal itself. The GB-CP is a small package in-and-of-itself being in a MXR size enclosure. It has decent weight to it. Knobs are plastic but the pots turn with authority. The black paint is applied pretty sloppy.

Input output jacks are side mounted and are low quality, plastic on the exterior. 9-volt power input is also side mounted.

Inside, there is an epoxy applied to a portion of the circuit board obviously intending to cover something.

It is an optical circuit design.

There are 6 dials and two LED's on the face of the pedal.

Level is there for overall output control of the pedal. There is plenty of volume available. The Gain dial definitely adds noise as you increase gain (to be expected) and it highly interactive with the Compression control. Rotating the gain all the way clockwise doesn't really introduce any distortion. It acts more like an input control level control. In other words, increasing the gain definitely increases the input level hitting the compression circuit. The higher the gain, the more impact on the Compression control.

I would prefer a blend control allowing a mix of dry and wet signal to the gain control.

The Slope dial allows you to set the compression ratio from 1:1 (no compression) to 10:1 which would allow for moderate limiting effect. The GB-CP offers a pretty wide range of compression control but would not be the best choice as a limiter. Yet, it would do a pretty good job in a pinch if need be. My sweet spot was with the dial set around 11:00 to 12:30 which would be ratios of roughly 2.5:1 or 3.5:1 for some mild compression that was obviously working.

The Compress dial is really a threshold control. The more you turn the dial clockwise the lower the threshold at which the pedal starts compressing. At first I found this dial to be far too sensitive with really only a small window of usefulness. However, once you dial in the gain for your particular instrument the Compress dial becomes more intuitive. Be aware that a little twist goes a long way with this device. You really need to experiment with the interaction between Slope, Gain and the Compress dial in particular. All of these controls are useful but you must work them together (as you should). This pedal makes that interaction obvious.

The Release dial sets the duration of time the compression circuit clams down from .1 seconds to 3 seconds. Thats quite a wide range and the SanJune GB-CP makes a great device for adding sustain.

Likewise, the Attack dial has a nice range from 1 ms to 100 ms.

I found I liked the Attack around 50 ms to allow some transient through with release set to taste. Faster release for quicker, tighter passages of music and slower for more melodic or ballad style playing.

Then you have two LED's. There is a blue LED that illuminates when the pedal is active. There is red LED that indicates threshold/gain reduction which works surprisingly well. I've said before in other reviews that single LED's have nothing on multimeter LED displays and that holds true here. But at least having something is better than nothing. The red LED is quite responsive to playing which I appreciate.

So how does it sound?

The GB-CP is definitely on the transparent side of things. There is no obvious coloration or tonal change. It is not a "tone magic" type of compressor. It is not the quietest of compressors but isn't really all that bad either. No issue for the majority I'd say.

There is no real loss of lows or highs but makes your clean tone bigger and better. It's great for rounding out your playing. That said it isn't clinical sounding either.

Overall the SanJune GB-CP is a good clear, quite transparent compressor with a pretty good amount of control. Certainly far more value than just about anything in its price range.

That's probably the best way to summarize this device. I was pleasantly surprised and I wouldn't be dismayed to have this one on my pedalboard. Just don't expect it to do more than what a decent compressor does.

Should you have an issue with the SanJune compressor I don't know what customer support would look like. At the price point, should something fail you might be better off getting a new one.

The SanJune GB-CP is nice, not phenomenal.

Can you find better? For sure. But at just $66.99 what can you really expect? There is nothing glaringly wrong with it to say "stay away". It sounds good, sounds good, functions fine and looks OK. All-in-all it's a decent device and I can safely say what you get for that price is a lot of compressor. It might be just what you are looking for and could very well be all you ever need in a compressor. I was pleasantly surprised by this one.


• Price

• Functionality (controls for Attack and Release and Ratio and Threshold)

• Quite versatile

• Threshold/gain reduction LED

• Form factor


• Tricky Compress control to dial in

• Quality (but consider the price point)

• Not the quietest compressor out there

• Sloppy paint job

• Customer support?

Retail price: $66.99 via Amazon at time of writing

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