Mars Compressor King Bass: A manufacturer in China that mainly produces goods for various other pedal brands has lately been marketing their own line of pedals under the names Mars and Real Sound. The flood of Chinese pedals incoming over the last 10 years mostly consists of cheap ripoffs of popular designs by Japanese brands like Boss, Maxon, Guyatone, etc.--however occasionally there is something new or interesting or well-made that floats to the top. We all want to get something good for cheap, so people are constantly asking whether such-and-such pedal from China is a good value, "as good as" the more expensive options. With Mars, just like Moen, it's a mix of good news and bad.
Starting with the good: the Comp King does not lose any of the lows or highs; the tone is clean and full-sounding; and the action is smooth. At ratios up to about 12:00 on the ratio knob, the action is very natural and unobtrusive; going higher than 12:00, it starts to get a bit congested or squashed-sounding. It is capable of some peak limiting, but that's not its best aspect. It's better as a fattening, sustaining boost.
The Volume knob controls the output gain, and the Ratio knob controls the ratio, clear enough; but what about the "Color" knob? The Ebay retailer says it "will round out the bass notes... brighten or darken them just a bit", which would make sense if it was a tone knob, but it's not. The Moen comps from the same retailer have a "bias" knob that acts kind of like the seller's description, but this is not the same thing at all. The instruction sheet says it is for "frequency compensation" and then says when you increase the "compensation", the dynamic range will also increase. Spectrum analysis shows it boosts a narrow spike of frequencies around 100 Hz, and it sounds to me, subjectively, like it blends in some of the original uncompressed signal.
On the bad side, unfortunately it's pretty noisy. The make-up gain stage hisses a bit worse than average. Also I found it was sensitive to picking up radio signals. There is no threshold indicator or metering. And the housing is huge, about 6" x 5" (136 mm x 117 mm). For these reasons I don't recommend it, unless you find one used, for cheap.
The metal box is sturdy, and the internal construction seems decent. It runs on standard Boss-type 9V DC. The bypass is buffered, not "true" bypass, but it's a good clean buffer.
Price in USD: new $65, used $30
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