Gurus Optivalve MKII Compressor Review

Gurus Pedals is based in Italy and you might recognize them as the creators of the Echosex, their legendary echo unit. The Echosex has quite a following and is used by a slew of notables.

The Optivale MKII is the latest version of the Gurus compressor pedal sporting a smaller footprint than the original. It is a tube-optical circuit meaning the compression is handled via optical design with the tube influencing the gain stage. There is a 12AU7 tube inside. Gurus says the Optivalve MKII is based on the Teletronix LA-2A studio unit.

In practice, it does feel like an optical pedal but you also benefit from some tubey content too.

There are four dials: Tone, Ratio, Output, and Input.

The Ratio dial controls the compression ratio. The dial is marked 0 - infinity. Towards the end of the rotation (more clockwise) the pedal does get quite squishy, almost limiting territory. More on the Ratio control in just a bit.

The Input dial sets the amount of gain hitting the compression circuit. It is helpful to think of it almost like a threshold control. The more rotation clockwise, the more of your circuit is hitting the compression engine thereby allowing more signal to be compressed. I like compressors that have this control because it allows for compensating between all different types of instruments output levels. You can really dial in a compressor well when you can control the signal coming in to the device.

The Ratio and Input dial are highly interactive. The markings on the Input dial are really not all that helpful to use as a guide because of how the input dial interacts. If you have the input dial low, you are really going to have to turn up the ratio (more clockwise) to notice any effect. So use your ear and the compression meter (more on that later) to guide you as you dial in the Optivalve.

The Output dial controls the amount of volume coming out of the pedal and makeup gain for volume lost when implementing higher levels of compression. It works as expected and there is plenty of gain on tap.

Finally, the EQ dial. It is a tilt EQ type control (similar to the Diamond, JHS Pulp 'N Peel, Smoothie, and Becos Stella. Turning the dial more counterclockwise increases lower frequencies and reduces treble. The converse is true when rotating the clockwise.

The sweet spot for me was somewhere around 1:00 or 2:00. 10:00 or lower really doesn't sound good on bass, to my ear anyway.

I sent an inquiry to Gurus asking about the eq tilt point and am waiting for their reply. To my ear, I prefer the tone control of the aforementioned pedals more than this one on the Gurus because the sweet spot range is so limited. That said, with the EQ dial set at 1:00 or 2:00 there is some nice sparkle to the high end that is addictive and really helps bring life to a bass guitar signal. Using my Fender Stratocaster guitar, I found the dial to be more useful across the range.

The compression meter is different than any other LED gain reduction metering I've encountered before. There are 6 bars that light up. As the pedal is compressing the outer two bars (far left and far right) light up first. As you increase the impression level then the inner 4 bars illuminate together in different intensity. It works, but is unconventional. It's like a pulsating glow. Definitely better than not having a meter at all and preferable to compressors that have a single LED that flutters between none to compression active with no real change identifying intensity (like the Keeley Bassist, for example). I prefer LED's that illuminate in a row as gain reduction increases because it is easier to quickly glance and see what is really happening.

So how does it sound?

When you first turn it on you might think the pedal is inherently transparent.

But as you adjust the dials and use it for a while you come to appreciate the effect. Turning it off makes you want to turn it back on because you miss the effect. It is definitely doing the job of compression while adding some sparkle at the same time. It isn't a huge, fat type of compressor but it definitely ads a flavor of its own. Reminds me of a cross between something like the Markbass Compressore and Cali76 CB. A bit of tubey goodness with the high end sparkle of the Cali compressors. The Markbass is definitely more colored than the Optivalve MKII but the Optivalve is much smaller.

Another similar compressor that comes to mind is the Effectrode PC-2A which has a more syrupy flavor. I found the articulation of fingerstyle to be excellent with the Optivalve. I would probably prefer using the Optivalve on faster, more articulate patterns. The PC-2a is smoother and more gooey. I prefer the ratio and tone controls the Optivalve offers.

Where the Optivalve MKII really shines is in its subtle but beautiful compression. Once on, you don't want to turn it off. I admire compressors that are easy to dial in and quietly do their job. I didn't hear much at all in the way of low end reduction or loss of highs. The EQ dial is there to make small reaching changes to your compressed tone.

I am aware of comments that the first version of the Optivalve was quite noisy. I have not tested one of the first versions so cannot speak to this but the MKII is certainly not the most noisy compressor I have encountered. It is not the quietest though either. At lower compression levels the pedal is more than passable and won't be any issue for most. At higher compression levels you do hear the introduction of elevated noise floor but it is nowhere near that of other noisier compressors. Frankly, I don't think noise would be an issue for most anybody. So, Gurus must have focused on this matter in the MKII release.

The pedal itself is very light weight. The enclosure does not seem like it would be rugged and I think the casing is plastic or maybe very light weight aluminum. I believe the top is plastic. Yet, the pedal doesn't feel cheap. I think it is an attractive package.

There are LED's inside the enclosure that light up when power is supplied. In low light scenarios, the entire enclosure seems to light up. Pressing the foot switch to activate the pedal illuminates a blue LED behind the tube.

Footswitch is true bypass. I did not notice any popping when activating.

Power and input/output jacks are top mounted. Power requirements are 9 - 12 volts max.

Overall, the Gurus Optivalve MKII is a nice compressor. It is pedalboard friendly, looks great, sound great, and offers a nice feature set. It might not knock a Markbass Compressore or Cali76 CB or Effectrode compressor off your board but it is another nice option out there definitely worth trying.


• Tube tone

• Form factor

• Top mounted jacks and power input

• Sound

• EQ dial

• Looks cool


• Possibly build quality

• Maybe not colored enough for some seeking a tube compressor

• Limited range of useful EQ

Retail price: $349

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Reviews by Chris Tromp 

Bassist and Marketing Guru

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