Build Quality:4.9 out of 5 stars
Hardware:4.8 out of 5 stars
Electronics:4.8 out of 5 stars
Sound:4.8 out of 5 stars
Value:4.9 out of 5 stars
Average:4.8 out of 5 stars

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  • Very functional
  • Delivers clear sounds
  • Extremely versatile


  • Bit expensive
  • Toggle switches are not easily accessible

It has been a long-standing conception that bass guitars weren’t compatible with audio effects. Everybody used to think that they had a distinctive character of their own, or simply limited the potential of this instrument to the background of various setups. There was a time when nobody took basses seriously and that caused everyone to believe that they didn’t deserve the leading position. Fortunately, that tendency has changed and continues to revolutionize the way we perceive music. It shows us clearly that we shouldn’t create boundaries even if we dislike or look down on something.

Music has no limits – rather, it empowers us to keep experimenting even when we think that we’ve already explored our full potential. I think I’m going too far with this, so I’ll try to demonstrate my main point briefly: bass is a wonderful instrument that has an unimaginable sonic spectrum – at least for me. And it diversifies and opens up even more when paired with audio effects, in general, and distortion, in particular.

If you enjoy the combination of these two, then you should definitely check out Microtubes B7K Ultra from Darkglass Electronics. This fancy piece of equipment has everything you could ask for – not only does it add distortion to your low-end, but it also acts as a powerful preamp. Let’s begin this review and discover together the real gems that are hidden beneath its shell!


If there was a competition for revealing the most versatile bass distortion pedal, Microtubes B7K Ultra would definitely hold the leading position. Boy, this thing is stacked with diverse features and modifiable properties. Though it has countless important qualities up its sleeves, I can’t help but mention just how wonderful it looks. I do my best not to pay attention to appearances, but when the units are so fancy and stylish, it becomes really hard to control myself.

It has a matte black surface with shiny black knobs, accentuated silver switches and sides. Its blue LEDs display what is going on in the unit and add a pop of color that cranks it up a notch. The combination of these tones creates the ambiance that proves with each glance that this puppy is expensive. Such appearance is also indicative of sleek and meticulous wiring on the inside and durable shell on the outside. This fella is built to last!

More importantly, Microtubes B7K Ultra is an updated version of its predecessor, which means that it offers everything the previous one lacked. In other words, it has an extended EQ section. Not only does it offer 4-band equalizer that takes care of all the frequency ranges, but it also lets you choose a precise midrange that will be altered. Such a level of accuracy and meticulousness is what turns this one into such a powerful preamp. What’s more, it has an added footswitch for distortion, enabling you to engage the effect independently and trigger it on the fly whenever needed. It also means that you can add dry signal to the wet one and accentuate the character of your instrument even more. Microtubes B7K Ultra has a balanced output that routes your signal directly to the PA or a recording/mixing machine.


It’s only natural that the control section of Microtubes B7K Ultra is packed as much as the features are. I would say that available knobs and switches are rather detailed and let you grab your hands on all the needed parameters. This way you can adjust and mess around with everything you want to change and, thus, create scrupulous, well-structured sound. Don’t think that it complicates anything – things are quite simple here.

The first row begins with Master volume, which modifies the overall volume of the unit and enables you to keep the effect in sync with the rest of the band/mix/whatever. Blend mixes together with your original and affected sounds, making it possible to let your bass shine a tiny bit more. The level determines the volume of wet signal, while Drive increases/reduces the amount of gain and, thus, intensifies the distortion.

Moving on to the second row, we have all the EQs in here. Bass, Lo Mids (switchable frequency: 250Hz, 500Hz, 1kHz), Hi Mids (switchable frequency: 750 Hz, 1.5kHz, 3kHz) and Treble boost or cut up to 12dBs in low, mid and high frequencies, respectively. Attack toggle modifies the amount of higher frequencies that will be affected (Boost increases, Flat doesn’t interfere with, Cut reduces this amount), while Grunt does the same thing for bottom-end. And finally, the Distortion footswitch triggers the effect, while the Bypass activates EQ section or bypasses the unit.  

Darkglass Electronics Micro Sound

There are certain characteristics that are shared almost by every pedal out there. It’s natural that you’ll come across the same words to discover various units. That is completely normal, keeping in mind the fact that they all do the same job. What you should look for are distinctive qualities. In the case of Microtubes B7K Ultra that unique pattern is the ability to be equally subtle and crazy. You can easily achieve saturated and full-bodied overdrive with lower settings, then crank everything up and create that girth-filled distortion.

Attack and Grunt set this puppy apart from the competition – they can attenuate or emphasize high and low frequencies, giving you more precision when it comes to adding heavy distortion. They can change the character of your sound completely and take you to a whole new place. The ability to utilize distortion and EQ section separately is a cherry on top for those scenarios when you just need a preamp and nothing else. All in all, the sonic spectrum here is limitless – experimenting with all these controls will yield versatile, yet jaw-dropping results.


My final roundup is that Microtubes B7K Ultra from Darkglass Electronics is one of the best bass distortion pedals out there. It does have its flaws: weird control layout or maybe its high price point (and even these are forced out of this pedal). But once you experience its sound, its feel and the unit as a whole, you’ll discover that sometimes you have to pay money for the quality. Good luck! 

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