Darkglass – B3K Microtubes Bass Overdrive REVIEW

The Darkglass pedals seem to have been the flavor of the month for several years. Let’s find out what the fuzz – or rather overdrive – is all about…

The Microtubes B3K CMOS Bass Overdrive has rapidly become a modern bass classic, and it has been hyped a lot in recent years. While the first impression when opening the box was indeed very good, I reminded myself to stay calm and not run with the hype unless absolutely necessary…



darkglass-b3k-bass-overdrive-control-knobsThe user interface of the B3K consists of three knobs and two 3-way toggle switches. The two lower knobs are the traditional LEVEL and DRIVE parameters that you will find on any overdrive, distortion or fuzz pedal. ‘Level’ may be named ‘Volume’ and ‘Drive’ may be ‘Gain’ or similar, but the functions of these buttons are universal across all drive pedals.

The BLEND knob is not unique to the B3K, but also not a feature that every drive pedal has. It does what it says – blends the clean signal with the FX signal – and it comes in very handy as we will discover in a bit.

The ATTACK toggle switches affects the high frequencies and you can set it to either FLAT, BOOST or CUT. And at the other end of the spectrum, the GRUNT toggle switch deals with the low end where you can choose between FAT, THIN and RAW settings. The descriptions of these settings are quite accurate and they pretty much do what you would expect them to.



white headphone with rhythm symbol

I should stress that one of the sub-communities where the B3K has gained loads of street cred is in metal and other hardcore genres. While I have absolutely nothing against any kind of music, this is not really a world that I have explored first-hand. So, while I have no doubt the B3K is great for metal (and I have heard some very convincing demos in that territory online) I would not be helping anyone by trying to review this pedal in that context. So, I will add more dirt than I am used to in some of the sound clips, but will (in most cases) also apply it in ways that I would actually use on the stage, which also means that some of the demos are more about tone-shaping than dedicated overdrive. That said, the B3K is nothing but subtle…

Finally, with 9 possible combinations using the two toggle switches alone and the BLEND option as well as the ‘usual suspects’, I found it best to go for demonstrating various playing styles and bass types used with a handful of different B3K tones, rather than taking a methodical approach that could potentially mean hundreds of audio examples that I don’t have time for creating and you don’t have time for listening to… Glad we agree on that, so let’s get started!


NOTE! Please use headphones or ‘real’ speakers. You simply can’t judge low-end material on laptop, tablet or phone speakers…!

NOTE! If you are on a mobile device, please turn it to landscape mode to see the knob settings of the pedal for each audio clip.




As mentioned in the opening, I did remind myself to keep calm and don’t get carried away. Having played around with the B3K Microtubes on several different basses, I have to admit that I am having a hard time keeping my cool. I really, really like it and even though the circuit is anything but subtle – in fact it colors your tone a lot – the BLEND knob allows you to make it subtle by only adding small amounts of FX signal to your dry tone. That one knob increases the versatility by a mile, but even that aside, the toggle switches can bring out a ton of different OD flavors.

Further, if you utilize all of the knobs and switches you can go for gentle, characterful tube charm, push the tubes to the edge of breaking up, taking them just over the edge adding some real ‘hair’ to your tone and finally you can go all in by adding full-blown overdrive that can be fat and rumbling or cutting-through-the-mix like a razor – or anything in between.



In just a few words, the quality seems very high. The knobs feel firm, jacks connect with confidence, the footswitch is solid and the toggle switches seem capable of being poked around for years without any problems. Obviously, I have not had a chance to long-term test it and would not be able to say that I have used it for a decade with no issues as is the case with some of my old Boss and TC pedals. But the initial impression is that the quality is top notch.

From a design point of view, I really like the decision to use the two toggle switches. Sure, some tone controls would have been great, but I guess that’s why you can also get the B7K that is essentially this pedal plus a 4-band EQ and DI functionality. If I should point out one thing, it would have to be the location of the power supply input. It’s on the right side of the pedal next to the input jack socket. Now, most of my short patch cables that I use on the pedal board have a 90-degree angle jack, which tends to clash with the power supply connector.

Also, there is no option to run the pedal on a battery, which according to the Darkglass website is for ecological concerns and not a design issue, but if you take a look inside the pedal, it’s actually a little hard to see where there should be room for a battery. Darkglass could have chosen a bigger chassis as the B3K is in fact a little smaller than most ‘regularly-sized’ pedals (those that are not intentionally ‘mini’ and not significantly larger than a standard Boss pedal). At the end of the day, I applaud the compromise of the slightly smaller footprint over the option of a battery. In fact, I never run any of my pedals on batteries so it would never be an issue for me, but it may be to others so it should be mentioned.



Today (2015), you can pick up a new B3K Microtubes Bass Overdrive for around $250. It’s not the cheapest pedal around, and the Value for Money parameter is of course harder to increase as the price goes up.

That said, I think there is a chance that a very expensive pedal can be so great that even this parameter peaks, whereas I would never give a poor-sounding pedal a high Value for Money score just because it’s dirt cheap. Maybe the B3K won’t skyrocket this parameter, but it sure represents a lot of value – even at this price.



It’s hard to find reasons not to like this pedal. If you’re an overdrive aficionado, the B3K delivers, and if you’re new to drive this could easily be the pedal that makes you wonder why you have never entered that tonal territory before.



Sounds great

Extremely versatile

Solid as a tank



Power supply jack on the side

Relatively expensive









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