MI Audio Tube Zone Overdrive



MI Audio about the v1 and v2 (2006-2008)


It's fair to say that the Tube Zone is my personal favourite overdrive pedal. I'm sure there's a sentimental element to this. The Tube Zone, after all, was my first commercial pedal. It grew out of nearly a decade of playing around with overdrive pedal design. I built my first Tube Zone in 1995.

It grew out of a few observations. Firstly, a few stacked overdrive pedals often sound much better than just one pedal with a lot of gain. Secondly, a high gain tube amp gets its sound by progressively clipping the signal through multiple gain stages. These two observations lead to the conclusion that cascading gain across multiple stages is an excellent way to get a natural sounding, tight, and touch sensitive overdrive. So after experimenting with various configurations (from 2 to 8 stages), I settled on a design which featured 4 clipping stages. This, as it turns out, is also the number of gain stages in a typical high gain tube preamp.

The surprising thing about this design was not only how good the high gain sound was, but also just how amazing the low gain sounds were. It seems I had come up with a design which handled both beautifully. There was also no humbucker/single coil bias. Both work really well with the Tube Zone.

It wasn't just the overdrive section which attracted my attention. I also went to work on the tone control circuit. This involved designing a tone control which affected both highs and lows at the same time, to give you the same functionality a a bass/treble control, but with just one control. As the tone control is turned down, the lows increase, and the highs decrease. The reverse happens as you turn the tone control up. In the original design, a mid switch was added to allow the user to drop or 'scoop out' the mids. This powerful tone shaping was then married to an ultra quiet, single ended pure class A output section.

Second Generation

Over time, the Tube Zone design was tweaked. The second generation of Tube Zones was moved into a lower profile enclosure. A 3rd mid switch position was added, and the output volume was increased by a whopping 15db. Also, I developed a series of tweaks for controlling other pedal parameters. The first of these was an brightness trimmer for controlling the top end of the pedal (actually, it controls how far into the highs the Tube Zone's response goes). This allowed the user to tailor the Tube Zone to match bright or dark amps.

The second of these controls (a unique feature available only on MI Audio pedals) was the character control. I'm really proud of this one. This control (also an internal trimmer) is effectively a pre-overdrive bass control. You see, the low frequencies are very important for controlling the character of an overdrive. It works the opposite way than expected. If you have very little low end before the overdrive, the sound stays tight and focused. More low end pre-overdrive, and the sound has more momentum, but also feels a but more elastic and mushy. So with this amazing little control, the user could dial in the exact 'character' of the Tube Zone.

The Final Evolution

The current Tube Zone is the final evolution of this amazing design. I am extremely excited about this pedal. For starters, the two internal controls have now moved to the outside of the case. This means that it is no longer necessary to open up the pedal in order to tweak the pedal. New gig with an unfamiliar amp? Not a problem. With the new Tube Zone, you can dial in your sound, regardless of the equipment you have to work with. Also, the mid switch has evolved into a continuous midrange control. This allows perfect setting for the mids. If these 6 external controls weren't enough (Gain, Tone, Volume, Character, Mids, Brightness), a seventh 'presence' trimmer was added to adjust the overall balanace and sparkle of the Tube Zone.

Finally, the Tube Zone has received a cosmetic upgrade. The die cast enclosure is now plated in genuine chrome, for striking good looks.

I believe that this version of the Tube Zone is the best pedal I have ever made. If you're after a 'desert island' overdrive pedal, I'd seriously check out the Tube Zone.


  • Drive Control: The gain control adjusts the gain of all 4 gain stages. As mentioned previously, the Tube Zone gets it's unique tone by mimicking the signal path of modern valve map, and by clipping the signal up to 4 times. This doesn't just make the Tube Zone great as a high gain pedal, but also as a low gain pedal. By having the Drive control control multiple stages at once, you can effectively control how many of these stages clip. With the gain turned down low, it may be that just the last stage clips (or maybe last 2 stages). As the Drive increase, more stages 'light up'. This is very different to the way that pedals normally work, where one stage has it's gain changed dramatically in order to cover higher gain sounds.

    One interesting feature of the Tube Zone is that I have designed drive control to have a very unique sweep. With the drive set to 50%, you're actually only using about 3% of the available gain. By designing the Drive sweep like this, you're able to get a lot of control over the lower gain sounds. So despite that fact that the Tube Zone has about 250% more gain than the most popular 'metal' pedal on the market today, you can still have very fine control over the lower gain sounds (which are just stunning!)

  • Character Control: This is a feature which is not available from any other manufacturer (as far as I know!). This is effectively a pre-overdrive bass control. By controlling the amount of bass in the pre-overdrive signal, you can change the character or feel of the overdriven sound. By turning character all the way down, you can get great, tight, high gain sounds, wonderful for palm-muting. Turning up the character adds more 'momentum' to the tone, and works wonderfully with single note work. Most other pedals will only have one static 'character' for the overdrive.

  • Tone Control: This is a 'balancing' control. Unlike other designs which progressively roll off the top end of your guitar sound, this tone control affects both the low and high frequencies. It's effectively like having a 2 band low/high EQ. As you turn down the tone control, the lows increase, whilst the highs increase. Visa versa as you turn up the tone control. This, in conjunction with the mid, brightness and internal presence controls means that you can dial in almost any tone you like.

  • Mid Control: The first generation of Tube Zones had a 2 position mid switch (mid hump, and mid cut). the second generation had a 3 position switch (mid hump, 'flat' and mid cut). For the latest Tube Zone, the mid control has evolved into a continuous external control. The reason for this is that the mids are probably the most important frequencies for determining the overall sonic footprint of the pedal, so the more control the better! The mid control featured on the Tube Zone is unique in that it is highly interactive with the tone control.

  • Brightness Control: This was initially an internal control (like the character control), but has been turned into an external control. The brightness control was initially designed to allow users to match the brightness of the pedal for their rig and taste. It was intended as a set-and-forget controls for people with a consistent rig. However, a common request from many professional players who found themselves using different 'house-rigs' every night was to make this control external so that they sound set the brightness from night to night. This is the last tone shaping control in the signal path.

  • Presence Control (Internal): Another request I've received from users is a way of controlling the neutral 'shape' of the Tube Zone's tone. You see, my ears tend to gravitate towards a full low end. I like pedals to move a bit of air. Some people found that there was a bit too much low end with the Tube Zone, and that they had to turn the tone control up a bit too much in order to reduce the low end. So I came up with the idea of adding this 'presence' control. Of course, it's not a true presence control (which is a power-amp feedback control), but the way that this control affects the frequency response is quite similar to the way that a presence control works on modern tube amps. Hence the name. This control adjusts the top 'band' of frequencies. By turning this up, you can make the top band more promiment, and hence create the feeling that the lows are not as boomy. Similarly, this allows people who prefer a huge low end to dial in an even more extreme low/high ratio.

Other Features: Of course, the new Tube Zone contains all the standard features of all MI Audio pedals, namely, True Bypass switching, highest quality components, die-cast enclosure, and a power supply which can run up to 25V DC with a suitable external power supply. But the Tube Zone also features genuine chrome plating for the enclosure, as well as chrome knobs and an ultra bright (13,000 mcd) blue LED.

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