The MI Audio Tube Zone Guitar Effects Pedal delivers tone with valve amp-like response. The 4 clipping stages of the Tube Zone pedal are similar to the number of gain stages in a typical high gain tube preamp. The extremely flexible Tube Zone pedal has evolved since 1995 into a pedal that excels equally in low or high gain settings.
The Tube Zone pedal's Gain control adjusts all 4 gain stages. The Tube Zone gets its unique tone by mimicking the signal path of modern valve amps, and by clipping the signal up to 4 times. This doesn't just make the Mi Audio Tube Zone great as a high gain pedal, but also as a low gain pedal. By having the Drive control operate multiple stages at once, you 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 increases, more stages light up. This is very different to the way that pedals normally work, where one stage has its gain changed dramatically in order to cover higher gain sounds.
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 the 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!
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.
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, while 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.
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 version of the 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.
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):
This is 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 prominent, 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.