Firmware 10

06 Apr 2013



...are the magic words.

In reality Firmware 10 is providing every Axe-Fx II user with a brand new device. The beta testers actually suggested renaming the black box Axe-Fx III. This is what gave us the idea for the April Fools' joke, as there really are so many changes and improvements that such a name change really could be justified. Although we have used these words before, we are looking at the biggest firmware update in the history of the Axe-Fx II; an update that has required dedication, passion and staying power (Cliff: “Firmware 10 was 80-100 hours a week for months”); an update that has an unbelievable amount to offer:

  • Above all, the groundbreaking new MIMIC™ technology. We'll try to describe it, but you really need to hear it...

  • ...because after all, what is the description of a sunrise compared to actually seeing one and feeling its warmth on your skin?

  • Further fine-tuning of the amp modelling.

  • Many new amp models have been added as well as a large number of completely new cabinet IRs, including ones from James Santiago and John Petrucci.

  • The number of available user cabinet slots has been doubled to 100.

  • The looper has been given increased control options. 

  • Many improvements to the Drive models and countless other detail advancements.

What makes an amp sound the way it does? What makes it special? Why don't two identical amps always sound identical and why is it that one of a series of identical amps can sound better than the others, or better than all others? Why are the last few centimetres on the way to a completely authentic amp sound and feel so difficult, even for the best modeller? Since the last update in December Cliff Chase has been working on these questions intensively. His answer is “Multi-point Iterative Matching and Impedence Correction” - in short, MIMIC. Okay, but what does it mean?
Here we need to digress slightly. This development shows us once again just what a long journey it has been for Fractal Audio on the way to perfect tone and Cliff Chase has not been resting on his laurels. He hasn't been spending his hard-earned cash on expensive gold watches or rare stamps, nor did he buy a marzipan cake for G66 at Christmas. Instead, he has built up an extraordinary collection of rare and expensive guitar amps.

He has found the perfect combination of passionate work and rewarding pleasure: he buys himself the most valuable amps, immerses himself in their undoubted virtues and then programs them into the Axe-Fx II so that the whole world can enjoy them too. And what about us? Well, we get left with a (fairly simple) choice: Do we buy an old Dumble for 55000 dollars or would we rather have an Axe-Fx II with a perfect Dumble sound built in for around one twentieth of the price?

The acquisition of all these wonderful treasures and their thus permanent availability for research purposes has made it possible to study them in much more detail.

Now, there are obviously a few things going on in old tube amps that couldn't previously be modelled correctly. However, it is important to realise that there is no esoteric voodoo involved, but rather complex physical processes – and while they may be complex, they are still subject to the laws of physics and can thus be recognised and understood.

Let's take so-called “parasitic” voltages and currents: the isolation of a brand new cable may be a true 100%. As the cable ages however, the effectiveness of its isolation will tend to decrease. Likewise, the electrical values of capacitors change as the years pass by. And when after many years dust has collected on the paths of a circuit board and the humidity of the surrounding air increases, this dust can become slightly conductive and suddenly there is a bit of electricity flowing where it shouldn't. All of these things can make an amp sound different from how it should sound in theory. Anyone who has owned an old amp for a longer period of time will recognize this changing daily “form”.

This is where MIMIC comes into play. The sound and impedance of the original amp is measured at numerous points in its circuitry. Based on these measurements mathematical corrections are then applied at the same points inside the virtual amp. The result is a more accurate representation of the original amp, one that takes into account the differences between its theoretical sound and its real sound. For the first time it is now possible to reproduce processes that are not theoretically defined by the schematics of the amp.

Calculating something like this is, of course, a huge undertaking, mainly for the developer programming the model, which makes it no surprise that so far only Cliff Chase has managed to do it. It is also hard work for the processor that has to deal with all this data in real time, so it's once again no surprise to hear that all this can only work on a system as powerful as the Axe-Fx II.

At school in our Physics lessons we all learned how to calculate the speed of a falling object, but we will almost certainly have deliberately ignored such details as friction caused by air resistance. We learned that a kilo of feathers falls just as fast as a kilo of lead – at least in a vacuum, anyway - as soon as there's an atmosphere in the way the lead is on the floor long before the last feather touches down. None of us were too interested in calculating such intricacies, however, and we were quite happy to stick to the idealised model. In a way, amp modelling has so far been similar.

But now MIMIC has arrived on the scene and put an end to approximate calculation. It works rather like a more advanced Tone Matching system, but measures what is happening at numerous points within the original amp, rather than just at the final output. It then uses these measurements to correct the amp simulation at exactly the same points, modifying the theoretical model until it is identical to the real thing.

The result is frighteningly good. Every simulation is closer to the original than ever before, because it is being checked and corrected at so many different points within the amp's schematic. And we are not just talking about sound here. The same realism applies to the behaviour of the pots controlling the amp's settings. Whilst MIMIC works without any input from the user, there are still the usual editable parameters to allow fine-tuning of the sound at every possible (and impossible) point in the signal chain.

The big difference between Firmwares 9 and 10 is thus that the new version is much better at reproducing the quirks and peculiarities of tube amps, characteristics that from a purely technical point of view may not always be desirable. This will appeal to those who up to now have found that the sound was a little too perfect. Now it can definitely have a rougher edge to it too – making your Axe-Fx II sound angry and unfriendly is no problem (if that's what you want). This new limitless ferocity is only possible with MIMIC.

Although the new Axe-Fx II does sound better in our opinion, the change this time is not primarily to do with sounding “better”, but rather with expanding the spectrum of possibilities in the direction of “untamed” tube sound. Those who don't like this development have the option of disabling it.

All of the amp models have been updated and adjusted with the help of MIMIC and they all now have a default master volume level, depending on the type of amp. The new “Master Trim” control allows master volume settings higher than the original would have allowed – turning it up past eleven is no problem. But the further development of amp modelling goes even further.

It is a well-known fact that an amplifier will produce additional harmonics when it is overdriven. Human ears tend to find harmonics that are an even multiple of the input frequency more pleasant than those that are odd multiples. Tubes tend to produce more even-order harmonics than transistors do, which is one of the reasons for their continuing popularity and the power amp simulation of the Axe-Fx II has now been finely tuned to put slightly more emphasis on even-order harmonics, making it sound even sweeter than some of the modelled originals. 

  • The modelling of the triode behaviour has been improved to remove “glare” from the distortion. This results in more clarity and better string separation in the sound.

  • The power amp has also been given a little more punch and pop and now reacts even more dynamically.

  • The amp block power supply can now be switched between AC and DC and ghost notes can thus now be produced – actually a less desirable side-effect of tube amps, but one that comes with the territory and makes the simulations even more authentic.

  • Even the type of tube can now be selected, the options being either tetrode (6L6, KT66, etc.) or pentode (EL34 etc.).

  • The accuracy of the drive stack in the Amp block has also been improved, making the behaviour of the Drive control authentic throughout its control range.

Two new parameters, Dynamic Presence and Dynamic Depth use virtual output transformer leakage inductance to alter the response of the virtual power amp as it is pushed. Depending on the setting the former provides a brighter tone when you dig into the strings (as with a real tube amp). The latter provides more or less bass response as the power amp is pushed (which is not something you can do with a real amp). The equally new Character and Thunk parameters offer further ways of fine- tuning the distortion behaviour.

A very special morsel is the new addition to the Amp block. There is now a real bias tremolo effect. While not the easiest effect to get to grips with, it produces a fantastically vintage tremolo effect, especially when used with an old (virtual) Fender amp – instant Tarantino vibe.

Many of the amps have been reworked to make them even more authentic and some have been renamed to avoid confusion. With existing presets the amps should be reset by selecting a different model and then reverting to the original one. The new Amp Select page offers an alphabetical list and quick access to the Drive, Master and Level parameters for quick auditioning of amp models.

And once again a large number of new amp models has been added. Alongside the previously mentioned Dumble Overdrive Special we now have access to models of the following fantastic amps:

- Peavey 6505+ 
- Soldano SLO100 
- Mesa Triaxis LD2 
- SAE 3+ SE Kanal 1 
- Marshall JVM410 (Green Modes)
- 1963er Fender VibroLux 
- Modified Marshall JCM800
- Swart Atomic Space Tone
- Both channels of a Bludotone Ojai

For those who have up to now had difficulty parting with their unwieldy old 4x12 cabinet and moving on to FRFR amplification, the moment might just have arrived. Fractal Audio have gone to great lengths in a special studio to record IRs of numerous cabinets. These will shortly be available as “Producer Packs” for all Axe-Fx users.

Firmware 10 includes the first 35 of these cabinet models. They are custom blended IRs, using multiple mics to record the signal. Included in this first series are also several artist IRs, with two from James Santiago and one from John Petrucci. And these new cabinet simulations are so good that most of the beta testers don't want to use anything else anymore.

The number of user cab slots has been doubled so that now 100 can be saved. This may not sound very spectacular, but if you've ever tried to find a stage or a rehearsal room with enough space for 100 4x12 cabinets, you'll appreciate having this much storeroom! And it all still fits in a 2U rack space...

As with every firmware update there are once again countless detail improvements – we'll just mention the most important ones here. Full details can be found in the release notes that are included in the downloadable zip file.

  • The Tone Match block is now more accurate, especially with low frequencies. It also now allows the simultaneous starting and stopping of both acquisition channels, which improves quality, especially when matching live sources.

  • The Looper has received several improvements for live use. The beginning and end of the loop can now be trimmed and the Play, Reverse and Half parameters can now be controlled by modifiers.

  • The accuracy of mid-frequencies in the Rotary block has been improved. The Filter block now has additional HiCut and LoCut parameters.

  • In the Chorus and Flanger blocks the sound of LFO types such as square and saw has been improved by adding LFO smoothing. This allows the desired sound, but without any undesirable jumps.

  • All Drive models based on the Tube Screamer circuit have been improved. This applies to the Super OD, T808 OD, T808 OD Mod, Full OD, BB Pre, Eternal Love and Zen Master. The Esoteric ACB, Esoteric RCB and Bender Fuzz have also been reworked.

  • The general user interface has also received some attention. Among other improvements it is now possible to restore single patches from the backup memory.

  • And last but not least, the preset switching latency has been further reduced.

This update is without doubt the biggest one ever for the Axe-Fx II and therefore this time more than ever: what sounds better will also sound different. Allow enough time between the update and your next gig to adjust your existing presets. And we don't want to pull the wool over your eyes – the 'firmware update latency' is especially large this time: by this we mean the amount of time that will slip by unnoticed when you just want to spend five minutes checking out the new amps. The next time you look out of the window the sun might just be rising again... Don't say we didn't warn you.

Our April Fools' joke hinted at it: with this update your Axe-Fx II is actually mutating into a completely new device. The fact that it is once again a completely free update makes this knowledge even more pleasant. After all, the price of the newly added amps and cabinets would come to many times that of the Axe-Fx II, let alone all the fantastic jems that were in there to begin with.


  • Very soon the first two CAB packs with hundreds of cabinet IRs will be released, not only for the Axe-Fx II but also for the Axe-Fx Standard and Ultra..

  • A new firmware version for the MFC-101 is also due to be released shortly.

  • Fractal-Bot - a lightweight, standalone firmware updater has already been released.