[Comparison] Fractal AM4 vs FM3: Comparing the uses and features of compact devices! [Sound demo and reviews]

The AM4 has arrived and is a very attractive compact multi-channel player, but there are some things that can be confusing.

"Which should I choose, FM3 or FM4?"

Equipped with amp modeling directly derived from the Axe-Fx, it reproduces everything from clean to high gain with first-class quality. So what's the difference, and which one will work best for you?
In this article, we'll keep the core of sound quality as simple as possible, and delve into the areas that tend to make a difference: the number of effects used simultaneously, scene switching, connectivity including 4CM and MIDI, size and weight, and price.

The small and ready-to-use AM4 or the multi-functional and customizable FM3?

We'll explain how to choose the patch that suits your patch usage and portability needs so you won't regret it!

Fractal Audio Systems / AM4 AMP MODELER

Fractal

176,000 JPY(TAX+) (As of 2026:05, March 16, 13 | Rakuten Market research)

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FRACTAL AUDIO SYSTEMS FM3 MARK II Turbo

Fractal

242,000 JPY(TAX+) (As of 2025:05, March 26, 17 | Rakuten Market research)

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Sound House

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Fractal AM4 vs FM3 | Appearance and Specs

Model name	AM4 (Amp Modeler)	FM3 Mark II Turbo
Main use/product type	Specialized for amp modeling and pedal boards	All-in-one multi-FX floor unit
Amp Modeling Engine	Cygnus X3 (Axe-Fx III direct descendant)	Cygnus X2 (derived from Axe-Fx III)
Number of Amp Models	More than 240 species	More than 300 species
Speakers/Cabinet	DynaCab compatible (over 45 types of built-in cabs)	UltraRes IR + DynaCab compatible (many factory IRs + user IR slot)
Number of effects and block configuration	The bare minimum: 77 types of drive, 79 types of reverb, various modulations, etc. / 4 fixed blocks	Extensive. Delay, reverb, modulation, looper, etc. Equivalent to Axe-Fx III / Flexible number of blocks
Number of presets/scenes	104 presets x 4 scenes (gapless switching)	512 presets x 8 scenes (gapless switching)
DSP/CPU	1GHz ARM Cortex-A15 + TI C66x DSP x 1 (approximately half the computational scale of the Axe-Fx III series)	3-core "Griffin" DSP + dedicated GPU (compatible with FM9/Axe-Fx preset assets)
Input/Output Terminals	Guitar input (Auto-Z), stereo effects loop, balanced outputs (TRS x 2), headphones, S/PDIF in/out, USB-C (4x4 audio & MIDI), MIDI In/Out, EXP x 2	Guitar input (Humbuster compatible), stereo input, stereo output x 2 (including XLR), headphones, S/PDIF output, USB 4 x 4 audio & MIDI, MIDI In/Out, EXP x 2, FASLINK II
Foot Control	4 switches on the main unit: preset/scene/effect switching, tuner, 4 channel switching in Amp mode	3 switches on the main unit (LED ring + small LCD). Multi-functional with multiple layouts and views. Expandable with FC-6/FC-12.
Size / weight	Approximately 254 x 160 x 57mm, approximately 1.6kg	Approximately 512 x 233 x 88mm, approximately 5kg
Price (approximate price including domestic tax)	About 176,000 yen	About 242,000 yen

Fractal AM4 vs FM3 | Sound quality and sound demo

Both the AM4 and FM3 are equipped with the same cutting-edge modeling technology as the flagship Axe-Fx III. The AM4 uses Fractal's proprietary Cygnus X3 amp engine, while the FM3 uses the Cygnus X2 (with over 400 presets available in the latest Mark II).

This means that they faithfully reproduce the tone and response of actual tube amps, allowing for a wide range of sound creation from clean to high gain. The AM4 has over 240 built-in amp models, while the FM3 boasts over 300. Both are equipped with Axe-Fx-style cabinet simulation, with the AM4 featuring intuitive DynaCab™ (over 45) + UltraRes™ IRs, and the FM3 adding DynaCab™ to the vast Axe-Fx III original IRs (over 2,200 + 1,024 user IRs).

As you can see, the modeling performance is almost identical in terms of sound quality, and Fractal Audio claims that "the AM4's amp sound is completely on par with the flagship model." However, the AM4 deliberately strips out features to simplify the signal chain. It comes equipped with four effect blocks (amp, delay, reverb, etc.) that provide just the essentials, and pre-installed gate/EQ/boost and a built-in reverb with a free dial function for creating a thicker sound. Meanwhile, the FM3 includes almost all of the blocks from the Axe-Fx, and offers a wide range of effects, including a looper and even more diverse modulation options.

DEMO

Fractal AM4 vs FM3 | Effects and Signal Chain

In terms of the number and types of effects, the AM4 covers the bare minimum with 77 drive effects, 79 reverbs, and over 150 modulation effects. In contrast, the FM3 is equipped with the same blocks (including a looper) as the Axe-Fx III, offering all the basic effects such as delay, reverb, compression, and modulation, as well as a wealth of expansion options. In fact, the AM4 does not include some specialized blocks such as Formant, IR capture, pitch, and ring modulator, but these have been intentionally omitted because they are not necessary for an amp chain. On the other hand, the FM3 offers most of the available effect blocks, including these, giving it the expandability of an effects board.

The FM3 also offers greater signal chain flexibility. The AM4 is clearly structured with four fixed blocks (amp, drive, delay, and reverb), emphasizing intuitive operability. In contrast, the FM3 allows for free grid-based arrangement of blocks, allowing for more complex routing and parallel effects. Even when used with the 4CM (4-cable method), the AM4 has a stereo effect loop terminal, allowing for integration with pedalboards. The FM3 also has stereo inputs and outputs, offering greater flexibility in sending and receiving effects, making it ideal for use with external effects and amplifiers.

Fractal AM4 vs FM3 | Presets, Channels, and Controls

The FM3 has an overwhelming number of presets and switching functions. The AM4 has 104 presets x 4 scenes (each scene can have 4 different channel settings). The FM3 has 512 presets x 8 scenes, allowing for a wider variety of sound banks. Both support gapless switching, allowing for seamless preset switching without any sound interruptions while playing.

The AM4 features four large footswitches, each with a different function for each mode, including "Preset," "Scene," "Effect," and "Tuner." The newly designed "Amp Mode" allows for four-channel switching with the footswitches. Each channel is identified by its own LED color, allowing for intuitive control. Meanwhile, the FM3 features three footswitches with color LED rings and a mini LCD, allowing for multi-functional operation with different press methods (tap/hold) and eight layouts. Another major feature is the ability to increase the number of switches by connecting to an FC-6/FC-12 via FASLINK.

Fractal AM4 vs FM3 | Inputs, Outputs and Connectivity

Both the AM4 and FM3 offer high-performance I/O, making them ideal for home recording and stage performance. The AM4 features a low-noise guitar input (with Auto-Z) and USB-C (4-in/4-out audio/MIDI), allowing direct recording and re-amping via USB audio interface functionality. It also features stereo TRS outputs (balanced), a headphone jack, S/PDIF input/output, and a stereo effects loop. The FM3 offers an XLR stereo output and additional stereo inputs/outputs for further audio routing.

For example, the FM3 allows for flexible wiring, such as sending stereo outputs 1/2 to a PA and outputs 3/4 to a separate power amplifier. Both are equipped with MIDI terminals and expression pedal terminals (two systems each), allowing for extensive connectivity with external devices. Therefore, even with a 4CM connection, a wide range of applications are possible, such as connecting to the power amplifier section of an amplifier to apply effects alone, or branching the output in parallel with the amplifier.

Fractal AM4 vs FM3 Review

AM4

FM3

Fractal AM4 vs FM3 | Which Should You Choose?

If you're looking to incorporate it into your pedal board and simply pursue an amp sound, we recommend the AM4. The AM4's design philosophy is "100% sound quality, minimal functionality," making it ideal for players who prioritize mobility, such as connecting to a pedal board or playing wirelessly. It also features a USB audio interface and headphone jack, making it convenient for home recording and streaming.

On the other hand, if you prioritize versatility and expandability of internal effects, the FM3 is the right choice. The FM3 is like a "mini Axe-Fx" that shares the same worldview as the FM9/Axe-Fx, with a wide range of built-in effects and blocks. It's ideal for guitarists who want to create a self-contained setup by combining it with a larger board or rack.

In summary, the AM4 is lightweight, compact, and easy to handle, and is for people who want to focus on the core of their sound (the amp and cabinet). The FM3 is for people who want to create any sound they want with just one unit, taking advantage of the wide range of presets, effects, and expandability. It's best to choose the one that best suits your needs, taking into consideration your budget, the situation in which you'll be using it, and how it will work with your existing system.

Fractal Audio Systems / AM4 AMP MODELER

Fractal

176,000 JPY(TAX+) (As of 2026:05, March 16, 13 | Rakuten Market research)

Amazon

Rakuten

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Mercari

Sound House

Amazon

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FRACTAL AUDIO SYSTEMS FM3 MARK II Turbo

Fractal

242,000 JPY(TAX+) (As of 2025:05, March 26, 17 | Rakuten Market research)

Amazon

Rakuten

Yahoo

Mercari

Sound House

Amazon

Reverb

Pochip