AX8 amp modeler and multi-fx pedalboard

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The information on this page supplements the official manuals.

AX8.jpg AX8-rearA.jpg


About the AX8

The AX8 is an all-in-one floor version of the Axe-Fx II, designed for the gigging musician. It provides Quantum amp modeling and UltraRes speaker cab sims, plus hundreds of effects and the familiar 4x12 grid, with the same quality as the Axe-Fx II. It differs from the Axe-Fx in that it offers only one instance per preset of amp, cab and some effects blocks (e.g. Reverb, Flanger, etc.) Also, certain esoteric effects found on the Axe-Fx are not included in the AX8 (Vocoder, Megatap, etc.) It has multiple outputs offering Humbuster technology, S/PDIF out, and an effects loop.


More specifications in the Owner's Manual.

Mounting the AX8

You can remove the rubber feet of the AX8 to mount it on a pedalboard with Velcro. BUT: do not use the same screws again, use substitute screws. You need M3.5 x 6mm flat head screws. source

Where to find these substitute screws in Europe.


"When I designed the AX8 I designed a product based on my 25 years playing as a pro and what I used 99% of the time during a gig. Even with the Axe-Fx II 99% of the time I dial up an amp, a cab and a few effects. What I care about most is a great tone. The Axe-Fx amp modeling algorithms are the best in the world. I wanted to design something portable and affordable enough to get those algorithms into the hands of a lot more players." source

"They are very cool. They're not an Axe-Fx but they're close. Same amp and cab modeling. Stripped down effects section. Two 450 MHz DSPs; one for amp modeling the other for effects/housekeeping. Uses the same silent switch technology as the MFC-101 Mark III and FX8. Switches are assignable per patch via our new "Switch Assign Matrix" feature." source

"It's pretty much "Axe-Fx Lite". All the advanced parameters are available in the amp block, you access them via the traditional edit menu. The dedicated Bass, Mid, etc. knobs can be accessed at any time. And it sounds like an Axe-Fx, so there's that." source

"The switches are multi-function. They operate as preset, scene, looper or bypass switches. There are four expression pedal inputs. There is a stereo effects loop. The dedicated knobs control only those parameters for which they are indicated. There are five soft knobs under the display that are used for adjusting other parameters." source

"The AX8 has two ADSP-21469s and two microcontrollers. It will only do one amp model at a time. Our amp modeling algorithms use up the entirety of one DSP. The second DSP is running at over 90% utilization. That's how detailed our algorithms are." source

"I'll just say a few things: source

"Footswitches are freely assignable. There is a footswitch assign menu." source

"There will be no pay-to-play stuff. All amp models from the Axe-Fx II will be included as well as all the Drives, etc." source

"It has SPDIF." source

"It does not have a headphone output but the outputs should be able to drive phones with ease. You'd just need a Y-cable adapter." source

"Both the AX8 and FX8 are made in the USA." source

"The AX8 isn't exactly featherweight either though. It has a heavy steel chassis and aluminum end-caps. It's pretty heavy but very durable." source

"The DSPs used in the Axe-Fx are far too costly and require exotic cooling that is not suitable for a floor application. The AX8 covers the needs of 99% of performing guitar players." source

"The Axe-Fx II can run multiple instances of amps, cabs and most effects. The AX8 cannot. The processors used in the AX8 are not nearly as powerful as the processors used in the Axe-Fx II. They are also significantly less expensive." source

"AX8 and Axe-Fx II share the same code base so any updates to the Axe-Fx II apply to the AX8." source]

"Dimensions and weight are the same as the FX8." source

"Each pedal jack support pedals or switches." source

"Unbalanced to monitors, XLRs to mains. Or use FX Send and echo to the send. Same as an Axe-Fx." source

"The eight main footswitches are assignable per preset. A screen shows you at glance what each switch controls. The function switches are configurable globally." source

"The XLRs on the main outputs vs. the FX Sends, yes those are independently adjustable but, like the Axe-Fx, you lose your fx loop." source

"The AX8 is not "way more powerful" than the FX8. The AX8 has one additional DSP that is DEDICATED to amp modeling. If you don't use the amp modeling the AX8 has the same power as the FX8. The AX8 will not work as well as the FX8 in 4CM. It is not designed for that. It will do 4CM, as will most digital processors but the FX8 is the only processor of which I'm aware that is truly optimized for 4CM. That optimization requires a lot of expensive circuitry. The op-amps used are very expensive and there's dozens of them just to support the 4CM stuff. Add to that relays for true bypass, metal film capacitors, etc., etc., and you end up with an expensive design. The FX8 and AX8 are built on the same code base. There is a single folder that is used to build the common elements for both products. Enhancements to one automatically enhance the other. All this work we've been doing for the AX8 will improve the FX8. The AX8 will be much more popular than the FX8. That should be obvious. Most people want the amp modeling. If you don't care about the amp modeling then the FX8 is the better product and the whole reason for having two different products." source

"Precisely. The loop's intended use is, well, as a loop." source

(Does the cab/mic/ir use the fx dsp or share the amp dsp?) "Neither really. They are done in an a separate accelerator so they have minimal CPU loading. An accelerator is a DSP unit dedicated to performing a defined task. In this case it performs convolution. The difference is that a "DSP" as we commonly call them is really just a microcomputer optimized for Digital Signal Processing. The term DSP most correctly refers to any device that does signal processing using numerical computations. That device can be an FPGA, ASIC or fixed hardware unit. In the AX8 it is a convolution processor." source

"You can have more than 8 effects in a preset. For example, you could have 12 effects in a preset. You then assign which of those effects you want to be able to switch on and off via the footswitches." source

(How many effects can you run at a time?) "Depends on the effects but typically 8-10 in addition to amp and cab. The amp and cab block use very little of the main DSP. The amp runs in a dedicated DSP and the cab processing runs in an accelerator. Therefore most of the main DSP is available for effects." source

"Same grid as Axe-Fx II. 512 user cab slots, 512 preset slots. Same factory amps and cabs as Axe-Fx II. Same high-quality, low-noise design as Axe-Fx II XL+. True differential I/O to the converters, not the single-ended stuff used in consumer-grade gear. Silent Switch technology from the MFC-101 Mark III. Humbuster I/Os. Most importantly it has Quantum and the "Fractal Sound". source

"Layout grid which is just like the Axe-Fx II." source

"The AX8 uses assignable switches. So rather than a dedicated Looper control mode, you can choose which Looper controls you want on the assignment page. Most people don't use all the Looper controls so this system is more flexible." source

"The AX8 was built to a price point with quality of sound the primary consideration. It's primary use is as a live performance product. A color LCD and USB audio were not deemed pertinent for the intended application. Had those been included the price would be much higher than $1399." source

(can I use the USB to send and receive midi for switching from a computer?) "Yes." source

"The AX8 uses the same converters as the Axe-Fx II. We put the money where people can't see it but where they can hear it." source "The AX8 and FX8 uses the same converters (CS4272-CZZ) and op-amps. The circuit design in the FX8 is necessarily much more complex to support true-bypass switching (without pops and clicks) and to optimize the outputs for use in 4CM. The AX8 removes the dedicated true bypass switching circuitry and simplifies the output design to save money. The cost savings is used towards an extra DSP." source

(Can the Ax8 run a stereo UR cab and the AxII HD reverb?) "Yes, with ease." source

"The chassis is made in China. The electronics are made in the US and installed in the chassis here." source

"The AX8 has Humbuster outputs as well. It will do 4CM but probably not as good as an FX8 which was purpose-designed for 4CM. If we used the output topology of the FX8 in the AX8 the AX8 would cost a LOT more." source

"It does not have the vocoder and several of the other more esoteric effects. It does have the looper, synth and all the bread-and-butter effects. And it has the beautiful high-quality reverb from the Axe-Fx and FX8 (because I'm a reverb junkie). Most importantly, though, it sounds like an Axe-Fx." source

"The output impedance of the 1/4" outputs is 600 ohms IIRC. This may be too high for some headphones. We always use a small output impedance on our designs to help protect the output devices against improper connections, ESD, etc. The outputs were not really designed to drive headphones, they are designed to drive high-impedance inputs (>10K). Headphones will work but it won't be optimum. For optimum results use a dedicated headphone amp." source

"The AX8 was not designed for use with Global Block." source

"The AX-8 is not an Axe-Fx II on the floor. If it was it would cost a heck of a lot more than it does. It uses the exact same modeling code as the Axe-Fx II. The overwhelming majority of people love the AX-8 and understand its place in the Fractal Audio model line-up. Putting an Axe-Fx II on the floor wasn't feasible due to the DSPs used in the Axe-Fx II requiring active cooling and being very expensive. The AX-8 was designed as a lower cost, simpler product that would address the needs of 99% of users. Power users will want an Axe-Fx II which is still the best modeler in the world." source

"The SHARC processors in the AX-8 support 40-bit word lengths and we use them just as we do in the Axe-Fx II." source

"The XL+ front input circuit is identical to the AX-8 except the AX-8 doesn't have the variable impedance circuitry." source

(about memory in AX8) "More than will ever be used." source

"The TigerSHARC architecture is vastly superior to the SHARC, and it's a shame it has been discontinued. In our tests a TigerSHARC performs about 50% faster clock-for-clock. Then factor in the higher clock speed and it's about twice as fast. See here for independent benchmarks: The newest SHARCs are the same as the 213xx except they have the FIR accelerator. As one can see a TigerSHARC (Axe-Fx's use the ADSP-TS201S) is about twice as fast. (...) The TigerSHARC has a more modern core and much better architecture (larger register file, wider buses, better DAG units, etc). It can do six floating point operations per clock. In practice this is two multiplies, two adds and two store/fetch instructions. This means a 4096 point IR only requires 2048 clock cycles. Secondly the TigerSHARC has a much wider bus than a SHARC. The TigerSHARC has a 512 bit bus whereas a SHARC has a 128 bit bus. The TS can move data around much faster and pipeline stalls due to bus contention are far less frequent. It can load or store eight words in a single clock cycle whereas a SHARC is hard pressed to do two. The TS also has a LOT more on-chip memory. A TS has 24 Mbits of on-chip memory compared to 5 Mbits for the best SHARC. This means more code/data in fast memory and less stalls waiting for data access. Also the TS has a superior cache unit which caches both instructions and data, as opposed to instructions only on a SHARC. There are numerous other improvements as well including better DMA engine, better interrupt handling, vastly superior 40-bit floating point support (which we use for amp modeling), etc. Having written hundreds of thousands of lines of code for both (including coding the SHARC's FIR accelerator) my experience is that the TS is a much better chip but it is much more expensive. We moved to SHARCs for our floor processors for a variety of reasons but performance was definitely not one of them. The FIR accelerator is nice and all but it only applies to cab modeling which is a small percentage of a typical preset. On an Axe-Fx II a stereo Hi-Res cab block only uses 11% of the DSP. On an AX-8 it's still a couple percent as the accelerator doesn't handle everything needed in the block. So the net savings is less than 10%. The rest of the effects then run about twice as fast which means almost twice as many effects per preset on an Axe-Fx compared to an AX-8. While "all about the code" has some merit, in reality it's "all about a lot of things" including the architecture and clock speed. Algorithm complexity is also very important and it becomes diminishing returns (i.e. it takes twice as much CPU to improve the sound quality 10%). If it were just about the code everyone would still be using the original 33 MHz SHARCs. The TigerSHARC enjoyed a long run as the best DSP on the market but, alas, all good things must come to an end. The good news is that Atomic, Fractal and Line6 are all using the same DSP family in their respective floor products so it's highly unlikely Analog Devices will discontinue them and there are now more choices for the consumer." source

"Final test, programming and QC will still be done in the US. We test and inspect every unit. We do not do random sampling. Every single unit is put through a full functional test and inspection. A second QC operation is then performed prior to shipping. Costs more but results in less returns due to defects." source

"Our modeling is very detailed and whenever the amp model changes the "virtual circuit" needs to be reconfigured. We can switch quickly but often this causes clicks and pops due to the reconfiguration. So the amp block needs to run silently for a bit so things will settle. Then we unmute the block. This mute period is what you are hearing. Most other products just use a fixed algorithm and change the input/output EQ and gain. With this type of algorithm you can switch quickly without clicks and pops but, of course, you don't get the realism and detail." source

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