Read the Owners Manual first!
Latency
Contents
About processing latency
Latency is the time it takes for the signal to enter the processor and exit through an output. Basically, it's the time it takes the device to perform analog-to-digital-to-analog
(ADC
-> DAC
) conversion plus additional processing overhead.
Note that this is different from DAW latency, where the time is measured between playing your thing and hearing the sound through the system.
Fractal Audio's internal processing latency is very. It depends on the hardware, preset contents, and oversampling mode (Axe-Fx III only). The Axe-Fx III has the lowest latency. The latency of the FM3 and FM9 is the same.
Important: connecting other hardware can increase the overall latency. The perceived latency by the end-user is the sum of all components in the chain. Possible components include a digital wireless guitar system, which is typically around 2-4 ms, wireless headphones, digital mixers, DAWs, DSP-controlled monitors, additional digital effects devices and so on.
Using an I/O loop on the unit increases latency when using both the input and output ports.
Adding blocks to a preset doesn't add latency unless it's an Amp or Drive block, or a Cab block which links to an IR with leading silence at the beginning. Some other effects may increase latency as well, such as through-zero flanging, time-based and pitch shifting effects which run in series and are 100% wet, look ahead
compression, and feedback send/return loops.
Fractal Audio explains latency in Latency of amp modelers
.
FRACTAL AUDIO QUOTES
[1] Latency is a simple, one-dimensional parameter that indicates the time delay between the input and output of a system. If a signal is input to a system, latency is the amount of time /it takes for that signal to appear at the output.
Oversampling parameter (Axe-Fx III only)
The Oversampling Mode parameter, for the Axe-Fx III only, lets you choose between Best Quality and Minimum Latency. This applies to Amp blocks and Drive blocks only (non-linear blocks). Best Quality is equal to previous firmware, and is linear-phase oversampling, Minimum Latency is minimum-phase oversampling.
FRACTAL AUDIO QUOTES
[2] It selects between two different interpolation/decimation kernels. Best Quality yields the least aliasing and best phase response at the expense of latency. This is the kernel used in prior firmwares. Min. Latency trades aliasing and phase response for reduced latency. The Amp and Drive block have about 0.5ms less latency each when using Min. Latency. You can achieve total latency of around 1.5ms or less when using Min. Latency.
[3] The Axe-Fx III has two oversampling modes: Best Quality and Min Latency. One is not "simpler" than the other. The CPU usage is the same for either mode. Min. Latency uses a minimum-phase kernel which minimizes the latency of the block at the expense of phase distortion. The FM3 and FM9 use Best Quality mode all the time. There simply isn't enough CPU available to run two amp blocks on the FM3.
[4] There is no "Quality" setting. There is an Oversampling Mode which selects between a linear phase and a minimum phase kernel. CPU usage is the same in either case.
[5] The A/D/A latency of the Axe-Fx III is 1.0ms. The A/D/A latency of the FM3 and FM9 is 1.33ms. Those figures I posted were for a preset including amp, cabinet etc. blocks. Amp blocks *usually* add latency due to the need to oversample. The Helix uses minimum-phase oversampling so its amp block doesn't add latency but that causes phase distortion. The Axe-Fx III Min Latency setting also uses minimum-phase oversampling.
