Cab block

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User contributions

What's an Impulse Response (IR)

• An Impulse Response (IR) is a collection of data representing sound measurements taken from a speaker cabinet or system and used by the Axe-Fx II to enable the Cabinet block to emulate a particular speaker cabinet. A test signal is played through the actual speaker, recorded, and used to generate a profile utilized by the Axe-Fx II to reproduce the measured respons. The Axe-Fx II also uses IRs for microphone simulation. 
• The terms "cab" and "IR" are often mixed up.
• More information in Wikipedia

Nearfield and farfield IRs

• Most IRs represent the tone of a speaker that was recorded with the microphone close to the speaker ("nearfield" or "close-mic'd"). "Farfield" IRs on the contrary represent the speaker sound when there's some distance between the listener and the speaker. See also Close-miked versus amp-in-the-room. There are 3 farfield IRs among the stock cabs, created by Jay Mitchell ("JM").

Matching amps and cabs

• It’s a matter of personal preference which cab model (IR) you want to combine with a specific amp model. You can choose for traditional combinations. Or be creative and innovative. The differences can be huge.
• When comparing cabs, don't judge too quickly. Each time you select a cab, you may need to adjust the amp settings to dial in a tone.
• Common combinations of amps and cabs are listed here: AMP (block): list. Forum member Shasha put together an Excel spreadsheet which shows the suggested cabinets for each amp model, based on the wiki. You can download the file here.

• More information about speaker types
• G12M and G12H comparison
• EVM 12L and EVM 12S comparison

Cab block: position on the grid

• In the "real" analog world it makes a difference if you put effects before or after the speaker cabinet. It's different with the Axe-Fx II. 
• Javajunkie: "You can place the effects loop anywhere in the chain (just add the fx loop block). Unless you are running a stereo cab or 2 mono cabs panned hard L/R, you may want to place stereo effects after the cab. The cab is a linear time invariant effect (unless you add drive) so effects like delay and reverb will sound the same before or after it. As Cliff and others have stated on numerous occasions LTI effects can be placed before and after each other and they will sound the same. Only when placed before or after non-LTI effects (drive, amps, et. al) it really matters. The one caveat there is that some effects are mono, placing effects before and after that makes a difference."
• Cliff: "The difference in having the cabinet before or after the effects is usually subtle. It depends on how non-linear or time-variant the effect is. For effects like EQ, which are linear and time-invariant, it doesn't matter at all. For slightly time-variant effects like chorus and flanger the difference isn't very pronounced. For highly time-variant effects, like pitch shifting, the difference can be marked."
• Cliff: "The cab block is level-dependent if the Motor Drive is non-zero. So if you turn up/down the level out of the amp block you may need to compensate by doing the opposite with the Motor Drive." Source
• Keep an eye on the mono/stereo configuration. When placing the Cab block at the end of the grid, set to HiRes Mono or LoRes Mono, the output signal will be summed to mono. And if the Cab block is set to Stereo but it is followed by a mono block (such as Drive), the resulting signal is also mono.
• Cabinet blocks in parallel rows sound louder than a single Cabinet block. Here's the explanation. Bakerman: "It depends on how you're panning. Assuming a mono signal sent to cabs: Stereo cab w/ Pan L and Pan R fully left & right will be the same output level as 2 mono cabs w/ balance L & R. If pans/balances are centered the 2 mono cabs will be 6 dB louder. Balance elsewhere would be between 0 and 6 dB louder, and balance doesn't correspond 1:1 to pan L/R for the same placement. Balances will need to be further toward -50 or 50." Source

Cab block: HiRes Mono, LoRes Mono, Stereo

• A HiRes (high resolution) Cab block contains an IR consisting of 2040 samples. It requires more CPU capacity than a LoRes Cab block (1024 samples). You can often use a LoRes Cab block without any negative impact on the tone.
• A stereo Cab block contains two LoRes IRs.
• Cliff: I started out with 8192 but didn't hear any difference so couldn't justify wasting all that space and CPU. You can hear it with room mics but the room simulation sounds nearly identical. There are a couple reasons for 2040. Probably most important is that it allows 1024 in stereo mode. To be able to do stereo 1024 requires a 2040 convolution engine. Secondly, some IRs benefit to