Cab block

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User contributions

CPU overhead of Cab blocks

• A HiRes (high resolution) Cab block contains an IR which contains 2040 samples. It requires more CPU capacity than a LoRes Cab block (IR with 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.
• If you never need Cabinet simulation, for example because you're using the Axe-Fx II for effects only or exclusively with a power amp and speaker cabinet, switch it off in the Global menu. This will decrease CPU utilization in all presets considerably.

Matching amp models with appropriate cabs

• It’s a matter of personal preference which cab you want to combine with a specific amp model. You can choose for "traditional" combinations. Or go wild. The differences can be huge. For example the Fractal 4x12 20w (vintage, low power) has little bass, the Fractal 4x12 German has loads of it. Differences between cabs may also originate from the way the IR was captured. The Fractal 4x12 German sounds like the mic is very close to the speaker (proximity effect), where the 4x12 Brit sounds like the mic is at some distance (thinner bright tone).
• 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 nice tone.
• Common combinations of amps and cabs are listed here: AMP (block): list. Forum member Shasha put together an spreadsheet (Excel) which shows the suggested cabinets for each amp model. You can download the file, hosted by Mr.X, HERE.

• More information about speakers

Room ambience

• Close-mic'd IRs do not contain enough samples to recreate room ambience. The Axe-Fx II provides specific room ambience parameters in the Cab block (special reverb effect).
• Also see Close-miked versus amp-in-the-room.

Low Cut and High Cut parameters

• The Cab block in the Axe-Fx II provides low-pass and high-pass parameters. These make it easy to adjust boomy or harsh sounds. You can also use the same parameters in the Amp block, or use a separate EQ block. Common settings are 80-150 Hz for high pass (cutting bass), and 5-8 kHz for low pass (cutting treble), but YMMV.

Impulse Response (IR)

• See Impulse Response (IR).

IR Capture

• See Impulse Response (IR).

Cabs placed in parallel rows increase loudness

• 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

User cab slots

• If you are looking for something different than the stock cabs, try 3rd-party Impulse Response (IR). The Axe-Fx II has 50 "user" cab slots. You can upload external IRs into these slots, using Axe-Edit or a MIDI librarian.
• The Axe-Fx II and Axe-Edit will display the name of IRs in the user cab slots. The name is contained in the sysex data of the IR file with a maximum of 32 characters. IRs can be renamed using Axe-Edit.
• The process of uploading IRs is described in the manual. Also, forum member Cobbler describes the process here.

Speaker Size parameter

• Firmware 2.0 introduced Cabinet Size Warping. This allows the user to change the relative size of the speaker (not the cabinet). This parameter is accessible only when the Cab is set to Mono.
• Cab Size was renamed to Speaker Size in firmware 5.

Motor Drive parameter

• Firmware 5 release notes: "Added speaker motor modeling to Cabinet block. This models the effect of high power levels on the tone of the speaker. The Motor Drive parameter controls the relative drive level and, therefore, the intensity of the effect."
• Cliff: "Motor drive isn'T EQ. It models efficiency reduction due to thermal effects." Source
• Here's a tutorial by forum member Manny Fufish.
• Cliff: "The Motor Drive will cause compression if not set to zero (as it models driver compression). Otherwise the cab block is completely linear and will not cause any compression." Source

Frequency response curves of stock cabs

• If you want to see the frequency response curves of the stock IRs, look here and here (Red Wirez IRs).

Grid position of the Cab block in regard to other blocks

• In the real 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 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.

Mic models

• Don't underestimate the impact of the mic model on the tone. E.g., adding a R121 (Royer 121, captured at 6", front) will add lots of highs and lows to the tone. The 57 DYN (Shure SM57) works with almost everything. Many users like to combine the Royer and SM57 for recorded tones.
• The "None" setting still involves mic modeling. All Fractal cab sims were created using a neutral Earthworks mic, placed close to the speaker (the "far-fields" are an exception, see above). So the sound is still a close-mic'd tone. But selecting "none" with stock cabs is a good way to remove tonal influences from a mic from the tone.
• Firmware 3.0 added the Proximity parameter. This simulates the proximity of the recording mic to the speaker. Higher numbers translate to the mic being closer to the speaker. The default setting is neutral. When set to "none", keep Proximity at its default setting.
• There's great info about mics in the document Dialing in Your Tone by Red Wirez.
• Wikipedia:
  • Shure SM57
  • Shure SM58
  • Shure Beta 87A
  • Neumann U87
  • Royer R-121
  • AKG D112
  • Neumann U67
• More information:
  • http://www.recording-microphones.co.uk/index.shtml
  • http://www.barryrudolph.com/stellar/guitar.html
  • http://www.gearslutz.com/board/so-much-gear-so-little-time/201972-mic-standards.html
• Additional information in this Wicked Wiki thread.

Air parameter

• The Air parameter mixes direct signal with the signal going through the Cab block. The Air Frequency parameter lets you adjust the cutoff frequency of the mixed signal. Increase the Frequency to its maximum value for a straight mix.

Delay parameter

• Firmware 6 added the Delay parameter. This is a "micro" delay for stereo application.
• Release notes: "When running a stereo mode, or two cab blocks in parallel, delaying one cabinet relative to the other can achieve interesting comb filter effects. A common practice in studio recording is to use multiple mics on a speaker at different distances to intentionally introduce comb filtering."