Always consult the official Owners Manuals and Guides first.
Information about the FM3 may be incomplete or wrong, it's being worked on.
Headphones and IEM
About connections and levels
Read this: Connections and levels
Axe-Fx II and III, FM3 – use the Output 1 knob to set the headphones level. If you have both monitors and headphones connected and want to listen through headphones only, use one of these methods:
- switch off the monitors
- feed the studio monitors through another output
- use a line level attenuator to turn down the monitors' level without affecting the headphones level.
"The amp on the Mo-Fi's is designed for use with consumer stuff like iPhones and such with really low output drive strength. The headphone amp in the III is a pro-quality amp designed to drive low-impedance pro headphones. It's not designed for use with things like headphones with built-in amps and IEM amps. source
"The volume knob is virtual. It's read by an A/D converter and the data value controls the volume. The data value is quantized so you're hearing the step change." source
"Headphones are hardwired to Output 1." source
"That's a hardware connection. Phones will always match Out1." source
AX8 – the AX8 does not have a dedicated headphones output. You can use a Y-cable with the outputs. If you connect your headphones directly to the AX8, you may get less signal level than from a dedicated headphones output on other devices. A popular solution is to use a small headphones amp, e.g. from M-Audio or Rolls.
"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
"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
If the volume level through your headphones is very low, switch to lower impedance headphones (such as 32 Ohm), use a headphone amp or use headphones with a built-in amplifier (such as Blue Mo-Fi). The Axe-Fx III is better at feeding sufficient signal level to hard-to-drive headphones than the Axe-Fx II.
Sound through headphones can be dull:
"Because there's no string and body reinforcement. When you play through speakers the sound couples into the guitar body and strings. With headphones you don't get this so the sound is very sterile and lifeless. Now, if you use speakers during recording and then playback through headphones it will sound fine."
"It's lack of acoustic reinforcement. I did a test a few years ago and I don't remember the actual numbers but having a speaker aimed at the guitar adds many dBs of power to the lower mids coming out of the guitar. IOW, if you measure the spectrum of the signal coming out of a guitar alone and then compare that to the signal coming out with a cab or monitor in proximity at a reasonable volume there are a LOT more lower mids with the speaker present. This results in a "thin" sound without the speaker." source
"The problem with headphones is that there is no acoustic reinforcement of the guitar. There is zero coupling between the speakers (inside the headphones) and the guitar. Without that coupling, which is a type of positive feedback, the sound is lifeless, thin and harsh. When your heroes recorded their guitar parts that weren't using headphones. On "Appetite for Destruction" Slash recorded his guitar parts in the control room. To get even more coupling into the guitar a combo amp was in the control room with him pointed at the guitar. A volume pedal allowed him to adjust the volume of the combo amp so he could control the coupling. With the volume pedal all the way up he could get controlled feedback. I've actually done tests comparing the spectrum out of the guitar when there is no coupling (i.e. monitors turned off) and with typical coupling (monitors loud or using a conventional cab). The boost in the low midrange is significant. I forget the actual numbers but it was at least several dB." source
"I did some studies years ago and having a speaker in proximity to the guitar actually changes the final tone considerably. I compared the frequency response with the amp in isolation to the frequency response with the amp in proximity and measured several dB difference in the lows and mids. It was clearly audible when the recordings were played back." source
Tips for improving sound quality through headphones:
- use a far-field Impulse responses (IR)
- increase Proximity in the Cab block
- increase Room Level in the Cab block
- always use a stereo input signal
- add the Enhancer block to presets, or add Micro Delay in the Cab block
- increase De-Phase in the Cab block
- use Speaker Compression and Speaker Compliance in the Amp block
More information about headphones:
In Ear Monitoring (IEM)
In-Ear Monitoring (IEM) provides a way for musicians to monitor sound through earbuds, instead of floor wedges etc. While this provides a superior listening environment, it takes getting used to the direct sound into your ears and the absence of surround sounds.
The same tips as for headphones apply.
The I/O architecture of the Axe-Fx III makes it easy to send and receive IEM-specific signals, without the need for an external mixer.
WARNING: always use the built-in limiter of your IEM system to protect your ears against sudden spikes and peaks!