Hello,
acoustic guitar IR's that transform the sound of a pickup to that of a mic'ed guitar are one way to obtain a nice acoustic sound without the hassle of mic'ing up the guitar. However, IR's are so-called linear time invariant transforms, which means that they cannot model non-linear effects like compression and variances in timbre due to how 'hard' the guitar is played (to name but a few) and that are not present in the pickup signal. Basically an IR produces the same sonic result whether the input is low or high, it's just softer or louder. Also when determining an acoustic instrument IR this is usually based on a musical performance that is recorded at the same time with a microphone and with built-in pickup-system. As such it represents a kind of 'average' response of the instrument during the performance. Clearly some of the variances of how the instrument behaves will be lost due to this ...
IR's can be extended to include non-linear behavior, but this is a labyrinthian rabbit hole (Volterra Kernels, Wiener Hammerstein models, dynamic convolution, ....) that is not only pretty complex, but also not implemented on our FAS (and other ) devices.
I wanted to test this out using a much simpler approach, based on 2 IR's that represent 2 extremes in playing a guitar: fingerpicking ('low' volume) and strumming ('high' volume). These 2 IR's are blended together in realtime using an envelope follower. This mixing is seamless, and the volume remains constant.
To my ear this seems to work well, providing a different timbre when fingerpicking compared to strumming.
Admittingly the effect is small, and possibly not relevant for any live sound. In the studio one is most likely better served with a DI recording and adding an IR and approppriate EQ afterwards anyway. In that sense the exercise maybe academic ..... Also maybe a similar idea could be applied to one IR + 2 PEQ (or 2 GEQ).
Guitar: Taylor 816 Builders edition
Pickup: Taylor ES2
Microphone: Rode M3
'Soft' IR: fingerpicking and soft slow strumming of some chords
'Loud' IR: strumming with pick.
Notes:
1. The threshold and settings of the envelope follower must be adapted to the pickup of your guitar. Adjust them until you get 0 - 100% for soft playing to 100 - 0% for hard playing in the mixer block that has the 2 IR signals as input.
2. I use input 2 for acoustic guitars (1 is always for electric guitars on my presets). When using combined electric acoustic presets this setup is not possible due to the lack of IR blocks on the FM9.
3. When using a looper to finetune a preset we have a problem: the envelope follower CANNOT use the looper as a source. This means that if we want the IR blending to work with a looper we need to record it on input 3, and then patch output 3 to input using a TR-cable when playing it back (output 3 knob fully open is unity gain) ... This is a FAS limitation!
4. Note that the included IR's are specific to a Taylor 816 BE, they may or may not suit your guitar at all!
I can compute the appropriate IR's for you, see also https://github.com/yvdh/Acoustic-IR-Generator.
Any comments welcome!
Yves
acoustic guitar IR's that transform the sound of a pickup to that of a mic'ed guitar are one way to obtain a nice acoustic sound without the hassle of mic'ing up the guitar. However, IR's are so-called linear time invariant transforms, which means that they cannot model non-linear effects like compression and variances in timbre due to how 'hard' the guitar is played (to name but a few) and that are not present in the pickup signal. Basically an IR produces the same sonic result whether the input is low or high, it's just softer or louder. Also when determining an acoustic instrument IR this is usually based on a musical performance that is recorded at the same time with a microphone and with built-in pickup-system. As such it represents a kind of 'average' response of the instrument during the performance. Clearly some of the variances of how the instrument behaves will be lost due to this ...
IR's can be extended to include non-linear behavior, but this is a labyrinthian rabbit hole (Volterra Kernels, Wiener Hammerstein models, dynamic convolution, ....) that is not only pretty complex, but also not implemented on our FAS (and other ) devices.
I wanted to test this out using a much simpler approach, based on 2 IR's that represent 2 extremes in playing a guitar: fingerpicking ('low' volume) and strumming ('high' volume). These 2 IR's are blended together in realtime using an envelope follower. This mixing is seamless, and the volume remains constant.
To my ear this seems to work well, providing a different timbre when fingerpicking compared to strumming.
Admittingly the effect is small, and possibly not relevant for any live sound. In the studio one is most likely better served with a DI recording and adding an IR and approppriate EQ afterwards anyway. In that sense the exercise maybe academic ..... Also maybe a similar idea could be applied to one IR + 2 PEQ (or 2 GEQ).
Guitar: Taylor 816 Builders edition
Pickup: Taylor ES2
Microphone: Rode M3
'Soft' IR: fingerpicking and soft slow strumming of some chords
'Loud' IR: strumming with pick.
Notes:
1. The threshold and settings of the envelope follower must be adapted to the pickup of your guitar. Adjust them until you get 0 - 100% for soft playing to 100 - 0% for hard playing in the mixer block that has the 2 IR signals as input.
2. I use input 2 for acoustic guitars (1 is always for electric guitars on my presets). When using combined electric acoustic presets this setup is not possible due to the lack of IR blocks on the FM9.
3. When using a looper to finetune a preset we have a problem: the envelope follower CANNOT use the looper as a source. This means that if we want the IR blending to work with a looper we need to record it on input 3, and then patch output 3 to input using a TR-cable when playing it back (output 3 knob fully open is unity gain) ... This is a FAS limitation!
4. Note that the included IR's are specific to a Taylor 816 BE, they may or may not suit your guitar at all!
I can compute the appropriate IR's for you, see also https://github.com/yvdh/Acoustic-IR-Generator.
Any comments welcome!
Yves
