Amp recording: miking a speaker cabinet vs. using IRs
This is one of those music techie posts that if you’re not actively involved in recording music, you can probably go ahead and skip. But recording guitar amps in small spaces can be a challenge, if you don’t have the opportunity to turn up the volume a little and stick a nice microphone in front of a speaker cabinet. So I decided to do some tests of an alternate recording method. I’ll discuss what I did and share some audio files after the cut.
One way to record silently is to take a line out from the amp and record that directly into your DAW, then run the signal into an impulse response (IR) running in a convolution reverb. This processes your audio through the IR of the recorded speaker and theoretically can make your audio sound like it was recorded by a mic on the speaker cabinet the IR was taken from.
So I made two recordings from my Ironheart; one recording was my Royer R-121 ribbon mic placed 7 inches off the cone of my Egnater oversized 1×12 cabinet loaded with a Celestion G12H Heritage speaker. Simultaneously, I ran a signal from the line out of a THD Hot Plate directly into my RME Fireface audio interface and into Logic Pro. In Logic Pro, I processed the line out signal through the built-in convolution reverb Space Designer, running the free Redwirez IR of a Marshall 1960A 4×12 cabinet loaded with Celestion G12M speakers, recorded by a Beyerdynamic M160 ribbon mic 5 inches off the cone.
Below are clean and dirty snippets of around 30 seconds each. You can definitely hear a difference, which you’d expect. The IR is not of a similar speaker, speaker cabinet or mic. But it certainly sounds “real” in the sense that it sounds like a guitar running through a cabinet, rather than a line out from a guitar amp going through a simple high cut and low cut filter.
I think that the miked cabinet has a certain punch and immediacy that the IR does not, but both sound good. Of course, a speaker responds differently to the frequency and power of the signal put through it, while an IR is static impulse of the cabinet’s response. So it could never sound *exact* even if you’re talking about the exact same speaker and IR. But it’s good to know that in non-optimal environments, recording through IRs can be a viable option.