Apple Impulse Response Utility - Manual (Page 27)

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Recording Impulse Responses From Guitar Speakers and
Hardware Devices
You aren’t limited to creating impulse responses from rooms and spaces. You can make
an impulse response from any device that you can play a broadband sine sweep into
(and record the results). Two examples are; guitar speaker cabinets and hardware
processing devices, such as tube equalizers and reverb effects units.
The sound of an electric guitar through a guitar amplifier is very heavily influenced by
the frequency response and tonal color of the guitar speaker cabinet. If you make an
impulse response from a guitar speaker cabinet, and then run a direct guitar amp
signal through that impulse response in Space Designer (set to 100% wet), the direct
signal will sound as if it was played through the speaker cabinet.
You will still need a microphone and audio interface to create an impulse response
from a guitar speaker, but you won’t need an additional monitor speaker for the sine
sweep—you will play the broadband sine wave into the guitar amp/speaker itself. If
your guitar amplifier has an effects return, you can use it to create the impulse
response. If your guitar amp does not have an effects return, you can either use a “re-
amp” box (that will raise the impedance of your audio interface’s line out to the level
required by your guitar amplifier at its input), or you can use a line level amplifier in
place of your guitar amplifier (to amplify the sine sweep through the guitar cabinet).
You can experiment with microphone placement just as you would when miking a
physical space, although the most common microphone placement is “close miking”—
placing your microphone as near as one inch from the speaker itself. The illustration
below shows how you might want to set up your guitar speaker cabinet when creating
your impulse response.
Imagine that you want to create an impulse response from your favorite tube
microphone pre-amp, allowing you to use its unique color on your audio. This way, you
can run a signal through this impulse response in Space Designer (set to 100% wet)
and add the color of your microphone pre-amp to your signal.
Guitar amplifier
with microphone
Computer Audio interface