Implulses

[liv_rong]

Can someone please explain to me what they are? I think I know, but I'm not sure and I'd rather you explain instead of Google. It's basically like a plugin that mimics an amp kind of, right?

[Greg_L]

An impulse response is the digital character of a room, or hardware, or speaker by feeding whatever you're testing a short test signal and then capturing the output of that signal and reverse processing it to leave you with the "DNA" of whatever you're working with.

For example...you "profile" an amp by injecting a known signal, capturing the output, and then processing the output compared to the original signal. That leaves you with the character of the amp in digital form and you can pull it up with the right software and in theory have "your amp" anywhere you go. Same with speakers or rooms. I made a bunch of speaker impulses and they came out great. Reverb impulses are awesome and sound better than any hardware or plug-in IMO.

This is very general, but that's basically it.

[vomitHatSteve]

It's basically like a plugin that mimics an amp kind of, right?

To clarify, it can mimic a speaker or a room, not an amp.
Essentially, it's an audio clip that should - more or less - map all of the audible frequencies across time.
Whereas an amp sim needs to react to frequency, time, and amplitude.

Let's try to walk through a simple example.

You have a room which is a perfect cube. One wall is perfectly reflective of all sound; the others and the ceiling and floor perfectly absorb all sound.
You play a dry sample of a clap into the room and record that.
Your original sample consists of the single pulse of noise with a wide frequency range.
Your new recording consists of that sound as modified by the room - the original pulse plus a series of smaller peaks as the various frequencies reflect a single time off the one reflective wall.
Then you run those two files through the confluence software to create an impulse file that just contains information about the reflections - a series of peaks at various frequencies.
Then your reverb or cab sim plugin (turns out they're basically the same thing) processes the incoming signal against that impulse file, repeating the various frequencies across time.

I think that's mostly how it works.

[Greg_L]

To clarify, it can mimic a speaker or a room, not an amp.
Essentially, it's an audio clip that should - more or less - map all of the audible frequencies across time.
Whereas an amp sim needs to react to frequency, time, and amplitude.

Let's try to walk through a simple example.

You have a room which is a perfect cube. One wall is perfectly reflective of all sound; the others and the ceiling and floor perfectly absorb all sound.
You play a dry sample of a clap into the room and record that.
Your original sample consists of the single pulse of noise with a wide frequency range.
Your new recording consists of that sound as modified by the room - the original pulse plus a series of smaller peaks as the various frequencies reflect a single time off the one reflective wall.
Then you run those two files through the confluence software to create an impulse file that just contains information about the reflections - a series of peaks at various frequencies.
Then your reverb or cab sim plugin (turns out they're basically the same thing) processes the incoming signal against that impulse file, repeating the various frequencies across time.

I think that's mostly how it works.

This is correct, but there is also a way to profile amps. The Kemper is a profiling amp. You can hook it up to an existing amp and the Kemper will do some magic and steal the essence of the real amp. Then with the Kemper you can pretty much sound awfully close to the amp you just profiled. It uses impulse response technology, but through the guts of a real amp. It's some weird sorcery.