guitar amp/cab impulses, how it works?

Posted: Sun Jul 20, 2008 8:09 am

Hi all,

was wondering if anyone can explain how guitar amp/cab impulses work, is it purely software? Do you need hardware,i.e. guitar amp, preamp, etc?
Can you use a pre-recorded dry direct gtr track (that you would usually use for reamping) with amp/cab impulses? I dont know much about this, did a google but am still a little confused as some of the things I read were a little vague. Any clarity would be appreciated,

cheers,

Sammyg

Posted: Mon Jul 28, 2008 3:15 pm

An impulse response (IR) of a cabinet is a data representation of the transfer function of the cabinet. It is obtained by sending a very transient signal through the cabinet, mic'ing it with a measurement mic, and recording the change.

That "change file" or IR, is used by a plugin or software application called a "convolution engine", that takes that IR plot, and applies the encoded transfer function to whatever signal you're sending through the engine.

So, yes, you need more than just the IR. Having that, without the engine that uses it, is like having a CD, but no CD player.

dwoz

Posted: Mon Jul 28, 2008 5:03 pm

There are free convolution plugins out there.

http://www.knufinke.de/sir/

http://freeverb3.sourceforge.net/

Of course you need a VST host for these plugins.

As far as Amp sims are concerned, I believe they work in a similar way except that the samples are taken from direct line out, close and distant mic with variations in between. Amplitube and Guitar Rig will both work as stand alone software but also work as plugins for your DAW.

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