Guitar Cabinet Impulse response

Hey everyone. So I’m in the studio with my band and as some of you may know time in the studio runs weirdly fast and we are running out of time to record everything. That’s why I am considering skipping some of the planned guitar overdubs and later record them. I would still love to have a somehow similar sound to the already recorded parts.
Here guitar setup:
Guitar -> preamp -> effects -> Poweramp -> 2x12 stereo cab -> 2x EV re320 mics

OK my questions:

  1. Is it possible to capture the cabinett and microphone combination with impulse response
  2. How would I do that and what equipment do I need for it
  3. How much of the original sound would I loose
  4. If it doesn’t work what else could would you do in that situation?

Thanks a lot in advance!

I’m not sure which OS you are on but to answer question 4… If on Linux this sounds like a job for Guitarix. You won’t get an exact replica but might be able to get close enough. Combining with existing Cab impulse responses using convo.lv2 might work well. On Windows and Mac there are plenty of freeware and paid options, of course, but a friend of mine in a similar situation to you has had great success with Magix Vandal https://www.magix.com/us/music/vandal/.

Yes,

No new equipment, just a cable from your PC that will feed the preamp or amp (maybe some impedance matching is needed, but some buffered bypass of any Boss pedal might do).

To create an IR of electronic equipment, you’d play a generated sine-sweep (or noise pattern) into the amp, then record the result, like you’ve recorded the guitar (and postprocess it to generate the IR).

There are various tools available, depending on the OS.
On GNU/Linux there are a couple of jack applications that can be used, most notably perhaps “Aliki” – http://kokkinizita.linuxaudio.org/linuxaudio/downloads/aliki-manual.pdf

Thanks for the quick replies. I will see his how our recording goes. Its good to know though that it is possible which in turn might make me more relaxed playing all the stuff in which case hopefully I won’t need it :slight_smile:

Just a quick heads up: if you have not done this before, try it first, perhaps with some other amp and mic that you have around.

For a well-practiced engineer, recording a few responses and creating IRs can be a task of 5 mins, but if you’re doing this the first time, set maybe 1-2 hours aside and also do some listening tests until you’re confident you can do this later under time-pressure in the studio.

“aliki” is available on most GNU/Linux distros, but its UI is somewhat idiosyncratic.

The overall process is

  1. Generate a sine-sweep
  2. Play the sweep into the amp, record the output
  3. Deconvolve the recorded sweep to create the IR
  4. Edit the IR, (cut initial silence. trim long near-silent tail, apply gain)

Apart from aliki, there are a couple of other tools that can be used for this, e.g. jack-ir. And there are also proprietary tools for Windows and macOS.

After you have created the IR, load the file into a convolution plugin (convo.lv2 or lsp-IR or Klangfalter or …) and test that it matches your expectation.

In theory nothing. Amplifiers, speakers, cabinet and mic are all linear systems. However amps are not perfectly linear.

You’ll also record the guitar DI (after the effects and pre-amp) instead of the mic.
Again, in theory there should be no difference when using a convolver to emulate the rest of the chain. In practice however there may be subtle differences.

You could use existing tools (like guitarix), some EQing and/or use existing IRs:
perhaps http://www.osirisguitar.com/wp-content/uploads/7deadlysins%20Impulse%20Pack.zip to match it as close as possible.

or just live with it and create a new sound that works within the mix.

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