Apple’s Logic software includes Impulse Response Utility, which can generate sweep tones, record the results, and “de-convolve” them into presets for Apple’s Space Designer reverb.

Fake speakers. IRs can mimic not only rooms, but also such gear as speakers and cabinets. When I set up for that initial dry recording, I routed a sine-sweep signal from Impulse Response Utility through a ReAmp into the Marshall clone (Photo 1). I recorded the results back into Impulse Response Utility, creating an IR that mimics that amp’s 12" Weber British Classic speaker (Photo 2).

Warning: Clip 2a sounds nasty—it’s a line out signal from the amp head, with no speaker sound, recorded directly into Logic. Clip 2b routes that harsh sound through the speaker IR, with a 100% wet signal. Compare the result to the “real” speaker in Clip 1a. The sounds are very similar, and slight EQ adjustments would yield a near-perfect match. (Note: I’m recording guitar here via a dedicated line out jack, not the speaker out jack. Doing the latter can wreck your gear.)

You can probably guess where this is going. Clip 2c routes the same recording through an IR made from a 10" Jensen speaker in a 1950s Fender tweed amp. Clip 2d substitutes an IR from a plexi-era Marshall 4x12 cab with Celestions. Clip 2e combines the Jensen and Celestion sound, panned slightly in stereo. And Clip 2f adds an IR on top of the IRs for a touch of room reverb. See why this is such a powerful sound design tool?

(Left) I played the sine sweep through this toy Marshall and recorded it inside a Styrofoam cooler. (Right) I put this tiny lavalier mic inside my classical guitar and held the guitar up against the speaker while the test tone played. Now I can put anything “inside” the guitar.

Trapped in a box. So far we’ve mimicked true-to-life sounds. Let’s get more fantastical.

I sent a test signal from the ReAmp to a toy Marshall practice amp inside a Styrofoam cooler and recorded a new IR—the dry, claustrophobic sound heard in Clip 3a [Photo 3]. After that I made an IR from inside a classical guitar using a small lavalier mic [Photo 4]. I couldn’t fit the tiny amp inside the guitar, so I just played the sweep through my studio speakers, holding the guitar in front of them. Result: the boxy, compressed tone in Clip 3b.

Not glorious tones in their own right—but they sound cool and intriguing when blended with conventional sounds, as in Clip 3c, which combines a Marshall cab IR with the Styrofoam box sound, and Clip 3d, a blend of Marshall cab, Styrofoam box, and inside-the-guitar, plus added room reverb.

You don’t have to dig these particular sounds to grasp the exciting implications. With patience and imagination, you can sculpt startling new tones to taste.

Just for fun, help yourself to a few IRs I made. (They should work with most IR reverb plug-ins.) I’ve included an expensive-sounding outboard tube reverb, an über-cheesy solid-state reverb from a funky old amp, and the Styrofoam box IR.

(Click here to download.)

Now you can be trapped in a box—just like a mime! I’ll come back and check on you in a month or so.