Fig. 3. — The well-worn Gallien-Krueger 1001 RB head and beer-streaked Ampeg 4x10 cabinet used for the bass clips are parked at NYC’s Nublu Classic club. The mic is an Electro-Voice RE20 placed close to the grille.

I wondered how well IRs would work with a bass amp, so I grabbed a bass and played the two phrases you hear in Clips 6–9. Again, I recorded each phrase into the Boss RC-2, played them into a Gallien-Krueger 1001 RB bass amp head driving an Ampeg 4x10 closed-back cabinet miked with an Electro-Voice RE20 (Fig. 3), and then captured the results using my RME Babyface Pro interface and Logic Pro X. For the A/B comparison, I played the same phrases from the RC-2 directly into my interface and laptop, and then ran them through Logic’s Space Designer plug-in loaded with an IR I’d made of the GK bass rig.

In all four bass clips, I just hear the same beefy tone. But for the record, Clip 6 and Clip 8 are the miked amp, and Clip 7 and Clip 9 are the direct recordings running through the Space Designer IR.

Adding FX to Clean Amp IRs
While you can’t capture amp distortion or compression with IRs, you can run effects into your clean amp IR with great results. Listen to Clip 10, which I made in GarageBand using one direct guitar audio file to create two separate tracks with two different IRs: a stereo IR of my Deluxe Reverb II and a mono IR of a Fender Princeton Reverb.

To make the IRs, I put a close mic on the Princeton and both a close mic and distant mic on the Deluxe. Going into GarageBand, I used a J. Rockett Animal Overdrive and a touch of MXR Carbon Copy analog delay set to a single slapback echo.

I also used the Rockett Animal Overdrive to record Clip 11, as well as two different convolution plug-ins: ReaVerb and LAConvolver. I used the former on my Deluxe Reverb and the latter for my Princeton. I captured both IRs with the amps’ spring reverb on, which raises an important point: Both ReaVerb and LAConvolver allow for long IRs, which is not always the case. If you intend to make clean amp IR using generous amounts of spring reverb, you’ll want to bear this in mind. [For a list of alternative IR tools—some of which are free—see the sidebar “Other Convolution Plug-ins.”

Clip 12 uses the same IRs as Clip 11, but I set different panning and relative levels, and also added a touch of compression to the clean guitar.

Clip 13 features a stereo IR of my Deluxe Reverb II; a close mic is panned left and a room mic is panned right.


Fig. 4. — A screenshot of the Poulin LeCab 2 plug-in running six clean amp IRs, as heard in Clip 14.

And finally,I couldn’t resist simultaneously running six different clean amp IRs in yet another convolution plug-in—Poulin’s LeCab 2 (Fig. 4). For grit, I again used the Animal Overdrive pedal into my interface and DAW.

Glad I didn’t have to set up six mics and amps at once to try this! Clip 14 is the result. In case you’re curious, I created the six IRs using the five amps shown in Fig. 5.


Fig. 5. — Clip 14 features six IRs made from these amps: my trusty Fender Deluxe II and Princeton Reverb, a Reverend Kingsnake, and Pignose and Danelectro HoneyTone mini amps.

As you can tell, I’m an evangelist for the power of IRs. If hearing IRs in action has made you a believer, now I’ll show you how to create accurate digital reproductions of your miked-up clean amps using different DAW’s and plug-ins. So we can dive right into the process, we’ll skip the theory and computation behind creating IRs and convolving them with audio signals. If you’re interested in understanding the underlying technology, there’s a lot of info on the interwebs.