Stacking Amps For Stereo

It is not true Congress passed a law in 1957 forbidding the use of bass in stereo; that’s just a vicious Internet rumor. You can do anything you please—well, at least nowadays.
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It is not true Congress passed a law in 1957 forbidding the use of bass in stereo; that’s just a vicious Internet rumor. You can do anything you please—well, at least nowadays.

One reason why bass loves mono traces back to the days of vinyl, when music was reproduced by dragging a rock through yards and yards of plastic (I’m not making this up). It was difficult for a phonograph needle to track different bass waveforms in opposite channels; it was much safer just to keep it in mono.

Synth basses have broken the mold somewhat, but there’s a great technique for stereo bass using amp sims—stereo stacks. Guitarists have known about this for years: They split the signal to two different amps, which become their two channels.

 Fig. 1. Line 6’s POD Farm has
lots of bass models, and the
ability to create parallel bass
chains in “Dual” mode.


She Talks in Stereo

Vinyl aside, there’s another reason why bass is usually in mono: It has more strength and power that way. Stereo sound broadens the bass, but diffuses it somewhat as well. So, think of stereo as another way to add a different type of dynamic to a song, where you can dial in whether you want the bass to lead the song, or follow. Another option is to “split the difference”—pan the bass slightly right and slightly left of center.

For example, don’t use stereo bass throughout a song, but throw it in during the Big Chorus when the guitar is playing power chords—then fold it back into mono when the verse hits, and it’s just you and drums. You can totally change a song’s emotional character by what you do with two bass amp sims and a couple of panpots.

Fig. 2. The Amplifier module
in Waves’ G|T|R offers stereo
and panning capabilities for
the cabinet in each channel.

Make it So!

The “universal” way to set up stereo bass is to copy the track, pan the two bass tracks left and right of center, then process them individually. However, many of today’s amp sims make it easy to put amps in parallel, then pan them as desired in the stereo field, so you can hear the results in real time as you play.

Line 6 POD Farm: Click on the Dual button to create two separate chains (Figure 1). The panpots are toward the lower right of each chain. The screen shot shows two different bass sounds, with the selected cabinet, room relationship, and mic shown for the lower chain.

Native Instruments Guitar Rig 3: Use the Split module to create two parallel chains (remember to pan the two Split Mix panpots oppositely). There’s only one bass amp and one bass cab, but the Jazz Amp works well as a second channel.

Peavey ReValver Mk III: The Signal Splitter module works like the Split in Guitar Rig. ReValver also has only one bass amp—the bass channel in the Basic 100 amp—but split those using different cabs, and you’ll get a very wide bass sound.

IK Multimedia AmpliTube 2: You can select two parallel paths by clicking on routing #2, which splits the bass into two independent paths. AmpliTube has one bass preamp, but three bass cabinets. The difference between cabinets is sufficient to create a stereo image. For the widest possible stereo, pan the Cabinet and Rack for each channel oppositely; to pull things in a bit but still get some spread, leave the Cabinet pans centered, and pan the two Racks left and right.

Waves G|T|R: You can’t really set up a true parallel chain without copying the track and using two instances of G|T|R, but you can come really close by using the Stereo Amp (Figure 2). You have seven bass amp models and six bass cabinets, so you can split the amp sound into two different cabinets, and pan them oppositely. Experiment with the virtual mic placement, too; this can make a huge difference.