Product Review: Softube Acoustic Feedback Plugin

Long before it reached its status as an iconic scream machine in the hands of rock guitarists such as Jimi Hendrix, Jimmy Page and Eddie Van Halen, the solidbody electric guitar was created in the 1930s and ‘40s by George Beauchamp of the Rickenbacker Corporation and by the legendary Les Paul, each tinkering away somewhat in isolation on what at the time, was a radical new concept in musical instruments, but working to solve a common problem.

The magnetic electric guitar pickup was originally mated to traditional hollow-bodied steel-string guitars. Attached to the body of a traditional guitar, this pickup gave, in theory, as much volume as the amplifier on the end of the cable could generate, but at some point, the sound produced inside the traditional hollow guitar body would begin to resonate, spill over into the guitar’s magnetic pickup, and then create a howling feedback loop with the amplifier’s speaker. This was considered not a good thing, to say the least.

The solidbody guitar, as popularized by Leo Fender’s minimalist Telecaster design, which debuted in 1950, and then, in my opinion, aesthetically perfected in the beautiful craftsmanship of the Gibson Les Paul electric guitar, which first hit music showrooms in 1952, was designed to temper feedback by — though no one used the word back then — deconstructing the traditional guitar. Since the amplifier was producing all the sound, there was now little need for the guitarist to have to lug around the big thick appendage of a traditional hollow-bodied guitar. While feedback still occurred on occasion at loud enough volumes when the pickup became in-line with the amplifier speaker, it was now much more under control. And not coincidentally, a newly invented genre of music called rock and roll would supplant the big bands of the 1930s and ‘40s, since technology allowed a small combo of drums, an electric guitar, and another invention of Leo Fender, the electric bass, could easily produce as much volume as the loudest of orchestras – and for much cheaper rates than hiring a large group of musicians.

Opinions vary on which electric guitarist began to use feedback as a welcome musical texture. In his epochal 1977 Guitar Player interview, Jimmy Page intimated that it was Les Paul on his beautiful 1945 recording accompanying Bing Crosby, “It’s Been a Long, Long Time.” Les’s musicianship is exemplary, but I’m not detecting feedback in his sensitively-played solo. Others say the short burst of noise at the beginning of the Beatles’ 1964 single “I Feel Fine” is an early example of feedback. (John Lennon always claimed it was the first recorded example of feedback in the studio.) Having pioneered the development of the Marshall stack, Pete Townshend employed frenzied bursts of feedback right from the start with The Who, and Jimi Hendrix and Jeff Beck followed soon after. In the 1970s, Carlos Santana became legendary among his fellow guitarists for his controlled use of feedback soloing atop his namesake band. Tony Visconti, David Bowie’s longtime producer, tells of once and future King Crimson mastermind Robert Fripp laying out strips of masking tape at various distances in front of his amp in the studio while recording Bowie’s landmark 1977 song “Heroes,” to mark where various notes would feedback.

OK, Computer

If you’re recording at home on digital audio workstation (DAW), odds are you may not want to disturb the wife, kids, and neighbors by roaring away on a Marshall stack to produce feedback-laden solos. Particularly when guitar modeling hardware and software can produce extremely credible recreations of vintage amp sounds inside the comfort of your own headphones. But how to generate feedback when you’d like a taste of psychedelia or a punky blast of energy?

Enter the Acoustic Feedback plugin from Sweden’s Softube comany, which puts a credible recreation of feedback into any DAW. It’s available in the VST, VST3, Audio Units, AAX Native and AAX DSP formats (RTAS is also available, although it’s no longer officially supported), so it should work with most commercial DAW software. From left to right, it has three simple knobs, Mix, Feedback, and Tolerance. As Paul White of England’s Sound on Sound magazine noted in his review of the product (which also worth your time reading if you’re considering purchasing this plugin):

Normally the Acoustic Feedback plug-in will be inserted in the guitar track before any amp modelling plug-in, and the guitar needs to be connected via a high-impedance input for best results (most interfaces now have an instrument input option, but if yours doesn’t, an active DI box would do the job).

There are very few controls, but adjusting them correctly is imperative for the best results. ‘Mix’ sets the balance between the actual guitar sound and the simulated feedback that is added to it and, as with the other controls, it can be automated (assuming the host application has automation facilities). ‘Feedback’ sets the rate at which the simulated feedback builds up, and also seems to affect the harmonic structure of the feedback: at low settings the effect is more subtle than at higher settings, where the timbre becomes more aggressive. A further control, ‘Tolerance’, sets how well the feedback effect tolerates string bending or vibrato. It is the counterpart to real-life amp volume and the relative position of the guitar and speaker. Low settings only allow feedback to build up on stable notes, while higher settings make the feedback effect ‘take off’ more readily, but can lead to less natural-sounding results at very high settings. Tolerance has three settings (Moderate, Normal and Rampant, which are easy to understand), while the other controls also have their ‘normal’ areas of operations highlighted. A virtual lamp shows how the feedback effect is developing.

Each of three controls on the Acoustic Feedback plugin can be controlled via MIDI and by DAW bus animation. For example, via Novation’s Automap routing system, I could route the Feedback knob to my venerable Roland EV-5 expression pedal attached to my Novation 49SL USB MIDI keyboard, and put the Softube plugin into feedback just before hitting the last note in a guitar lick (say, a bluesy bent note with plenty of finger vibrato on it) and then pull back before playing another run of notes.

It’s also possible to play the Acoustic Feedback plugin without any additional MIDI control by carefully adjusting its virtual knobs to match your playing style. Occasionally, the feedback at the end of a lick would continue “singing” and decay under the next passage of notes, but you may find this a desirable special effect. And via careful editing and/or pitch and time correction plugins such as Celemony’s Melodyne, it should be possible to fine tune the finished results to exactly the sort of burst of feedback you’re looking for.

Unfortunately, Softube recommends using the Acoustic Feedback plugin on single notes only, which is a shame; Pete Townshend made feeding back after long sustained power chord a key part of live playing style, and hopefully Softube will rectify this limitation in a future update.

At $99, the Softube Acoustic Feedback plugin is a fun addition to any virtual music producer’s palette, whether it’s used while tracking solos, or adding a special effect during mixdown. If you record in a setting where your neighbors might hear you, they’ll definitely appreciate your using this plugin rather than standing in front of a giant Marshall stack! (Your ears will thank you too. What?)