The importance of pickups in amping acoustics.

I have been gigging out more recently, and I found myself in need of decent acoustic amplification. The good news is that there are more options available to acoustic guitarists than in the past – we no longer have to buy an acoustic/electric and hope it sounds good with our Twin. We can build an entire signal chain that meets the specific needs of acoustic guitars – starting with the pickups.

Because of the resonant nature of the acoustic guitar, designing a pickup that accurately recreates the sound of the instrument and is resistant to feedback has been a challenge for manufacturers. The available pickup products fall into four major categories: piezo (undersaddle), magnetic, mini mic and body sensor. A fifth option is to combine two or more of these.

Piezos
Piezo (short for “piezoelectric”) pickups fit under the bridge saddle. They have a wide, even frequency response, are rugged and low-noise, and don’t exhibit feedback problems at loud stage volumes. They are inexpensive and can be added “aftermarket” to guitars that come without pickups. There are two types: the traditional pressure and vibration-sensitive variety, and, for those using really light strings or low tunings, vibration-only sensing piezos.

Fishman recently introduced a twist in this area by adding modeling to piezos with their Aura Acoustic Imaging products. With this technology, they have physically modeled
the sounds of professionally mic’d acoustic guitars – they can even model your specific guitar. By applying these models to the piezo pickup output, the body resonance and “air” that the undersaddle piezo lacks is added back in. They’re incredibly convincing; you won’t believe you’re hearing your old undersaddle pickup.

Magnetic Pickups


The Seymour Duncan SA-3 “Woody” magnetic soundhole pickup
is available in either single-coil or humbucking versions.
Magnetic pickups have been used to amplify acoustics for years – they’re quite similar to the pickups found in your electric guitar. Remember those old Harmonies or Gibson
J-160s? Those have a P-90 variant in them. Of course, the technology has improved a great deal since then and several manufacturers, including Dean Markley and Seymour Duncan, have humbucking acoustic guitar designs. The magnetic designs are easy to mount (they typically clip into the soundhole) and take into account body resonances, so gain before feedback is very good.

Internal Mics
Mini microphone technology now allows us to mount an acoustic guitar-specific mic inside our guitars to pick up the natural body resonance and character. Although very natural sounding when set up correctly, these solutions often have feedback problems at high stage volumes. As a result, they are often paired with one of the other solutions discussed here – more on hybrid approaches below. Of course, not just any mic will work – specialized mics that mount inside the guitar, such as the GHS MiniFlex Mics, the Joe Mills internal-mount electret condenser mics (unfortunately not in production as of this writing) or the Highlander Internal Mic, are voiced to provide natural sound quality.

Sensors

Body sensor pickup technologies like the Taylor Expression system can sound truly amazing, although in my experience they are not as feedback resistant as piezo or magnetic pickups. These systems use sensors to detect vibration in different areas of the instrument and then blend them in a preamp that has been voiced to give a natural-sounding result. K&K Sound, Trance Audio and other manufacturers offer transducer systems that can be installed aftermarket – there are even versions
that work with nylon-string instruments.

Hybrid
A solution that’s becoming more and more common is the hybrid approach, which combines two or more of the above technologies. The designer can take the best part of each approach to achieve natural-sounding resonance and feel, while reducing feedback problems. Manufacturers including K&K Sound and Highlander offer hybrid systems that combine an internal mic with an undersaddle pickup or an undersaddle pickup with a magnetic pickup.

Electronics
Piezos, in particular, require a fair amount of preamp gain and EQ to get rid of that spanky, quacky, under-the-string sound – this may mean onboard electronics or an external preamp/EQ unit. Other pickup and mic technologies also benefit from basic built-in EQ controls that allow the player to tweak the guitar tone. You can take that to another level using an outboard EQ for even greater control, paying particular attention to the midrange. Having a sweeping mid control is a plus for getting rid of that annoying nasal quality.

Try a number of guitars with various pickup and mic’ing systems to hear the differences and to find what you like. In many cases, these technologies can be retrofitted to your existing guitar. Whatever method you choose, installing the right pickup system in your guitar is essential for great live acoustic guitar sounds without fear of howling feedback. And don’t forget that an electro/acoustic guitar is useful in the studio as well, as a blended texture with mics or as a fresh tonal voice all
its own.



David Hess
David Hess grew up in a guitar shop. He has been involved in selling, repairing, and collecting guitars and amps since he was 14 years old. For the past ten years he has been a Sales Engineer at Sweetwater. Reach him at (800) 222-4700 ext. 1398 or david_hess@sweetwater.com.

The Royer Labs R121 ribbon microphone has become very popular for recording guitars, drums and other instruments. Its durable design allows it to handle high volume levels without damage.


Guitar Tracks
The Royer Labs R121 ribbon microphone has become very popular for recording guitars, drums and other instruments. Its durable design allows it to handle high volume levels without damage.
A ribbon microphone is a special type of transducer that uses a thin strip of metal, or “ribbon,” in place of the metal-coated mylar diaphragm typically used in dynamic and condenser mics. Though ribbon mics excel on many audio sources, such as drum overheads, horn sections, string ensembles and vocals, they’ve also gained a great reputation as electric guitar microphones.

I happen to love using a ribbon mic on my guitar cabinet for natural and balanced tones. The biggest reason I prefer ribbons on my amp is when I dial in a killer tone, I can trust that it will shine through on the recording. This is due to the fact that ribbons are relatively flat in their response compared to other types of microphones. I’m not saying that condenser and dynamic microphones don’t have their place when mic’ing guitar cabinets – a well-placed AKG C 414 can produce a great-sounding recording! But if you want to capture your sound without adding much tonal color from the microphone, a ribbon is a fine way to go.

Why is this so? Many users feel that ribbons respond like our ears – and if you’ve used a ribbon in the studio, you know that’s an accurate description. Every microphone, from a Shure SM57 to a Neumann U87, has its own EQ curve. If we looked at a graph of the EQ of a ribbon microphone versus a condenser, we would see the ribbon is more neutral. Because you start with basically a neutral mic tonality, if you decide to add a bit of high-end to the recording, it still sounds natural without becoming harsh.

In the past, many believed ribbon mics were too fragile to handle the high decibel levels of rock music. On the contrary! Eddy Kramer, known for his work engineering Jimi Hendrix records, used a ribbon on Jimi’s cabinet in the studio. Can you imagine the decibel levels coming from that amp room when Jimi was laying down “Third Stone from the Sun” or “Voodoo Child?” Staggering, one would presume!

Still, ribbon mics gained a bad reputation because the delicate ribbon element could be damaged by just blowing on it! In fact, broadcasters of the thirties and forties sometimes blew into old RCA mics in an attempt to stretch the ribbon element to achieve better low-end on their voices. Needless to say, the ribbon would need repair, which wasn’t cheap. So after World War II, when recording engineers were able to get their hands on sturdy Neumann and Telefunken mics from Germany, it seemed to make sense to use those more durable models in the broadcast and recording industries. Ribbon mics were consigned to the back of the microphone closets of many studios. They became hard to find, and the people that knew how to repair, build, or even use them became even more rare.

Toward the end of the twentieth century, David Royer, a brilliant audio designer of rare and respected custom condenser mics and preamps, developed the Royer Labs R121 ribbon mic, which laid the groundwork for the future of ribbons. Engineers and musicians began to use these mics to make recordings and the R121 became a secret weapon for many engineers. Around the same time, Wes Dooley of AEA (Audio Engineering Associates) reintroduced the vintage ribbon mics from the past. Wes first created the R44C, which was based on the classic RCA 44 ribbon model. The R44C immediately grabbed the interest of the recording community, and has become a studio mainstay. AEA’s ribbon designs are more “traditional” and darker than Royer’s, with a lovely, full natural sound.

Recently there have been many ribbon mics introduced into the market at various price levels. Because of the honesty in tone these mics can yield, you’ll find many of today’s respected guitar players using them in the studio as well as onstage, either alone or combined with a dynamic mic (such as a Shure SM57 or a Sennheiser MD421) or a condenser.

If you’re interested in checking out audio examples of an AEA R84 and Royer R121 in action, go to myspace.com/joelgragg and listen to “Redemption Draws Nigh.” I used the R121 on the lead with a Telecaster through Jensen-voiced Fender Blues Junior amp. An AEA R84 was used on the rhythm guitar, which was an old Harmony hollowbody through a 5-watt Silvertone amp. This should help give you an idea of how ribbons capture tone and texture.

If you haven’t used a ribbon microphone to record your amp, try one out!




Joel Gragg
Joel Gragg is a Sweetwater Sales Engineer who has experience as a singer/songwriter, engineer/producer, and guitarist in the Nashville music scene. He can be reached at 1-800-222-4700 or at joel_gragg@sweetwater.com.
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