Monday, January 26, 2015

5 Inch Diameter Loudspeakers: The Ideal Acoustic Guitar Loudspeakers?

Even though amplified acoustic guitars inevitably ends up sounding like an electric guitar, could 5-inch diameter loudspeakers provide a solution?

By: Ringo Bones 

Let’s face it, any attempt to amplify the acoustic guitar sound output since the days of Lee De Forrest’s Audion vacuum tube inevitably – then and now – end up making the acoustic guitar sound like an electric guitar. Fortunately, the R&D team at Trace Elliot had discovered a novel solution to this perennial problem back in the late 1980s. 

More than an interesting design concept, it seems that the R&D team at Trace Elliot had discovered that five-inch speakers are ideally suited to the acoustic guitar’s frequency range since using them as speakers in acoustic guitar amplifiers tend to lessen the resulting amplified acoustic guitar sound’s tendency to sound like an electric guitar. The mono version of Trace Elliot’s acoustic guitar amplifier – the TA 100 – has four 5-inch speakers and the stereo version – the TA 200S – has eight 5-inch speakers. The amplifier’s controls (control panels) are located at the center of the front grille area of both models. Both Trace Elliot acoustic guitar amplifiers look like a “modern” circa 1990 version of those classic Stromberg Carlson radios from the 1930s. 

There’s a “Dynamic Correction” scheme that optimizes the speaker movement for reproduction / reproducing acoustic guitar frequencies. An Alesis reverb chip comes built in the stereo model of the Trace Elliot acoustic guitar amplifier while you get the mono model with or without the chip. Not quite a “budget product” it is perceived to be given that stand alone / discrete Alesis digital reverb units at the time retailed for around 3,000 US dollars each.  

Was there already a perfect version of “Dynamic Correction”? Models that are domestic friendly enough were bought in droves by audiophiles during the late 1980s by with mixed results. Dynamic Correction via motional feedback used in Velodyne’s high-gain servo subwoofers origins date back to the 1970s where Graham Bank of hi-fi loudspeaker manufacturer Celestron had documented his own “trials and tribulations” on making motional feedback speakers more consumer and domestic friendly. 

Motional feedback in a nutshell senses loudspeaker cone movement and applies correction in a similar fashion to negative feedback. During its early days of development, a lack of a position reference resulted in an enormous crack from the loudspeaker cone as it attempted to leave the loudspeaker chassis during musical peaks. Each time it did this, the connecting braids carrying the signal from the loudspeaker frame to the voice coil broke, even though they were long enough to cope with the movement. It appeared that they fractured under the enormous acceleration involved. Once perfected though, it became the working principle behind Velodyne’s F-Series subwoofers during the 1990s. 

1 comment:

  1. I think the "ideal" acoustic guitar amplifier is a set-up where you play your acoustic guitar in front of a 3,000-U.S. dollar tube condenser microphone connected to a PA system that sounds as transparent as a single-ended vacuum tube amplifier capable of delivering clean 130-dB SPL in a rock stadium setting. Does Trace Elliot have this sort of product?