Acoustic Image Corus S4-PLUS 2ch Combo Amp - Used  From Acoustic Image

Although Acoustic Image is a relatively young company, it is owned and operated by people with decades of experience in the professional music and sound industry. They're engineers (and, like their customers they're also musicians) who insist upon superior sound quality and reliable performance from our audio equipment. Acoustic Image was founded because they were never satisfied with the products available for the working musician. If you play guitar or bass, violin, keyboard, a woodwind or even a brass instrument, or you are a vocalist, they've got a sound reinforcement product designed with you in mind. Great product designs go far beyond having the right knobs in the right places. Acoustic Image’s company charter is to design and build unique, innovative, and functional audio products... there is nothing "me too" about what they do. In essence, they have merged advanced acoustic design and switching amplifier technology to create incredibly compact, ultra-lightweight products offering highly accurate sound for serious musicians. Ultimately, their pledge to you is for quality... to build a well-constructed reliable audio product that serves you well night after night, year after year. And, quite frankly, they believe the best way to do that is to design and manufacture each and every Acoustic Image product in the U.S.A. Their Technology Applying "musical thinking outside the box", they have taken a different approach to the technology of musical instrument amplification in order to improve the performance and portability of combo amps for the working musician. So, what's so unique about their products? There are three key differences: 1) The use of downfiring low frequency drivers 2) The use of switching power amplifiers and switching power supplies instead of the traditional linear designs 3) The use of unique enclosure shapes to improve portability and sonic performance Each of these differences provides an improvement in the performance of their products. Here's how: The downfiring woofer makes a small driver sound bigger and allows a smaller enclosure for a given driver size. Omnidirectional output produces a more natural and more transparent sound, and means you are more easily heard on the bandstand. The switching (Class D) amplifier design is smaller and more efficient than traditional linear amps. It has less weight because there are no heatsinks or cooling fans and it has a unique "warm" sound (unlike traditional solid state amps) because its output stage is radically different from traditional amps. The switching power supply eliminates large bulky power transformers with a resulting dramatic decrease in weight. With their unique enclosure shapes, form follows function. A cylinder is an inherently stiffer enclosure. And no resonances in the enclosure walls means less coloration in the sound. Also, the stiffer enclosure allows the walls to be thinner and lighter in weight. Add to that the use of acoustically inert polymer materials and the cabinet becomes ultra light. We don't use these new technologies to “be different.” They use them because they make their products better. It all adds up to a more portable, better sounding products. Because of their small size and high sound quality, they virtually disappear on stage, leaving the sound of the instrument being amplified, only louder.