Alesis RA 100 Power 100+100 w, NEW

http://www.alesis.com/downloads/manuals/RA100_Manual.pdf

Alesis' RA100 power amplifier has long been a favorite choice of musicians, hobbyists and professionals alike. Now Alesis extends the RA's range throughout the recording and production spectrum with a bold new series of affordable amps in three distinct power ratings. With their rugged construction, striking good looks among the first examples of Alesis' groundbreaking new approach to industrial design and a long list of features, the new RA series will quickly find a home in project and commercial recording studios, broadcast an post-production control rooms around the world. Popular prices, powerful performance. Even with the increasing use of powered speakers, many popular speakers and headphones still require external amplification. These new amps are designed to provide more power and better performance at a lower overall cost per watt than even our own RA100 as well as any other competing models. As a result, they can more closely match the power needs of virtually any passive speaker or studio monitor, offering a significantly better fit for an exceptionally wide range of budgets, applications and customers. And providing a crisp, clean signal for outstanding performance and extended speaker life.

• 100 watts per channel into 4Ω, 75 watts per channel into 8Ω• Dual clipping indicators alert you of any type of non-linear operation, notjust clipping• Output short circuit protection to minimize down time and protect theamplifier’s circuitry• Massive, conservatively rated, custom-designed extruded heat sinks(individual for each channel) for cool operation• No ventilation fan is needed, allowing for quiet operation and reducedambient noise in the studio• Extremely low noise and distortion; suitable for quiet applications such asrecording studios, church installations, and museumsHowever, some of the RA-100’s most important features are hard to put on aspec sheet. In a quest for a “musical” sounding power amp that can stand upto a tough life on the road as well as continuous operation in the studio,Alesis has made some changes—some minor, and some very significant—tothe standard power amp.• The RA-100 doesn’t produce any audio transients during power-up or power-down. Nonetheless, there’s a 2-second mute on power-up tocompensate for any pieces of equipment plugged into the RA-100 thatproduce transients upon power-up, and receive power at the same time asthe RA-100. Also, because the amp doesn’t produce power on/off thumpsitself, the mute circuit can be pre-power amp. This allows simpler circuitrythan what would be required for shutting down the power amp stages.• The RA-100’s power supply has plenty of reserve capacity to handlepercussive transients, but if someone kicks the RA-100’s plug out of thewall, you want all amplification to cease immediately. Therefore, if theamp senses any loss of power, it instantly mutes the audio.• Because power-up and -down are noiseless, the on/off switch doubles as amute or “panic” button.• The output stage uses full complementary-symmetry circuitry throughout.Although there are cheaper ways to design an output stage, this time-testedapproach is generally considered superior to non-complementary-symmetry types. The output devices are rated at 30 Amps of peak current,and boast a 20 MHz FT(transition frequency) for superior bandwidth.• Extremely good stability with reactive loads (e.g., speakers and crossovers).Stable operation is essential when presented with the changing loadcharacteristics of typical speakers; the RA-100 uses several stabilizationtechniques to maintain consistent feedback network characteristics.• Alesis recognizes that amplifiers will sometimes be driven into clipping—even though this is not good practice—during a recording session or underthe pressures of live performance. As a result, a great of deal of researchwent into creating the best possible clipping entry/recovery characteristics.Amps with lots of overdrive and saturation tend to create overshoot andringing during the clipping process, which degrades the sound; the RA-100has been designed so that it exhibits very little saturation, even whenoverloaded. As a result, it enters and exits clipping very cleanly. Cleanclipping allows the RA-100 to be driven harder, which makes the overallperceived sound louder.Monitoring a sine wave being clipped confirms this action. With the RA-100, the amp will follow the original input signal as soon as clipping ceases(a). With some conventional amp designs, the signal will “hang” at theclipped level for a while before catching up with the input signal (b. Thissaturation-caused overshoot can sometimes sound worse than the clippingitself.s2
• No “speaker stress” during shutdown. With traditional protection circuitry,the act of clamping the output devices to a safe value can make the ampunstable with particular notes that interact with the speaker resonance,thus producing oscillation or “motorboating.” This could damage yourspeakers. The RA-100 uses an elegant clamping design that observes theload at all times but also integrates the signal characteristics into theclamping action. Thus, the clamping action is gentle and, after clamping tothe maximum current encountered in normal operation, will slowly (over1 to 2 seconds) clamp based on the load and signal characteristics. If thesource of the problem (e.g., a short across the speaker terminals) isremoved, the signal recovers instantly.• Alesis also recognizes that whatever else, “the show must go on.” As aresult, under conditions of extreme abuse (such as ultra-low speakerimpedances or mounting that allows for no ventilation), the RA-100 willlimit its signal rather than simply shut down. Taken to an extreme, thiswill produce distortion but sound will still come out.To acquaint yourself with the RA-100’s operation, and to use it properly invarious applications, carefully read this manual. Power amplifiers are high-current devices that are the next-to-last link in the audio chain. Properattention to cabling, power distribution, ground loops, and other topicscovered in this manual is vital to have the RA-100 live up to its fullpotential.As always, we welcome your suggestions and comments concerning thisproduct, or any other product in the Alesis line.Unpacking and InspectionYour new Alesis power amplifier was carefully packed at the factory, and thecontainer was designed to protect the unit during shipping. Please retain thiscontainer in the highly unlikely event that you need to return the RA-100 forservicing.Upon receiving the RA-100, carefully examine the shipping carton and itscontents for any sign of physical damage that many have occurred in transit.If you detect any damage, do not destroy any of the packing material or thecarton, and immediately notify the carrier of a possible claim for damage.Damage claims must be made by you. If you picked up your amplifier directlyfrom an Alesis dealer, contact the dealer.The shipping carton should contain:• This instruction manual3
• Alesis RA-100 power amp with the same serial number as shown on theshipping carton• Power cord.• Four stick-on rubber feet (for shelf mounting, to prevent the RA-100’sbottom surface from scratching the shelf)• Alesis warranty card. It is important to register your purchase; if you havenot already filled out your warranty card, please do so now.About This ManualThe manual presents information in a logical order. Chapter 2 coversinstallation, and Chapter 3, how to use the RA-100. Chapter 4 covers severaltypical applications. The manual closes with information onmaintenance/servicing, troubleshooting, and operating specifications.Please remember that a power amplifier is a high-current, high-power deviceand should be treated with respect and care. Even if you are an audio veteran,we urge you to read the entire manual to make the best use of the RA-100.4