AKARSH SHEKHAR
HOW TO SELECT THE RIGHT AMP
For Yourself
There is a very wide range of amplifiers and brands available in the market , but if we could classify them , we would say that there are those for use at home , which can be stereo amplifiers or audio and video receivers for Home Theater . Usually , these amplifiers are for directly coupled speakers and they have low power per channel ( about 90w / 100w at 8 Ohms per channel ) they are designed for momentary use such as watching a movie , listening to music for a couple of hours and they are air-cooled , they usually have slits throughout the chassis for air to circulate , and storing them in unventilated cabinets shortens their lifespan .
Amplifiers for live sound speakers are typically stereo amplifiers , that is to say , two channels , and we find them for all types of power from 100w to 1000W in 2.4 and 8 Ohms , they have heat sinks and installed fans that help air circulate through them . They are placed in racks and can be attached to each other , they are said to be for professional use and normally it is sought that the nominal power of amplification exceeds the nominal power of the speakers at the same Impedance ( Ohms ) multiplied by a factor of headroom , that is : if we want to amplify a 350W speaker at 8 Ohms , we will first multiply the value of 300W x 1.25 ( headroom factor 25 % of the nominal value ) = 375W , we will look for an amplifier that at 8 Ohms guarantees us to have 375W if we find an amplifier that delivers 400W at 8 Ohms will be a good option .
An amplifier that is below 350W at 8 Ohms playing at full volume may not deliver enough current that the speaker will draw and the audio signal will behave as direct current , which will damage the speakers .
These amplifiers are used in group tours , auditoriums , concert halls , and anywhere where the demand for sound pressure and frequency response is very high due to high musical content .
Then we have the amplifiers for installation . These are amplifiers that are designed to work 24 hours a day , they are cooled by air with fans and heat sinks , they can be placed in a rack or stored in furniture , and some have multiple lines and microphone inputs to offer an all in one product , compatible with direct coupling or low impedance ( 4 and 8 Ohms ) but are also compatible with high impedance ( 70V / 100V ).
While in direct coupling we have to find compatibility between Ohms and Watts with high impedance we only care about not exceeding the final load considering the headroom .
The high impedance is achieved with the use of coupling transformers and what the amplifier does is send a voltage through the audio cable , the idea is to send that high voltage from the amplifier and in each speaker that is used , a coupling transformer from high to low impedance is placed , connected in parallel only . This definitely facilitates the installation in places with many speakers . A single cable from the amplifier allows us to reach the first speaker and from this speaker go to the next and so they all end up being in parallel .
This technology is widely used in environmental audio applications or in places where it is only used for voice messages , such as paging at bus terminals , and background music in a clothing store or restaurant , and this is due to the fact that using the transformer , the frequency response of the speaker suffers an alteration or loss in low and high frequencies .
The Score
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