If you mean why are some amplifiers capable of delivering a greater sound to large speakers than others it is because the amplifier output stages can develop more current at a specified voltage across a load (i.e., speakers). Power, simply put, is a product of current and voltage for DC circuits. In AC circuits (like audio) the power is the rms product of the current and voltage. Power is typically measured in watts denoted sometimes by W but usually by P: P(ac) I(rms)E(rms) or P(dc) = IE. Because the root mean square of all of the infinitesimal segments under the sine curve (the AC expression) is .707 we sometimes use that value to compute power. Actually, however, it is not quite that simple because factors such as phase and other things need to be considered, depending on the actual circumstances of the design and application. In a simple balanced three phase circuit, for example, the power would be P + IE times the square root of three. You know what will happen if you replace your 100 watt light bulb with a flashlight bulb. You will not have the same light output. And you know what will happen if you try to put 120vac into it. The load must also be capable of dissipating the power that is input. The question about the impedance is simplified by thinking of impedance as a form of AC resistance. The lower the load impedance the more current is needed to drive it. Does that make sense? So what makes some amplifiers more powerful? They can deliver more rms volt-amp product to a given load that is capable of dissipating it. The question about clipping is one of driving the output components into saturation. For example, if you have a gain of 10 and the amplifier operates at a maximum of 20 volts you can input a signal of up to 2 volts because 2 volts times the gain of 10 will be 20 volts. Suppose you input a sine curve of 2 volts. You will get a sine curve of 20 volts at the output. But if you input a sine curve of 4 volts you will still only get 20 volts at the output and the sine curve will look more like a square wave because everything above 20 volts will be maxed out at 20 volts and stay flat until the input level falls below the maximum allowable input of 2 volts. Sometimes analog comparators such as the LM 339 or the LM311 are used to convert a sine to a square by this principle. The analog comparator is a special type of high gain amplifier that has what is called a high slewing rate. That is another way of expressing the rate of change of voltage with respect to time. I hope this helps get you started. ----- Original Message ----- From: "Thomas" To: Sent: Friday, June 18, 2004 12:40 AM Subject: [EE:] What makes a powerful amplifier... powerful? > Hi Everyone, > > I have been using many different kinds of low powered > Audio Amplifiers (below 2W) before. Some can deliver > 200mW. Some can deliver 2W. > > What makes a powerful amplifier... powerful? Is it > because its output impedance is low? > > If you try to force it to deliver more that what it is > designed to do, the output signal clips or distorts. > Why is that? (Please try not to give me answer like > "because you force it to deliver more that what it is > designed to do..." > Please help! > > > > > __________________________________ > Do you Yahoo!? > New and Improved Yahoo! Mail - 100MB free storage! > http://promotions.yahoo.com/new_mail > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body