Difference between "Watts" & "Currunts"?

Wattage is a measurement of how much voltage AND current an amplifier can produce at a specific impedance. Most amps are rated with 8 ohms used as the reference level. This is a common rating for many speakers. While most amps would have no problems at that impedance, going down to a lower impedance like 6 ohms, 4 ohms or even 2 ohms can tell you a lot about just how beefy the amp is. Since there is less resistance at the lower impedance, the amplifier should be able to deliver more power. Theory dictates that because there is half the resistance when going from 8 ohms down to 4 ohms, you should have twice the power capacity. In other words, a 100 watt per channel (wpc) amplifier at 8 ohms should THEORETICALLY do 200 wpc @ 4 ohms and 400 wpc @ 2 ohms. Not many amps can do this. The common term for performance like that is referred to as "doubling down" since the amp doubles it's output as it goes down in impedance. Most amps are limited by how much current the power supply can feed the amplifier circuit and then again by how much actual current the output devices ( transistors or tubes, etc..) can actually pass before burning up. The closer that we can come to "doubling down" in terms of the rated output, the "beefier" the amp is. This is a generalization at best since there are ways to "fudge" the numbers and specs. While the power output or current capacity of an amp might not seem important with 8 ohm speakers, most speakers vary impedance quite a bit and therefore require the "extra muscle" that a high current amplifier offers. I have seen speakers rated for a "nominal 8 ohm" impedance that actually went down to about 2 ohms. This would mean that a "common" or "measly" amp could literally "buckle" under the pressure and start distorting, overheating or going into it's self protection mode if being pushed at all. Keep in mind that 0 ohms is a short circuit, so there isn't much resistance that the amp sees with only 2 ohms connected to it. For the record, i have a set of speakers that measure 1.1 ohm, so they require very sturdy amplifiers to operate properly. Some "exotic" speakers like electrostatic's, ribbon's, etc... can sometimes be "highly reactive" and be very low impedance. What this does is causes the amp to try to put out all it can while the speakers actually try to "push" power back into the amp. Having the extra "oomph" of the high current design helps to overcome this and controls the speakers better. It also comes in handy when running very large woofers with giant magnet / motor assemblies or quite a few woofers. Like the "reactive" loads mentioned above, these speakers can generate a lot of "backpressure" (reflected EMF) and the "beefy" amps can deal with that easier. True High current amps are usually noted for very tight and controlled bass output for this very reason. Tube amps typically don't do well with lower impedance speakers, putting out measurably less power and having poorer bass performance. Just like speakers, the amps actually have an impedance rating for their output. Since tubes are typically much higher output impedance than transistors, they tend to like higher impedance speakers for best results. That is why many tube amps have been characterized as having "mushy bass", especially when used with low impedance speakers. I hope that i kept this simple enough for you to follow and understand. While it was quite basic, it was a generalization at best. Keep in mind that there are exceptions to every rule and there are amps that don't fit into any of the above categories. Sean >

HAHHA.... Looks like we were doing this at the same time with both of us writing novels : ) Sean >