siddharthdas
Active Member
Let's first understand why active.
90% of a regular stereo amps power is wasted. Bass takes 10x as much power as the rest of the specturm. Since a regular two channel amp, can chosse which part of the spectrum to amplify, it needs to do so proportionally throughout the sudio specturm, i.e. deliver the same amount of gain to all frequencies. Only a small amount of an amplifier's bandwidth is available to it for bass - roughly 2 octaves out of the 10 amplified. so 80% of the avilable power is effectively wasted. Which is why a great amp for main speakers run to about 80-100 hz + sub are a such great idea. Can for a give $$ amount, give you 10X the dymanic range than with a full-range speaker setup.
Now let's look at cone control. By bi-amping (not bi-wiring, which is I'd say a bit silly), or tri-amping, we get amplification efficiency but not cone control. Passive crossover components between amp and driver disspate power, but even worse cost the amp in terms of control of the speaker. What does that excatly mean? Ideally you want the diaphragm to track the signal precisely. The passive components in the crossover are like a spring between a lever arm that's moving a cone and the cone itself. when that happens, depending on how stiff the spring is, the cone tracks the lever arm only partially - the cone seems to have a life of its own. On the other hand, if the lever arm is coupled directly to the cone, the cone will move exactly with the arm. Not perhaps the best example, but good enough to illustrate the idea of loss of control. Then there's the matter of power dissipation through passive components.
All told, active is just way superior to passive amplification. But then for most folks that means buying active speakers - having a crossover before power amplification, choosing the right amplification for each band, all of that is perhaps too much trouble for the average audiophile. In the era of bluetooth, active speakers are getting rather popular.
For the DIY enthusiast, active with DSP is perhaps the best choice. DSP provides unlimited crossover, and eq choices at your fingertips. And now with inexpensive high-performance class D amps, it doesn't even break the bank. I don't think the day is far when most sound systems shall employ active designs + dsp. It just makes way more sense now than ever before.
90% of a regular stereo amps power is wasted. Bass takes 10x as much power as the rest of the specturm. Since a regular two channel amp, can chosse which part of the spectrum to amplify, it needs to do so proportionally throughout the sudio specturm, i.e. deliver the same amount of gain to all frequencies. Only a small amount of an amplifier's bandwidth is available to it for bass - roughly 2 octaves out of the 10 amplified. so 80% of the avilable power is effectively wasted. Which is why a great amp for main speakers run to about 80-100 hz + sub are a such great idea. Can for a give $$ amount, give you 10X the dymanic range than with a full-range speaker setup.
Now let's look at cone control. By bi-amping (not bi-wiring, which is I'd say a bit silly), or tri-amping, we get amplification efficiency but not cone control. Passive crossover components between amp and driver disspate power, but even worse cost the amp in terms of control of the speaker. What does that excatly mean? Ideally you want the diaphragm to track the signal precisely. The passive components in the crossover are like a spring between a lever arm that's moving a cone and the cone itself. when that happens, depending on how stiff the spring is, the cone tracks the lever arm only partially - the cone seems to have a life of its own. On the other hand, if the lever arm is coupled directly to the cone, the cone will move exactly with the arm. Not perhaps the best example, but good enough to illustrate the idea of loss of control. Then there's the matter of power dissipation through passive components.
All told, active is just way superior to passive amplification. But then for most folks that means buying active speakers - having a crossover before power amplification, choosing the right amplification for each band, all of that is perhaps too much trouble for the average audiophile. In the era of bluetooth, active speakers are getting rather popular.
For the DIY enthusiast, active with DSP is perhaps the best choice. DSP provides unlimited crossover, and eq choices at your fingertips. And now with inexpensive high-performance class D amps, it doesn't even break the bank. I don't think the day is far when most sound systems shall employ active designs + dsp. It just makes way more sense now than ever before.
