class d amplifiers

class d just means a type of input that reduces the power consumed for reproducing bass-notes - over a class a/b design they save a bunch of electricity - however, because of the way class d amps are designed, they cannot reproduce frequencies much higher than the standard octaves for a subwoofer system - this is why you don't see a "class d 4-channel" 

- well - JL's got some magic in the works but nothing yet.

haemphyst wrote: sedate wrote: s_goodie wrote: beacuse im really into car stereos and alot of people ask me things on what to look at fora good class d amp and i really am not sure class d just means a type of input that reduces the power consumed for reproducing bass-notes - over a class a/b design they save a bunch of electricity - however, because of the way class d amps are designed, they cannot reproduce frequencies much higher than the standard octaves for a subwoofer system - this is why you don't see a "class d 4-channel" - well - JL's got some magic in the works but nothing yet. I really hope that you are kidding with that answer... Class D is ANY group of amplifier (including Tri-Path, Class "T", and ICEPower) that uses a full rail-voltage swing, between off and on, in a high frequency PWM method (some amplifiers, up to 350,000 pulses per second ) to drive the speaker cone. While the Tri-Path and the ICEPower use PWM, they adjust the output frequency dynamically, based on the analog frequency. This is claimed to allow for a more effective damping ratio. The reason for the efficiency ratings that you see, is because the output devices are ALWAYS either fully ON, or fully OFF, therefore there is VERY minimal voltage drop (or zero, when in the "off" state) across the device, thus, very minimal heat. Alpine, Eclipse, JL, and I think even Zapco ALL offer full-range Class D amplifiers. Spectron, a home amplifier manufacturer builds full-range Class D, (and were the first to do so, IIRC) and their amplifiers are regarded as some of the best sounding amplifiers in the world today! Class D is no longer relegated to low-frequency use. BTW, the "D" in Class D, does NOT mean "digital". It simply happened to be the next letter in the alphabet to be used to describe the next amplifier class.

x2.

I can tell you from personal experience that class d amps with the ICEPower chipsets are perfectly capable of reproducing the entire frequency range . I have 2 of the new Eclipse XA4000's(which are indeed fullrange class d 4 channel amps), and they are currently pushing my DLS midbasses and Focal tweeters(freq. range of ~80hz to about 20khz) - it sounds fantastic. Class D amps are no longer limited to sub duty

-Matt

heamph wrote: Class D is ANY group of amplifier (including Tri-Path, Class "T", and ICEPower) that uses a full rail-voltage swing, between off and on, in a high frequency PWM method (some amplifiers, up to 350,000 pulses per second ) to drive the speaker cone. While the Tri-Path and the ICEPower use PWM, they adjust the output frequency dynamically, based on the analog frequency. This is claimed to allow for a more effective damping ratio. The reason for the efficiency ratings that you see, is because the output devices are ALWAYS either fully ON, or fully OFF, therefore there is VERY minimal voltage drop (or zero, when in the "off" state) across the device, thus, very minimal heat. Alpine, Eclipse, JL, and I think even Zapco ALL offer full-range Class D amplifiers. Spectron, a home amplifier manufacturer builds full-range Class D, (and were the first to do so, IIRC) and their amplifiers are regarded as some of the best sounding amplifiers in the world today!

Are you trying to beat me over the head with syllabes? 

Okay look heamph - this is a fantastic explanation - admittedly much more complete than mine my sort of nibbling Best Buy-clerk-style explanation, I think we both know that the basic idea behind a class D amplifier was, and is still marketed as, a low(er)-cost, higher-efficiency amplifier for driving subwoofers.  This is changing I suppose - I don't particularly follow Alpine or Eclipse - I think both make *ugly* gear - but JL does NOT offer any full range class D amplifiers - not thier original amplifiers, not the E, A, TMA, or G series - only the upcoming HD series, due around June I believe. 

http://mobile.jlaudio.com/jlaudio_pages.php?page_id=239

Anyway, I was speaking in broad generalities, responding to a generalized question about the overall state of car audio class D amplifiers.  I think if we take a look at our OP:

Is he looking for a broad explanation about what a class d amplifier is as a mainstay of car audio? 

Or a polysyllabic white paper about specialized, spendy gear which has just been released in the past few months and does NOT represent a particularly large swath of car audio installations?  Or maybe information about home gear that runs on a 120v circuit?

Could you dumb it down for us slower people and explain why class D amplifers were one relegated to subwoofer use and have very recently been expanded?  What changed?