ratings

[SlammeD_SiR 10+ year member]

well is there a big diffrence in sound from class a/b and class d

generally class d is better no ?

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[zachzchw 5,000+ posts]

Class D is more efficient, usually used for mono amps.

A/B is less efficient, but more "pure", generally used for speakers.

 

[zachzchw 5,000+ posts]

In subs, distortion is less evident than in speakers, which is why class d amps are usually used for subs.

 

[goodrich 10+ year member]

i believe class D is designed for low freq only.

 

[helotaxi 5,000+ posts]

Most Class D have a limited bandwidth because of the switching design of the output stage. To maximize efficiency, a lower switching freq is used and the bandwidth is limited on the upper end to prevent the switching from producing an audible hum in the output. There are full range Class D amps, but they are not as efficient.

The linearty of a Class D is entirely dependant on switching frequency. Higher switching freqs allow for a more linear output at the cost of efficiency, lower switching is the opposite. With Class D amps the output signal is only an approximation of the input signal the higher the switching freq the closer the approximation.

Class A/B amps are linear amps. Distortion in this case is caused by exceeding the design specs of the amp and/or resonances with the components that make up the amp.

 

[jroyal]

I bought a Class A/B amp for my subs accidently. I didn't realize it was not Class D. Am I going to have that noticeable a difference? I bought it off E-bay so I don't think I can return it.

I bought the Hifonics ZXi1006 Class A/B 1000 watts RMS. I plan on using it with 2 Audiobahn ALUM12 Subs. Any suggestions on how to run them.

 

[jroyal]

Class D is more efficient, usually used for mono amps.A/B is less efficient, but more "pure", generally used for speakers.

When you say efficient, are you talking about the power that it uses or the power it produces?

THanks.

 

[helotaxi 5,000+ posts]

Power in times efficiency equals power out. Basically a more efficient amp will lose less power to heat and will require less amperage from the car's electrical system to produce a given amount of power. Typical Class A/B amp is in the 50-60% efficient range at full tilt so it would take 1600-2000W from the car's electrical system (about 120-150A) to make 1000W. With a Class D operating in the 75-85% efficienct range would only take 1200-1300W (less than 100A) to make that same 1000w.

 

[thch 10+ year member]

Differences between efficiency in class AB and class D.

a major factor is looking at the efficiency of the amp for a variety of signals.

class D is 80% efficienct (+-10%) over a wide range of outputs.

class AB peaks around 70% efficiency at full output power. at lower output powers, like -6dB, the efficiency can drop to 35% or less.

this means that really big class AB amps still burn a lot of power even when the volume is lowered.