Difference in class of amp?

[xdetroitx]

Been researching amps and was wondering what the difference is in classes of amps? Which class is best?

[Jay481985]

class A amps supposedly sound the best but are not very efficent being 20% or so. 1000 watts at the plug means 200 watts at the speaker..... unless your radiator broke.....

class B is more efficent. I believe most recievers are Class AB merging efficency of b with sound of a

Class C is not for audio

Class D is technically digital but it does not mean it has to be. It was coincidental that Digital and Class D went together. The efficency can be up to 90%

Class G/H is for subwoofers, mostly for high efficency giving up to sound quality

[xdetroitx]

class A amps supposedly sound the best but are not very efficent being 20% or so. 1000 watts at the plug means 200 watts at the speaker..... unless your radiator broke.....

class B is more efficent. I believe most recievers are Class AB merging efficency of b with sound of a

Class C is not for audio

Class D is technically digital but it does not mean it has to be. It was coincidental that Digital and Class D went together. The efficency can be up to 90%

Class G/H is for subwoofers, mostly for high efficency giving up to sound quality

So class D is best. But, AB is not a bad choice? Depending on your budget?

[Jay481985]

Efficency wise yes its the best but that does not mean best for music. I mean A toyota Prius is great for fuel efficency but not that great a drive. A Ferrari is a great drive but not very fuel efficent.

[xdetroitx]

Efficency wise yes its the best but that does not mean best for music. I mean A toyota Prius is great for fuel efficency but not that great a drive. A Ferrari is a great drive but not very fuel efficent.

So what would you recommend. I plan on mostly for music and I will be upgrading to Rf-83s eventually keeping my 82s for surrounds. So, I will most likely be getting a 5 channel. Maybe even a 7 channel. So far I am leaning towards B&K since they are made in America.

[Jay481985]

I mean the purests listen to class a and so. Go by what your budget and ears like

[Guest " "]

Here is a technical extract

Class A amplifiers use one or more transistors that conduct during both the positive and negative cycles of the signal. This Class of amplifier has the lowest distortion but it is very inefficient and generates a lot of heat. A Class A amplifier requires that the amplifier generate the full current no matter what the output is. If you were simply listening to FM or watching a movie, the amplifier would be consuming as much power as if you had it turned up to full volume.

In order to increase efficiency, Class B amplifiers use one transistor to conduct the positive portion of the waveform and another transistor to conduct the negative portion of the waveform. 99% of all audio amplifiers today are Class B. Class B amplifier can be built today so that its distortions are well below what the human ear can detect and nearly to the point where it is unmeasurable.

Many amplifiers call themselves Class A/B. In reality, very few are. Early Class B amplifiers had a problem known as switching delay. In a class B design, a transistor works 50% of the cycle while another transistor works 50% of the cycle. In early class B amplifiers, there was a distortion created between the time the devices were switching back and forth. Some people referred to this distortion as notch distortion because there was a notch appearance on an oscilloscope between the two waveforms.

Class A/B was created to leave the transistor conducting while the second transistor was conducting. This created an overlap between the two signals. The problem with this approach is that it created its own distortion called gumming. This means that the signal would get a little fatter where the two devices were both conduction.

Today, if you look at a properly designed Class B amplifier on a scope, you will see no switching distortion.

Class D amps are sometimes called digital amplifiers. There is really no such thing today as a digital amplifier. A Class D amplifier uses transistors that are either switched on or off to represent positive or negative values. The transistors are either on or off. The advantage of such a system is that it is highly efficient and generates very little heat. The disadvantage is that there can be a distortion caused between the switching of the positive and negative transistors as the positive and negative transistors can not be on at the same time.

Many Class D amplifiers are finding their way into Subwoofers. They are inexpensive to build and the logic is that the switching distortion is not important in a subwoofer.

Class T amps are a more refined switching amplifier developed by Tripath. It uses signal processing to eliminate the switching distortion of Class D. nOrh is currently working with parts from Tripath to determine the sonic merits using the Tripath parts. Our current view is that advantage to using Class T and Class D amps is not to achieve better sound than can currently be achieved with standard A or A/B amplifiers. Rather it is an attempt to create a lower priced amplifier that offers good performance.

[DrWho]

I would never purchase an amplifier based solely on its class. Heck, I wouldn't even make a purchase based on SS or Tubes (yes, despite my defense of SS all the time...).

Every type of amplifier topology has good sounding and awful sounding implementations.

What kind of amp are you in the market for and with what equipment will you be using it?

[xdetroitx]

I am upgrading to Rf-83 or 7s eventually so that is my goal. I hear the 7s are a bit picky on what makes them sound great and the 83s are a little less picky. So, probably rf-83 and I already have the 82s, I have a rc-64 for my center channel so I will want to push atleast 4 channels maybe 5. But, I will be doing alot of 2 channel listening of r&r, and the likes. Buying seperate amps is most likely going to be out of my budget.

[DrWho]

So just a 2 channel amp? What kind of budget are you talking about? What kind of music and how loud do you listen?

[xdetroitx]

I would like a 5 channel since my rf-82s are rated at 150 rms same with the center channel. But, I listen LOUD. Mostly rock-n-roll(harder stuff than Metallica), but I also like to listen to Jewel, Aretha Franklin, gospel, all sorts. My budget will probably be around 1500 to 2000. I plan on buying used.

[DrWho]

http://www.outlawaudio.com/products/7200.html

($1850)

[j-malotky]

Nice description of classes Speakerfritz.

Damon, you should copy this to your Klipschcorner site for others to reference!!!!

JM

[mmiles]

Isn't there a Class H (in pro gear)?

ARC (Acoustic Research Corp. - high end, famous for tube gear) has a Class T amp.

Speakerfritz is correct Class D is not digital.

TactAudio claims to be the only digital amp out there.

Regards,

Mike

[Colin]

I would indeed seriously consider class topology when purchasing an amplifier for big ole horns for the most accurate music reproduction.

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My current view is that using analogue-input digital Class T amps like the palm-size $35 Sonic Impact 5066 digital class T amp, with power adapter and the Red Wine Clari T (both 2 channel) does achieve more musical sound for the money than standard A or A/B amplifiers. It does create a lower priced amplifier with very good performance.

I dont know of a bad sounding class A tube amplifier, only ones with not enough power for low impedance speakers in conditions like loud rock music in large rooms.

Can you bridge another amplifier off the Yamaha for more power?

What about Crown, arent they supposed to be lots of solid-state horsepower?

[jacksonbart]

Just because they from the other side of the tracks does not mean they will knock up your daughter and take money from your dresser draw.

[oldenough]

I always read these type of threads with great interest, but never seem to come away anymore educated. I understand that as a general rule i should expect better performance from a class A amp, but strangely one of my favorite "sounding" amps is a Hitachi Dynaharmony series that i use in my workshop. I have been led to believe that this is in fact a class G amp, always wondered why i enjoy it, just know that i do. But then again i think that some of the forum members would be suprised by my choice of main amp for 2 channel listening(JVC A-x5). I use this in preference of much more illustrious brands, i.e marantz, h/k, etc, of which i have a good number of. So anyone wanna esplain class G to an electronic's dummy. Have a good one, keep up the good work.

John

[Guest " "]

Long story short, class G is simular to class AB, main difference is the AB and A class amp has a fixed power supply line votage reguardless of the sound level of the amp out put. Class G, provides for a variable power supply voltage that sets the power supply voltage close to the output of the amp, then switches to the next voltage level as the amps output level meets the power supply bus level.

Heres an extract

Class G
Class G improves efficiency in another way: an ordinary class AB amplifier is driven by a multi-rail power supply. A 500 watt amplifier might have three positive rails and three negative rails. The rail voltages might be 70 volts, 50 volts, and 25 volts. As the output of the amplifier moves close to 25 volts, the supply is switched the 50 volt rail. As the output moves close to the 50 volt rail, the supply is switched to the 70 volt rail. These designs are sometimes called "Rail Switchers". This design improves efficiency by reducing the "wasted" voltage on the output transistors. This voltage is the difference between the positive (red) supply and the audio output (blue). Class G can be as efficient as class D or T. While a class G design is more complex, it is based on a class AB amplifier and can have the same clean characteristics as well.

[oldenough]

Thanks Speakerfritz, I at least now know the difference even if i do'nt understand it.

[Guest " "]

let me try again.

The G amp can apply gas pedal as needed based on the sound level, where as other amps aways run with the pedal to the floor.

The end result is less heat, lower distortion, etc