David is correct Class D is NOT digital. It stands for the class of the topology.
The Wet Sounds SYN amps use Class H and Class G/H. Class H and Class G/H, ARE switching amplifiers so they are very efficient. Like a Class D. They just achieve the efficiency in a different way.
So really what you are looking for in a boat application is efficiency. More power with less current draw. Which is Class H and Class G/H, full range Class D and Class D. All of these achieve the same end goal. But there are pros and cons to each.
Some of the other brands you mention are Class AB. Which is inefficient topology as compared to Class H, G/H and D.
Also, there have been Class D amps for years. I used them back in the old school car audio days. What you are referring to is the new Full Range Class D amps.
There are a lot of different amplifier topologies. http://en.wikipedia.org/wiki/Electronic_amplifier
Anyone who has a LOT of time and is interested in learning some more.
Let me try to explain them in real world terms so everyone can get a better understanding of the pros and cons of each.
In most 12 volt amplifiers, You will see Class AB, Class D, and Full Range Class D. Very few Class H and Class G/H. Even less true Class A and since Tripath is no longer around, even less Class T. (this was the one mikeski talked about, it is a version of a class D amp made by a company called Tripath, but since the company went out of business, you do not see any class T around anymore)
Class AB is the typical topology used in most 12 volt and many home amplifiers. It can provide a clean solid sound. But lacks efficiency. So it wastes a lot of current as heat as the power supply is at full voltage all the time. So you get a larger amp that needs a larger heat sink to dissipate the heat. It also pulls a lot of current and pulls that current all the time no matter the volume level.
Think of it as a car without a gas pedal. Only a brake. You turn the car on and it pegs redline. To go, you let off the brake and the car goes. But no matter what speed, it is at red line. And even when sitting at a light with your foot on the brake. The engine is at full red line. So obviously the car will run hotter and this is not an efficient way to run a car.
PROS: Good sound. Lots of power possible.
CONS: Inefficiency. So pulls lots of current. Larger in size as compared to a switching amp and runs very hot.
Switching amplifiers like Class H and Class G/H and Class D and full range Class D are called switching because the switch the voltage. Class D switches each of the output devices on and off. While Class H and Class G/H switches to different rails. It couples a class AB output stage with the rail switching to achieve the efficiency.
So you get the car with a gas pedal. You need more power, you stomp on the gas. At idle, the engine can sit there are run and run nice and smooth and not generate a lot of heat, power is then needed to go, push the gas and it goes, get to a cruising speed, engine will run nice and efficient.
Class D was originally used only as sub amps because of the distortion created by the switching on the high end. The newer ones are called Full Range Class D as they have circuits designed to compensate this problem on the upper end of the spectrum. There are different ways to do this and a few IC companies that make the chipsets for full range class D.
PROS: Lots of power in small footprint and efficiency
CONS: Can only be used for subwoofer duty as there are sound quality issues on the upper end of the frequency spectrum.
Full Range Class D:
PROS: Small Size. Very Efficient. Low Heat.
CONS: Most of the IC's cannot produce as much power as a class AB or Class H so limited amount of power and sound quality is not up to par as class AB and Class H
Some can hear the difference. Some cannot. I can close my eyes and you could switch back and forth and I can tell you what class I am listening to. I am not a fan of the full range class D amps. (YET!) They are getting better and YES we have prototypes we are working on that are getting better with each version. Because of the market trends of smaller and more efficiency. More and more development and engineering time is being devoted to full range class d amps. So the sound quality is getting better and better every year. And the costs are getting lower. So we will have full range class d when I feel the amps can deliver the sound quality and high power I am after.
I agree with David that most are fine for in boats but lack the power needed for the tower. And with the sound quality not up to par. I do not like putting them on the towers, especially HLCD. Although we have many dealers and customers that do and love them.
So maybe I worry too much about the sound quality or maybe it is because I can hear every nuance. The best way for me to describe it. Is the difference between listening to a MP3 player and a CD. A MP3 is compressed. So it sounds like something is missing (because it is) Switch to a CD and the dynamics open up. Sound Stage opens up. So to me when I listen to a full range class d, I can hear the lack of dynamics as compared to a class H, G/H or AB. But in the end. Most people probably cannot hear those nuances.
But this is why we use Class H and G/H. It sounds like a Class AB so I get the sound quality and power with the efficiency of the Class D. So I feel it is the perfect topology. I get the best of both worlds.
Class H and G/H
PROS: Great Sound, lots of power and high efficiency
CONS: None with the exception that our version is a bit more money than some of the new entry level full range class D but still less than some of the other upper end full range class d.
Hope this helps! Best advice I can give is look for amps with efficient topology when shopping. And if you can get a demo. Listen to them. You may like the sound of one over the other. You may not hear a bit of difference. As everyone hears different. So get a demo. Always the best advice I can give when looking for audio gear.
Plus, getting a demo and listening is part of the fun or building a system!
(Message edited by wetsounds1 on January 25, 2010)
(Message edited by wetsounds1 on January 25, 2010)