View Full Version : Worth Upgrading Sub Amp To Class D??
06-20-2011, 06:21 PM
Heres my situation. Im currently adding a 3rd battery (2 new stereo, 1 starter) to my system. I have my 3 amps on 3 different on/off switches. When we board or sit in the cove I turn my in boat speakers/amp off & run my 4 tower speakers on my Arc Audio Amp(basically a wetsounds syn2) & my 2 12" rockford subs on my Rockford 800.4 amp. I usually dont run the subs while sitting in the cove to keep the battery from draining way down. Sometimes we sit while playing music at a moderate volume for about 4-5hrs. I am not unhappy with the performance of the Rockford amp at all. I just want to be able to run the subs & towers while sitting & be as effecient as possible because I cant always charge the batteries in between lake days. Basically is it worth spending to the $ to upgrade to a more effecient class d amp? Here are my two choicses.
06-20-2011, 07:55 PM
Heck yes! Its definitely worth upgrading to Class D for all amplifiers.
Class D is 60 percent more efficient than Class AB. Here is an illustration to put that into better perspective.
A Class AB amplifier will draw 2000 watts of supply to produce 1000 watts of output power. 1000 watts is generated as wasted heat.
A Class D amplifier will draw 1250 watts of supply to produce 1000 watts of output power. Only 250 watts is lost as heat.
A Class AB will generate 400 percent more waste and heat at the identical output power as a Class D amplifier.
Class D promotes longer play time, less voltage sag and higher output power levels, shallower battery cycles and longer battery lifespan, less battery reserve costs, less stress on you alternator with less HP loss, and more predictable ACR/VSR operation. I've scratched the surface.
We are fortunate that in the last 10 years faster transistors and microprocessors have brought Class D to fullrange as well as sub amps.
Btw, I'm also an advocate of the Arc Audio or Wetsounds Class G/H as another more efficient topoplgy.
06-21-2011, 01:39 AM
So are there any disadvantages to a class D vs a class AB amp?
06-21-2011, 02:33 AM
MK - as it applies to your subwoofer the answer is yes. A class D amplifier is probably advisable. As it applies to the rest of your system, I'd say no its not worth changing out. The sub zone of any given system typically gets run very hard and therefore consumes a lot of energy from your battery reserves. David's assessment states largely empirical data which I don't really disagree with persay but please dont think class d is some magical pixie dust. Because its not. If you load down a class D amplifier the amazing efficiency on paper goes right out the window. Even so, it would still out perform other classes of amplifier from an efficiency standpoint.
Also, all class D amplifiers are not created the same. You will find very expensive versions and also relatively inexpensive types. In the end, you get what you pay for. The ones you linked to are middle of the road gear. I'd also, consider purchasing whatever gear you buy from an authorized source that will help you with the tuning and or design of your upgraded system.
Cab - Disadvantage of class D power should be looked at from 2 perspectives:
SUB amps - No disadvantages
Full Range amps - sound quality and overall output power is an issue
My take is Class D is finding its way into after market as a viable option for midfi price/power points.
06-21-2011, 10:40 AM
The ones you linked to are middle of the road gear.
My take is Class D is finding its way into after market as a viable option for midfi price/power points.
Really Brian? Middle of the road??????
A buddy of mine still watches his old Standard Definition tube TV. I go over there and I tease him but he justifies his choice. He grew up watching analog signals on a vacuum tube and he says he likes how it looks. He claims that flat screens and HD are too unnatural. I laugh, and we go on but the fact of the matter he, he justifies what he has because it's all he has. At least he stops short of slamming HD...
I am going to make sure and save this forum thread for the day if and when you come up with a digital line to buy and sell... :D
For your appplication, there are several advantages for flipping to a digital sub amp. As David points out, a Class D amplifier is way more efficient than a Class A/B amp. Efficiencies for a pure Classs D amp are quite real, not just paper-theoretical BS. Class D efficiency directly correlates to cooler amplifers and longer playing time in the cove. Contrary to comments, the Kicker IX1000.1 is certainly not mid-fi. There is a lot of technology and innovation packed into that little amp, and you should not be disappointed with it should you decide to get it.
Application-wise for your system, if you have two woofers on a bridged 4-channel amp you are using woofers that show a 4-ohm load each, assuming you have your amp loaded to 4-ohms per side. Assuming I am right, you can wire the two woofers in parallel and get the full power outpout of the IX1000.1 without having to change out woofers. Bonus... :D
FYI, Class D has come a very long was as David points out. Full-range Class D is very real now, and the version I have heard is very hi-fidelity, (this from a guy who ran concert pro sound and did studio recording).
Kicker's new Full-Range Class-D amplifiers take advantage of a new class of power supply called a Boost Converter, taking the Kicker Full-Range Class D power supply efficiencies to greater than 90% Very little energy is turned into heat. Less heat, more music, longer play times.... I am not sure you will find another amplifeir that can boast that kind of power supply efficiency. Sound quality is quite good.
Your full range amp already takes advantage of Class H technology, so you already have an amp that is more efficienct than your sub amp. Replacing the Class A/B sub amp for a digital one is a good choice, regardless of brand, (as long as you don't go all flea-market on us). the Kicker IX1000.1 is a good choice. If you decided to take a step to all Class D, take a look around and take the opportunity to listen to the new class of Full Range amps out there. I think you will be pleasantly surprised.
06-21-2011, 11:14 AM
Just to clarify a few things related to amplifier class.
If you drop the impedance load of a Class D amplifier the typical 80 percent efficiency will decrease. If you drop the impedance load of a Class AB amplifier the typical 50 percent efficiency will also decrease. So, you are still going to enjoy a 60 percent efficiency difference or in other terms 60 percent less current draw difference at the identical power output level. The output impedance load effects both classes of amplifier efficiency. Neither is static.
Most consumers don't realize that most amplifiers are rated at 14.4 volts. As the voltage drops to 12.5 volts the power loss can be as much as 20 percent. The power continues to drop as the voltage continues to drop. Independent test reviews which I can produce make this crystal clear. Remember that a fully charged battery rests at around 12.7 volts. As you draw more current the result will be a reduction in voltage. If you have any doubts, don't take my word for it. Use a multimeter to check the voltage at the amplifier primary terminals after you have been hammering on the system for only five minutes.
Like with Class D, G/H, AB, certainly not all amplifiers within the same topology class are created equal. The performances range from low end to high end in all classes, Class AB and Class D included. But if you are going to make an objective comparison I would compare the better offerings of one against the better offerings of the other.
But here is an illustration for you. The JL Audio HD series of Class D amplifiers use a feedback circuit (all amplifiers apply feedback in one form or another as a means to improve distortion) that compares the signal input and output and makes corrections over 400,000 times a second.
When used in a erou vehicle with extensive sound damping and the very best component speakers available these Class D are the equal of the very best Class AB amplifiers. There are warm, rich and smooth with all the same listening attributes. JL Audio should know what sounds good. Their AB amplifiers have been given rave reviews by Robert Zeff (originally Zapco) which is one of the top Class AB gurus in moblie electronics. Also, The electronic engineering department of JL Audio consists of leading personel previously with Precision Power & Xtant, Rockford Fosgate and Phoenix Gold to name a few. Engineering is in house. They have the talent and have been steadily moving towards Class D. As long as there are still Class AB enthusists they will continue to build the Slash series of Class AB amplifiers.
But JL Audio, who makes both, will tell you that their Class D HD amplifiers sacrifice nothing in sound quality. That is the present state of the technology rather than at some previous era.
There are many Class D subwoofer monoblock amplifiers with BIG power so we know it can be done. Its only a matter of whether you have the components and technology to do Class D at much higher switching speeds so that the upper end response is well above the audio range. That threshold or ceiling has been broken long ago. We now have fullrange and multi-channel Class D amplifiers with big power to go toe to toe with many of the larger Class AB. And even bigger models are in the pipeline.
06-21-2011, 04:35 PM
Phil and David pretty much covered it. Efficiency is key in boats. Whether is be class H or class D. Starting with a higher efficiency amplifier gives you more play time at rest and less strain on the electrical system. And also since there is less energy wasted as heat, a cooler running amplifier. which is very important in marine and many times overlooked when talking about amplifier topologies. We are from Texas, it is 105 right now! Out on the water in your boat in July or August with an amp in a closed locker. You need a cool running amp. A class AB amp strapped down to a super low impedance will not work for long and wind up shutting off. And who wants that when you are having a great set or hanging in a cove.
06-21-2011, 06:03 PM
Ha, the last several post made me laugh!
MK, I cannot offer any knowledge that comes close to what you received above. FWIW, I run 2 class d's to power the tower and a class d to power the sub and am happy with the results, both sound quality and play time. I do use an AB amp to power in boats.
I'm running a mix of 3 JL and 1 Alpine.
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