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Old 8th January 2008, 08:55 PM   #1
Flyin11 is offline Flyin11  United States
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Join Date: Sep 2007
Default Class AB vs Class D?

Hey all...Just got my Punch 300-1 amp in today by UPS and it is a Class AB. I ordered it for it's size cause I thought I was going to be able to install the capacitor under the seat but I moved everything back to the back of the sub box. One of the other MAIN reasons for me getting it was for the input sensitivity so I could use my 5V HU with it. I figured what the heck and wanted to try it and I just installed it a couple hours ago. The amp came with a certificate rated at 431 into 2ohms. About 31 watts more than the Alpine MRP-M450 I had hooked up. The Punch pounds!!! It hits harder than my Alpine and it is more cleaner sounding. I only have the gain at half way and this is what blew me away.

So my question is this...How much of a difference is there really between a Class D and a Class AB amp? I might want to keep the Rockford and sell the Alpine but I also don't want to keep it if it is going to put a real strain on my electrical system as some suggest with a AB amp. I do have the capacitor so that should defiantly help and the Punch doesn't have any fuses on it, it operates off the fuse you have in your distr block so I'm thinking that should save some power there..no? Any suggestions? I have yet to complete my connections to my amp for my highs which I should be able to do tomorrow. If I have to then I will stick with the Class D Alpine if it'll help save my electrical system that much or try to find another Class D with the input sens range I need.
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Old 8th January 2008, 09:03 PM   #2
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Class AB is usual around 50-60% effictiant wheres the class D can be up to 85%+

which means for 100w class AB at 50% efficincy you need 200w of power into the amp to get the full 100w.
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Old 8th January 2008, 09:05 PM   #3
Flyin11 is offline Flyin11  United States
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I might go ahead and just stick the Alpine in then and leave it at that then. Sounds like a huge power draw...Was just trying to figure out if all the answers and talk about Class D amps were right and I guess it seems to be....
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Old 8th January 2008, 09:50 PM   #4
shagone is offline shagone  United States
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if you have a decent battery and cables with clean connections then you should not have to worry about power draw? people have been running class A/B amps on subs for many years without issue. go with what sounds better to your ears. your altenator should be able to keep up unless you were running several amps with tiny power, grouns, and speaker wires. are you running the system with the engine off? this will drain your battery no matter what amp you use. maybe all you need is a fresh battery?
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Old 8th January 2008, 10:09 PM   #5
Flyin11 is offline Flyin11  United States
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Nope..Battery is brand new and all. The thing about me and my music is I only crank it up when I'm out on the road or the highway. If I come to a stop light, I turn the volume almost all the way down...to like 8 out of 35 on the HU but when I get on the interstate or a long stretch of road without lights, I listen to it loud at 28-29 out of 35 on the volume dial. If I ever listen to my music in my car in the parking lot, it's at like 2 or 3 and the car is running so I don't run the battery down. That's just me though...I don't like to draw a lot of attention to myself at the stop lights but when I'm cruising down the road to work or so on, I crank it and enjoy my music I'm not cranking the system all the time that's not a concern for me...I just want to make sure like in other threads I have posted that if I'm going down the road, that everything is keeping up and it's not draining my battery or killing the alternator as I'm driving. Then there is a problem if the car dies going down the road...
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Old 8th January 2008, 10:13 PM   #6
ppia600 is offline ppia600  United States
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If you don't use the full wattage of the amp all of the time you won't need to worry. Just remember it is capable of drawing about 900 watts from your car at full output to produce the 431. The class "d" putting out that level of power would only draw about 600 from the car.
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Don't worry... you can always turn the gain down!
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Old 8th January 2008, 10:21 PM   #7
Flyin11 is offline Flyin11  United States
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It does say on certificate that maximum wattage is like 1273watts...but I don't think I need to worry about that as it's only the 431 I'm using but even after looking at the wire demo thingy, my power loss from wire length and all is 360watts actual power. That demo of Perry's does work cause when I talked to a Crutchfield guy last week he said my other amp was putting out 375watts and I put in the calculations on the demo when I got home and got 375. Of course 375 will be lower now with me moving the stuff to the trunk but still. I'm actually only outputting 360 out of the Rockford.
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Old 9th January 2008, 01:35 AM   #8
jol50 is offline jol50  United States
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Drive it at night and try it. If your lights get dim then your voltage is dropping. RF amps usually put out a little more than rated.
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Old 9th January 2008, 02:44 AM   #9
Flyin11 is offline Flyin11  United States
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Just went and gave that a try and no flickering or dimming what so ever even at my top volume on the radio Also used a voltage meter and it's reading 14.3 volts coming from the cap so that's a good thing, means it's doing it's job. I even turned on the heat and no flickering but just like it did before there is some dimming when I use the rear defroster but I could care less. I barely use it and if I do it's only for like 5 minutes while the car warms up before I even get in it. I don't even look out my rear view mirror as I have it turned up cause it distracts me. So that's nothing for me to worry about. Sounds good and it's actually turned 1 mark over half way on the amp which is about where my Alpine was but the bass is substantially more and clean. The real test comes after tomorrow though. After I hook the other amp up, then we will see what it does at night. I might not be able to run 2 amps at once but it might be ok as well. Won't know till later tomorrow night. Sounds dern nice right now though.
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Old 9th January 2008, 05:31 AM   #10
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gain setting really has nothing to do with how much power the amp is putting out...depends on the input voltage.

if your voltage is above 12.5-8 volts with the system on and engine idling than you are fine.

Also 400 watts should be nothing for a stock electrical...just upgrade your big three
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