Class A/B and D amp question

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10-07-2014, 11:43 AM
JGP54321

Class A/B and D amp question

I am considering switching out a couple of my amps for Class D amps. I have the jx360/4 running my cabins and the e4300 running the tower- both are Class A/B and the e4300 is OLD. The amp for the sub is class D, but old as well. I have a Group 29 battery for the stereo and all other electronics but still think it dies a little quickly on the beach - maybe 2-3 hours of only running towers. I am considering upgrading those two amps to Class D amps, something along the lines of the Kicker IX500.4 for the towers and not sure on the cabins yet. Even with the increase in watts, I assume the Class D amps are much more efficient. Could anyone tell me if I could expect to get a noticeable gain in how long I can play the stereo from the A/B to D switch? My gut tells me no given I'm not pulling tons of wattage, but this isn't my specialty. Thanks!
10-07-2014, 11:57 AM
sivs1

I can't answer your A/B to D question, I don't worry about it with dual Interstate Marine Batteries power is not an issue with me. My thought on the Kicker IX500.4 is would it give you enough power for your needs, may want to go bigger if you can.
10-07-2014, 12:08 PM
JGP54321

That's the thing, I've got the dual battery set up as well so I never worry about a battery truly dying because I can start no issues - or maybe you meant dual batteries for stereo/accessory? Either way, having to go out to the boat and turn it on for awhile to charge the stereo/accessory battery is a pain. I figured the one battery would/could last longer?
10-07-2014, 01:52 PM
MLA

The Kicker IX500.4 is a perfect amp for the KM6500.2 setup as it will deliver 250W rms to each side. It would also be perfect for 2-3 pair of in-boats. Just and FYI, the IX line was discontinued by Kicker at the close of 2013.

A class-D can be 60% more efficient than a class-A/B, but its hard to calculate an exact current draw, even with two amps with nearly equal output. At best, its a guess.
10-07-2014, 02:34 PM
JGP54321

Quote:

Originally Posted by MLA

The Kicker IX500.4 is a perfect amp for the KM6500.2 setup as it will deliver 250W rms to each side. It would also be perfect for 2-3 pair of in-boats. Just and FYI, the IX line was discontinued by Kicker at the close of 2013.

A class-D can be 60% more efficient than a class-A/B, but its hard to calculate an exact current draw, even with two amps with nearly equal output. At best, its a guess.

Thanks Mike, 60% is quite a bit more than I was expecting, guess we'll have to wait and see on battery life...

I saw they were discontinued but have found some decent deals elsewhere for lightly used or refurbished models to save a little coin. I was considering an IX500.4 as well for the 3 pairs of polk in-cabins I have, seems like it should do the trick just fine.
10-07-2014, 06:43 PM
David Analog

Joey,
Yes Class D is generally 60% more efficient than Class AB so you would naturally expect a 60% increase in play time with the same power level before you hit the low voltage threshold. Although the efficiency within any class of amplifier will vary based on the impedance load and the percentage of its power level you are running. So we are assuming that all is fairly equal in stating the 60%.
If you do not play the in-boat coaxials while at rest there may not be a major benefit to replacing that particular amplifier. Tower (the way its used) and subwoofer (the content) amplifiers usually draw the most.
Since you deep cycle your battery often your battery reserves at this point may only be a fraction of the original specifications and performance, especially if you are repetitively discharging below 12.0 volts. As the boating season progresses you may have noticed a steady decline in playtime. This would be a good time to measure your battery status.
10-07-2014, 09:40 PM
valleywine

Couldn't you just add a 3rd battery? I did and my power issues went away.
10-08-2014, 12:04 AM
Birdman

Quote:

Originally Posted by David Analog

Joe
Since you deep cycle your battery often your battery reserves at this point may only be a fraction of the original specifications and performance, especially if you are repetitively discharging below 12.0 volts. As the boating season progresses you may have noticed a steady decline in playtime. This would be a good time to measure your battery status.

isn't that what a deep cycle battery is for?
10-08-2014, 09:18 AM
JGP54321

Quote:

Originally Posted by valleywine

Couldn't you just add a 3rd battery? I did and my power issues went away.

That would probably be the easiest thing to do, but we tend to fill up that space with towels and what not so I'd like to keep the space if I can. Plus, I like justifying an extra 100 watts per side for the towers haha

David - good point. This has only happened 3-4 times and the battery is two seasons old now. We also keep it on a cheap maintainer/charger when it's put away so it'd be interesting to see how it does test.
10-08-2014, 09:40 AM
David Analog

Quote:

Originally Posted by Birdman

isn't that what a deep cycle battery is for?

Yes it is because a standard cranking battery has little to no tolerance for more than a repetitive surface discharge.
However, a consumer grade deep cycle battery will only give you a long and high performance life if you limit the discharges to 50%, meaning at 12.0 volts or 11.8 minimum. Much deeper cycles (when the audio system shuts down for example) will yield an inordinate fewer total cycles before serious degradation begins. Limiting the depth of discharge yields an inordinate high number of total cycles.
Also, having a deep cycle bank with the typical usage dictates that you will not burn enough gas for full restoration so a shore charger becomes essential to the deep cycle battery longevity. The size of the charger is then determined by the normal depth of discharge in combination with the bank's size of reserves.