Class A/B or D amplifier for full range speakers?

[Bruce]

I am considering adding a Fusion amplifier to my boat. They are available as either class A/B or class D versions with similar wattage.

I am tempted by the supposed lower power consumption of the class D models. Power consumption is a big issue for me and the reason I have avoided an amplifier for so long.

The 4 channel amplifier will be pushing 6 or 8 Infinity 6912m speakers with pairs in a 2 ohm configuration on some or all channels.

What do those with experience think?

@David Analog, I hope you will give your opinion.

Thanks

 

[DCB-270]

D

 

[mattschepker]

D

 

[DCB-270]

A good amp will wake up your system. Night and day.

 

[DCB-270]

D

Good looking Blue Yamaha

 

[Drift Away]

Definitely the class D the power consumption is much much less than the others

 

[jawsf16]

Yep class D for efficiency is what I have always read.

 

[Bruce]

So you guys are not buying into the class A/B sounds better argument?

 

[DCB-270]

I had a 4 channel ab that would always get hot. Put a fan on it. Helped a little. Replaced it with a DDss4a. Plays all day with low power consumption. Big watts.

 

[DieselCamel]

So you guys are not buying into the class A/B sounds better argument?

A/B does sound better. But you'll never notice in a Boat

 

[Drift Away]

So you guys are not buying into the class A/B sounds better argument?

Not i. I am running 2 JL 6 channel amps (you can hear me befofe see me). If you pushig that many watts it dont much matter. My boat is good for about 2-2.5 hours at 75% volume. If your just looking at adding a little punch a ass D will do just fine

 

[maboat]

I agree with all the other posts. Go with D on the boat.

There is a difference in sound, but its very hard to notice the difference in the listening environment of outdoor boating. But you WILL notice a big difference in how long your batteries will last with a Class D over a Class A/B

And Bruce, don't you have a Fusion head unit? If you've been using that without an external amp, then you've been listening to Class D amplification all along. An external Class D in your setup should be no reduction in audio quality than what you've already had.

 

[Bruce]

@maboat, I do have a Fusion IP600 head unit. The head unit alone will push the speakers louder than I am allowed when we are in the boat. I would like a little more volume when swimming or paddle boarding away from the boat in a cove. The head unit is rated at 43 watts RMS at 2 ohms. If I could double that for another 3 dB it would be perfect. Those 6x9s have a high SPL so I do not need a lot of amplification.

 

[Mainah]

Class D for a boat and class AB for a car provided it has enough alternator for the load and won't be playing for extended periods with the engine not running.

The link below gets deeper than most need to know but explains the main differences of a bunch of classes. http://www.electronics-tutorials.ws/amplifier/amplifier-classes.html

When it comes to audio amplification you want headroom meaning that you should never have to turn up your amp or head unit past 80 percent gain. So an amp is well advised and for efficiency nothing beats class D. Well class T is about the same but I have not seen any produced for a boat as there is no need without a suitable digital input. As for the sound reproduction, if you can tell the difference in an open air environment then you have a very good ear.

I have previously made a couple of budget amp recommendations but I am back to JL audio or nothing as far as what I will recommend for a boat. The JL audio M series aren't the sexiest looking amps on the market and certainly not the cheapest but they perform very well and will stand the test of moisture, salt, and time.

I will also call on @David Analog for his thoughts and opinion as he has much more applied/practical knowledge and experience than I.

 

[Deuces WIld]

@Bruce

I went through the same debate about Amps. I chose two of the JL Audio M400/4 for my 242. I use one for the Front & Back channels of the in boat speakers and I bridge the other for the tower speakers. I also installed a second accessory battery and as near as I can tell I've never come close to needing that extra battery. The Class D Amps are so much more efficient and the upgraded power is so much better than the stock head unit amps. You might get a slightly warmer and more natural sound from a class A/B, but underway I defy anyone to tell me they hear the difference. On the hook, the sound is great with upgrades to Polk speakers. I'm very happy with this combination as many others have stated before me.

 

[David Analog]

In a home 2-channel system, nothing may compare to vinyl with Class AB amplification, but that is reserved for the ultra expensive systems. Why? Because the less you tinker with the signal the better it sounds. As archaic as a needle riding in a vinyl groove may sound, a pure 100% analog chain, from studio mic to home speakers, maintains the integrity of the original signal. The signal remains the exact same through all processing and in all transducers (mic, cartridge, speaker, electronics, etc.). You could say that Analog to Digital and D to A conversion is like turning steak into hamburger then trying to turn it back into steak again. But that's home. And keep in mind that Class D is not digital. It's still a form of analog. You may not tell any difference between decent AB and great D in any environment. And high quality D is in everything now, $80K a pair home DSP speakers (B&O, Lexicon, etc.), whole home distribution, fullrange pro-sound arrays, everywhere. So Class D 'can' be superb in every aspect of sound quality.
There is good and bad in both AB and D. Both have independent switching power supplies prior to the output/audio section. High current matters. Switching speed matters. Not all Class D are created equal. I have to agree with the comments about the JL Audio amplifiers, which contain the highest quality parts and proprietary designs.
At this late date, in the context of a boat, it would be crazy to consider anything other than the 60% more efficient Class D. The focus should now turn to quality....not Class.

 

[Bruce]

@David Analog, @Mainah, I would like to expand the efficiency question further. Currently I have a Fusion IP600G head unit that has a 15 amp fuse and a built in class D amplifier rated for 43 watts x 4 RMS at 2 ohms. The head unit is connected to six Infinity 6912M speakers, four of which are inside the boat. This system is capable of producing ~ 90 dB which is approximately the max that will be allowed with the family in the boat. I plan to add two 6912M to the bow but those speakers have sadly been sitting on a shelf since 2014.

If I add a class D amplifier and disconnect the speakers from the head unit should I expect similar power consumption for the same dB level that I experienced using the head unit only? I understand that higher dB levels will draw more from the battery but will a larger class D amplifier be less efficient than a smaller one?

 

[David Analog]

Bruce,
Fuses are for protection from catastrophic failure and don't necessarily correlate to power production based on current draw.
Power specs are based on very narrow parameters, such as one frequency only and one supply voltage only, so comparing power between HUs and external amplifiers is rarely accurate.
A smaller and larger Class D amplifier should have the identical efficiency so that a difference could never be detected. Only higher listening levels will draw more current....with perhaps one small caveat. I believe a larger amplifier operating conservatively and well within its capacity will be more efficient than a smaller amplifier driven into clipping.

 

[Mainah]

@David Analog, @Mainah, I would like to expand the efficiency question further. Currently I have a Fusion IP600G head unit that has a 15 amp fuse and a built in class D amplifier rated for 43 watts x 4 RMS at 2 ohms. The head unit is connected to six Infinity 6912M speakers, four of which are inside the boat. This system is capable of producing ~ 90 dB which is approximately the max that will be allowed with the family in the boat. I plan to add two 6912M to the bow but those speakers have sadly been sitting on a shelf since 2014.

If I add a class D amplifier and disconnect the speakers from the head unit should I expect similar power consumption for the same dB level that I experienced using the head unit only? I understand that higher dB levels will draw more from the battery but will a larger class D amplifier be less efficient than a smaller one?

43 watts x 4 at 2 ohms output should be pretty light on power consumption but remember that is the max and at 2 ohms. The speakers you are driving are 4 ohm speakers so comparing apples to apples your head unit is really 21.5 watts x 4 at 4 ohms. If you never push the gain past 50% then you then the head unit is never outputting more than 50 watts and for argument lets say that fusion head unit is 80% efficient which would mean it is drawing 60 watts on the amplification side of the house at 50% gain (just running the display and other logic for the head unit also consumes a small amount of power). That is very low overall draw.

I agree with @David Analog about the a small amp clipping vs a big amp having head room. That said adding an amp will likely draw more power. Adding an amp will also make an instant difference in how those speakers sound especially in the low frequencies and you will be able to push them louder than ever without damaging them. I could venture a guess at power draw but it would be just that; a guess. The only way to know what the difference is would be to measure it both ways. Lets go with a high guess and say you end up drawing twice as many average watts as you are now by powering all 6 speakers off the amp instead of 4 speakers off the head unit. You know how long you listen for so the math of how many more total watts you are drawing should be pretty simple from there.

More to your question of at the same db level for the same speaker load on head unit vs. amp .. lets say the amp is a JL m600/6. The traces and various board mounted components are bigger providing less resistance but those pathways also need to fill up so to speak and there is a lager surface area that heats up and disperses heat. I would think that the amp would have a larger nominal draw because of this. It won't amount to much though. I know that your fridge is very important to you along with some background music if I have picked up on the normal vibe of your boat reading your posts. I have to admit I am glad that I don't have a fridge running full time or I would be in the same pickle deciding which takes precedence. Actually no I wouldn't; an amp is a must for me so perhaps I would be buying more ice but thats me.

 

[Bruce]

@Mainah, two pairs of the six speakers are in parallel so two channels of the head unit are 2 ohm with a RMS of 43 watts to those channels. The other two are 4 ohm loads which are rated at 26 watts RMS.

The fridge consumes around 1 Ah per hour.

I have two group 31 AGM batteries providing 200 Ah of capacity with around 100 Ah available to avoid damaging the batteries. That gives me 4 days of running the fridge before needing to charge the battery. I have plenty of battery capacity for audio on day trips but I want to avoid cutting into the capacity during longer trips. During a typical day trip the fridge reduces the power available for audio by no more than 12 Ah and is awesome to have on board.

I would love to see a dyno of a Fusion head unit to know what their class D amplifier actually produces. I know JL always surpasses the ratings in testing. My guess is the Fusion at minimum meets their rated output.

I may try to get some meaningful comparison data using an amp clamp at the same dB level using the head unit vs the amplifier.