Class d question

[MANTI5 10+ year member]

Are their any good class d amps that will do at least 1000 at 4ohms or are most doing that at 1? Also, in general, are they less taxing on electrical at 1 than class ab at 4?

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[chillin 10+ year member]

What speaker are you trying to run that it needs to be 4 ohms? There are lots of amps that will do it, but they will cost quite a bit because they are meant to put out 2-3 times that power at 1 ohm

 

[Cabin_Pressure 10+ year member]

A decent Class D will usually make 1K more efficiently @ 1ohm than most AB Class will @ 4ohm. That is on the AVERAGE, there are exceptions to everything.

 

[MANTI5 10+ year member]

The sub is a shiva x2, dual 2. It doesn't need to be run at 4, I was just curious. Mostly just wondering about the stress on the electrical, emailed mechman about an alternator for my civic and they said around $550. That's just too much for me.

 

[chillin 10+ year member]

It will be way easier to find a reasonably priced amp to run that sub at 1 ohm. with only 1000 watts, you may be able to get away with stock electrical, just do the big 3. What is the stock alt in your civic? At the most you would probably just need a second battery.

 

[akheathen Premium Member]

well, you also have the option of a "load sensing" amp. basically, it adjusts the output voltage, either by switch, like jbl crown series, or automatic. there is an 1100 crown, btw. other than that, you will be paying a lot more for "potential" power to get your 1k @ 4ohms, since any non adjusting ap that does that will likely do at least 2500, and as much as 4k+ to put it out. however, you will not really drag the amp down and can see better sq at that level, but same results can be had by adjusting a 1200 down to 1k.

 

[Cruzer 10+ year member]

run an amp @ 1ohm. its not any worse on ur electrical than 4 ohm as long as its class D

 

[MANTI5 10+ year member]

The stock alt is 90A. I've done the big 3 and am running the sub off a Rockford Fosgate 801s bridged. Not seeing any dimming but was thinking I'd like to get it some more power and go class d. If 1ohm is fine on a class d then I have more options.

 

[gunz4me2 10+ year member]

run an amp @ 1ohm. its not any worse on ur electrical than 4 ohm as long as its class D

So you are telling the OP that if he were to purchase the AudioQue AQ1200D, that it would be no worse on his electrical setup at 4 ohms compared to one ohm due to the fact that it is a class d amplifier? If so, I beg to differ since it is rated to make 510 watts RMS at 4 ohms versus the 1200 watts RMS it is rated to output at 1 ohm.

 

[Cruzer 10+ year member]

So you are telling the OP that if he were to purchase the AudioQue AQ1200D, that it would be no worse on his electrical setup at 4 ohms compared to one ohm due to the fact that it is a class d amplifier? If so, I beg to differ since it is rated to make 510 watts RMS at 4 ohms versus the 1200 watts RMS it is rated to output at 1 ohm.

No genious that's not what I said. He needs 1000 watts and he asked if it would be easier on his electrical if the 1000 watts was at 4 ohm vs 1 ohm.

510 vs 1200 is a huge difference in current and draw. I don't think the ohm level matters as far as draw but I guess the amp is working less so maybe it draws less on the electrical

but if u run so much power u need certain thickness of wire to carry the current so I would think it might be slightly better but it's still 1000 watts that needs to be supplied which requires a certain amount of amps right?

 

[gunz4me2 10+ year member]

No genious that's not what I said. He needs 1000 watts and he asked if it would be easier on his electrical if the 1000 watts was at 4 ohm vs 1 ohm.

Read YOUR general assertion statement again and tell me how it makes sense.

510 vs 1200 is a huge difference in current and draw. I don't think the ohm level matters as far as draw but I guess the amp is working less so maybe it draws less on the electrical

A little lesson in the application of Ohm's law is necessary here. A variation of Ohm's Law states that Volts x Amps x %efficiency = Watts

In the case I touted, lets assume voltage is 14.4, efficiency is 84%, and power output is 512 watts. Current draw would equal 42.33 amps. Now let's look at the same example but assume 1200 watts, current draw would be 99.21 amps. Granted, things will be different in the real world, as this is just a text book example.

Then again, the OP is also driving a Honda, which has another set of issues in and of itself. Honda chose to implement an Electrical Load Detector (ELD for short) in order to conserve fuel. When the operations of the vehicle stabilize on a long trip, the ELD WILL cut alternator charging voltage back to a level between 12.5 and 12.7 volts to save fuel. It also does this when the vehicle is idling at a stop light. EDIT: While newer iterations of Honda's ELD will sense load on the electrical system as a whole, the ELD's reaction time is far from instantaneous. In other words, a dynamic load, like music, will play havoc on the ELD.

but if u run so much power u need certain thickness of wire to carry the current so I would think it might be slightly better but it's still 1000 watts that needs to be supplied which requires a certain amount of amps right?

While true, it is somewhat irrelevant to this discussion since we don't know what size wire the OP ran to power his 801s.

 

[akheathen Premium Member]

ok, how about putting the question like this- efficiency of the amp (system draw) at 1000watts full capable output load draw, vs efficiency of an amp at 1/4 full output capble load draw. basically, whehter a 4k amp wired down to 1k is going to draw less from the power source than a 1k wired to 1k. in theory, you should see higher efficiency, since a 1ohm load may see more rail sag, which will increase losses due to thermal dissapation, circuitry imp. rise, and basically voltage drop through the whole system. the output of each amp is set by rail voltage, and what current the components can handle, electrically, and thermally. basic class d, as control here, is going to put out close to the following voltages- 35vac will get you about 1k after rail sag @1 ohm, but 300 @4 with little rail sag. now a 4k should be pumping out about 65vac before rail sag, and get you 1k@4ohms, with little voltage drop, but will also get you around 4k@1 ohm, with greater sag/drop. in that case, you will be loosing around 50 watts from what you may calculate @4ohms, but more like 250watts @1ohm.... this is half guestimation, here, from voltages i have seen, but the theory stands to reason that you gain efficiency, and drop in losses @4ohms. also, this scenario relies on dummy loads that have no box rise, and a solid even power supply. general experience tells me that, aside from the efficiency/loss of the specific amp, overpowering, then tuning down yields nicer results in both efficiency and sq..... it just depends on the users' tendency to push it harder, lol.

 

[mclerico83 5,000+ posts]

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