Car Amp Wattage for new Speakers?

[Focus SE]

I never wrote that it can't be done and in fact, I would like 12V amplifier manufacturers to use the Power Cube testing that showed which amps had balls and the ones that were phoning it in but the manufacturers won't because they don't want to show the weaknesses in their products. I still have my Rockford-Fosgate binder with the test results and comparisons that we got at Boot Camp- those amps were/are beasts and needed the charging/reserve to be able to keep up with the current demands. Headroom is good, some amps weren't capable of any because their power supplies were so heavily regulated.

We did a lot of systems using 'tri-mode' too, but it's a lot easier and more precise to use active crossovers to counteract road noise and other issues as they arise.

It's not an "Oh, you're using passive crossovers and I can hear the effects" thing, it's about losing power needlessly- you can't have unity gain with passive crossovers and you can't add gain with them, as you can with active processors.

this post actually makes more sense of my ramblings in my post. It somewhat ties together what was missing in my thought process.
You responded before you even knew you were.
thank you

 

[highfigh]

I would like to jump in here and put my ignorance on display for all, as it relates to wattage and trying to upsell the amp. I am not looking to debate or argue my point because I don't even truly understand my understanding. Nor is this a criticism of any opinions expressed here. I'm questioning because I don't fully understand.

When it comes to car vs home audio as it relates to wattage, you will typically find the average recommended wattage rating in car audio much higher than home audio. Cars of the past were 12V systems and now more increasingly 24V systems. On the other hand, housing ranges between 110V and 120V. Take aside the specifics of the equipment here and crossover talk. But in theory you can ruin speakers with both too little and too much power. It generally happens more often with too little power because people tend not to spend excessive amounts on an amp when they budget shopped for the speakers.

Specs aside, assume you are comparing a quality speaker for home or car, the principles are the same you just need higher wattage in a car because of the lower voltage. On a home system with a quality speaker one can certainly power any set of speakers with 50 watts of amplification at lower volumes. Do you need higher wattage up to 200 watts or more? No but it does have an appreciable effect on the sound clarity and as it relates to head room and amp matching. As it relates to the OP's I have no idea spec wise Where the line in suggesting too much amp is when trying to maximize a speakers range. But the theory of suggesting seemingly too much doesn't seem totally unreasonable if the speakers can handle it in order to allow for always being able to get the full range. Will you ever use it and if you do will you go deaf is another story.

Like the difference between a 6 cylinder engine and an 8 in the same vehicle type. Or even 4 wheel drive when I'm only using it 2% of the time. IMO there is something to be said about having something available when you need/want it. Where in the audiophile spectrum that exact line is, I have not idea. My problem with the AVS forum is that everyone seems to know exactly where it is and none of them agree.

Just some food for thought

We used to refer to car audio power ratings as:

120WJBF- JBF stands for 'Just Before Fire'
120WWLS- WLS stands for 'When Lightning Strikes' or
120 Sony Watts because they were one of the brands with the most optimistic ratings

The car audio industry usually spec'd power output at 14.4VDC, which has been the typical charging voltage, 12VDC was the old number for batteries at rest, but even that isn't accurate- most measure around 13.2V at rest if they're well charged but with electrical loads on the charging system when the car is idling, especially in gear, the voltage isn't 14.4VDC- that often begins above 1000RPM and sometimes higher. I wouldn't trust an analog voltmeter on the dash but the digital ones are good. This is important if someone wants to prevent clipping due to low power supply voltage. The car's ECM won't like the voltage drop if it's excessive, either. The only car/marine amplifiers that output their rated power without being as dependent on voltage have less headroom and unless the system is designed around it by using amplifiers that are larger than the typical demands, it hits the ceiling and doesn't go farther.

Dynamic range in most systems is adequate. The systems that are operated at extremely high output are the ones that need to be designed more carefully if clipping is to be eliminated or avoided. Most people use less than 10W-20W and that's loud, with sensitive speakers.

 

[TLS Guy]

I would like to jump in here and put my ignorance on display for all, as it relates to wattage and trying to upsell the amp. I am not looking to debate or argue my point because I don't even truly understand my understanding. Nor is this a criticism of any opinions expressed here. I'm questioning because I don't fully understand.

When it comes to car vs home audio as it relates to wattage, you will typically find the average recommended wattage rating in car audio much higher than home audio. Cars of the past were 12V systems and now more increasingly 24V systems. On the other hand, housing ranges between 110V and 120V. Take aside the specifics of the equipment here and crossover talk. But in theory you can ruin speakers with both too little and too much power. It generally happens more often with too little power because people tend not to spend excessive amounts on an amp when they budget shopped for the speakers.

Specs aside, assume you are comparing a quality speaker for home or car, the principles are the same you just need higher wattage in a car because of the lower voltage. On a home system with a quality speaker one can certainly power any set of speakers with 50 watts of amplification at lower volumes. Do you need higher wattage up to 200 watts or more? No but it does have an appreciable effect on the sound clarity and as it relates to head room and amp matching. As it relates to the OP's I have no idea spec wise Where the line in suggesting too much amp is when trying to maximize a speakers range. But the theory of suggesting seemingly too much doesn't seem totally unreasonable if the speakers can handle it in order to allow for always being able to get the full range. Will you ever use it and if you do will you go deaf is another story.

Like the difference between a 6 cylinder engine and an 8 in the same vehicle type. Or even 4 wheel drive when I'm only using it 2% of the time. IMO there is something to be said about having something available when you need/want it. Where in the audiophile spectrum that exact line is, I have not idea. My problem with the AVS forum is that everyone seems to know exactly where it is and none of them agree.

Just some food for thought

Yes, car output specs are fantasy as just pointed out.

Power is Voltage times current. P = V X I. So the only way you can get more power from a 12 volt car system directly is to use low impedance speakers. Now P = I squared X R. Now unless you have a voltage converter the maximum voltage to the amp is 12 volts. From ohm's law V = IR. So if you have an 8 ohm speaker the current will be V/R. So for a 12 volt system the current will be 1.5 amps. Actually a little less as you won't get 12 volts at the speaker terminals. Anyway the maximum power possible is 18 watts. Now if we make the speaker two ohms we get 72 watts possible. For a four ohm speaker 36 watts. In practice those numbers will be a bit less.

Now, you can't easily increase DC voltage. So you have to convert the DC to AC with an oscillator and then back to DC.

Now from those numbers you can see the advantage of raising car voltage from 12 to 24 volts and some are suggesting going to 48 volts. But that is enough to give you a nasty nip, especially in the wet.

But there is safety in going with a higher voltage, as the heat losses in the wiring go up by the square of the current. There is not a lot of room in car wire chasses to use larger diameter wire, and it adds weight.
So raising voltage allows for less loss and heat in the wiring and lowers the fire risk.

 

[highfigh]

Yes, car output specs are fantasy as just pointed out.

Power is Voltage times current. P = V X I. So the only way you can get more power from a 12 volt car system directly is to use low impedance speakers. Now P = I squared X R. Now unless you have a voltage converter the maximum voltage to the amp is 12 volts. From ohm's law V = IR. So if you have an 8 ohm speaker the current will be V/R. So for a 12 volt system the current will be 1.5 amps. Actually a little less as you won't get 12 volts at the speaker terminals. Anyway the maximum power possible is 18 watts. Now if we make the speaker two ohms we get 72 watts possible. For a four ohm speaker 36 watts. In practice those numbers will be a bit less.

Now, you can't easily increase DC voltage. So you have to convert the DC to AC with an oscillator and then back to DC.

Now from those numbers you can see the advantage of raising car voltage from 12 to 24 volts and some are suggesting going to 48 volts. But that is enough to give you a nasty nip, especially in the wet.

But there is safety in going with a higher voltage, as the heat losses in the wiring go up by the square of the current. There is not a lot of room in car wire chasses to use larger diameter wire, and it adds weight.
So raising voltage allows for less loss and heat in the wiring and lowers the fire risk.

One of the other reasons for higher voltage is to save money on the harnesses.

As far as a nip, sitting on the door sill of a '90s Corvette on a humid Summer day didn't prevent me noticing the strong tingle in my leg while I was touching a live wire after I had removed the sill plate. I wasn't expecting that.