home vs car

[tmannian]

ok, im sure this is prolly covered somewhere in the forums, but i couldnt figure out what search terms to use to find it... What i want to know is why there is such a discrepancy in subwoofers/amps for home audio and car audio... What i want to have is a sub that i can feel the bass. I had a 150 watt home sub and it would shake the room and most of the house, and in the car i have a 800 watt sub and it sounds just as loud in the car, but on the outside, not so much. Im wondering why a 150watt home sub seems to put out more noise than a 800 watt sub system. Also, i was looking at home amps and it seems that they have about 10% of the power of a car amplifier, and im wondering why, especially since i can get a 1000W car amp for less than a 100W home amp, which one would put out more sound, a 12" sub driven by the home amp or the car amp? I could probably get a car amp and the ac-dc converter to get the 1000W powered for about the same as a 200W home amp. I thought that most home speakers were 8ohm and car audio was 4 ohm, which would mean that the car speakers have about 1.4 times the current through them, does this have some effect on the power ratings?

 

[Sheep]

A search will answer this question, but I'll give you the brief answer.

Wattage doesn't equal sound. Some drivers need more power just to operate properly, while others need little. They are less sensitive. The Enclosure also plays a part in the amount of sound produced.

Think of a top fuel drag car. Yeah, it produces 7000Hp, but you need 500hp just to turn the supercharger.

SheepStar

 

[Haoleb]

basically what your saying is you want a car subwoofer that sounds as loud outside the car as it does inside....



Thats all there is to say about that really.

 

[Seth=L]

Inside the car I have noticed that even some cheap subwoofers can be quite loud. Impedance on car subwoofers is typically 4 ohms and could possibly go lower at certain frequencies (so the power ratings may refer more to a peak output over very short terms). Consider the market for car audio, where everyone thinks watts means everything, never will you see more overrated amplifiers.

As far as output outside a car vs. in a room in your home, that is a no brainer. The subwoofer is in an enclosed listening area in a home but the sub in the car to the outside, well you can't fill the outside with sound quite as easily and it becomes more difficult over distances.

 

[markw]

i was looking at home amps and it seems that they have about 10% of the power of a car amplifier, and im wondering why, especially since i can get a 1000W car amp for less than a 100W home amp, which one would put out more sound, a 12" sub driven by the home amp or the car amp? I could probably get a car amp and the ac-dc converter to get the 1000W powered for about the same as a 200W home amp.

Remember, a battery can supply unlimited current for a limited period of time.

Assume a battery rated to supply 100 amps for one hour. It can supply 1,000 amps for 6 minutes, 200 amps for half an hour, or 400 amps for 15 minutes, etc, etc, etc., until it's totally drained. But, ultimately, it runs out of power and must be rechanged.

A power supply, taking power from the wall, is limited to what it's transformers and internal circuitry can handle. It is far from unlimited like a battery.

Good luck finding a power supply that can supply the clean current you need to properly power a car amp to it's rated output.

 

[tmannian]

sheep- i thought ratings were for output power, and that the power can be translated to sound because the power translates to work done by moving the column of air (ie sub movement) so therefore more power=more air moved=stronger waves=louder... but if car amps are rated at power used not supplied than a 60% efficient amp at 1000W would only be supplying 600W...

haoleb- basically what i want to replace my blown home sub and i have a car sub sitting around that i thought i could use if i powered it, and im trying to figure out home amp or car amp via voltage conversion or just buy a new home sub altogether...

markw- i was thinking of old ham radio equipment and computer power supplies, get enough so that when the amp peaks its only about 60-70% of max power for the 12V lines, i didnt think it'd be too hard to get 100-110 amps from about 5-6 of these supplies, and theyre about 20-30 each, totals 100-180, compared with 3-500 for a dedicated home converter that could output 100A...


Seth - i figured that might be the case too, and i tried testing how loud the subs would be in an enclosed space about the size of the room where i want to put the sub (20x25), the garage. Now im not sure how much noise is lost by the car but it seemed to me the home sub i had was as loud if not louder than the car setup. yes, i had the trunk open, but i still had the box in the trunk, if that makes a difference...

basically im trying to decide if i should go jerry-rig a car system or just buy a home sub. I dont really want to spend more than 250 on this but i want to feel the movies/music when its up all the way. So i was trying to do a little research as to why car audio is rated so much more powerful than its home counterparts, but i guess its because people think more power= more sound, and so totally irrelevant?

 

[Gimpy Ric]

basically im trying to decide if i should go jerry-rig a car system or just buy a home sub. I dont really want to spend more than 250 on this but i want to feel the movies/music when its up all the way. So i was trying to do a little research as to why car audio is rated so much more powerful than its home counterparts, but i guess its because people think more power= more sound, and so totally irrelevant?

Don't frustrate yourself with rigging a car sub for your house, buy a REAL sub, like a SVS PB-13 Ultra, or what I have, a Hsu Research VTF-3 HO Turbo. You'll feel the bass, Scouts Honor

My sub has a 500 watt amp, peaking at 2000. Just one bad *** 12" in the proper enclosure, ported properly.

 

[Sheep]

sheep- i thought ratings were for output power, and that the power can be translated to sound because the power translates to work done by moving the column of air (ie sub movement) so therefore more power=more air moved=stronger waves=louder... but if car amps are rated at power used not supplied than a 60% efficient amp at 1000W would only be supplying 600W...

No. There is no equation 1W=1dB. The motor structure of the driver and the components used will change how it plays, and how much output it produces at a certain wattage.

Here is a good little test you can do to prove me right. Go to a stereo store or where ever it is you get your information (and then stop going there) and push on ALL the subwoofer drivers. Give them a good whack. You'll notice that some are harder to move then others. That is just 1 reason why some need more wattage. Magnet size and other parameters play a big roll as well. Efficiency and wattage ratings is a whole other beast, one that I am not going to touch with a 40 foot poll.

SheepStar