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Is there any reason for car speakers and subwoofers to require significantly more powerful amplifiers (in terms of watts) than home use equivalents?

JAD1326

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I've been planning on upgrading the stereo in my car since the front speakers are blown and I figured I might as well upgrade the entire thing anyways. The problem that I'm having is that obviously most car amplifiers are not exactly designed with good distortion and snr performance in mind. Therefore, I figured I'd go with some vintage a/d/s plate amps since they're rated for some pretty decent specs, they're relatively cheap (I don't wanna spend more than 200-250 usd on amps), and I know that in a/d/s' heyday their car audio gear was just as praised as their home stereo gear. The problem I have is that most a/d/s amps are rated for a pretty low wattage output. This seems fine to me, since around 35w per channel for speakers which are only handling the midrange and above and around 80w for a single sub would be perfectly fine for a near field home audio application, and considering the fact that the speakers I'm installing in my car are relatively sensitive at like 92-93dB I don't see why it wouldn't be alright in my car as well. However, most websites recommend having many times this amount of power for a decent car setup. Would this not be enough power for whatever reason? Are there reasons why a car stereo would demand more watts for it's speakers, or are people just compensating for the fact that the power output of most car amps are rated abysmally, using peak power output figures and such instead of continuous output?
(P.S. I'm sorry if this is the wrong thread for posting this question, this is the first time I believe I have made a thread post here)
 

DVDdoug

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people just compensating for the fact that the power output of most car amps are rated abysmally,
That's what I suspect.


But there could be some truth to it... The car is a smaller space but you do have to overcome road noise some people tend to listen louder in the car, especially when there is only one person in the car so you aren't bothering anybody else (at least on the highway) and you don't need to keep the volume down to where you can converse.
 

GXAlan

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You are fine with the power calculations that you have come up with.

In the hey day of aftermarket head units, it was pretty commonly to have power ratings which you describe.

1) Just like home audio, there is a wide mix of efficiency for speakers. You see more 2 ohm speakers in car audio.

93 dB/2.83V

89 dB/2.83V

88 dB/2.83V

2) unlike home audio, SPL is king for some competitions
https://mecacaraudio.com/category/world-finals/

This is not about listening to the music while you are driving but parking your car somewhere and blasting it for a party in the middle of nowhere.
 

Elgrosso

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In my experience power needs follow the same general rules than in home but with some twists, well more like a global tilt, bass would need more and highs less.
We seat closer to the drivers but they are usually smaller than in home, and the car itself is full of reflective surfaces for highs, and absorbent items for bass (seats, thick carpet, flexible panels or soft roof etc).
But of course it all depends of your goals, SQ, SQL, 2/3/4way, dsp or not, full diy or simply oem replacements, and typical listening use case/levels.
The house target is usually more bass heavy, to mask road noise and depends of the layout and cabin behavior.
Sub and midbass in very small boxes will eat a lot of power, while IB sub and midbass breathing outside won’t.
Then for sure it’s easy to listen loud there, and that goes very fast into insane levels (but so fun), cleaner sound calls for louder.
And maybe more important, EQ is needed for great results, and calls for a lot of headroom.

About the vintage amps, make sure to refurbish or at least check them. Got my share of old ones and even refurbished they were not all up to their reputation.
Recent amps as they improved a lot, and some now have integrated dsp (not only eq), they are also more efficient.

Also be careful, it’s a trap, even a simple swap of oems + eq can bring dramatic changes... and you could end up few years later butchering your dashboard ;)
 

restorer-john

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Car audio subwoofers are massively less efficient, have enormous mass in the cones, suspension and surrounds and must not only take large amounts of power, but also be subjected to rather hostile environments (car interiors in summer).

Ever tried moving the cone of a really high powered car subwoofer? There's your clue.

Car subwoofers are but one small step away from a bass-shaker.
 

DavidEdwinAston

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I had thought that powerful car sound systems were installed in order that the "Public", would be able to hear that actual music of any kind, isn't what you want to inflict on them! :cool:
 
D

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Let's differentiate between the car _speakers_ and the car _subwoofers_
The speakers don't need more power than any comparable HiFi system.

The subs in car audio are monsters with large surrounds and heavy diaphragms. Some with dual 2 ohm voicecoils or even dual 1 ohm to compensate for the poor efficiency by being a heavy load instead. I've parallelled a lot of subwoofer drivers to 1 and 2 ohms. You need a powerful amp to do that.

Speakers in cars are subject to extreme moisture, extreme dry air, extreme heat, extreme cold and is expected to survive being shaken and bumped around all the time without damage.
 

Doodski

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are people just compensating for the fact that the power output of most car amps are rated abysmally, using peak power output figures and such instead of continuous output?
The good brands of car amps give actual wattage figures in RMS power. I specialized in car audio gear repair in the 90s and worked on car amps from a handful size to ~4 feet long and all of them where honestly rated and tested at specification. I also compared the sound quality to a home audio head unit and the car amps sounded as good or the same to my ears.
 

DavidEdwinAston

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I had thought that powerful car sound systems were installed in order that the "Public", would be able to hear that actual music of any kind, isn't what you want to inflict on them! :cool:
Sorry, I should replace "able", with "forced".
 

Head_Unit

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are people just compensating for the fact that the power output of most car amps are rated abysmally,
Yeah I'd agree with @DVDdoug - also there's a number of folks who just like to crank the $#@% out of their systems (looking at YOU @MAB :D;)*)

As @restorer-john and @Holdt noted, car subwoofers kinda need more power. To fit in (usually) relatively tiny boxes with a low resonance, the mass must be very heavy, which takes more power to move back and forth. Then most vehicles have a fair amount of low frequency road noise which per some research done for Ford** needs something like a 10 dB boost at the lowest frequencies. Now I said "kinda" because the small volume of a vehicle boosts the bass a LOT, so for strong bass you don't actually need huge power. However few people putting subs in their car are satisfied with moderately loud.

The satellite speakers...well first off ditch those stupid rear speakers, don't waste amp channels on that. They are a historic leftover from the days of 3W tube amps. Nobody at home has stereo mirrored front and rear. Built-in head units all have maybe 12W real power-again enough to play fairly loud but an external amp can have better sound and more headroom for peaks. More important is that more expensive hence usually better SPEAKERS can sure improve the sound; jeez a buddy just went from stock to Focal component set in a stock radio Honda CR-V I think 2012 and it sounds WAY better.

*full disclosure: I'm occasionally the neighbor whose living room you can hear in your car...and the guy whose dorm room could drown out the fraternity house 1/2 mile away [guilty emoji]
**David Clark: Perceptual Transfer Function Measurement for Automotive Sound Systems (aes.org)
 

WinWiz

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Hoffmans law :-(
Space is limited in a car. And not only for subs but also for speakers in doors and pillars....
 

ZolaIII

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In generally space - size requirement/limitation to small in diameter cones with lower efficiency in generally than the not obligatory (there are people who put in on the back console even the 15~18" subwoofer's and no one is stopping them to chose more efficient variants [even over 100 dB SPL @1 m 1W 8 Ohms]). Subwoofer's are generally less efficient then regular woffer's as more rigid materials and there for with higher mass are used for cone to improve linear excursions limit along with maximum one. It really depends what you want to achieve and to what SPL.
 

ZolaIII

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Most car amplifiers are junk and real output capabilities are one order of magnitude (one zero less at the end) less than advertised.
Example of well almost deacent one:
I believe complete lineup performs OK so you can choose from it to requirements you have.
 
D

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Most car amplifiers are junk and real output capabilities are one order of magnitude (one zero less at the end) less than advertised.
Example of well almost deacent one:
I believe complete lineup performs OK so you can choose from it to requirements you have.

That's maybe a stretch. If you are interested in car audio in general and objective data you should follow this guy-->

 

ZolaIII

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That's maybe a stretch. If you are interested in car audio in general and objective data you should follow this guy-->

No not really interested in such small cabin it's almost impossible to do highs good as you can't position tweeters right. Had a friend who whose crazy regarding pimping it in the Alpine time (20+ year's ago) luckily he gave up.
Just wanted to point him up into the right direction.
 
D

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No not really interested in such small cabin it's almost impossible to do highs good as you can't position tweeters right. Had a friend who whose crazy regarding pimping it in the Alpine time (20+ year's ago) luckily he gave up.
DSP takes it a LONG way. So maybe your friend should try again. He may already have a car with in-built DSP for the drivers position.

Car audio is not deserving to be laughed at as much as it is by HiFi folks.
 

ZolaIII

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DSP takes it a LONG way. So maybe your friend should try again. He may already have a car with in-built DSP for the drivers position.

Car audio is not deserving to be laughed at as much as it is by HiFi folks.
There is no magical hocus pocus to compensate for right placement. Future more purity and performance are less of a concern for car manufacturers so you really get a mixed bag with manufacture pre installed one's even they did a deacent job integrating DSP. I of course have such in my car and it even has loudness that I also use but seriously I won't even compare it to my main in hause system. For car I guess it's OK, better performing amplifier would probably help (instead of stock and with stock DSP capacities).
 
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