why does a car's subwoofer seem boomier than a hometheater's subwoofer?

[LarMoeCur]

1. Most people put 300 watts to a 12" sub in a car that's maybe 12' X 8' X 4'

2. Most home stereos are a 10" sub with 100 watts of power for a room that's 15' X 15'x 10'.

Bigger sub with more power in a smaller area. Means more BOOOOOMMMM.

 

[furballi]

The key is FLAT frequency response with low distortion. It's very easy to amplify non-sub frequency outside the 23 to 85Hz range in the car. A good subwoofer will produce flat frequency response in the room (+/-2dB) at low distortion without addition "coloration" to the bass range (100 to 200Hz). Make sure the crossover frequency is set at 80Hz or lower with a steep roll-off curve (minimum 24dB/octave).

Most users also tend to over-boost the subwoofer in the car to overcome road/engine noise. It is possible to calibrate the passenger compartment for flat frequency response throughout the audible range. Unfortunately, this set-up will not "sound good" when the vehicle is in motion. Some automotive hi-fi vendors will use dynamic compression to increase the average loudness of the music...not very accurate but more listenable to the average customer.

 

[Pariah]

The OP is comparing one random car subwoofer to a one random PC subwoofer and trying to draw a conclusion about how they all perform. That's like picking Paris Hilton and a rock off the street and asking why rocks are smarter than humans. For that specific example it may be true, but it certainly isn't the norm. It all comes down to the quality of the subwoofer. By nature, car subs are not more boomy than lowerend HT subwoofers. It's just that you're unlikely to see an audiophile with an overpowering quality subwoofer in their car. Most of the people who put huge subs in their car are 17 year olds who don't have money for a quality sub and wouldn't know the difference even if they could afford it.

 

[mikeford]

Originally posted by: 13Gigatons
1. Cars have a natural FS where the whole car will "hum" making the output greater. Rappers and boomers exploit this, people who want sound quality will try and use an eq to produce a more flat response.

2. Car gain can be 12 db per octave below say 100 hertz and all the way down to 10 hertz. Great if you listen to pink floyd and want really loud 10 hertz bass.

Wow, finally a post that gets it right.

In a car you are "inside" a box with typically the longest dimension "maybe" a 12 foot diagonal, with a very small compared to a room volume of air. To get flat in car response a woofer needs to reduce its output below 60 to 100 hz (depends on car) between 6 and 12 db per octave (50 hz needs to be 6 db lower than 100 hz), which means its VERY easy to get flat frequency response at say 16 hz, my Porsche 944 actually measured 8 db higher at 16 hz vs 100 hz and used a pair of 4" subwoofers.

So why is it boomy? Bad taste. Period.
60 to 120hz is the thumping frequency, it "impacts" on a human chest cavity and many people enjoy the effect (I actually love it), but to get the chest slap you need about 115 db, and thats a bit on the high side of what can be done CHEAPLY. A tuned enclosure, kind of a electric drum with one note, is the easy way to make a cheap loud speaker, and thats what many do.

When a "less" tuned box is used, it takes more power, requires better materials, etc etc, but the real joke are people that use high quality woofers setup like cheap junk only louder.

Low bass in a car is EASY, whats hard is flat frequency response especially in the mid bass between 80 and 320 hz because that is the range where the wavelength starts fitting inside the car.

 

[bigboxes]

Originally posted by: PurdueRy

I don't know what you mean by it takes 37 feet for a bass wave to mature...

Sound waves are measured from peak to peak (or trough to trough) to find the cycles per seconds. This is what is known as the frequency (what you might refer to as 30hz). Sound waves can also be measured for their size or height. This is what is known as the amplitude (or loudness, size of pressure differences). The average sub bass note takes 37 feet to mature simply means that when you measure the sound wave of those low frequency subs the distance between peak to peak (or trough to trough) is roughly < drumroll > 37 feet! So, the average car stereo listener (assuming they are listening IN the car) will never hear the mature sub note. They hear one that has not completed it's movement.

I can agree with most of your statements in that a "sub" woofer takes on frequencies that a normal woofer will have a hard time reproducing. In my defense, I did edit to include the masses use of band-pass subwoofers - a cheap, loud (boomy), and easy way to get that desired sound that is so popular in the rap culture. I'd forgotten about that as I was always into quality, not quantity.

 

[PurdueRy]

Originally posted by: bigboxes

Originally posted by: PurdueRy

I don't know what you mean by it takes 37 feet for a bass wave to mature...

Sound waves are measured from peak to peak (or trough to trough) to find the cycles per seconds. This is what is known as the frequency (what you might refer to as 30hz). Sound waves can also be measured for their size or height. This is what is known as the amplitude (or loudness, size of pressure differences). The average sub bass note takes 37 feet to mature simply means that when you measure the sound wave of those low frequency subs the distance between peak to peak (or trough to trough) is roughly < drumroll > 37 feet! So, the average car stereo listener (assuming they are listening IN the car) will never hear the mature sub note. They hear one that has not completed it's movement.

I can agree with most of your statements in that a "sub" woofer takes on frequencies that a normal woofer will have a hard time reproducing. In my defense, I did edit to include the masses use of band-pass subwoofers - a cheap, loud (boomy), and easy way to get that desired sound that is so popular in the rap culture. I'd forgotten about that as I was always into quality, not quantity.

I know about waves. I just don't agree with your "Maturing" idea. Speaker measurements are made with a mic that is usually a meter or less away from the speaker. According to your analogy, the microphone could not pick up the low frequencies produced by the speaker which is absolutely not true.

 

[bigboxes]

Sorry, never said that a microphone couldn't pick it up. That's just like saying that the occupants of said car cannot hear it. They both can. It's a fact that the occupants (and the microphone) won't hear the wave as it was intended. That sub note will be at it's peak at ~37 feet. There's no way anyone (or thing) in the car can pick that up. That is why if you point your sub rearward (instead of forward) you can gain 3db. Simple trick, but it gives the sub note a couple feet more to mature. It's really just the limitations of car stereo. There's lots more, but were really just talking about subwoofers.

 

[PurdueRy]

Originally posted by: bigboxes
Sorry, never said that a microphone couldn't pick it up. That's just like saying that the occupants of said car cannot hear it. They both can. It's a fact that the occupants (and the microphone) won't hear the wave as it was intended. That sub note will be at it's peak at ~37 feet. There's no way anyone (or thing) in the car can pick that up. That is why if you point your sub rearward (instead of forward) you can gain 3db. Simple trick, but it gives the sub note a couple feet more to mature. It's really just the limitations of car stereo. There's lots more, but were really just talking about subwoofers.

I still disagree.

The way you describe it would be the case if the wave was a standing wave. However, the wave is traveling, therefore it has its peak at many points along this distance in relation to time.

The reason you point the sub backwards is because of reflections. By having the wave hit a solid surface, it is reflected backwards and a "doubling" can occur.

You are hearing the same low frequency whether you are 37 feet away or one foot away.

EDIT: Just to clarify, I could be wrong, but from my electromagnetics wave theory class this is what makes sense to me. If anyone else can help confirm any of this I would appreciate it.

 

[mattburk]

Most car subs are garbage. Many of them are one note wonders and do not accurately reproduce a large frequency range. Instead of producing a signal with a linear spl from lets say22hz-85hz like a good home theatre sub, they will produce a solid output in lets say the 40-70hz range but not much above that or below that, that is why they seem boomy. A solid enclosure is also important; many car subs do not have an enclosure as they are using the car as the enclosure. If possible it is better to have a solid enclosure built for your sub.

 

[Howard]

Originally posted by: bigboxes
Sorry, never said that a microphone couldn't pick it up. That's just like saying that the occupants of said car cannot hear it. They both can. It's a fact that the occupants (and the microphone) won't hear the wave as it was intended. That sub note will be at it's peak at ~37 feet. There's no way anyone (or thing) in the car can pick that up. That is why if you point your sub rearward (instead of forward) you can gain 3db. Simple trick, but it gives the sub note a couple feet more to mature. It's really just the limitations of car stereo. There's lots more, but were really just talking about subwoofers.

What's the difference between the note that's heard and the note that would be heard in an outdoor field?

EDIT: Besides the change in SPL from the loss of room gain

 

[Goi]

cabin gain.

 

[Excelsior]

Originally posted by: bigboxes

Originally posted by: Excelsior
Car subs are optomized for output in the mid-bass region (over 30hz) and this is the cause of boomy bass. It is often thought that true deep bass causes this, but that is not true.

Sorry, but I think it's the sub-bass (below 25hz) that is the boom you speak of. The reason it's called sub is for sub-hearing (20hz). You feel more than hear. It's that ultra-low bass that travels much farther than normal audio waves. A (sub) bass wave takes 37 feet to mature explaining why it sounds so much louder in your living room than to the idiot sitting at the traffic light. I used to have a sub in my trunk and had a sub-sonic filter on the sub. This cut out all frequencies below 25hz. The sub was much tighter, less boomy, the tweaters and mids sounded much more natural, and the amps (and charging system) were much less stressed. You rarely heard the sub-bass outside the car, but you stuck your head thru the window and "wow".

Edit: my bad... I forgot about the ghetto band-pass boxes. They sound boomy and are cheap to purchase and power. A favorite of the rap generation.

And you are wrong.

A good sub will not sound boomy at any frequency, whether it be 15Hz or 40Hz.

 

[thorin]

Your Sub @ home sits on a solid floor. Cars are moveable and suspended, not to mention the resonation box a car represents.

 

[Makaveli]

I don't know to much about speakers but am enjoying this Thread keep it going guys.

 

[rstrohkirch]

Originally posted by: mattburk
Most car subs are garbage. Many of them are one note wonders and do not accurately reproduce a large frequency range. Instead of producing a signal with a linear spl from lets say22hz-85hz like a good home theatre sub, they will produce a solid output in lets say the 40-70hz range but not much above that or below that, that is why they seem boomy. A solid enclosure is also important; many car subs do not have an enclosure as they are using the car as the enclosure. If possible it is better to have a solid enclosure built for your sub.

Your statments are silly

There are just as many garage drivers marketed towards home theater as there are towards car audio.

Very few subwoofers in a vehicle use Ib alignments like you mentioned

Your 40-70hz frequency comment is rather invalid as well, as almost all drivers from either side are designed to cover much more then that. Your talking alignments, that's not the subs fault if an improper one is chosen

 

[rstrohkirch]

Originally posted by: Excelsior

Originally posted by: bigboxes

Originally posted by: Excelsior
Car subs are optomized for output in the mid-bass region (over 30hz) and this is the cause of boomy bass. It is often thought that true deep bass causes this, but that is not true.

Sorry, but I think it's the sub-bass (below 25hz) that is the boom you speak of. The reason it's called sub is for sub-hearing (20hz). You feel more than hear. It's that ultra-low bass that travels much farther than normal audio waves. A (sub) bass wave takes 37 feet to mature explaining why it sounds so much louder in your living room than to the idiot sitting at the traffic light. I used to have a sub in my trunk and had a sub-sonic filter on the sub. This cut out all frequencies below 25hz. The sub was much tighter, less boomy, the tweaters and mids sounded much more natural, and the amps (and charging system) were much less stressed. You rarely heard the sub-bass outside the car, but you stuck your head thru the window and "wow".

Edit: my bad... I forgot about the ghetto band-pass boxes. They sound boomy and are cheap to purchase and power. A favorite of the rap generation.

And you are wrong.

A good sub will not sound boomy at any frequency, whether it be 15Hz or 40Hz.

Alignment determines response
A "good" driver could easily have a exaggerated response

 

[Howard]

Originally posted by: rstrohkirch

Originally posted by: Excelsior

Originally posted by: bigboxes

Originally posted by: Excelsior
Car subs are optomized for output in the mid-bass region (over 30hz) and this is the cause of boomy bass. It is often thought that true deep bass causes this, but that is not true.

Sorry, but I think it's the sub-bass (below 25hz) that is the boom you speak of. The reason it's called sub is for sub-hearing (20hz). You feel more than hear. It's that ultra-low bass that travels much farther than normal audio waves. A (sub) bass wave takes 37 feet to mature explaining why it sounds so much louder in your living room than to the idiot sitting at the traffic light. I used to have a sub in my trunk and had a sub-sonic filter on the sub. This cut out all frequencies below 25hz. The sub was much tighter, less boomy, the tweaters and mids sounded much more natural, and the amps (and charging system) were much less stressed. You rarely heard the sub-bass outside the car, but you stuck your head thru the window and "wow".

Edit: my bad... I forgot about the ghetto band-pass boxes. They sound boomy and are cheap to purchase and power. A favorite of the rap generation.

And you are wrong.

A good sub will not sound boomy at any frequency, whether it be 15Hz or 40Hz.

Alignment determines response
A "good" driver could easily have a exaggerated response

He said a good sub, not a good driver.

 

[rstrohkirch]

I am refering to a loudspeaker driver

 

[spikespiegal]

A couple years ago I helped a friend build an 'audiophile' class subwoofer for his home theater system because we didn't like any of the commercial options. The big, commercial subs we heard we're simply too expensive, and didn't have any real impact unless they distorted. We were convinced we could build a better unit from scratch.

We designed the thing around a 15" Adire driver, which is oddly used in both high-end home theater applications and car pro audio. When we finally got the thing built to specs we had a cylindrical enclosure about the size of a 55gallon oil drum tuned to about 16hz free air resonance. We added a generic 700 watt plate amp even though we knew it was over-kill.

Sound quality is amazing. Not only is the beast entirely free of distortion at wall splitting levels and sounds awesome for even classical music, the depth of bass would make a T-Rex run in terror.

I live in 'ghetto-ville' USA, and am treated daily to the best boom trucks and 'boom-chucka-jungle-jumpin-music' money can buy. Trust me, that Adire rig is an order of magnitude lower in bass frequency, can go louder, and far cleaner. I wrote a custom .WAV file that does a low frequency sweep from 0-20hz, and there is no boom truck I've ever heard that can compare to what the Adire does while that WAV file is playing. A boom truck will rattle your windows and door hinges, and otherwise be annoying. The Adire sub while playing the frequency sweep will shake various walls in the house violently as it hits resonance points while your sinus's feel like they are going to explode - and you can't hear a damn thing. We've already stress fractured his front wall, and we never turn the amp up beyond 25%. I'd love to put that Adire rig in my trunk and pull up next to some boom trucks at a stop light and treat them to some *real* bass.

 

[Howard]

Originally posted by: rstrohkirch
I am refering to a loudspeaker driver

I know. But he may not have been.

 

[Minerva]

I never liked "high end" car audio because you basically sit inside the speaker and that's not very ideal for listening to music. I say music as in real acoustic music. If you really want to have an orgasm with techmaster peb blaring from your strokers at 170 dB then have at it. Just stay away from our street.

 

[Excelsior]

Originally posted by: rstrohkirch
I am refering to a loudspeaker driver

I am referring to a subwoofer driver.

 

[Excelsior]

Originally posted by: spikespiegal
A couple years ago I helped a friend build an 'audiophile' class subwoofer for his home theater system because we didn't like any of the commercial options. The big, commercial subs we heard we're simply too expensive, and didn't have any real impact unless they distorted. We were convinced we could build a better unit from scratch.

We designed the thing around a 15" Adire driver, which is oddly used in both high-end home theater applications and car pro audio. When we finally got the thing built to specs we had a cylindrical enclosure about the size of a 55gallon oil drum tuned to about 16hz free air resonance. We added a generic 700 watt plate amp even though we knew it was over-kill.

Sound quality is amazing. Not only is the beast entirely free of distortion at wall splitting levels and sounds awesome for even classical music, the depth of bass would make a T-Rex run in terror.

I live in 'ghetto-ville' USA, and am treated daily to the best boom trucks and 'boom-chucka-jungle-jumpin-music' money can buy. Trust me, that Adire rig is an order of magnitude lower in bass frequency, can go louder, and far cleaner. I wrote a custom .WAV file that does a low frequency sweep from 0-20hz, and there is no boom truck I've ever heard that can compare to what the Adire does while that WAV file is playing. A boom truck will rattle your windows and door hinges, and otherwise be annoying. The Adire sub while playing the frequency sweep will shake various walls in the house violently as it hits resonance points while your sinus's feel like they are going to explode - and you can't hear a damn thing. We've already stress fractured his front wall, and we never turn the amp up beyond 25%. I'd love to put that Adire rig in my trunk and pull up next to some boom trucks at a stop light and treat them to some *real* bass.

This is an example of how true low frequency is not the cause boominess.