I have messed around with home audio a little, but I'm no expert at it. I was wondering how you can get painfully loud home audio bass with a 8 or 6 ohm speakers on a 300 watt amplifier, but in my car I need a 1ohm configuration and 2400 watts.
I know the acoustics are a little different, but there has got to be some other reason. There is no way my car is 8x louder than my home! Otherwise my next project is going to be a 40amp power inverter, and some dennon home theater equiptment in a 98 grand caravan.
Replies (7)
ttocs on 01/16/2007 23:31:19
if you bridge your home audio amp down to 1 ohm, you might get 2400 watts fer a second before you let the smoke out.
Now, is the 300 watt home stereo rated at max power or RMS? The car amp is generally rated at is max power out.
swez on 01/17/2007 09:37:36
A true 300 watts RMS in a HT should deliver pretty solid bass. The trick will be optimizing the bass performance in this room. Consider moving your sub around to various locations and see if you can take advantage of the transfer function of this room to the best possible degree. Corner locations often give the biggest bump, but not always.
One thing you may also have issues with, the preamp output of home gear is often limited to about 0.7 volts @ 0dB reference. (typically) Here, a good gain structure modification, (Crossover/Line Driver) may help bring up the bass as well. This is especially true if you have a separate bass amp for your sub(s).
Comments?
Swez
cplkittle on 01/17/2007 12:39:25
I need to clarify. I kinda jumbled my question up with a comparison.
I'm trying to figure out why my home is almost as loud as my car.
The strange thing is that my home sub is 300watts peak power on a 6 or 8 ohm 10" sub (ported). My car has 2 12" subs on a 2400 watt peak amp at 1 ohm.
My car is 8x more powerful, but not 8x louder. Not that my car isn't that loud, my home is impressively loud.
Victor on 01/17/2007 14:40:24
Did you ever try measuring the SPL of both the systems..??
Probably you may be experiencing a lot of boom in the home audio due to the huge difference in acoustic than a car...
and your questions stating "my car is 8x powerful and not 8x louder"
well, if your home system is say 120db's your car system cannot be 120 x 8 , ever doubling of power you get a 3 db raise meaning a 8X powerful system will only sound 24 db's louder which is only a 20% rise in SPL.
what comes into consideration here is voltage... your car has a 12 volt supply where as your home audio gets a 110 volts supply.. means a smaller amp can give much much more power as compared to car audio. A home audio amp is much different in design and construction than a car audio amp.
Another factor that is to be considered is the sensitivity of your home audio compared to car audio sub..
A good home/pro audio sub can be rated from anywhere between 90db's to a 110 or even 120db's. meaning the sub can play much louder with lesser power, where as car audio subs are generally rated as less as 80db's and some rare ones around 90/95db's.
Also there may be certain spots in your room where u may be experiencing a louder boom as compared to other spots.. the reason being big spans of flat vertical walls which help produce a lot of standing waves, which overlap and rise to acoustically amplify the bass sound.
The wavelength of Bass Freqs are very big and there is a lot of reflection and cancellation in an environment as small as your car.
Try measuring the SPL and lets see what numbers u get there with each system.
Victor....
jamesp on 01/17/2007 15:56:49
Doesnt it take 10 times the power to double the volumne of a given system?..In other words, if you have a head unit that puts out an honest 10wrms..dont you have to amplify that system to 100wrms to double the volumne?
swez on 01/17/2007 17:41:40
If we double the wattage, we gain +3dB.
To double apparent volume, we need a +9dB boost in SPL. It goes like this:
10 watts = 110 dB SPL
20 watts = 113 dB SPL \
40 watts = 116 dB SPL ....+9dB
80 watts = 119 dB SPL /
That's how it works!
Swez
cplkittle on 01/17/2007 17:42:12
I understand that doubling the volume is a 3db increase. It just dosen't seem to scale comparing my home with my car. I also understand that 120vac will run an amplifier cooler than 12vdc because it only takes 1/10 of the amperage.
I guess room acoustics and sensitivity could explain the difference I never thought about the sensitivity.. the difference between 95-110 is 5x volume. I don't have any idea what the sensitivity of the bass driver is. I will look it up.
James, Theoretically double the wattage will double the output if you have not already reached the maximum power handling of the sub.
I know the acoustics are a little different, but there has got to be some other reason. There is no way my car is 8x louder than my home! Otherwise my next project is going to be a 40amp power inverter, and some dennon home theater equiptment in a 98 grand caravan.
Replies (7)
ttocs on 01/16/2007 23:31:19
if you bridge your home audio amp down to 1 ohm, you might get 2400 watts fer a second before you let the smoke out.
Now, is the 300 watt home stereo rated at max power or RMS? The car amp is generally rated at is max power out.
swez on 01/17/2007 09:37:36
A true 300 watts RMS in a HT should deliver pretty solid bass. The trick will be optimizing the bass performance in this room. Consider moving your sub around to various locations and see if you can take advantage of the transfer function of this room to the best possible degree. Corner locations often give the biggest bump, but not always.
One thing you may also have issues with, the preamp output of home gear is often limited to about 0.7 volts @ 0dB reference. (typically) Here, a good gain structure modification, (Crossover/Line Driver) may help bring up the bass as well. This is especially true if you have a separate bass amp for your sub(s).
Comments?
Swez
cplkittle on 01/17/2007 12:39:25
I need to clarify. I kinda jumbled my question up with a comparison.
I'm trying to figure out why my home is almost as loud as my car.
The strange thing is that my home sub is 300watts peak power on a 6 or 8 ohm 10" sub (ported). My car has 2 12" subs on a 2400 watt peak amp at 1 ohm.
My car is 8x more powerful, but not 8x louder. Not that my car isn't that loud, my home is impressively loud.
Victor on 01/17/2007 14:40:24
Did you ever try measuring the SPL of both the systems..??
Probably you may be experiencing a lot of boom in the home audio due to the huge difference in acoustic than a car...
and your questions stating "my car is 8x powerful and not 8x louder"
well, if your home system is say 120db's your car system cannot be 120 x 8 , ever doubling of power you get a 3 db raise meaning a 8X powerful system will only sound 24 db's louder which is only a 20% rise in SPL.
what comes into consideration here is voltage... your car has a 12 volt supply where as your home audio gets a 110 volts supply.. means a smaller amp can give much much more power as compared to car audio. A home audio amp is much different in design and construction than a car audio amp.
Another factor that is to be considered is the sensitivity of your home audio compared to car audio sub..
A good home/pro audio sub can be rated from anywhere between 90db's to a 110 or even 120db's. meaning the sub can play much louder with lesser power, where as car audio subs are generally rated as less as 80db's and some rare ones around 90/95db's.
Also there may be certain spots in your room where u may be experiencing a louder boom as compared to other spots.. the reason being big spans of flat vertical walls which help produce a lot of standing waves, which overlap and rise to acoustically amplify the bass sound.
The wavelength of Bass Freqs are very big and there is a lot of reflection and cancellation in an environment as small as your car.
Try measuring the SPL and lets see what numbers u get there with each system.
Victor....
jamesp on 01/17/2007 15:56:49
Doesnt it take 10 times the power to double the volumne of a given system?..In other words, if you have a head unit that puts out an honest 10wrms..dont you have to amplify that system to 100wrms to double the volumne?
swez on 01/17/2007 17:41:40
If we double the wattage, we gain +3dB.
To double apparent volume, we need a +9dB boost in SPL. It goes like this:
10 watts = 110 dB SPL
20 watts = 113 dB SPL \
40 watts = 116 dB SPL ....+9dB
80 watts = 119 dB SPL /
That's how it works!
Swez
cplkittle on 01/17/2007 17:42:12
I understand that doubling the volume is a 3db increase. It just dosen't seem to scale comparing my home with my car. I also understand that 120vac will run an amplifier cooler than 12vdc because it only takes 1/10 of the amperage.
I guess room acoustics and sensitivity could explain the difference I never thought about the sensitivity.. the difference between 95-110 is 5x volume. I don't have any idea what the sensitivity of the bass driver is. I will look it up.
James, Theoretically double the wattage will double the output if you have not already reached the maximum power handling of the sub.
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