Eva said:
In other words: "Upgrade the entire beast, don't forget or mess anything. + Disclaimer "
...Eva: You state not to be an real engineer, but usually give quite profund answers... and now suddenly a disclaimer..
...hm, my new assumption: You have been engineer, before you
noticed that lawyers earn more... and changed profession.
Now you have money and time to do the electronics you want.
Hi, Astro Power,
If I may, I will give my view.
The most loudest is 2x12", with this you can get the right box volume, and pick up subwoofer with large surround rubber, big Xmax, big power handling.
Try to get the tuning like in my earlier post. Build a properly volumed box for your system (like for 2x12" or 1x15"), put it in your car in its fixed positon, but do not play it on. You put another box of woofer, sealed, and sweep from 30hz-100hz to find the tuning of your car system, in the condition of box installed. Once you get the loudest frequency (maybe 43hz, maybe 55hz, I dont know), you use BoxCad to make ported box with that volume for that woofer. Choose the port area as big as possible, so your box will look like a tunnel. This is the loudest box. Once you get the final measurement, you do final readjust by sliding the port to make minor frequency adjustment.
Hope you win
If I may, I will give my view.
I've done this, putting 2x15" sub in car. It NEVER works. Why? because you will never get the appropriate box, even it is hard for 1x15" in car cabin. The tuning will be too high and not loud enough. Properly volumed 12" will give SPL much-much louder than not-properly volumed 15" box, although the surface area is smaller.
The most loudest is 2x12", with this you can get the right box volume, and pick up subwoofer with large surround rubber, big Xmax, big power handling.
This is the typical thinking of SPL contestant. I used to think this way too in the earlier times. I wanted to FORCE a certain tuning frequency to the car. Why? Because in BoxCad, I can get great result with my box design. Again it will NEVER works. Why? You cannot force the system (car + sub box) to behave in the frequency that you want. It is "you" that has to follow what frequency your system wants, not the car system has to follow "you".
Try to get the tuning like in my earlier post. Build a properly volumed box for your system (like for 2x12" or 1x15"), put it in your car in its fixed positon, but do not play it on. You put another box of woofer, sealed, and sweep from 30hz-100hz to find the tuning of your car system, in the condition of box installed. Once you get the loudest frequency (maybe 43hz, maybe 55hz, I dont know), you use BoxCad to make ported box with that volume for that woofer. Choose the port area as big as possible, so your box will look like a tunnel. This is the loudest box. Once you get the final measurement, you do final readjust by sliding the port to make minor frequency adjustment.
Hope you win
BoxCad is any program for designing subwoofer box. There are so many of them. You can look in subwoofer forum.
If you push the frequency that is not the tuning frequency that the car wants, it is like pouring water into the pool. You will never add significant dB until your voice coil burns up, no matter how much power you put into that sub.
If you get the exact tuning of the system + your box, you can play 1000's of watt without damaging anything.
There are so many of them. You can look in subwoofer forum. If you push the frequency that is not the tuning frequency that the car wants, it is like pouring water into the pool. You will never add significant dB until your voice coil burns up, no matter how much power you put into that sub.
If you get the exact tuning of the system + your box, you can play 1000's of watt without damaging anything.
Eva:
...companies should lick fingers to get employees with
your skill set, no matter which paper degree or non degree..
crazy europe!
car spl:
...just wondering about what I am reading....
do i understand correct?
The goal is to produce max sound pressure level at a frequency that
you can choose...?
So people are searching the most dominant resonance of the car cabin
and the adjust their speaker system to this... and during the contest you play this special tone as loud as you can??
...companies should lick fingers to get employees with
your skill set, no matter which paper degree or non degree..
crazy europe!
car spl:
...just wondering about what I am reading....
do i understand correct?
The goal is to produce max sound pressure level at a frequency that
you can choose...?
So people are searching the most dominant resonance of the car cabin
and the adjust their speaker system to this... and during the contest you play this special tone as loud as you can??
I have to agree with Anatech
6x 15Inch JL Audio's in an Opel Kadette.
Standing outside the car - our clothes were being blown around. I cannot understand dudes who love sound so much they will destroy their hearing for it.
Astro Power - Maybe you hope it is so loud it will blow your girlfriends clothes off. Well good luck.
lumanauw - In this sort of case - wouldn't a narrow band - bandpass enclosure produce higher SPL's (Only in its limited tuned range though)?
6x 15Inch JL Audio's in an Opel Kadette.
Standing outside the car - our clothes were being blown around. I cannot understand dudes who love sound so much they will destroy their hearing for it.
Astro Power - Maybe you hope it is so loud it will blow your girlfriends clothes off
. Well good luck.lumanauw - In this sort of case - wouldn't a narrow band - bandpass enclosure produce higher SPL's (Only in its limited tuned range though)?
Hi, ChocoHolic,
Hi, Chris,
. And the manufacturer is also adding fuel to this. Former Rockford Fosgate's creating dB Drag SPL competition, and with TV show ! And some of SPL contest here have a brand new CAR for the champion of the SPL contest.
Putting a sealed/ported SPL box in car cabin is actually making a bandpass box, if you view the whole box+cabin as one system. And actually, when you are measuring car's SPL, you are actually measuring the SPL "inside" a bandpass box. Like putting the microphone inside a box. So this is another secret. It is how to make the microphone sees louder SPL "inside" the box, not "outside" the box.
AstroPower, I think if you look in CarAudio Forum, you can get more information about this. I haven't touch SPL for a long time now.
That is exactly what is happening in the SPL contest. You follow the nature frequency that your car/system wants and boost in that 1 frequency with test tone (square wave is more evil here) with 1000's of watts.
Hi, Chris,
He..he.. you are right. Majority of people dislikes SPL or SPL contest. They are annoying the neightbourhood. I don't know why, some people take this with their life. I have a friend who is SPL champion, no.5 in world ranking, he said he dreams about subwoofer box which is louder. And when there is a big SPL contest coming up, he rerely sleep in 2 weeks, every second thinking how to make his car louder. How bad is that
. And the manufacturer is also adding fuel to this. Former Rockford Fosgate's creating dB Drag SPL competition, and with TV show ! And some of SPL contest here have a brand new CAR for the champion of the SPL contest. I'm afraid this can never work in car. I've tried this. The tuning of a bandpass when you tuned outside a car will shift quite a lot when you put the same box in the car. It is because the car's cabin is forming a very finite/small enclosure. The bandpass box sees the car's cabin as a part of resonance chamber, and shifts it's tuning frequency alot.
Putting a sealed/ported SPL box in car cabin is actually making a bandpass box, if you view the whole box+cabin as one system. And actually, when you are measuring car's SPL, you are actually measuring the SPL "inside" a bandpass box. Like putting the microphone inside a box. So this is another secret. It is how to make the microphone sees louder SPL "inside" the box, not "outside" the box.
There is no Sound Quality here. In SPL contest, they only play 1 tone with test tone. And the driver is not inside the car, he play it outside the car. They do not hear what its like inside the car. Crazy, eh...
AstroPower, I think if you look in CarAudio Forum, you can get more information about this. I haven't touch SPL for a long time now.
There are ways to make 4th and 6th order bandpass enclosures to sound nice inside a car, but such designs have nothing to do with commercial enclosures. Some requierments are:
- Designing the box with the cabin acoustics in mind (it should show a smooth low-frequency rolloff in excess of 6dB/oct across its passband so it won't be flat at all outside the car, altough placing it in a corner of a room flattens it a lot).
- Using an oversized front chamber tuned high (around 100Hz) and and undersized rear chamber tuned low (around 35Hz) with little or no gain over a closed chamber.
- Avoiding paralell walls.
- Tuning the box inside the car with an adjustable frequency generator while checking cone displacement with a finger (duct lengths inside a car are always smaller than predicted so manual tuning is a must).
- Leading reflex ducts to the cabin while mantaining its expected tuning frequency (this imposes a lot of limitations on chamber layout). Note that tuning a big front chamber to 100Hz requires a wide and very short duct, I've even used ducts with 20cm diameter.
On the other hand, no commercial bandpass enclosure meets that criteria, altough most of them improve a lot by just raising the tuning of the front chamber to approx. 80..90Hz.
- Designing the box with the cabin acoustics in mind (it should show a smooth low-frequency rolloff in excess of 6dB/oct across its passband so it won't be flat at all outside the car, altough placing it in a corner of a room flattens it a lot).
- Using an oversized front chamber tuned high (around 100Hz) and and undersized rear chamber tuned low (around 35Hz) with little or no gain over a closed chamber.
- Avoiding paralell walls.
- Tuning the box inside the car with an adjustable frequency generator while checking cone displacement with a finger (duct lengths inside a car are always smaller than predicted so manual tuning is a must).
- Leading reflex ducts to the cabin while mantaining its expected tuning frequency (this imposes a lot of limitations on chamber layout). Note that tuning a big front chamber to 100Hz requires a wide and very short duct, I've even used ducts with 20cm diameter.
On the other hand, no commercial bandpass enclosure meets that criteria, altough most of them improve a lot by just raising the tuning of the front chamber to approx. 80..90Hz.
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