Wanted: Little Known Secrets To Increase SPL

hey, i was wondering besides the basics ive covered how one could achieve greater spl , say from a basic system ie, h/u, outboard electronic x-over, cap, bridged amp, and heavy ga. wiring, optimum box design,sound proofing enviroment is there any thing else that would produce more spl that i may need to know? i realize i could remove some componets perhaps ,and achieve better sq maybe,but is there anything else anybody could suggest? all advice welcomed . thanks

You covered sound proofing, but more importantly sound deadening. ie. make the panels rock solid so no energy is used in flexing them. thats roof, door skins, boot, etc. remove soft seats which can absorb some energy too.

do you really have the optimum box design? ported to the right frequency for that subwoofer and car combination?  the maths behind setting up a box for max SPL is pretty major. work out the frequency the car is loudest at, calculate the wavelength, set the box so the speaker is the right distance from the mic. every speaker will be different.

here's a few rules-of-thumb you probably don't know.

double the power gives +3dB

add extra sub gives +6dB

a good box gives +6dB

the car itself can add a few.

-------------
2001 Ford Fairmont
Alpine DVD, screen,
5.1surround processor,
5ch Class-T amp, TV tuner
and centre channel.
Focal 3way Utopia splits.
VDO navigation. Stinger cap.
Soundstream Exact subs.

audio control line drivers can increase spl ,also running 14.4 volts constant,having your subs fire toward your front windshield as close as possible can also help .i have 6 15"jls in my truck in the bed  once i made a wall firing at the front window it increased my spl by 10dc.it also had a cap on it  if you were wondering

is your box ported?  is it round ports?  if so make it a slot port that will help alot too

-------------

eargasm might be a bit a bit optimistic on the numbers, adding a second sub only adds 3 db of gain. This of course isn't an automatic gain. Distances between drivers can cause gain or losses at certain frequencies. Some types of boxes, band-pass for instance, can add 3 db of gain. 6 db from just the box? let me know how! The vehicle gain or "cabin gain" can boost output, but not always the frequencies you want!

To make sound, you must move air! physics!

REMEMBER: If you blow your ears, you can't get them reconed!

-------------

When you look to buy speakers look for high sensitivity ratings. If you can find a driver(s) with a rating of say 92 + you need less power to achieve volume. Rockford Woofers for instance require huge amps because the speaker is 86db. Not very efficient! More Amps, more current, just to make up for a heavy cone and VC so the woofer fits in a smaller box. There are always tradeoffs.

I have known a few competitors to use pro sound drivers, some 101 db @ 1W/1M, in the 50W power class and still reach 120 db. Not magic!

audiocableguy wrote:

---

eargasm might be a bit a bit optimistic on the numbers, adding a second sub only adds 3 db of gain.

---

I think the implied assumption here is that you're adding a second sub AND providing it with the same amount of power as the first sub.  You're right, just doubling the cone area alone would only give you +3dB, but doubling the cone area *and* the power is probably where Eargasm is getting the +6db.

Scott Gardner

yeah, the sensitivity is an important one. for the same final dB reading, a sub rated at 88dB sensitivity needs twice the power of a sub rated 91dB sensitivity.

this can take some time, but theory goes you put a sub in a basic box and measure its spl performance over a range of frequencies while running in open air. then measure over the same frequencies in the car. you will notice that in the car there will be higher readings, usually with a bit of a peak. thats the cars resonant frequency and if you can find a sub that has a similar tuning frequency, and tune your box and port to that frequency, it gets you a long way towards a high SPL figure coz everything is working together.

had a guy near here win an SPL shootout with 2 8inch subs. just gotta put it all together right.

-------------
2001 Ford Fairmont
Alpine DVD, screen,
5.1surround processor,
5ch Class-T amp, TV tuner
and centre channel.
Focal 3way Utopia splits.
VDO navigation. Stinger cap.
Soundstream Exact subs.

P.S. you can check but i believe the rule is the subs must be behind the "B" pillar.

-------------
2001 Ford Fairmont
Alpine DVD, screen,
5.1surround processor,
5ch Class-T amp, TV tuner
and centre channel.
Focal 3way Utopia splits.
VDO navigation. Stinger cap.
Soundstream Exact subs.

 fantastic ! thank all of you folks for the very informed replies ,  truly proffesional .