Reducing subwoofer boominess - Tilted Forum Project Discussion Community

irseg · 01-12-2005, 02:05 AM

I hooked up a subwoofer for a friend. It's a custom-built bandpass box with 2 JL Audio 10w0's. The box was built by a guy I know who is somewhat of an expert in the field; he built it to JL's recommended specs for the enclosure volume and port size.

However, it sounds very boomy in his car ('98 Vette convertible). It hits hard enough to be rather painful, but it doesn't sound very clean or musical.

What would you guys recommend? I think part of the problem is there is no enclosed trunk and very little sound insulation; it just fires straight into the cabin and bounces off the windshield and dash. I put the box in my car, which has far more sound deadening material, and sounded a lot better.

Are there any subwoofer equalizers on the market that'll flatten out the response curve a bit? Would Dynamat help? I'd really like to get it sounding better, it's too nice of a car to sound like a ghetto blaster!

iamtheone · 01-12-2005, 05:28 AM

I am sure you already tried the first steps of turning down the gain on the amp. Also, adjust the BASS input on the reciever?

irseg · 01-12-2005, 12:01 PM

Yes those help of course, but it still doesn't have a nice tight sound. Then again we were testing it against a sealed box with two 12's, so of course the odds are against it. But I'd still like to see if there's anything that can be done to improve the sound quality.

Shizukana · 01-12-2005, 02:47 PM

Try futzing with the placement... you may try placing it with the speakers facing the rear of the car, so that it bounces off the back glass and into the cabin. If that is too boomy, try sideways or back-to-front (that is, in the very rear of the car with the speakers facing the front of the car).

canuckguy · 01-12-2005, 05:49 PM

an eq would certainly help with the boominess, but i always thought that bandpass boxes were built to produce that boomy sound. i remember reading that they boost the freq that they are tuned to, to help great additional bass for speakers that could otherwise not produce that loud of a sound. i have 4 JL12w0 in a simple sealed box, i don't recall hearing a jl in a bandpass box before. stop by a car stereo place and ask to demo a another box to see if your looking at a function of the box or the car. as cars have a natural boost to certain frequencies. there was a dude who wrote for carstereoreview that had a vette he used for testing and i remember it had a nasty boost to a certain tone.

brandon11983 · 01-13-2005, 12:09 AM

The biggest factor contributing to the boominess is the bandpass box they are in. They are inherently boomy within a certain frequency range and pretty crummy on the rest. Coupled with the fact alone that its a hatchback car adds to this. Also, having used all JL subs before, I can tell you the W0's (their entry level offering) are the least musical of the bunch. If it is an option, see if you can get him into a single 10W6v2, as they are vastly more accurate.

Nelson · 01-13-2005, 09:06 AM

The bandpass box is most likely the culprit. The boominess you are hearing is the inherant gain in the pass band of the enclosure. Most likely the box was tuned with a very narrow pass band that is in the upper freq. range. A parametric EQ would be a descent band-aid, but the best thing to do would be to replace the enclosure.

SteveMcFloyd · 01-19-2005, 03:20 PM

actually, you'd be suprised at how much damage a HUUUGE sub can do to the actual sound. i'm not saying you got ripped off, but the soundwaves that a subwoofer creates have such a long wavelength, thay're sometimes outside of the car before they complete one cycle. if you have a base kick or something, everyone outside your car will hear it but you won't.

same principal goes for when a pilot is flying faster than the speed of sound, and creates a sonic boom, the pilot can't hear it. the sound waves are behind him.

impulse03 · 01-20-2005, 05:48 PM

well these are only 10in subs. even though they are JL audio which is a top of the line brand, these are some of their older subs. I have a 12in W6v2 in my car, and that sounds amazing. Ive never heard the W0s. It may just be the way that the sub hits and you wont be able to do anything about it...

definitely try switching up the box. bandpass boxes are made to give off a much more booming sound. if you want the sub to hit harder, try a sealed box. otherwise give a ported one a shot.

dynamat will certainly help, but it is rather expensive. you would probably want to double layer the trunk to help with insulation, and that can get rather pricy. I dont think it would be worth it to do the doors due to the car being a convertable. you get plenty of roadnoise just from that so I doubt the dynamat change would be noticable.

BoCo · 01-23-2005, 07:04 PM

If you want tight bass, usually a sealed box does the trick. The ports are usually tuned at a certain frequency, and if that happens to be around 60-80Hz, it's going to be very boomy. Research what size sealed box is appropriate for those subs, keep them in their own airspace, and see what happens. Also, if you want an even smaller sealed enclosure, go with 1lb of polyfil per cubic foot and make the box 20% smaller than suggested. It'll play as though it's in the correct size enclosure.

jujueye · 02-14-2005, 09:36 PM

Quote:

Originally Posted by SteveMcFloyd

...but the soundwaves that a subwoofer creates have such a long wavelength, thay're sometimes outside of the car before they complete one cycle.

DING! Correct Answer!!!

While the bandpass portion of the discussion is heading in the right direction, I want to add that the cabin size has just as much to do with the sound of the sub as the sub itself. Below a certain frequency, the sub will do nothing more than pressurize the cabin of the car. As the cabin size gets smaller, the frequency goes up. If the frequency that the bandpass is tuned to is below the frequency at which the cabin is getting pressurized, you will begin losing frequency detail and added boominess.

While those two 10s might look cool and sound cool in this car, something different just might be a better fit. I know years ago Roseanne Barr had a small fleet of 8s in her Viper... The point is: the size of the room (or cabin) that speakers fire into is quite important.

I'm with some of the others: since the box has already been built, try sealing the ports first and give it a try. Or, have a sealed box built for them before giving up.

01-12-2005, 02:05 AM	#1 (permalink)
irseg Junkie Location: Florida	Reducing subwoofer boominess I hooked up a subwoofer for a friend. It's a custom-built bandpass box with 2 JL Audio 10w0's. The box was built by a guy I know who is somewhat of an expert in the field; he built it to JL's recommended specs for the enclosure volume and port size. However, it sounds very boomy in his car ('98 Vette convertible). It hits hard enough to be rather painful, but it doesn't sound very clean or musical. What would you guys recommend? I think part of the problem is there is no enclosed trunk and very little sound insulation; it just fires straight into the cabin and bounces off the windshield and dash. I put the box in my car, which has far more sound deadening material, and sounded a lot better. Are there any subwoofer equalizers on the market that'll flatten out the response curve a bit? Would Dynamat help? I'd really like to get it sounding better, it's too nice of a car to sound like a ghetto blaster!

01-12-2005, 05:28 AM	#2 (permalink)
iamtheone Psychoholic Location: Ein tov she'ein bo ra!	I am sure you already tried the first steps of turning down the gain on the amp. Also, adjust the BASS input on the reciever? __________________ Music is holy, art is sacred, and creativity is power... Think for Yourself Question Authority

01-12-2005, 02:47 PM	#4 (permalink)
Shizukana Insane Location: Plano, TX	Try futzing with the placement... you may try placing it with the speakers facing the rear of the car, so that it bounces off the back glass and into the cabin. If that is too boomy, try sideways or back-to-front (that is, in the very rear of the car with the speakers facing the front of the car). __________________ "The power of accurate observation is frequently called cynicism by those who don't have it." - George Bernard Shaw

01-13-2005, 12:09 AM	#6 (permalink)
brandon11983 Stereophonic Location: Chitown!!	The biggest factor contributing to the boominess is the bandpass box they are in. They are inherently boomy within a certain frequency range and pretty crummy on the rest. Coupled with the fact alone that its a hatchback car adds to this. Also, having used all JL subs before, I can tell you the W0's (their entry level offering) are the least musical of the bunch. If it is an option, see if you can get him into a single 10W6v2, as they are vastly more accurate. __________________ Well behaved women rarely make history.

01-13-2005, 09:06 AM	#7 (permalink)
Nelson Tilted	The bandpass box is most likely the culprit. The boominess you are hearing is the inherant gain in the pass band of the enclosure. Most likely the box was tuned with a very narrow pass band that is in the upper freq. range. A parametric EQ would be a descent band-aid, but the best thing to do would be to replace the enclosure. __________________ Nelson

01-12-2005, 12:01 PM	#3 (permalink)
irseg Junkie Location: Florida	Yes those help of course, but it still doesn't have a nice tight sound. Then again we were testing it against a sealed box with two 12's, so of course the odds are against it. But I'd still like to see if there's anything that can be done to improve the sound quality.

01-12-2005, 05:49 PM	#5 (permalink)
canuckguy I read your emails. Location: earth	an eq would certainly help with the boominess, but i always thought that bandpass boxes were built to produce that boomy sound. i remember reading that they boost the freq that they are tuned to, to help great additional bass for speakers that could otherwise not produce that loud of a sound. i have 4 JL12w0 in a simple sealed box, i don't recall hearing a jl in a bandpass box before. stop by a car stereo place and ask to demo a another box to see if your looking at a function of the box or the car. as cars have a natural boost to certain frequencies. there was a dude who wrote for carstereoreview that had a vette he used for testing and i remember it had a nasty boost to a certain tone.

01-19-2005, 03:20 PM	#8 (permalink)
SteveMcFloyd Upright	actually, you'd be suprised at how much damage a HUUUGE sub can do to the actual sound. i'm not saying you got ripped off, but the soundwaves that a subwoofer creates have such a long wavelength, thay're sometimes outside of the car before they complete one cycle. if you have a base kick or something, everyone outside your car will hear it but you won't. same principal goes for when a pilot is flying faster than the speed of sound, and creates a sonic boom, the pilot can't hear it. the sound waves are behind him.

01-20-2005, 05:48 PM	#9 (permalink)
impulse03 Crazy	well these are only 10in subs. even though they are JL audio which is a top of the line brand, these are some of their older subs. I have a 12in W6v2 in my car, and that sounds amazing. Ive never heard the W0s. It may just be the way that the sub hits and you wont be able to do anything about it... definitely try switching up the box. bandpass boxes are made to give off a much more booming sound. if you want the sub to hit harder, try a sealed box. otherwise give a ported one a shot. dynamat will certainly help, but it is rather expensive. you would probably want to double layer the trunk to help with insulation, and that can get rather pricy. I dont think it would be worth it to do the doors due to the car being a convertable. you get plenty of roadnoise just from that so I doubt the dynamat change would be noticable.

01-23-2005, 07:04 PM	#10 (permalink)
BoCo Fear the bunny Location: Hanging off the tip of the Right Wing	If you want tight bass, usually a sealed box does the trick. The ports are usually tuned at a certain frequency, and if that happens to be around 60-80Hz, it's going to be very boomy. Research what size sealed box is appropriate for those subs, keep them in their own airspace, and see what happens. Also, if you want an even smaller sealed enclosure, go with 1lb of polyfil per cubic foot and make the box 20% smaller than suggested. It'll play as though it's in the correct size enclosure. __________________ Activism is a way for useless people to feel important.