Sub Install Question...Need Some Help
Thread Starter
Burning Brakes
Joined: Sep 2001
Posts: 1,091
Likes: 0
From: Ellicott City MD
St. Jude Donor '05
Sub Install Question...Need Some Help
Hey,
Got a question....when you install a sub what happens when you dont have the sub in a air tight place?
The place I have my subs in now isnt exaclty bolted down and the hole for the subs was cut a little bigger than it is. So it isnt a air tight seal.....will this hurt the sub or just hurt the sound?
Got a question....when you install a sub what happens when you dont have the sub in a air tight place?
The place I have my subs in now isnt exaclty bolted down and the hole for the subs was cut a little bigger than it is. So it isnt a air tight seal.....will this hurt the sub or just hurt the sound?
Instructor
Joined: Apr 2002
Posts: 237
Likes: 0
From: Plano TX
Re: Sub Install Question...Need Some Help (USMUSCL)
I don't know about hurting the sub, but it will sound like crap if the box isn't sealed very well. I bought an Image Dynamic Sub without every hearing it, just because I heard such good things about it. I made a stealth type box and dropped in the sub before I sealed the box with liquid nail, I was so excited I didn't want to wait. There were a few small air leaks, and one big one where the boards were angled together. I was very dissappointed and even mad at the sound quality when I first hooked it up. I didn't know that making a box air tight was so important. After I filled in all the cracks I was blown away. It sounds ten times better, I am not exageratiing.
Racer
Joined: Oct 2002
Posts: 452
Likes: 158
From: Newark, DE
Re: Sub Install Question...Need Some Help (lofarris)
He's right. The whole point of building a box is that it HAS to be air tight. The pressure of the air inside the box acts like a damper for the sub. You probably won't damage the driver, but if it was me, I wouldn't run it at anything near the rated power without having it in the box. Down around the resonant frequency there is a slight possibility that you could damage the driver.
GO JACKETS!! (just saw your avatar)
[Modified by GTLocke13, 10:02 AM 11/6/2002]
GO JACKETS!! (just saw your avatar)
[Modified by GTLocke13, 10:02 AM 11/6/2002]
Safety Car
Joined: Jul 2001
Posts: 4,178
Likes: 2
From: Windermere FL
Re: Sub Install Question...Need Some Help (GTLocke13)
Reprocussions:
1. Loss of performance
The box needs to be air tight for two reasons if you are making or the sub requires a sealed box. The point of the box is to seperate the air in contact with the front of the woofer from the air on the rear of the woofer. If you don't do this, the negative waves caused by the rear of the cone can offset the positive waves coming out the front. Kinda like trying to push something(in this case air) with roller skates on. If you port the box, you set up a specific amount of air that escapes the box at a certain frequency with a port that is tuned to that frequency. This will increase your performance for a certain frequency but the rest of the bass will suffer.
You will also loose performance because you have no negative pressure behind the woofer. In a sealed box, when the woofer pushes out, it creates a partial vacuum behind the woofer that pulls back on it. This increases the speed back to its rest position and allows you to fire another wave immediately. This will result in you being able to generate tigher cleaner sounding bass than in a non-sealed box.
2. This vacuum effect, rather the lack of it, can also damage woofers. If a woofer is designed to work with this effect, and it isn't present, it can allow the woofer to push out to far, damaging the voice coils, etc. This is a very easy and common way to blow a woofer. You also need to have the proper volume of air in the box to create the correct amount of back pressure, etc. so make sure you design a box that meets the makers specs. Hope this gives you some easy to understand insight as to the issues and problems you are addressing.
1. Loss of performance
The box needs to be air tight for two reasons if you are making or the sub requires a sealed box. The point of the box is to seperate the air in contact with the front of the woofer from the air on the rear of the woofer. If you don't do this, the negative waves caused by the rear of the cone can offset the positive waves coming out the front. Kinda like trying to push something(in this case air) with roller skates on. If you port the box, you set up a specific amount of air that escapes the box at a certain frequency with a port that is tuned to that frequency. This will increase your performance for a certain frequency but the rest of the bass will suffer.
You will also loose performance because you have no negative pressure behind the woofer. In a sealed box, when the woofer pushes out, it creates a partial vacuum behind the woofer that pulls back on it. This increases the speed back to its rest position and allows you to fire another wave immediately. This will result in you being able to generate tigher cleaner sounding bass than in a non-sealed box.
2. This vacuum effect, rather the lack of it, can also damage woofers. If a woofer is designed to work with this effect, and it isn't present, it can allow the woofer to push out to far, damaging the voice coils, etc. This is a very easy and common way to blow a woofer. You also need to have the proper volume of air in the box to create the correct amount of back pressure, etc. so make sure you design a box that meets the makers specs. Hope this gives you some easy to understand insight as to the issues and problems you are addressing.
