I am having some subwoofer problems

**durwood** · 11-07-2006, 01:20 PM

I was curious about the sound going away when you hit a bump. That part might be a connection problem or ground problem and your amp turns off. the other problem is that if your speaker is in a sealed box (no venting or ports) then any tiny airleak can cause whistling.

You can still repair the dust cap if that has a hole in it but if its leaking from around the surround or where the sub meats the box then it is not sealed properly. Sealled boxes need to be completely sealed. If you ahve wires coming directly out of the box, then that must be sealed too.

In a properly sealed box, if you carefully push on the speaker cone and let go, then the speaker should slowly return to its resting postion. If there is no "spring" or seal then it will return very quickly resulting in poor performance from your box.

**furball69** · 11-07-2006, 02:56 PM

Originally Posted by durwood

In a properly sealed box, if you carefully push on the speaker cone and let go, then the speaker should slowly return to its resting postion. If there is no "spring" or seal then it will return very quickly resulting in poor performance from your box.

Hmm, I've seen someone else state that as well, but I disagree. First of all, it's contradictory. If there IS a perfect seal, the cone should return to it's resting position very quickly.

Don't believe me? Go find a basket ball, squeeze it, your finger indentations disappear immediately after you stop squeezing, now put a hole in the ball and try again.

**durwood** · 11-07-2006, 03:23 PM

Originally Posted by furball69

Hmm, I've seen someone else state that as well, but I disagree. First of all, it's contradictory. If there IS a perfect seal, the cone should return to it's resting position very quickly.

Don't believe me? Go find a basket ball, squeeze it, your finger indentations disappear immediately after you stop squeezing, now put a hole in the ball and try again.

You are correct about a basketball. Let me clarify my statement.
A speaker box is slightly different. There will always be some air leakage from the surround (if its foam), the screws, etc. A speaker compresses air. IF YOU CAN MANGAGE TO PUSH THE CONE IN THEN IT WILL RETURN SLOWLY WITH A GOOD SEAL. IF you can push the speaker in with ease and it returns fast then that is bad...similar to being in free air.

**Mikdiz** · 11-07-2006, 03:58 PM

Okay then, I will patch up the hole and check out the back of the box - where the positive and negative wires connect. And I will also switch the ground to a new place and see if that helps. Thanks for such quick responses!

**furball69** · 11-07-2006, 06:01 PM

Originally Posted by durwood

You are correct about a basketball. Let me clarify my statement.
A speaker box is slightly different. There will always be some air leakage from the surround (if its foam), the screws, etc.

I disagree; maybe you are used to shoddy workmanship or materials... I am not.

Originally Posted by durwood

A speaker compresses air. IF YOU CAN MANGAGE TO PUSH THE CONE IN THEN IT WILL RETURN SLOWLY WITH A GOOD SEAL. IF you can push the speaker in with ease and it returns fast then that is bad...similar to being in free air.

YOu are correct about a speaker compressing air. My boxes are sealed, the cone can be pushed in, slightly, and they spring back to position immediately.

**durwood** · 11-07-2006, 06:52 PM

Originally Posted by furball69

I disagree; maybe you are used to shoddy workmanship or materials... I am not.

**furball69** · 11-07-2006, 07:11 PM

heh.

I realized where I read your statement before... from Dan Marx's page: http://www.danmarx.org/audioinnovation/servosub.html

An air tight seal is essential. This can be checked by pressing in the cone and then watching how fast the cone moves back up to its rest position. Our cone sure enough took about 3 seconds to return so we were definite we had a good sealed box.

I emailed dan, last year, about the error but it's not likely he'll change that page, since it is a direct quote from a magazine.

If you read the quote, I fail to see the logic behind that statement. Something that's supposed to be sealed, and pressing the cone, which compresses the air inside the box, that compressed air should react immediately when you release and there shouldn't be any extended period for the cone to return to normal position. That would mean there is a slow leak adn the air is slowly leaking back into the box.

BTW, Dan replied and admited to building leaky boxes.

**durwood** · 11-07-2006, 07:16 PM

Congrats!

Let's leave it at this then:

Hard to press speaker in and returns to postion quickly = Super sealed box
Hard to press speaker in but returns slowly = Sealed box with possible minor airleak
Easy to press speaker in and returns to postion quickly = Poorly sealed box

**furball69** · 11-07-2006, 07:25 PM

Cool!

**Mikdiz** · 11-09-2006, 07:25 PM

Thanks for your help! I took a look at the back of the sub box and saw that the connector where the pos and neg wires go was starting to fall in. I simply popped it back out with a screwdriver and no more noise! YAY! If I have anymore problems, I'll be sure to come back here.