# Subwoofer break-in ?



## CortGideon (Jul 19, 2012)

So I watched my 2nd movie with the sub last night and we heard some mysterious "popping" sounds coming from the cabinet. It kind of reminded of wood at a campfire. Every time there was heavy bass from bombs or the like this would happen. The dog jumped out of his seat and ran away, quite funny actually!

Is this normal? I built my cab with 3/4" MDF wood and glued it together. Nothing unusual...


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## Mike P. (Apr 6, 2007)

Either the sub is bottoming out or the amp is clipping. Turn the gain down a bit.


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## CortGideon (Jul 19, 2012)

Whats the difference? Its only halfway right now.... Why would it clip?


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## fusseli (May 1, 2007)

I'm guessing sub bottoming out. What sub/box/amp combo are you running? In the mean time, turning the gain down a bit will solve the problem.


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## CortGideon (Jul 19, 2012)

I've got CSS Trio 12 and PA-500..... the knob was at half-way on the volume, but, I was listening at a -13 db level on my receiver. It was loud... yes. 

Why would it clip if it's only set at halfway? This only happened the one time during the movie. Video games and music have been fine. I'm really confused. It's in a 20" x 18" x 18" sealed cabinet.


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## Mike P. (Apr 6, 2007)

> Why would it clip if it's only set at halfway?



The "volume control" on a plate amp is really a gain control, it is dependent on how strong the voltage is that is coming from the receiver. Receiver output voltage to the subwoofer varies from manufacturer to manufacturer. If a receiver's output voltage is strong, it takes less gain on the plate amp to reach the plate amps maximum output. 

I have a pair of plate amps connected to a Pioneer receiver, the gain controls are set at the 10 o'clock position, any more and the amps will clip.

If your amp is clipping then turn down the gain control a bit, if you are at the 12 o'clock postion then try 11 o'clock, and so forth until the popping sound stops.

And also realize that there is only so much a 12" sealed sub can do. 


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## CortGideon (Jul 19, 2012)

What do you mean sealed? Does that stop it from reaching a potential or something?

I have a port I just don't know how to calculate it. I have a flared port that runs 18" total, when assembled. I was going to start a new thread but maybe you can help me? How long does the port need to be? I need to cut it somehow...


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## Mike P. (Apr 6, 2007)

In post 5 you stated _"It's in a 20" x 18" x 18" sealed cabinet." 
_
OK, we'll figure this out. Are the 20" x 18" x 18" dimensions the external measurements?

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## CortGideon (Jul 19, 2012)

Yes, internal is approx. 16.5" x 16.5" x 17.25" I believe or thereabouts. Definitely not "cnc" accurate cuts lol...


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## Mike P. (Apr 6, 2007)

Do you have a 3" or 4" round port?


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## CortGideon (Jul 19, 2012)

3"


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## Mike P. (Apr 6, 2007)

So how did you get a 18" port in a 16.5" x 16.5" x 17.25" box?


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## CortGideon (Jul 19, 2012)

That's what I was sold... It said on the assembly you need to cut to your own length... I just need to know what my length is :help:


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## CortGideon (Jul 19, 2012)

I haven't installed the port yet... it's just sitting here. I don't know what to cut it too...


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## Mike P. (Apr 6, 2007)

OK, the box IS sealed and you were hearing noises. You have a port and want to install it.

A 3 round port is too small for your sub/amp combination. The port air speed will be way to high. If you install it be prepared for port noise. Depending on what side you mount the port, you need 3" from the end of the port to the back wall.


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## CortGideon (Jul 19, 2012)

Hmmm... too small? The guy that sold me the port also sold me the amp and sub, and knew my cabinet size. In fact, he chose this size for me. I should mention my sub is downward firing.... don't know if that makes a difference. 

I'm really confused.... :huh:


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## Mike P. (Apr 6, 2007)

I have to go fix a water leak in my basement, I'll be back.


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## Tonto (Jun 30, 2007)

I hope it's not dripping onto your screen or projector!


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## Mike P. (Apr 6, 2007)

I'm back. I strongly suggest you don't use a 3" port for your sub, if you want to go ported then exchange it for a 4" port.


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## CortGideon (Jul 19, 2012)

I'm already over-budget on this thing so I don't know... Being a noob, how much of a difference will it sound? I'm not too familiar with subs as I've never owned one. Just wondering if it its going to be worth it and if it will make much of a difference.


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## Mike P. (Apr 6, 2007)

Yellow is what you currently have.

Orange would be if you added a 4" round port 18" long. You would notice more output in the 25-55 hz range.

If your sub is for home theater then you should consider building a bigger cabinet at some point in the future. Your box is currently too small for the driver to produce 20 hz output.


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## CortGideon (Jul 19, 2012)

Are you still designing cabinets? I wrote you awhile back but never heard a response. I'd be interested in getting a ported cabinet for my goods along with a flat pack (in Canada) if possible. Are you making, or will you make, a flat pack?


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## Mike P. (Apr 6, 2007)

I have no messages in my PM box from you, if you emailed me I never got it. I don't do flat packs, you should look around Toronto for wood workers who do that sort of thing. That way there wouldn't be any shipping charges which can add up on heavy flat packs.


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