Subwoofer Ports?

[iidarklaw]

Hi my subwoofer has 2 ports, and I feel like i should block one of the ports. I tried it for a few seconds and the quality sounded better overall. But I'm not sure whether this is a good idea or not?

 

[ryanosaur]

What sub?

If they supplied a bung, then yes, you can. depending on the sub, it might have a switch for changing the EQ/DSP settings.

My subs have 2 ports, plugging one adds more extension, or I can plug both for sealed. They also have such a switch to change the EQ.

 

[Verdinut]

Hi my subwoofer has 2 ports, and I feel like i should block one of the ports. I tried it for a few seconds and the quality sounded better overall. But I'm not sure whether this is a good idea or not?

Blocking one of the ports lowers the tuning frequency of the box, so there is no risk in doing it if you find that your sub performs better in your room. As a matter of fact, your subwoofer driver will accept lower frequencies down to the new fb without risk of being damaged. It should also put out slightly less sound at some frequencies, which I believe is most likely preferable in your listening room, but more SPL at lower frequencies than with the 2 open ports.

 

[iidarklaw]

My subwoofer actually moves less when one port is sealed.

 

[shadyJ]

Unless the sub is designed to run with the option of plugging a port, I wouldn't bother. By plugging the port on a multi ported subwoofer that does NOT have variable tuning, you are lowering the port resonance lower than a point that the amplifier expects. You are also halving the volume that the air vibrates in, and that can lead to port turbulence at much lower levels than is intended. It doesn't really increase extension that much because there will still be electronic filters that cuts off low end output. There isn't any upsides to plugging a port on a sub that is not designed for that.

 

[highfigh]

Hi my subwoofer has 2 ports, and I feel like i should block one of the ports. I tried it for a few seconds and the quality sounded better overall. But I'm not sure whether this is a good idea or not?

Why do you feel this way? The length and diameter are found through calculation, not feelings.

It may have sounded better at that time, with you in that position, but that's not your normal listening position and what you heard isn't what you would have heard from your chair. Assuming the ports are correct, what you're thinking of doing will change the response of the sub enough that it won't do what it was designed to.

FYI- a port is a resonator, which works similar to blowing across the mouth of a bottle- it hits one note. However, that one note is supposed to reinforce the response from the driver in the box so it extends deeper into the bass frequencies. If you block one, your sub won't produce the low notes as well as it originally did, although it's possible that you don't need as much energy in that range.

Check it with this calculator- if you choose a frequency like 36Hz and enter 2 on the box for the number of ports, you'll see the length after clicking on the Calculate button. Change the number to 1 and enter different tuning frequencies, to see when you reach the same length. You'll need to measure your ports for length and diameter.

http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CAL Port lenth 1.htm

 

[ryanosaur]

My subwoofer actually moves less when one port is sealed.

But you still haven't told us what sub you use. Your owners manual will answer your question, too, I'm, sure... we are glad to help as well!