Can I close the port on my subwoofer?

[PashkaTLT]

Hello everyone,

I have huge subs and I love them, but there's some port noise with frequencies < 25 Hz. I tried closing the port just for a minute and the bass becomes weakers but stays clean always, even with 15-20 Hz frequencies.

CanI close the port or it may damage the subwoofer?

 

[Laika2]

I expect you can but you have the manufacturers link in your post with voice and email support. They would have the true answer while many of us will just guess. Is there a issue, do they not answer emails?

 

[antisuck]

I would first consider playing with the "room size" control, turning it more toward "small" no matter what the actual size of your room. This will be a shelving filter that variably reduces the lowest frequencies - it sounds like a bad thing, but if you're getting port chuffing perhaps knocking down the lowest lows will help. Try it at a few different settings and see how it compares to your experience plugging the port.

 

[mhardy6647]

Can you? Sure.
Should you? Probably not.
Two good suggestions from the two previous posters.

 

[Davey]

Can I close the port or it may damage the subwoofer?

Absolutely you can. And it will not damage the subwoofers.
If switching them to closed-box operation gives you a better balanced sound and/or no port noises, I don't see any issue with it at all.

 

[mj30250]

Damage may be unlikely, but you are going to be altering the frequency response and efficiency of the sub in a manner that may not be ideal if the internal DSP is programmed for ported operation. Assuming you are referring to the EV18s, as already mentioned, the Room Size control will attenuate the lower frequencies as you go further towards small, which may resolve the port noise on its own.

 

[PashkaTLT]

Thank you, everyone. I’ve already contacted the manufacturer but haven’t received a response yet, so I decided to ask here in the meantime.

I have a calibration microphone and can recalibrate the subs after closing the port.

My main concern is that I might damage the subs by doing so.

To be honest, I regret not getting sealed subwoofers. I chose ported subs because I didn’t want to sacrifice extra SPL at ultra-low frequencies. However, I didn’t expect port noise on 18" subs to become noticeable so early—below 25 Hz. I was under the impression it would only start around 15–20 Hz.

 

[mj30250]

In looking at the EV cabinet, it's a bit modest on internal volume given the driver size/power. If you're attempting to go loud and low in a large space, you should perhaps consider the TV series, which offers a much larger cabinet. Have you taken measurements and confirmed that the subs aren't positioned in a null that's sucking out the lower frequencies? If you can find a location that allows you to take advantage of room gain, that will help.

 

[PashkaTLT]

In looking at the EV cabinet, it's a bit modest on internal volume given the driver size/power. If you're attempting to go loud and low in a large space, you should perhaps consider the TV series, which offers a much larger cabinet. Have you taken measurements and confirmed that the subs aren't positioned in a null that's sucking out the lower frequencies? If you can find a location that allows you to take advantage of room gain, that will help.

Oh, I thought they had the same cabinet...
It's too late to change anything, though, it will be very expensive to ship them back now.

I've taken measurements and the left sub has a null, but it's at 41 Hz. Fortunately the right sub partly compensates for that null. But thank you for this idea, you're right I could have had a null at ULF.

Btw, I was not entirely correct regarding port noise at < 25 Hz. It, of course, depends on the SPL. At normal SPL, there's no noise. But at high SPL it can appear at < 25 Hz. At SPL above normal but not too high it can appear at 20 Hz for example.

I've played with Room Size knob and also with an EQ (decreased 10 & 20 Hz) and was able to remove or drastically reduce the port noise with either of these options.
Do I understand correctly that reducing SPL at these ULF with the above 2 ways is similar to what I'd get by closing the port?

Here are the measurements with different room size if anyone is interested:

 

[mhardy6647]

However, I didn’t expect port noise on 18" subs to become noticeable so early—below 25 Hz. I was under the impression it would only start around 15–20 Hz.

That depends on the port geometry more than on the driver per se.

 

[egellings]

Can you? Sure.
Should you? Probably not.
Two good suggestions from the two previous posters.

My guess is that if the port is plugged, the back pressure in the cabinet could get quite a bit larger on longer cone excursions because there is no air release with a sealed box.That could stress the driver components to possible failure.

 

[Keith_W]

My guess is that if the port is plugged, the back pressure in the cabinet could get quite a bit larger on longer cone excursions because there is no air release with a sealed box.That could stress the driver components to possible failure.

Not really, if you plug the port, the "air spring" in the cabinet gets quite a bit stiffer - i.e. the Q goes down. It reduces resonance, not increase it.

Lower Q = lowers resonance, better damping, faster bass decay. It also makes the bass roll off more gentle and occur higher up the freq range. The cumulative effect is a lot less bass, both in the time and frequency domain.

In short: there is no harm in plugging ports. It won't damage your driver, but it will give you a lot less bass.

 

[Davey]

Not really, if you plug the port, the "air spring" in the cabinet gets quite a bit stiffer - i.e. the Q goes down. It reduces resonance, not increase it.

Lower Q = lowers resonance, better damping, faster bass decay. It also makes the bass roll off more gentle and occur higher up the freq range. The cumulative effect is a lot less bass, both in the time and frequency domain.

In short: there is no harm in plugging ports. It won't damage your driver, but it will give you a lot less bass.

No, only less bass in the corner area of the roll-off. The sealed-box roll-off rate is actually shallower and the -10db frequency will now be lower than it would be with the vented-box. Even though the -3db frequency is lower with the vented box.

Vented/closed boxes are all about trade-offs. The same 'amount' of bass is still there. It's just rearranged.

 

[mhardy6647]

"We" have a thread

M

'Sealed speakers VS ported'

Oct 11, 2022

An observation from a bass player.

I've noticed that I seem to prefer the bass response on sealed speakers over ported ones.
Bass guitar notes appear tighter , have more texture, definition and notes just appear to be more even sounding through the range of a bass guitar.
With ported designs I always seem to hear some bass notes louder or weaker.

Are ported designs generally less accurate in bass response or have I just not listened to the right speakers?

• Mackie
• Replies: 138
• Forum: Speaker Reviews, Measurements and Discussion

• 

from page 2 of said thread:

Post in thread 'Sealed speakers VS ported'

Oct 11, 2022

I’ll post some examples later of reflex and closed systems eq’er to roughly the same response. You’ll see that the group delay will be equal as well.

So, here is goes. As an example the SB15CAC, closed and BR. Here the frequency response of both (green BR, blue closed):

And the group delay:

Now lets EQ the closed one very close to the BR version:

Close enough...

Now what does the group delay look like:

Well, well, closed does "worse", even though they look the same. Why? because the closed version has a tiny bit steeper downward...

• voodooless

• 

and of course there's that whole "Q" thing (Qtc)

source: https://techtalk.parts-express.com/forum/tech-talk-forum/52859-how-to-pick-a-q-sealed-box

An old, old trick from the heyday of sealed box (not necessarily acoustic suspension!) loudspeakers -- put a too-large woofer in a too-small box. Voila, that nasty-a$$ peak in the neighborhood of 70-100 Hz that people thought was bass...
but I digress (not uncharacteristically).

source: https://forums.stevehoffman.tv/thre...nese-atroicities-of-the-20th-century.1148633/ by way of

'Vintage loudspeaker musing: those boomy 1970s sealed box loudspeakers -- and a suggestion :)'

Mar 6, 2023

I realize that some of y'all are fortunate enough not to remember the 1970s. This thread topic may, or may not, be for you!

I was just reading a thread at audiokarma which contained a link to an "explanation" of sealed (and, by implication, acoustic suspension -- as opposed to other sealed box alignments) vs. ported loudspeakers. I share the link, which, at a quick read, is almost embarrassingly misleading

What is the Difference Between Ported and Sealed Speaker Cabinets?

Ported vs Sealed Speaker Cabinets - Which is best for performance? Depending on the audio setup you have and configuration of your listening space, each speaker type has benefits and drawbacks. We explore the difference between ported and sealed speaker enclosures.

blog.fluance.com

That's not, actually, what this post is about!
But...

• mhardy6647
• Replies: 49
• Forum: Speaker Reviews, Measurements and Discussion

•