Use of Speaker Port Plugs?

I notice many rear ported speakers (including my Monitor Audio Silver 300s), come with port plugs. How many of you are using these or have experimented with them?

I recently read that Jeff Joseph of Joseph Audio says most rooms he listens to his speakers in benefit from them. I thought this is especially interesting considering the quality of his speakers and how extremely well reviewed his setups are.

I’ve been playing with them a bit and can indeed hear improvements in instruments/vocal clarity, imaging, and soundstage…especially with the speakers closer to the rear wall. Admittedly, there is a bit of a sacrifice on the low end impact, but boy is the trade off darn near it worth it!

Well - you’ve answered your own question. And correctly. You are essentially changing the LF rolloff curve, and it can make things tighter and less bloated, particularly if you are getting too much reinforcement from the walls/corners.

Ports are a compromise in most cases, a way of extending the bass response beyond what a sealed cabinet of the same volume could deliver. But that added, externally-vented bass can be very interactive with the room. So tuning it to the room/position with plugs can be really helpful.

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Indeed. I was just curious how many people are actually using these plugs. Especially since the potential appears to be so noticeable. And of course I found it very interesting that Jeff Joseph finds them so helpful in most of his set ups. That being said, I wouldn’t be surprised if most people don’t use them.

Makes me wonder if these plugs are a tool primarily beneficial in rooms that haven’t been treated like mine.

I have plugs with my Focals… I don’t use them. Its all about the room… and you can change the LF response by just moving to/from the rear wall… small amounts make big changes.

I always assumed the plugs are more for situations where an owner does not have the freedom to move the speakers around much.

Bruce in Philly

I used to have Monitor Audio speakers which were rear and front ported. I felt the ports gave the bass an undefined, bloated sound. I kept them plugged.
The current owner of those speakers prefers them open, and he knows bass real well, as that’s his profession.


My experience has been that it takes a designer with a real ear and experience in this to do properly tuned ported cabinets. They typically draw attention to themselves, if you’re paying attention - though I would say that most folks just like the “more bass” part, and don’t sweat it as many of us would. At least until they hear tighter, more accurate bass, as with sealed subs.

Reviewers sometimes refer to hearing “chuffing” from a speaker’s bass port. I have not experienced this but I imagine it is annoying.

AKA “farting”. Many cheap HT subs are guilty of this. You can easily (and cheaply) get another octave of LF extension by putting a hole in the box. But how that port is shaped and sized is key. I recall noodling with the tuning by stuffing drinking straws into the hole.

They should bolster midrange at the expense of full low frequency extension. Chuffing and the such is a non issue in properly designed ports. People wonder why a speaker is so expensive. It is just a tube after all? Hundreds of hours went into tuning that tube hopefully. Of course only once and then just minor adjustments. Still, you pay for that. If well designed, it should be seamless. You can tell if it is poorly designed if port bungs make it sound much better. The difference should not be immediately obvious if well designed. It will be there though.

Monitor audio r352s here, somewhat modified.
Front port.
Have tried a well fitted cork bung in them, it tightens the bass and loses the lump around 80Hz, but the woofer cone is very thin and light so using the bung increases mid range distortion from cone breakup.
Partial bung with a pair of socks or some BAF wadding is better, possibly equivalent to the straws mentioned above but not tuned by the straw length.
I decided better without anything and eq the 80Hz bump out, allowing bass extension to go deeper than with the bung.
The bungs turned out to be good for standing speakers on though :slight_smile:

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I have the PSB T3s. I usually waver between plugging 2 or all 3. I have heard immediate improvement in the mid range and the bass is less “tubby”. I may turn my sub up one notch. I am 27 inches away from the back wall. I find the plugs to be sonically very useful. But then again, to each his own.

I’m an open baffle guy- would take a sleighful of socks to close my ports :wink:


Interestingly, Monitor Audio’s manual says the following about the port plugs and their effect on bass: “When fitting port bungs the overall bass extension will not be reduced, however bass energy/ output around the port tuning frequency will be reduced. This has the effect of reducing bass ‘boom’ while increasing bass clarity and apparent agility.”

I have indeed found the “boom” to be reduced with the plugs in, and perhaps this is why I have the impression that the bass is also reduced. Perhaps, too, I’ve just gotten used to listening to “boomy” bass instead of clear and accurate bass. I think more experimenting is in order. Also, each speaker has two plugs, so I also need to experiment with each of this.

There’s no doubt though that when my speakers are closer to the rear wall (approx. 12") the plugs help more than when the speakers are pulled out nearly 4’ for more critical listening.

Further, in my speaker’s instance, the manufacturer made the speakers to be placed closer to the rear walls (like PS seems to be shooting for)…recommending anywhere between 12" and 24" from the rear walls ideally.

I still prefer to pull them further out into the room however (3’ - 4’).

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Sorta wondering about the term “bung”, as over here in the US, I perceive that as a solid Plug you use to fix a hole in a boat (where the rain gets in, and stops my mind from wandering, where it will go…)

I have usually had foam ‘plugs’ with ported speakers, that let some portion of the the outflow of the port breathe through it. Correct me if you’re talking about solidly corking the thing ; )

I was wondering about that too prior to buying the speakers when I read the product literature, but it’s merely a light foam plug.

PSB seems to used these solid plugs in their T3, perhaps winston007 can chime in on that.

They are solid rubber. Nothing breathes through them. Like dbanker mentioned, the “boom” is reduced and gives me the impression, at least to my ears, of a more forward mid range. Personally, it makes vocals “sing”, pun intended.


I had some speakers that benefitted from using port plugs, but didn’t like the trade offs, so I used plastic straws instead of foam plugs. It ended up being the perfect compromise. Tightened the bass and didn’t roll of the lows quite as much. Plus I could fine tune the results, depending on how many straws I placed in the ports.


I may give the straws a try- socks didn’t do it for me;)

You have to use Clean socks.


Merino/silk blend- allows best ease in low to mid transition