Speaker Port Plugs: Could They Solve Bass Issues in Your System?

Today, I'd like to talk a little bit about this thing which is a port plug. And I've covered this topic previously but based on the number of customer calls and emails and things that ask about, "Should I use port plugs? Should I try them? What is it really doing? I don't understand. Why would I want to block a port if you put one in the speaker?"

So I thought maybe a little bit more detail quickly going over why and where you might want to use a port bung and what actually is it doing for you? So basically, you know, when we have a loudspeaker like this M3 here or an M2 for instance that has a port in it, what that port is doing is it's tuned to a specific frequency based on its diameter and its length in conjunction with the volume of air that's in the loudspeaker cabinet.

Now, you can think of the port as another woofer in the system because at a fairly narrow band of bass frequencies, most of the output at that frequency will be from the port, not from the woofer itself. So I think maybe you can understand a little bit if you have a port on the back of a speaker, and for instance, you have to place your speakers let's say very close to your back wall.

That's like having to a certain extent a woofer sitting right up next against the wall, and you know that if you did that with your bookshelf speakers or your floor standers, you can try it if you want, turn them around so that the woofers are pointing at the wall and put them fairly close, you tell me what you're going to hear. And I know the high frequencies are going to go down, but I'm talking about what happens to the bass.

It will pick up, usually in the mid bass and probably sound boomy and overly full and resonant and just muddy up everything else. So because there are situations where you might have to place your speakers, and they could be bookshelf or floor stander or anything like that, that have ports on the back of the cabinet and you have to place them fairly close to the rear wall because of the living situation or aesthetics or whatever, that output from that essentially another woofer in the system, the port, may build up too much bass energy and you'll get that boominess.

And that's a case where you can try using a port plug to block it off. So what happens now is that effectively, that bass information from the port is not going to be getting out the speaker and not interacting with the back wall in the room. Now, if you don't have port plugs, and these are specifically designed shape for our port designs, but a number of manufacturers offer them.

If you don't want to go out and actually buy the port plugs first without knowing if they're going to help you, you can ball up an old sock and put it inside so that it's fairly well sealed. That will at least give you an idea of how the performance at bass frequencies is going to change. Just make sure you don't stuff the thing deep in there so, you know, you have to take the speaker apart to get it out because it's fallen inside.

You don't want that happening. Now, another instance where you may want to try port plugs is you just have, because of your room acoustics and the room notes, and that's a thing that will vary from room to room depending on all of the dimensions of the room, what you have in the room, do you have carpet or do you have hardwood floor, and do you have hard furnishings and hard book cases and things, or they're soft things like upholstered sofas and things like that?

All of those things will impact the bass performance and room modes in your particular room. So it's impossible for us to know as loudspeaker designers exactly what environment our designs are going to go into. So, while we make them measure nice anechoically good smooth bass performance with as much extension as we can get out of a particular design with a particular woofer and a particular cabinet size.

You may find that speaker is boomy in your room or it's a little bit... the bass is drone-y. I think many of you who have experienced it know what I'm talking about here. So it's an easy trick to just stuff a balled up old sock in the ports of your speakers and see. If you think you've got too much bass boom in the room, try that. Now, another thing to point out, if you have a floor-standing speaker, often, you'll have more ports.

You could have two, three, four, however many ports. And you can block one of them, two of them, all of them, it doesn't matter. But the thing to remember is that what happens is that with each port that you're blocking in a multiported speaker system, you're changing the tuning of the entire system.The frequency that that air volume and the ports are going to actually be effective at. So you may find that blocking half of the ports with port plugs gives you the bass performance that you want. Now, one word of caution before I end this video. Because blocking a port in a ported system like this speaker, this bookshelf speaker that only has a single port.

By blocking that port, the system is not ported anymore. It's now behaving as a sealed system. So it has a different bass alignment as it's known. So how the low frequencies will roll out for you. Now, why I'm cautioning you a little bit is that changes the demands placed on the woofer or woofers that are in the system.

And in some cases, what can happen is that if you take a speaker that's designed to be ported and you block it and it's now a sealed cabinet, you're making too much demand on the woofer at some frequencies to now take up the slack and generate bass information that, you know, it wasn't designed for.

So as always with these things, you know, if you're going to test it out quickly, do it at, you know, medium levels. Don't be cranking it up just to get an idea. And then, if you decide that you do want to permanently block those by buying some port plugs, speak to the manufacturer of your loudspeakers and just ask them, "Hey, is it okay if I block the ports on your XYZ model speaker because I find that they work better in my room?"

If you get a thumbs up from them, then you're all good to go. In the case of any of our Axiom products, there's absolutely no problem blocking one or, if they have more ports, all of them or any combination of them. So I hope that that answers, you know, some of the confusion and the questions about port plugs and why you might want to use them. But basically, it's another tool that you have in your arsenal to be able to tune your speaker system to your room.

Thanks for sharing your questions!