Plugging the port on only one speaker. Go or no-go?

On this episode of Ask The Expert we're going to be looking at whether plugging one port in a speaker pair can cause problems – for speaker performance or for your amplifier.

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On this episode of Ask The Expert, we're going to tackle a couple of questions relating to asymmetrically-shaped and asymmetrically-treated listening spaces, and what might be the result of plugging the port on only one side of a speaker pair.

Both questions answered in this episode are real questions submitted to us by real Dynaudio fans. This is the essence of the Ask The Expert concept, so please keep sending in your thought-provoking questions via the "Send us your questions" form at the bottom of this page, and we'll keep on answering them on future episodes of ATE!


Today's question is a very interesting one, and one of many discussions we've had regarding speaker ports on Ask The Expert, which you can refer to here and here.

My speakers are placed symmetrically in my room, but my room is asymmetric with more bass reinforcement on the left side. If I plug only the left speaker port, I get a more balanced bass output.

However, doesn't the plugged speaker become less efficient than a ported speaker causing a mismatch in the rest of the frequencies?

To answer this question simply, the answer is ‘no’ – you are not going to cause a mismatch in the other frequencies. Plugging a port means decreases the bass output specifically in the area where the port is working typically 200 hertz and below – meaning that frequencies 200 hertz and above aren't going to be affected. There will be no difference, and your speakers will sound the same.

Aside from this, 200 hertz and below is exactly where the room has the most influence on loud speaker performance, and so that's exactly where you would want to correct things.

One way to do this is by utilising this ‘poor mans’ room correction, i.e  by plugging the port on one of the speakers, so that it better matches the other speaker. At the end of the day, if this results in the speakers being more balanced, then that's exactly what you should do. If it sounds better, then often it is better. There are no real drawbacks to this approach.


Does using only one plug at a time present any problem for the amplifier?

A related question, referring to the same approach, but concerning what this plugging of just the one port could mean for the amplifier. The answer is essentially the same: it doesn't make any difference to the amplifier.

Because your amplifier has a channel for each loud speaker –  and the one channel doesn't know what the other channel is doing it doesn't matter that it's a different load that the amplifier is seeing.

To reiterate: the impedance curves will be different from each of the loud speakers, because you've plugged one of them, but it doesn't matter for your amplifier because they are separate channels.

In fact, you could actually argue that the plugged speaker will actually be easier to drive for the amplifier, due to the simpler impedance curve.

Much like the our conclusion regarding the first question: if it works better in your room, if it sounds better in your room, then do it.


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