Slot Port vs Round Port

For some DIYers and audiophiles, they are very particular on which port shape is been used for the speakers. Why are they so focus on the speakers’ port, shouldn’t the speaker drivers be enough to produce high sound quality. Does using either slot or round ports can make a real difference in that area.

The speaker’s port does actually matter and will affect your listening experience if it is not implemented properly. I have a friend who is a DIYer, was rushing to complete his project, and in his haste, he sloppily tuned the port and now he needs to spend even more time to rebuild it. In this article, slot port vs round port, we shall find out which shape is the better choice or are they both equally matched.

Speaker Ports Explained

Speaker ports are also known as reflex port, bass reflex, and vented. These ports are used to increase the efficiency of the speaker at low frequencies than those that are sealed or closed boxes. It will look like a hole either situated at the front or back of the speaker enclosure, or for some cases, located below the speakers which are called a downward-firing port.

Still, there are other advantages due to its’ efficiency such as it could help you save on amp power because the reflex port will increase the bass output by about 3 dB when comparing to a sealed speaker enclosure.

Even though it helps to increase the bass response and enabling it to go lower in the low-frequency region, thus making it more efficient but there is a downside to ported speakers. Less accurate bass notes maybe reproduce and you may get a more boomy bass sound instead of the natural reproduction of the low notes. Another downside will be the speaker placement, especially for the rear-ported speaker enclosure design. When placing too near to the back wall, it will reinforce the bass, making your speaker sound too bassy.

Round Ports for your Enclosure Design

Round ports are more widely used by DIYers due to the simplicity of integrating them into the speaker enclosures. There are the diameter and the length of the port, harder to miscalculate them in your overall design with such a straightforward measurement. They also come in many ready-made sizes. It has the least internal surface per unit volume which means lesser air friction than slots.

Round Speaker Ports

The downside to this simplicity will be the port noises which are the chuffing sound made by air trying to be pushed in and out of the port that it can really handle. I used to own a downward-firing subwoofer with a bass reflex port at the back, the air chuffing sound never fails to ruin my movie-watching experience. This is why is not recommended to use round ports when the port air velocity is fairly high.

You can increase the port size to overcome this but you still need to make them long enough for tuning. Integrating additional ports will help as well. Even so, these will affect the overall design of your speaker.

Slot / Duct Ports for your Enclosure Design

Slot ports are usually used when you need to implement a very long port into a small speaker enclosure as it requires lesser tuning. It is because of its unique L bend design that makes it easier to integrate into most speaker enclosures. Slots have lower port noises since you can easily make them big enough to avoid this issue. The sound quality is usually better than the round ports.

Slot Ports

This is an amazing asset for speaker designers and DIYers as you can make smaller speaker enclosures that can fit into most modern homes. Able to accommodate most speakers’ designs, make it look more aesthetically pleasing and visually appealing.

The drawback will be for inexperienced DIYers especially, as one wrong measurement or cut when creating the “L-Port” will totally ruin your speaker thus forcing you to redo the whole thing again.

There is a unique drawback of slot port which can be beneficial at the same time. Due to the larger surface area, it will have increased air friction which means lesser efficiency. But due to the increase of air friction, this indirectly dampens any unwanted cone excursions below the tuning frequency thus in the end, it could be a blessing in disguise. Furthermore, this improves the quality of the bass.

In Conclusion

For DIYers, slot ports is a winner as it has slightly more pros and lesser cons than the round ports. Even so, the skill level of the builder plays a major role as at the hands of an expert, either slot can be better than the other. But for inexperienced DIYers, they should opt for a round port due to the ease of incorporating it into the speaker enclosure. The overall speaker design and its various drivers are also great influencers to which type of slots you will use as well.

For audiophiles, you should not be too focus on this aspect of the speakers as mentioned earlier, there are other parts of the speaker that are crucial in the sound quality as well. Be it round or slot/duct ports, unless you really like the visual appearance of either, then go for it. If it is the sound quality that you are after then you must audition them yourself. Another important thing to consider will be the port location whether if is situated at the front or back of the speaker enclosure. For example, if you do not have much space in the listening area then you should go for front ported speakers to avoid the walls reinforcing the bass too much that causes it to sound boomy.

I hope the information here is enough for you to decide which port is better for you. You can check out other helpful articles on my website.

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