Closings bass ports on monitors

[latestflavor]

well, the ports would be closed

you would get less artificial bass extension and resonance, and the speaker would perform differently than the designers intended.

some people do it, but i guess the only thing to watch out for is when the design of the amp's cooling ability is only through the ports. IIRC the 1031 doesn't have cooling fins on back of the amp, so i'd be careful and watch the heat buildup.

[AlexK]

Depending on the tuning of the driver, bass roll off may start at quite a high frequency, plus the bass driver will have to work harder meaning higher IM distortion and less headroom.

As well as what latestflavor said. Personally I'd leave your 1031s alone. If you want some sealed speakers, then buy some... =]

[Doc Mixwell]

Originally Posted by AlexK

If you want some sealed speakers, then buy some... =]

Proper Advice

[audiotech]

My Tannoy 800 monitors have two front ports each capable of blocking one or two of the ports with foam to suit the individual's needs. I can't notice much difference blocking one port, but I do notice a slight lack of the extended bass response by blocking both.





Dennis

[Enlightened Hand]

Originally Posted by Omega Arts

What would happen if I close the bass ports on Gen 1031?

It depends. In general, the speaker system would start to behave more like a sealed box.

The port is tuned to augment the bass frequencies just below those of the low frequency driver. The basic idea is to get more audible bass from an otherwise too small enclosure. The trade off is that the sound that leaves the port is always late, relative to the low frequency driver, and this causes an obscuring of the low frequencies in the time domain. That makes it more difficult to clearly hear the starts and stops of low frequency instruments, and to hear the articulation of low frequency transient detail. This lateness is resonance, and it's done on purpose with a ported speaker system design.

Blocking the port will cause the air mass behind the driver to be stiffer, as it would be with a sealed enclosure. This will limit the travel of the driver, which will limit it's audible output, due to it's motion being dampened by the stiff air mass behind it. That limit of travel will also lessen the driver's ability to produce lower frequency information, as those waves require greater driver travel. What this means for you is that you'll get less audible bass. But the the good news is that you'll greatly reduce, if not eliminate, the resonance from the port that obscures the transient detail of the low frequencies. That can make it easier to mix bass instruments, as a trade off for less audible bass output. However, you should know that active speakers have electronics involved, and the filtering in the amplifiers of active, ported speakers, might also create delays between the low frequency driver and the other drivers of the system. Those delays will not be addressed by the blocking of the ports, because they happen to the signal before it reaches the actual drivers. In that sense, it's best to just buy a sealed cabinet speaker if you want a sealed cabinet's advantages.

But all speakers are not designed alike, so how exactly the sound will change will vary from design to design. But generally, there is some benefit in the time domain from blocking ports, and it does come with trade offs. But it doesn't address the active electronics in the speaker at all, which still might trip you up in the time domain. Some speaker designers actually include port plugs; Tannoy did with their ellipse series.

[Chrisc_o]

Recent thread discussing this subject:

Bass ports, a good thing or a bad thing?