Anyway to reduce port noise from Velodyne CHT-12

[bjornb17]

I have a Velodyne CHT-12, which I really enjoy in my smallish 11'x14' listening room. The problem is that somtimes the port noise can be audible in scenes which have very deep bass. Running test tones, i don't hear port noise until i get to about 23 Hz or so (which makes sense, since that is below the tuning frequency). The sub will play below 25Hz at decent volume levels but with the thud of air coming out of the port.

Is it possible to supress this at all with some sort of damping material? If so, how would this affect the overall sound or response? This happens even at modest volume levels. Would there be another alternative to helping with this (besides replacing it)? Thanks!

[MikeyBC]

I have a Velodyne CHT-12, which I really enjoy in my smallish 11'x14' listening room. The problem is that somtimes the port noise can be audible in scenes which have very deep bass. Running test tones, i don't hear port noise until i get to about 23 Hz or so (which makes sense, since that is below the tuning frequency). The sub will play below 25Hz at decent volume levels but with the thud of air coming out of the port.

Is it possible to supress this at all with some sort of damping material? If so, how would this affect the overall sound or response? This happens even at modest volume levels. Would there be another alternative to helping with this (besides replacing it)? Thanks!

Maybe a foam plug, some ported speakers come with optional plugs. You may affect tuning frequency and reduce the output at the lowest frequencies handled by the port though, also you might find the woofer may bottom out easier and reduce the power handling beacause port tuning also helps control cone movement. Try blocking a port in a bass reflex speaker while playing it loudly and you'll see a noticeable increase in cone exursion.

[bjornb17]

Maybe a foam plug, some ported speakers come with optional plugs. You may affect tuning frequency and reduce the output at the lowest frequencies handled by the port though, also you might find the woofer may bottom out easier and reduce the power handling beacause port tuning also helps control cone movement. Try blocking a port in a bass reflex speaker while playing it loudly and you'll see a noticeable increase in cone exursion.

Will it just be an increase in excursion to meet the same volume levels, or even at the same volume settings on my receiver and the back of the sub?

[cam]

I have a Velodyne CHT-12, which I really enjoy in my smallish 11'x14' listening room. The problem is that somtimes the port noise can be audible in scenes which have very deep bass. Running test tones, i don't hear port noise until i get to about 23 Hz or so (which makes sense, since that is below the tuning frequency). The sub will play below 25Hz at decent volume levels but with the thud of air coming out of the port.

Is it possible to supress this at all with some sort of damping material? If so, how would this affect the overall sound or response? This happens even at modest volume levels. Would there be another alternative to helping with this (besides replacing it)? Thanks!
Try moving your sub an inch or 2 or 3 away from the wall. You can get alot of port noise or (chuff) when the ports are to close to the wall. Every sub has its limits. My Paradigm pw-2000 v2 exibits some port noise when placed too close to a boundary. Even when my sub is being put to its limits, if I put my open hand almost over the port it will exibit some (chuff). It's a matter of getting your sub close to a wall for reinforcement and having it far enough away so as to not get that annoying port noise. Let your sub breath and it will perform better.

[bjornb17]

Try moving your sub an inch or 2 or 3 away from the wall. You can get alot of port noise or (chuff) when the ports are to close to the wall. Every sub has its limits. My Paradigm pw-2000 v2 exibits some port noise when placed too close to a boundary. Even when my sub is being put to its limits, if I put my open hand almost over the port it will exibit some (chuff). It's a matter of getting your sub close to a wall for reinforcement and having it far enough away so as to not get that annoying port noise. Let your sub breath and it will perform better.

actually its about 2 feet away from either wall :( Maybe moving it close to the wall and turning the volume down will help?

[paul_pci]

My advice: plug it … calibrate it … play it and from there if you're still having problems, adjust its position in the room.

[kexodusc]

I wouldn't advise plugging ports unless the manufacturer explicitly says you can do this. Model a subwoofer in an ported cabinet, then drop model it in a sealed cabinet of the same volume. The air inside the cabinet is protecting the woofer from an excursion peak at the tuning frequency, plugging the port will remove this protection. Excursion requirements go up exponentially. No only that but response and distortion can be terrible. You run the risk of damaging the woofer at even modest volume levels when a low frequency hits. I've seen it with just a watt or two. Sometimes you get lead slap as a warning. Sometimes you don't and it's too late.

You could try it, and maybe nothing bad will happen. But it seems a bit too risky to me.

Port noise really shouldn't happen in any sub these days.
Is it really unbearably distracting, or just something you notice? I'd probably be inclined to leave things as they are...keep experimenting with proximity to the wall, maybe you'll find a good spot?

[brendy]

Port noise is usually an indication of overdriving it.By volume level and/or frequencies beyond it's design limits.

[bjornb17]

Thanks for the suggestions. I don't notice it too often. The DVD i notice it on the most is actaully U2 vertigo live in chicago, but it seems that they reallly had the bass maxed out on the recording, so the bass drum can cause some nice port thudding. I went to the actual concert and it was a bass-fest as well so i guess I cant blame them for that :p

Honestly though, It is a pretty rare occurance.

[westcott]

My advice: plug it … calibrate it … play it and from there if you're still having problems, adjust its position in the room.


If you have not calibrated your subwoofer and other speakers, I would start where Paul suggested. Here is a link that will help you place it properly in the room, set the dB level, speaker distance, etc.

http://www.audioholics.com/techtips/setup/index.php

I agree with the others, I think your sub is turned up too high and I would drop the crossover to 80Hz to reduce directionality. You will need an inexpensive SPL meter from Radio Shack and maybe a calibration DVD like Digital Video Essentials, AVIA, or others.
Should help your TVs too!

Good Luck

[bjornb17]

I think your sub is turned up too high and I would drop the crossover to 80Hz to reduce directionality.

Good Luck

It's set at 60 :)

[Kittyburgers]

Mine is set at 60 as well. I really like the CHT. I haven't noticed the port noise you're describing. I would try to re-position the sub or hide the port area behind a plant pot or something; I'd definitely try to experiment with positioning if this noise is too disturbing for you, but you mentioned it happened only rarely.

[jocko_nc]

Get a second sub and play them both a little quieter for the same effect?

jocko