RW-12d port noise?

[mathesar]

I recently bought a RW-12d sub and while I like the bass response & overall sound quality im hearing what appears to be port noise in certain situations. I have my reciever's sub output set at -6db and 0db on the subwoofer itself and also have the sub's EQ mode set on Flat, The first time I heard the noise was during Finding Nemo's "Darla" scene (Chapter 25 when she taps the aquarium glass a bunch of times) the port noise is fairly loud to where you can hear it over the bass .. is this common or could it be a problem with the subwoofer?

[Jay481985]

the darla scene is a subwoofer tester and killer. Since the RW12d is a ported sub it will have port noise especially on that scene or any that tends to ask or demand for plenty of bass.

[mathesar]

Thanks for the reply, From what Ive read other ported subs such as ones made by HSU or SVS don't exhibit this problem with the Darla scene. I guess it depends on the port location / design. I still have some time left to decide If I want a refund. The sub sounds great otherwise.

[kelA]

I wonder if it is being overdriven, I do not notice the port noise on this scene. I have the sub gain set to -6 and the receiver sub level on -3 in my room. I know every room is different but the RW12-D is pretty clean in my room.

[Jay481985]

place it in the corner and try it again

[CECAA850]

How large is the room and how loud were you playing it at that time. Has the sub been calibrated to the mains with an SPL meter?

[TheEAR]

The Darla scene is nothing special,energy centered around 30Hz. You hear port noise because this sub was working hard.

Klipsch should flare the ports more,what can I say. Extensive flaring like done by B&W helps in a big way. But this another story.

[xdetroitx]

Mine does the same thing. Also in the sub scene. I think Tenor is right. The sub is working real hard. Remember this is a 600 dollar sub and not a 2000 dollar sub. I am more than happy but if you plan on putting the sub through hell you may want to spend some more money.

[michael hurd]

My current homemade subs produce a small amount of port noise on certain frequencies, at high drive levels. They have a 4" flared port and a 12 mm xmax 10" subwoofer, nothing rediculous, and they are tuned to 25 hz. I can barely squeek out 105 db at 20 hz, and this is at the excursion limit of the drivers. They would certainly benefit from more enclosure volume and more port area, possibly a 5 or 5 1/2" diameter port.

My new ( in transit ) subs will use a passive radiator instead of a port, similar effects, slightly steeper rolloff but zero port noise.

[Jay481985]

you can still get resonance and pr noise! when you smack the pr and break the spider with those lms5400 you will get!

[mathesar]

Mine does the same thing. Also in the sub scene. I think Tenor is right. The sub is working real hard. Remember this is a 600 dollar sub and not a 2000 dollar sub. I am more than happy but if you plan on putting the sub through hell you may want to spend some more money.

Thanks ,After doing more research I ended up returning the RW-12d and ordered this sub http://www.hsuresearch.com/products/vtf-3-mk3-turbo.html , It should be here early next week []

[xdetroitx]

Good deal. What's the misses think of the starwars creature looking sub?

[mathesar]

Im currently single so not an issue lol. The funky looking "turbo" part of the subwoofer is used to extend bass response below the 20hz region, you can buy the sub without this add on ($100 less) but I figured what the heck ill go for the full effect.

[TheKillerTomato]

I was looking at picking up this sub, but I don't want it if port noise is going to be a problem. I currently have a cheapo 150 watt 10" down-firing sub that sounds fine and does not give me problems on that scene.

Why port noise? What does it sound like? Should I consider another sub?

[TheKillerTomato]

Anyone? I really would like to get a Klipsch sub if possible.

[Guest BobG]

The design of the RW subs ports is not the usual round-section tube. Others here have noted that flaring both inside and outside ends of a port tube reduces (but does not eliminate) port noise under high drive level.

Port noise happens because the air inside the port is pressurized and when that air leaves the port tube and enters the room, it expands and depressurizes, thus the "port noise".

Flared ports do address this to some extent, but also tend to shift tuning to a higher frequency. In the RW's we use a very long port tube which allows us to tune it to a lower frequency. In fact, the port tube is actually longer than the diagonal dimension of the cabinet which we accomplish by "wrapping" the port tube at the upper corner opposite the external port exit. Now, when you make a port tube long in order to tune it low, you also increase turbulence inside the port tube cause of all the internal surface area. to deal with this, we use a large diameter oval-shape tube that brings velocity of air in the port back down to a level that minimizes turbulence and port noise. is there still some under maximum drive level? Yep there is. Could we eliminate it? Yep by limiting the performance of the sub under normal operating conditions. Our engineering choice ( and good engineering requires lots of artful choices ) is to put up with the occasional noise from the port in order to extract more performance out of the design.

It should also be noted that one of the design criteria for the RW subs is low distortion. You don't hear much talk about sub distortion but the RW's are cleaner than most. You may or may not agree with our design choices, but there's lots of subs to choose from if your cup of tea is different than ours.

[oldbuckster]

Port Noise................Listen to NASCAR in Surround sound, you wanna' talk port noise...............

[mathesar]

I agree the RW12d's bass is very clean but the port noise was pretty noticable for me with certain scenes in movies (perhaps something was wrong with mine but i never heard any actual distortion), I recently bought an HSU VTF-3 MK3 w/ Turbo and when testing those same scenes I hear no port noise whatsoever and the overall bass quality is excellent ,it also goes very deep (with the Turbo attached its tuned to 18hz).

[TheKillerTomato]

The design of the RW subs ports is not the usual round-section tube. Others here have noted that flaring both inside and outside ends of a port tube reduces (but does not eliminate) port noise under high drive level.

Port noise happens because the air inside the port is pressurized and when that air leaves the port tube and enters the room, it expands and depressurizes, thus the "port noise".

Flared ports do address this to some extent, but also tend to shift tuning to a higher frequency. In the RW's we use a very long port tube which allows us to tune it to a lower frequency. In fact, the port tube is actually longer than the diagonal dimension of the cabinet which we accomplish by "wrapping" the port tube at the upper corner opposite the external port exit. Now, when you make a port tube long in order to tune it low, you also increase turbulence inside the port tube cause of all the internal surface area. to deal with this, we use a large diameter oval-shape tube that brings velocity of air in the port back down to a level that minimizes turbulence and port noise. is there still some under maximum drive level? Yep there is. Could we eliminate it? Yep by limiting the performance of the sub under normal operating conditions. Our engineering choice ( and good engineering requires lots of artful choices ) is to put up with the occasional noise from the port in order to extract more performance out of the design.

It should also be noted that one of the design criteria for the RW subs is low distortion. You don't hear much talk about sub distortion but the RW's are cleaner than most. You may or may not agree with our design choices, but there's lots of subs to choose from if your cup of tea is different than ours.

Bob, thanks again for the response.

When you talk about tuning to a certain frequency, what exactly does that do? Does that give optimal performance at a certain frequency? Does it have anything to do with the low end frequency response? As I stated in another thread, I am considering the HSU VTF 3.3, with dual flared ports. As a poster noted above, it does not have the port noise he noticed with the RW-12. Also, the HSU has a frequency response much lower than the RW. So, I don't understand the advantage of being able to tune it to a lower frequency, when the flared port sub has lower frequency response.

[nzorn]

Sorry to bump an old thread, but I figured this thread has the most information so far, so no point in starting a new one.

I'm not too happy with my bass during movies. It sounds great with music, but it seems it doesn't rumble like I would think it should.

I've also heard this port noise, I can't seem to pin it down though, at first I thought it was something vibrating on my wall, then I thought it was the grill of the subwoofer, but now after reading this I'm almost sure that it is port noise. What can I do about it?? My crossover on my subwoofer is at 120hz, and I'm not for sure what it is on my receiver, but I will check to see it's set at 80hz. It's set on Flat, but I seem to like Punch and Depth settings as well. The gain is set to 0 on the subwoofer, and 0 on my receiver. When I optimized my receiver it turned it down to -6, but I enjoy bass so I turned it back up to 0.

I guess it's all a matter of playing with it and getting it to sound the way I want it to, but that port noise is really annoying at times, and it doesn't seem like I'm over-driving it at the time since there's not much bass coming out whenever I hear it.

Let me know, this is driving me crazy!!