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Port noise?

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2010HHRUMADBRUH

2010HHRUMADBRUH
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East Bay, CA
I noticed what I think is referred to as "port noise" today.

I went to inspect it while I let the sub do it's thing, and I thougtht one of the panels or something was rattling, but I figured out it was the port making the noise. It almost sounds like a plastic bag was placed near the port or the sub is violently rattlling some panels in the cargo area...very confusing unless you physically inspect it while the sub is doing some work.

There is a LOT of air going through the port. I never noticed this happening with the lower powered subs I had in the box before, so I assume this might have something to do with the fact that the weaker 12"s weren't physically able to move that much air.

I went from a JL 12w3v3-4 (500w rms), to a VVME RD-12 (700-ish rms), and now I'm running a DC LVL 4 m2.

It still slaps, but it sounds like something is wrong now, at all frequencies. Maybe I didn't notice it because I wasn't used to the amount of bass it put out, but now that I've had it for a while, I got used to it and I'm able to hear how the sub and box are doing, instead of just being audibly blinded by the bass, perhaps?

The box was built exactly to spec for the JL 12w3v3, and up until now, has given me no problems.

12W3v3-4 - Car Audio - Subwoofer Drivers - W3v3 - JL Audio (scroll down to "ported enclosure specifications") the only thing I see different is that I remember JL saying that the box would be tuned to 32hz. Maybe it has changed? Anyways, DC recommends 1.5 cubes ported, and the displacement on the sub is 0.18, which would make the final internal volume at 1.57 if I'm not mistaken...would this .07 make a huge difference?

What should I measure/take pictures of? I can take pics of the inside of the box, and the port and whatever else...maybe that would help determine if there is a design flaw or other reason why I'm experiencing this?

I have heard people talking about "sloppy fart bass" and I always thought that was what I wanted, as bass is bass to me, but now I think I understand what they were talking about, and it's unnacceptable.

Click to read more...
 
The new woofer is probably displacing more air - hence needing a bigger port.Is it a slot port or round?
Click to expand...
Slot port. Would I need a wider port area, or more port area?

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You went from a low xmax sub to a high xmax sub and now you don't have enough port area. This is the reason why prefab boxes usually sound like shite... because people buy good quality subs and stick them in cheap boxes that are designed for entry level subs.

And, a wider port will be more port area.

 
I'd be looking for mechanical failure either in a seem of the box or the sub.
Click to expand...
Wouldn't the sub not be able to play at all if it was the sub failing? Can you list any specific reasons you think the sub might be failing, considering the information I have provided?

You went from a low xmax sub to a high xmax sub and now you don't have enough port area. This is the reason why prefab boxes usually sound like shite... because people buy good quality subs and stick them in cheap boxes that are designed for entry level subs.
And, a wider port will be more port area.
Click to expand...
OK, but this box is custom, and the internal airspace is 0.07 more than the manufacturer recommends, but I think you are mainly commenting on the port area. I know anything is possible, but I sure as hell hope that someone who gets an enthusiast/competition grade sub would know to get a proper enclosure for it, lol...

And about the wider port being more port area: what if the tuning stays the same? Wouldn't that mean the inside port length (how long the port extends into the enclosure) gets shorter? If I simply took this 30-32hz tuned slot port enclosure and hypothetically widened the port on the "exit" side, wouldn't that change the tuning? Basically, I'm under the impression that to keep a box tuned at 32hz, the port area would remain the same, but it would become shorter/wider to allow more air, and keep the tuning the same? Or it port area defined as the area on the exit part of the port? (the part that you can touch and see from the outside)

 
What are the dimensions on that port? 2" by like 14"?

Looks to be a bit on the small side...

Lack of round-overs on the edge can also cause some noise.

 
Wouldn't the sub not be able to play at all if it was the sub failing? Can you list any specific reasons you think the sub might be failing, considering the information I have provided?


OK, but this box is custom, and the internal airspace is 0.07 more than the manufacturer recommends, but I think you are mainly commenting on the port area. I know anything is possible, but I sure as hell hope that someone who gets an enthusiast/competition grade sub would know to get a proper enclosure for it, lol...

And about the wider port being more port area: what if the tuning stays the same? Wouldn't that mean the inside port length (how long the port extends into the enclosure) gets shorter? If I simply took this 30-32hz tuned slot port enclosure and hypothetically widened the port on the "exit" side, wouldn't that change the tuning? Basically, I'm under the impression that to keep a box tuned at 32hz, the port area would remain the same, but it would become shorter/wider to allow more air, and keep the tuning the same? Or it port area defined as the area on the exit part of the port? (the part that you can touch and see from the outside)
Click to expand...

The .07 cube difference is irrelevant. As for port area, it should be uniform from one end of the port to the other, unless it's an aero port so there's no need to clarify which end you're talking about.

As for port area, it's pretty simple. If you have a 2"x10" port, you have 20in² of port area. If you change that to 4"x5", you still have 20in² of port area. And adding port area will change the tuning of the box so if you want to make a larger port and keep the same tuning, the port will have to be longer.

 
1.375" x 12.5" = port area of 17.1875 sq. in.

DC says that woofer has an xmax of 23.5 mm, so your going to need a bigger port (around twice as wide as what you have now. As bbeljefe pointed out though - changing the port area is going to change the tuning - so you'll need to lengthen the port as well to keep the same tuning. Honestly, probably better off building a new box rather than trying to make this one work - it could be done with a bit of work - but it's going to end up being undersized anyways (you will be losing airspace to bigger port and bigger woofer).

 
Wouldn't the sub not be able to play at all if it was the sub failing? Can you list any specific reasons you think the sub might be failing, considering the information I have provided?


OK, but this box is custom, and the internal airspace is 0.07 more than the manufacturer recommends, but I think you are mainly commenting on the port area. I know anything is possible, but I sure as hell hope that someone who gets an enthusiast/competition grade sub would know to get a proper enclosure for it, lol...

And about the wider port being more port area: what if the tuning stays the same? Wouldn't that mean the inside port length (how long the port extends into the enclosure) gets shorter? If I simply took this 30-32hz tuned slot port enclosure and hypothetically widened the port on the "exit" side, wouldn't that change the tuning? Basically, I'm under the impression that to keep a box tuned at 32hz, the port area would remain the same, but it would become shorter/wider to allow more air, and keep the tuning the same? Or it port area defined as the area on the exit part of the port? (the part that you can touch and see from the outside)
Click to expand...
If it's making bad noises only at high volume it still could be a mechanical failure, but if it's doing it at low power it is NOT the fault of the port which should be adequate for low power. Most people here don't even read your post and start suggesting things that they think sound clever.

I'd be more suspicious of the box coming apart somewhere, but softparts coming unglued in cheap Chinese subs is not uncommon either.

 
also question - but have you tried using silly putty around your sub when you mount it ? i find that using some sort of sticky type removable sealing ring around my subs will help prevent air leaks - and or also any slapping sounds from contact between the actual woofer and box

i see 4 bolts on your box to hold down the sub. is that it ? your only using 4 bolts ? or are there more that i just dont see

for fun and also to rule out mechanical woofer failure- take it out of your box - and play it low power in free air. listen to the sub listen for mechanical noises that would seem totaly out of place. agian play in free air at low power please.

with the sub out of your box - id suguest trying to caulk the inside seams. every single one.

i had a custom box made before in my vette for a 18" re sx that i fed 1200w and it slammed for a good while before one of the rear pannels on my box decided to come loose inside near my port and start rattling around in there during bass notes. sounded dang awfull like the sub was toasted.

sub was fine - the box itself was coming apart with rattles of a wood joint loose slapping together.

so

have fun trying to figure it all out - its a hobby for fun. also dont rule out interior pannels vibrating on eachother making ugly noise during bass notes.

there is a multitude of products and tecniques to help eliminate rattles and vibration noises inside the car and outside the car

 
If it's making bad noises only at high volume it still could be a mechanical failure, but if it's doing it at low power it is NOT the fault of the port which should be adequate for low power. Most people here don't even read your post and start suggesting things that they think sound clever.
I'd be more suspicious of the box coming apart somewhere, but softparts coming unglued in cheap Chinese subs is not uncommon either.
Click to expand...
It's definitely the port man. I inspected the sub and the coils check out and everything looks good.

It's barely noticeable unless I really listen for it, and like I said, I played it at moderate volume and inspected the cargo area and confirmed the port was making the noise.

you need a new box with moar poart, rounded poart edges, and a 45 opposite the poart wall
Or AERO(S)

Poart.
Click to expand...
I think I'm gonna try aeros. I've had no luck finding someone to build a box for a reasonable price for the 18" I had, so I traded it for this sub. I'm pretty sure I can put together a sealed box, and add some aero ports. I have a sheet of 3/4" mdf laying around anyway. What airspace would be ideal for this sub? 26hz tuning too low? My car resonates above 41hz, and I don't like much over 36-38hz

also question - but have you tried using silly putty around your sub when you mount it ? i find that using some sort of sticky type removable sealing ring around my subs will help prevent air leaks - and or also any slapping sounds from contact between the actual woofer and box i see 4 bolts on your box to hold down the sub. is that it ? your only using 4 bolts ? or are there more that i just dont see

for fun and also to rule out mechanical woofer failure- take it out of your box - and play it low power in free air. listen to the sub listen for mechanical noises that would seem totaly out of place. agian play in free air at low power please.

with the sub out of your box - id suguest trying to caulk the inside seams. every single one.

i had a custom box made before in my vette for a 18" re sx that i fed 1200w and it slammed for a good while before one of the rear pannels on my box decided to come loose inside near my port and start rattling around in there during bass notes. sounded dang awfull like the sub was toasted.

sub was fine - the box itself was coming apart with rattles of a wood joint loose slapping together.

so

have fun trying to figure it all out - its a hobby for fun. also dont rule out interior pannels vibrating on eachother making ugly noise during bass notes.

there is a multitude of products and tecniques to help eliminate rattles and vibration noises inside the car and outside the car
Click to expand...
Yeah it's only 4 bolts. I took the sub out and the coils are good and everything checks out. I'll try free air tomorrow. I didn't check the inside of the box yet. It's possible that it's coming apart, since I didn't notice the port noise when I first started using the sub. It's def not the interior panels though. But there are a ton of rattles from my hatch now :\

 
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2010HHRUMADBRUH

2010HHRUMADBRUH

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