Sealed vs Ported Sub

[ZolaIII]

I’m using the Audyssey mic.

Some people compared it with the UMIK and it was pretty accurate on low frequencies.

Yes that's ARC, older one's where a little worser and new ones are on pair. Have a old one it had a rather good stand.

 

[caioferrari]

What I should measure on REW that suggests that my sub on sealed mode is better than ported ?

 

[ZolaIII]

What I should measure on REW that suggests that my sub on sealed mode is better than ported ?

Frequency sesponse showing along with it the waterfall and RT60 decay times.

 

[caioferrari]

Frequency sesponse showing along with it the waterfall and RT60 decay times.

Here it is. Is there something here to help me understand the differences?

 

[Kvalsvoll]

Here it is. Is there something here to help me understand the differences?

It shows that there is a differene in level, but no difference in decay rate. Which means the perceived improved "faster" bass with sealed is only due to a reduction in level, the resonances are not improved. This is because the room domnites the response, and thus masks any difference in the decay properties of the speaker itself.

 

[neRok]

Here it is. Is there something here to help me understand the differences?

The 4dB boost you used doesn't make sense because there should be no need for it in the higher bass region, because a port shouldn't be tuned there. Perhaps the app you were using had "binned" frequencies, and maybe that was enough to throw it off? But in your REW screenshots, you can see the sealed one is actually 1.5dB louder from 40-70Hz, which could be all the improvement you've heard.

Also the big peak at ~23Hz has come down, which suggests the port is tuned around there. Here's the response of an SVS sub for example, and you can see the response drops similarly port vs sealed;

You can also see the port does next to nothing above 40Hz, so having your RT60 graph at 50Hz isn't going to reveal any minute improvements in timing. There might be minor differences at say 25Hz because ported subs have increased group delay vs sealed (because the sound from the port has to travel out the port and is a opposite phase because it is from the back of the woofer). The difference in sealed is that the peak energy time will be related to the wave from the front of the sealed driver, whereas in ported it is the drivers back wave (out of phase) that has also travelled further. But this difference would only be apparent within the first 30ms at the listening position.

Lastly, how long is your room (or wide if width>length)? The way it is peaking at 23Hz even when sealed kind of suggests that's the first room mode. Sealed might sound better at that frequency (without EQ) because you aren't powering it as strongly and making it "boomy".

 

[caioferrari]

it’s pretty hard to say my room size. It’s 2,5 m x 2,1m. I‘m seated at 2,5m from the speakers.
the problem is this little space is opened at one side for a larger space where I have a dinner room and a kitchen.

My crossover frequency is at 40 Hz (I prefer the sound from my Revel M105 rather than the sub) and the sub is tuned at ~30Hz.

Since the response is that peaky, should I assume that is a low quality response and I should care knocking down those peaks to start listening sound from the speaker rather than room resonances ?

 

[ZolaIII]

@caioferrari this is one of my close enclosure 10" sub's (Wharfedale WH-D10) crossed at 80 Hz in a little bigger rectangle shaped room (4x2.4 m).

https://www.audiosciencereview.com/forum/index.php?attachments/rt60-decay-sub-jpg.304834/

This is full EQ-ed response:

KEF R3 new REW measurements (Do I need a subwoofer?)

Hi again ASR community. Some time ago you helped me a lot in this thread Since then I have changed my audio setup and now it is KEF R3 with Lyngdorf TDAI-3400 streaming amp. Below please find the measurements I did using REW and UMIK-1 mic with RoomPerfect enabled (Lyngdorf room correction...

www.audiosciencereview.com

Put the crossover higher so that you lower the pressure on M105 and on to the woffer and cut it's port output. In your case I would try first with 100 Hz to try to get that null out as much as possible (it will probably need and thick rug from corner to corner).
Sorry for not responding sooner, whose playing with my new projector last two days.

 

[caioferrari]

@caioferrari this is one of my close enclosure 10" sub's (Wharfedale WH-D10) crossed at 80 Hz in a little bigger rectangle shaped room (4x2.4 m).

https://www.audiosciencereview.com/forum/index.php?attachments/rt60-decay-sub-jpg.304834/

This is full EQ-ed response:

KEF R3 new REW measurements (Do I need a subwoofer?)

Hi again ASR community. Some time ago you helped me a lot in this thread Since then I have changed my audio setup and now it is KEF R3 with Lyngdorf TDAI-3400 streaming amp. Below please find the measurements I did using REW and UMIK-1 mic with RoomPerfect enabled (Lyngdorf room correction...

www.audiosciencereview.com

Put the crossover higher so that you lower the pressure on M105 and on to the woffer and cut it's port output. In your case I would try first with 100 Hz to try to get that null out as much as possible (it will probably need and thick rug from corner to corner).
Sorry for not responding sooner, whose playing with my new projector last two days.

I’ve tried a higher crossover, it didn’t solve the null and requires that I turn the subwoofer on everytime I listen to music.

The thing is, since my subwoofer is a DIY project, I feed it with a Crown XLS amp. So I don’t have the auto on feature. Sometimes I just want to stream my music from Spotify and get ready to listen…

 

[Deleted member 48726]

I’ve tried a higher crossover, it didn’t solve the null and requires that I turn the subwoofer on everytime I listen to music.

The thing is, since my subwoofer is a DIY project, I feed it with a Crown XLS amp. So I don’t have the auto on feature. Sometimes I just want to stream my music from Spotify and get ready to listen…

A workaround is a smart powet outlet with master/slave or a relay to trigger the sleep / power on function on your Crown.

 

[Steve81]

A couple thoughts on sealed vs ported…

This experience is derived from my ownership of the SVS PB13U and later the Funk 18.0 (and later addition of the 21.0LX).

In my room, I measured that when set to sealed mode, the PB13 essentially achieved a flat response down to the (admittedly limited) limits of my Omnimic. This result caused me to pursue sealed subs for further applications.

I decided to purchase a Funk 18.0 subwoofer, with the expectation that I might loose a little something in the low end, but should net me a little more infrasonic output. After calibration, I felt that the Funk sub was markedly superior to the PB13.

My explanation for this is fairly straightforward. Content is typically dominated, not by material at 20Hz, but by material in the 40-80Hz spectrum. Here, the Funk has a significant advantage thanks to a more efficient driver and more power from the amplifier. Where this content might cause the PB13’s amp to run out of steam, the Funk is happily cruising along. I believe Mr. Seaton of Seaton Sound observed the same effect in talks I’ve had with him, which explains why he designed the Submersive exactly the way he did, and consequently why it was so highly regarded.

 

[caioferrari]

A workaround is a smart powet outlet with master/slave or a relay to trigger the sleep / power on function on your Crown.

I thought about that, but I’m found to be a waste of money. Looking for todays SUB with PEQ, I’m loosing too much by using a DIY sub.

The other problem is changing crossover freq doesn’t solve the null.
I‘ve tried all frequencies from 40 Hz at my receiver. None of them solved the issue.

 

[Deleted member 48726]

I thought about that, but I’m found to be a waste of money. Looking for todays SUB with PEQ, I’m loosing too much by using a DIY sub.

The other problem is changing crossover freq doesn’t solve the null.
I‘ve tried all frequencies from 40 Hz at my receiver. None of them solved the issue.

Nothing changes the null in the measured position and the sub in its measured position. You need to move the sub, add a sub or change listening position.

REW has a useful room simulator where you can enter the dimensions of your room and add speakers and subs and define crossovers etc. It then shows the calculated frequency response where you see your room modes and your nulls and peaks. You can drag your sub in real time and see the response change. You should try it out.

 

[caioferrari]

Nothing changes the null in the measured position and the sub in its measured position. You need to move the sub, add a sub or change listening position.

REW has a useful room simulator where you can enter the dimensions of your room and add speakers and subs and define crossovers etc. It then shows the calculated frequency response where you see your room modes and your nulls and peaks. You can drag your sub in real time and see the response change. You should try it out.

I’ve tried it one, but since my room has a side opening, I don’t get accurate results.
My room is L shape and my listening room is on the small portion of the L

 

[ozzy9832001]

According to the data, your speakers begin their roll off of -3dB @ 60hz. So, I would set the subwoofer to 70hz-80hz. That would alleviate some of the strain on the woofer for the Revels. Your room is relatively small, so it makes sense you have long decay times, as shown by the waterfall.

The null looks like its reflection based, not modal, even setting the xover to say 100hz, won't do any good unless the mains aren't playing the sound at all. You'd probably need to move up into the high 100's for that to happen or it's still blending.

You have a fairly steep room curve. Looks like nearly a -15dB drop on avg from 30hz to 8k.

Otherwise ported vs sealed is more a matter of taste. I've had success with both and problems with neither.

 

[neRok]

it’s pretty hard to say my room size. It’s 2,5 m x 2,1m. I‘m seated at 2,5m from the speakers.
the problem is this little space is opened at one side for a larger space where I have a dinner room and a kitchen.

Your room is quite small, which means the problems pile up easy. The first mode in your room is ~68Hz. 23Hz and its multiples might be the adjoining room then. Interesting.

REW Room Sim shows a bit of a null related to the listening distance from the floor - on the floor is 82Hz null, and moving towards the mid-height moves the null towards 100Hz. If you can get to the middle, apparently it gets better. Also it suggests inverting and delaying the sub will help smooth things out below 120Hz.

 

[caioferrari]

Your room is quite small, which means the problems pile up easy. The first mode in your room is ~68Hz. 23Hz and its multiples might be the adjoining room then. Interesting.

REW Room Sim shows a bit of a null related to the listening distance from the floor - on the floor is 82Hz null, and moving towards the mid-height moves the null towards 100Hz. If you can get to the middle, apparently it gets better. Also it suggests inverting and delaying the sub will help smooth things out below 120Hz.
View attachment 306961 View attachment 306960

I’ll try room sim a little bit to try to understand what’s happening here. And yes, a small room is pretty hard to manage.

Sometimes I regret buying such a large sub (45L). It’s very problematic.

 

[caioferrari]

That's complete nonsense. The "decay rate" between a sealed box and a vented box is 2nd-order versus 4th-order. And indeed the resonances are also different because a vented box uses stored energy (by design) as its method for extending the response by trading off the increased roll-off rate. This is basic stuff.

For the responses posted here, the difference is not that stark because the microphone is placed at some distance from the woofer and room effects are contaminating the measurements.

Should I measure with the microphone near of speaker?

I measured at the listening position

 

[voodooless]

That's complete nonsense

Not at all, because of reasons you already eluded to:

room effects are contaminating the measurements

Your ears will be contaminated by this just as well. In the end, frequency response is king. And since EQ is needed to equalize the room, it’s rather irrelevant whether you use a closed or reflex box. EQ’ed to the same response, and property designed, you will have an extreme hard time keeping the apart within their respective operating windows. Obviously there are reasons to use either one or the other due to extension, power handling, efficiency, etc. It’s also pointless to compare the same woofer for both topologies, because it will only be useful in at most one of them.

 

[voodooless]

Why would I want to EQ a vented-box to be like a sealed-box? Or vice-versa?

You should do neither. You should EQ for a flat in-room response, and with enough power handling and bandwidth for your needs.

What I am implying is that the bulk of SQ differences are due to frequency response differences, and not due the supposed energy storage of reflex boxes.