Sealed vs Ported Sub

[caioferrari]

I have a DIY sub using a JBL GTO 1014D.

It was well made, with internal bracing, a flat response and well adjusted port.

I was looking some Dynaudio and Revel subs that are sealed and I decided to try mine in that mode.

My sub is playing up to 40 Hz, and above that I have a pair of Revel M105 (since I only hear at low SPL, I preferred to use my sub just to extend the bass response).



First of all I measured my sub with the port open and I made it sealed using two T-Shirts closing the port . I got a sealed speaker with a Qtc = 0,6.



I measured again and adjusted the gain until I’ve got the same spl at low frequencies. Just to know, I needed to increase the sub level by 4dB in my receiver until the curve matches (both on them was measured from 20 Hz)



So, I’ve started hearing.

I found the sealed sub more “soft”, damped, well behaved. My impression was that I was hearing more notes.



The problem is my test was not blind and I’m afraid to be hearing differences just because I read about them in the past.

Does someone made a test like this? What you guys think?

 

[fpitas]

Room gain can make a ported sub sound boomy. Sometimes a sealed sub is better, unless you EQ accordingly.

 

[caioferrari]

Room gain can make a ported sub sound boomy. Sometimes a sealed sub is better, unless you EQ accordingly.

The curves were matched.

 

[DVDdoug]

If you like it better sealed then that's the way you like it!

Just to know, I needed to increase the sub level by 4dB in my receiver until the curve matches (both on them was measured from 20 Hz)

Just so I'm clear, you had to boost with it "sealed", right? That could be normal depending on how the port was tuned. Typically you'd hear less-total bass with it sealed, but not in every case. And typically a sealed speaker can go lower and it rolls-off more slowly below the -3dB point so with EQ (and maybe more power) you can get more very-deep bass..

I got a sealed speaker with a Qtc = 0,6.

How did you measure that? You can model/predict performance of various designs/configurations with WinISD (or similar) assuming you can get the Theile-Small parameters for the driver.

The problem is my test was not blind and I’m afraid to be hearing differences just because I read about them in the past.

Yeah, blind listening is not always practical, and you probably CAN hear a difference so blind or not you'd know if the port is blocked.

You could get a measurement mic and compare with REW.

 

[Ron Texas]

Be careful when making generalizations about designs. Implementation is often more important.

 

[DWPress]

So you've measured with a mic then? I prefer sealed subs in my environment and have plenty of watts to throw at them. As mentioned, a sealed sub usually rolls off at a higher frequency but can also be tighter in response because there's no slight delay of sound coming from the port no matter how well tuned it is, distortion can go down as well since the cone typically isn't moving as much. If your mains do a good job down to 40Hz and you've HP and LP filters between (or just matching speaker roll off) then look at the data from the sweeps, if all you need is a 4dB boost and frequency response looks similar I'd look at decay differences to spot why you prefer sealed.

 

[caioferrari]

Just so I'm clear, you had to boost with it "sealed", right? That could be normal depending on how the port was tuned. Typically you'd hear less-total bass with it sealed, but not in every case. And typically a sealed speaker can go lower and it rolls-off more slowly below the -3dB point so with EQ (and maybe more power) you can get more very-deep bass..

That’s right. I have to boost sealed by 4dB to match the same response that I had from ported mode.

How did you measure that? You can model/predict performance of various designs/configurations with WinISD (or similar) assuming you can get the Theile-Small parameters for the driver.

I have the T-S parameters in WinISD and I have the internal volume of my enclosure.

Yeah, blind listening is not always practical, and you probably CAN hear a difference so blind or not you'd know if the port is blocked.

You could get a measurement mic and compare with REW.

I matched the SPL using a measurement mic. I used the Audyssey mic from my Marantz. I know that I don’t have a calibration curve for it, but, since my goal is just compare the two alignments, I found it was ok.
My measurement was using “House Curve” on my iPad connected to Marantz mic.
For me all discussion relies on the fact that the curves from both alignments are the same (may be there is a difference below 20Hz but the app doesn’t measure it) aaaand its does sound different!!!
Its pretty hard to find adjectives that describes the difference I’m hearing, but I’m hearing sealed more pleasant.
Could it be a placebo effect?

 

[caioferrari]

So you've measured with a mic then? I prefer sealed subs in my environment and have plenty of watts to throw at them. As mentioned, a sealed sub usually rolls off at a higher frequency but can also be tighter in response because there's no slight delay of sound coming from the port no matter how well tuned it is, distortion can go down as well since the cone typically isn't moving as much. If your mains do a good job down to 40Hz and you've HP and LP filters between (or just matching speaker roll off) then look at the data from the sweeps, if all you need is a 4dB boost and frequency response looks similar I'd look at decay differences to spot why you prefer sealed.

I’m already looked the data. I measured both and I matched the response graph. Above 20 Hz (measured from House curve app with Marantz Audyssey mic) with the 4dB boost, the sealed and ported curves matches but the sealed sound better.
I would like to know if there is a measurable parameter that indicates that. Otherwise I‘ll think this is a placebo affect and I’m being fooled.

 

[kemmler3D]

If your port had audible resonance then plugging it and matching the curves with EQ would clean up the resonance and leave you with the same quantity of bass. It's well within the realm of possibility that you would hear a difference from that. There's also now no (or maybe just less?) sound coming from the port, so if that had any unwanted interaction with your room, that would be cleaned up as well. Also, if there were any chuffing, that would be gone.

I personally prefer sealed subs because you simply don't have to worry about the port resonance or chuffing. Yes, you need more power and the group delay should work out to be the same, but my subjective emotional feeling about it is sealed subs are cleaner. Haven't done any A/B tests or anything.

 

[Chrispy]

How was your sub determined to have a flat response, what gear, measurements, etc?

I have a DIY sub using a JBL GTO 1014D.

It was well made, with internal bracing, a flat response and well adjusted port.

I was looking some Dynaudio and Revel subs that are sealed and I decided to try mine in that mode.

My sub is playing up to 40 Hz, and above that I have a pair of Revel M105 (since I only hear at low SPL, I preferred to use my sub just to extend the bass response).



First of all I measured my sub with the port open and I made it sealed using two T-Shirts closing the port . I got a sealed speaker with a Qtc = 0,6.



I measured again and adjusted the gain until I’ve got the same spl at low frequencies. Just to know, I needed to increase the sub level by 4dB in my receiver until the curve matches (both on them was measured from 20 Hz)



So, I’ve started hearing.

I found the sealed sub more “soft”, damped, well behaved. My impression was that I was hearing more notes.



The problem is my test was not blind and I’m afraid to be hearing differences just because I read about them in the past.

Does someone made a test like this? What you guys think?

 

[DWPress]

I’m already looked the data. I measured both and I matched the response graph. Above 20 Hz (measured from House curve app with Marantz Audyssey mic) with the 4dB boost, the sealed and ported curves matches but the sealed sound better.
I would like to know if there is a measurable parameter that indicates that. Otherwise I‘ll think this is a placebo affect and I’m being fooled.

Yes there is measurable data that would indicate what you are hearing but not with the tools you are using. HouseCurve is a great app for simple things but has no comparison to tools like REW or rePhase (both free BTW). If you really want to know why it sounds different download and learn the software, get a Umik and look at the decay, distortion and group delay.

I believe you, probably a noticeable difference in your room ported or sealed, you are not being fooled. The results CAN be explained by science and there are good reasons why speakers are designed both ways. A ported enclosure gets you lower frequencies but there's always a trade off.

 

[Deleted member 48726]

I have a DIY sub using a JBL GTO 1014D.

It was well made, with internal bracing, a flat response and well adjusted port.

I was looking some Dynaudio and Revel subs that are sealed and I decided to try mine in that mode.

My sub is playing up to 40 Hz, and above that I have a pair of Revel M105 (since I only hear at low SPL, I preferred to use my sub just to extend the bass response).



First of all I measured my sub with the port open and I made it sealed using two T-Shirts closing the port . I got a sealed speaker with a Qtc = 0,6.



I measured again and adjusted the gain until I’ve got the same spl at low frequencies. Just to know, I needed to increase the sub level by 4dB in my receiver until the curve matches (both on them was measured from 20 Hz)



So, I’ve started hearing.

I found the sealed sub more “soft”, damped, well behaved. My impression was that I was hearing more notes.



The problem is my test was not blind and I’m afraid to be hearing differences just because I read about them in the past.

Does someone made a test like this? What you guys think?

I've had both sealed and ported subs with stereo tower speakers. EQ'ed and room compensated there is no audible difference and the frequency response is the same.

 

[Chrispy]

Yes there is measurable data that would indicate what you are hearing but not with the tools you are using. HouseCurve is a great app for simple things but has no comparison to tools like REW or rePhase (both free BTW). If you really want to know why it sounds different download and learn the software, get a Umik and look at the decay, distortion and group delay.

I believe you, probably a noticeable difference in your room ported or sealed, you are not being fooled. The results CAN be explained by science and there are good reasons why speakers are designed both ways. A ported enclosure gets you lower frequencies but there's always a trade off.

Ported might be more efficient down to it's tuning point, but can lose ground below that (and sometimes in mid-bass too).

 

[Anonamemouse]

I made it sealed using two T-Shirts closing the port . I got a sealed speaker with a Qtc = 0,6.

You did not "seal" it, you just made a "leaking" cabinet.
Sealing means plugging the port with something solid. A t-shirt is not solid enough.

 

[caioferrari]

How was your sub determined to have a flat response, what gear, measurements, etc?

It was designed with a flat response with WinISD. After that, it was measured with the gear I said earlier and the room nodes were knocked down.

 

[caioferrari]

Yes there is measurable data that would indicate what you are hearing but not with the tools you are using. HouseCurve is a great app for simple things but has no comparison to tools like REW or rePhase (both free BTW). If you really want to know why it sounds different download and learn the software, get a Umik and look at the decay, distortion and group delay.

I believe you, probably a noticeable difference in your room ported or sealed, you are not being fooled. The results CAN be explained by science and there are good reasons why speakers are designed both ways. A ported enclosure gets you lower frequencies but there's always a trade off.

I will try to measure it with REW.
I cannot afford a Umik right now (I live in Brazil and there is a lot of importing fees over here), but I will use the Marantz mic just to compare both speakers.

 

[caioferrari]

You did not "seal" it, you just made a "leaking" cabinet.
Sealing means plugging the port with something solid. A t-shirt is not solid enough.

When we plug that foam on ports, does it make a sealed cabinet ?
Because I’m sure that two T-Shirts make a better job. Lol

 

[ZolaIII]

When we plug that foam on ports, does it make a sealed cabinet ?
Because I’m sure that two T-Shirts make a better job. Lol

No not really, try with cork plug (like for wine battles) if you can find large enough one and still use some fiber material around them so that you don't demage the port.
Edit: which Marantz mic? If you have lnterface with microphone amplifier try to obtain measurement microphone which you can find and afford (Behringer, Marantz...) or usb one even older ARC would do and second hand tho you won't be able to use calibration file in REW but most of them are precise enough up to 5 KHz. Without it you won't be able to see what you are doing.

 

[caioferrari]

No not really, try with cork plug (like for wine battles) if you can find large enough one and still use some fiber material around them so that you don't demage the port.
Edit: which Marantz mic? If you have lnterface with microphone amplifier try to obtain measurement microphone which you can find and afford (Behringer, Marantz...) or usb one even older ARC would do and second hand tho you won't be able to use calibration file in REW but most of them are precise enough up to 5 KHz. Without it you won't be able to see what you are doing.

I’m using the Audyssey mic.

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

 

[Gorgonzola]

I'm not one able to advise the OP, but I seems to recall from years ago the sealed bass has better transient response than ported. Also, that with equalization, sealed speakers can go deeper into the bass region that port although at cost of drawing more power from the amplifier. Any truth here?