Sealed Loudspeakers and Ported Subwoofers?

sbo6

Well-Known Member
May 19, 2014
924
71
85
Round Rock, TX
#81
sbo6, I would suggest you read up more on modes/nodes. They aren't caused by loading problems like you suggested in another post (corner loading). They occur from reflections in a room that causes overlapping or cancellation. That is why we can fairly easily calculate them, for a given frequency size and for given room size.
Yes, the positioning of a speaker close to a boundary may or may not exacerbate room modes but often results in louder bass often at the sweet spot, no?

Also, yes I get how room modes occur, thanks. If I made an earlier statement, especially last night that may have been a bit tilted off, that's the bourbon talking. ;-)
 
Last edited:

Ron Resnick

Site Co-Owner, Administrator
Jan 25, 2015
7,173
1,480
410
Beverly Hills, CA
#82
So where does this leave us with integrating ported subwoofers with sealed full range speakers? :D
 

sbo6

Well-Known Member
May 19, 2014
924
71
85
Round Rock, TX
#83
IME integrating ported subs with sealed speakers is easier than the opposite (ported speakers with sealed subs) since you have the luxury of placing the subs wherever you want in the room and can tune them via level, phase, Freq rolloff, etc. With the opposite scenario you're typically stuck with speakers' rear ports close to a surface in most rooms can = muddy bass. An option is to plug the ports which I do. This also limits the low bass range of the mains and if you have a room mode near the rolloff, you have less of an overlap between the mains and the subs = easier integration (again my situation @~30Hz). I believe sealed subs and sealed mains with a crossover like the CR1 would yield the best integration.

Of course, I got chewed out to no end so what do I know... ;-(

Apologies Ron for dragging this topic a bit sideways and down hill.
 
Last edited:

thomask

Well-Known Member
Dec 9, 2018
478
333
65
59
Washington State, US
#84
20200113_220159.jpg I started playing Lansche 4.1 (sealed speaker) with two 18 inch Scaena sealed subwoofer(120lb , Kevlar/Carbon composite cones) about 2 hours ago.

Wow, it is kind of magic with clean and deep bass and enormous dynamics and wider deeper soundstage.

Go for Scaena 18 inch subwoofers.

You will not regret it.
 
Last edited:
Likes: NorthStar
May 30, 2010
16,074
1,119
420
Portugal
#85
I have taken measurements with the XLF port in both positions and can assure you that there is a significant difference - the speaker is deep and the double of its value should be compared with the distance from the speaker to the front wall - in many rooms the critical aspect in the bass are the nuls due to cancellation caused by wall reflection.
I'm confused. First you're saying the distance between the port and the driver is insignificant. Now you are saying, " there is a significant difference". Which is it or am I missing something?
Sorry, you are the one creating confusion. I never said " the distance between the port and the driver is insignificant.". This was my first post on the thread and is simply a measured fact.

The debate on subjective aspects of ported versus sealed lasts for decades. Each side has its specific reasons, IMHO there are no winners. In the end what is relevant is the way the speaker energizes a particular room in the bass, not the anechoic measurements in a free space.
 

treitz3

Super Moderator
Dec 25, 2011
4,784
19
200
The tube lair in beautiful Rock Hill, SC
#86
So where does this leave us with integrating ported subwoofers with sealed full range speakers? :D
Hello, Ron and good afternoon to you. Please allow me to ask this...

Why would you want to blend a ported sub with a sealed main? I personally see no benefit into doing so, unless you are using the rig as an HT. IME, the sealed subs are better for low end reproduction on a 2CH rig than ported ones. Especially the direct-servo ones.

IMO/IME, the lower registers of the frequency spectrum are the absolute hardest to get right. This be whether it is integrating the lower registers from within the mains themselves as a speaker manufacturer or with the addition of a sub in one's personal rig. Why would you want to go ported on a sub when your mains are sealed is my question. I guess I'm not following why you would want to do such a thing. Would you be so kind as to clarify?

Thanks,

Tom
 

DaveC

Industry Expert
Nov 16, 2014
2,907
777
180
#87
One thing with ports that hasn't been addressed is the MASSIVE reduction in excursion a ported design enjoys, which reduces IMD (InterModulation Distortion). This doesn't matter as much with subs, but when the woofer plays higher up it makes a big difference.

So if you plug your ports, check out the amount of excursion you're getting, it's probably far more than the designer ever intended, you're increasing distortion and reducing the ability of your speaker to play clearly at higher SPLs. You can't just turn a ported design into a sealed design like that and expect good results. You may like the outcome, but that doesn't mean it's better.

Finally, talk of phase outside of crossover frequencies (at subwoofer frequencies) is a complete non-issue. Our ears are NOT that sensitive to phase and group delay of a well thought out ported design. Below the transition frequency of the room we hear constructive and destructive interference, not phase.

Anyways, I designed my speakers to play down to 20 Hz so I simply don't use subwoofers anymore. I think this is the best strategy, whenever you can keep it simple, that's usually the best design choice. I fully understand subs can be used to simply improve the linearity, and in some rooms and some situations it might be best, but there's also a chance you can setup your speakers to achieve decent bass performance without subs if the speakers are capable.
 

sbo6

Well-Known Member
May 19, 2014
924
71
85
Round Rock, TX
#88
One thing with ports that hasn't been addressed is the MASSIVE reduction in excursion a ported design enjoys, which reduces IMD (InterModulation Distortion). This doesn't matter as much with subs, but when the woofer plays higher up it makes a big difference.

So if you plug your ports, check out the amount of excursion you're getting, it's probably far more than the designer ever intended, you're increasing distortion and reducing the ability of your speaker to play clearly at higher SPLs. You can't just turn a ported design into a sealed design like that and expect good results. You may like the outcome, but that doesn't mean it's better.
In my case I've checked my mains which I have plugged the ports on and see no noticeable increase in excursion of woofers (woofers crossed over at 220Hz for reference). Also, unless I am mistaken, plugging ports (emulating a sealed design) should add mechanical resistance to the driver and reduce cone excursion, not the opposite. Can you please help me understand if I am mistaken?

Edit: Adding this info: https://www.css-audio.com/single-post/2019/02/19/Plugging-a-Port---What-is-Happening-to-Your-Speaker
 
Last edited:

DaveC

Industry Expert
Nov 16, 2014
2,907
777
180
#89
In my case I've checked my mains which I have plugged the ports on and see no noticeable increase in excursion of woofers (woofers crossed over at 220Hz for reference). Also, unless I am mistaken, plugging ports (emulating a sealed design) should add mechanical resistance to the driver and reduce cone excursion, not the opposite. Can you please help me understand if I am mistaken?

Edit: Adding this info: https://www.css-audio.com/single-post/2019/02/19/Plugging-a-Port---What-is-Happening-to-Your-Speaker

That's a very bad article you linked.

Ported designs are generally not used below the tuning frequency of the port. In the case of the article, that's about 45 Hz. Look at excursion at 45 Hz, it's many times less vs sealed, and it also doesn't say what the SPL is, this is important because it's much less in the sealed example assuming the same power input. If SPLs were the same the sealed woofer would exceed Xmax and damage it's self.

So saying that plugging a port and turning a ported design into a sealed design won't damage your speaker is ridiculous, it will often cause your woofer to exceed Xmax, which will cause damage. A port provides more resistance vs a sealed box around it's tuning frequency, and boosts output so the end result is a woofer that requires FAR less excursion for the same output vs a sealed box.

The article also doesn't go into IM distortion. Basically, it's a crap article that doesn't give you the full picture and arrives at wrong conclusions. Unbelievable that stuff like that gets published...
 
Likes: jeffrey_t

sbo6

Well-Known Member
May 19, 2014
924
71
85
Round Rock, TX
#90
That's a very bad article you linked.

Ported designs are generally not used below the tuning frequency of the port. In the case of the article, that's about 45 Hz. Look at excursion at 45 Hz, it's many times less vs sealed, and it also doesn't say what the SPL is, this is important because it's much less in the sealed example assuming the same power input. If SPLs were the same the sealed woofer would exceed Xmax and damage it's self.

So saying that plugging a port and turning a ported design into a sealed design won't damage your speaker is ridiculous, it will often cause your woofer to exceed Xmax, which will cause damage. A port provides more resistance vs a sealed box around it's tuning frequency, and boosts output so the end result is a woofer that requires FAR less excursion for the same output vs a sealed box.

The article also doesn't go into IM distortion. Basically, it's a crap article that doesn't give you the full picture and arrives at wrong conclusions. Unbelievable that stuff like that gets published...
I just picked one of the first Google results and didn't have time to search for a white paper, or read through a book from Geddes, etc..

If we can be clear, let me know if this is correct: A ported speaker with closed form foam (or an equivalent dense material) in the port(s) will yield less cone excursion that unstuffed port(s) up to the port tuned frequency? If this is true, unless your tuned port frequency is greater than the most common musical audio instruments' band (let's say >40Hz) your risk of extended excursion is low. This all of course depends on your level of preferred listening.
 
Last edited:

Robh3606

Well-Known Member
Aug 25, 2010
1,042
57
145
Destiny
#91
Hello Dave C

You need to run some sims. A sealed speaker unassisted won't have much change in excursion. It' s only when you apply EQ to compensate for the falling low end response that you have an issue just like a relex box being driven to low. My Revel Performa F206's came with resistive plugs to limit bass output if required.

Sealing a reflex box will not cause the driver to exhibit excessive excursion. The reflex box will have minimum cone movement at Fb if you seal it that movement may increase compared to Fb but would not increase it enough to exceed it's X Max given the same input power

Rob :)
 
Likes: sbo6

DaveC

Industry Expert
Nov 16, 2014
2,907
777
180
#92
Hello Dave C

You need to run some sims. A sealed speaker unassisted won't have much change in excursion. It' s only when you apply EQ to compensate for the falling low end response that you have an issue just like a relex box being driven to low. My Revel Performa F206's came with resistive plugs to limit bass output if required.

Sealing a reflex box will not cause the driver to exhibit excessive excursion. The reflex box will have minimum cone movement at Fb if you seal it that movement may increase compared to Fb but would not increase it enough to exceed it's X Max given the same input power

Rob :)
No, I don't need to run more sims thank you very much! And the suggestion is insulting and condescending. Great way to argue a point! ;)

The evidence for what I said is right there in the article sb06 linked. Look at the excursion at 45 Hz. I'm not talking about adding eq, I have no idea where you got that from.

And the sentence I bolded is just plain wrong, assuming a full range signal. (edit: define "excessive". If the ported setup is at xmax then sealing it will cause it to exceed xmax at the same SPL, which is excessive) Again, the evidence is in the simulation in the link sb06 posted. I'm having a hard time wrapping my head around how this isn't extremely obvious... Everyone knows ported boxes are more efficient! To argue otherwise is ridiculous. Who needs to run more sims? Lol...
 
Last edited:

sbo6

Well-Known Member
May 19, 2014
924
71
85
Round Rock, TX
#93
I just went and ran a 30Hz sin wave (near port tuning) again as I had done this when initially implementing the stuffing. Ported vs. "sealed" = no discernible difference in cone excursion. BTW - level was ~89DB @ 2' from the right woofer.

I ran this same test with my Ushers and had the same results, the woofers' excursion was the same. Could probably dig up the measurements if I had to. I can try with the KEF monitors in my office for a 3rd data point if need be but I bet the results will be the same.

Net is - Stuffing ports will "Cause your woofer to exceed Xmax, which will cause damage" is not the case with both of my speakers. Also, curious if there was risk to plug ports why would companies like B&W, Axiom, etc. provide them? Would there be something permissible in the design to allow both configurations (less aggressive port tuning or?
 

DaveC

Industry Expert
Nov 16, 2014
2,907
777
180
#94
I just picked one of the first Google results and didn't have time to search for a white paper, or read through a book from Geddes, etc..

If we can be clear, let me know if this is correct: A ported speaker with closed form foam (or an equivalent dense material) in the port(s) will yield less cone excursion that unstuffed port(s) up to the port tuned frequency? If this is true, unless your tuned port frequency is greater than the most common musical audio instruments' band (let's say >40Hz) your risk of extended excursion is low. This all of course depends on your level of preferred listening.
That last sentence is hard to understand, but I think so...

A ported box isn't designed to be used under it's tuning frequency, if it is the box loses "grip" on the woofer and you will get excessive excursion. Almost all pro speakers will include a filter to prevent this, many home speakers don't but I'm not really including this as a case, as most high end speakers will have lower tuning frequencies.

As far as your last post, IDK what to say, the evidence is in the article you posted yourself. The difference is only applicable around the tuning frequency of the port, but that's where a great majority of excursion is required. These are cold, hard facts that are widely accepted by every speaker designer and is apparent in every speaker simulation on the planet. The resistance to this baffles me. Robh's post is so far out in left field I don't even know what to say, it contradicts the most basic aspects of speaker design that are the first thing anyone interested in the subject learns, and are included in the most basic free simulation software. :rolleyes:

Also, yes, some speakers are designed to be used either way, you'll just get a bit less SPLs sealed, and more IMD at higher SPLs, but that depends on the crossover point of the woofer. For a sub, IMD doesn't matter nearly as much as a woofer that runs up into the midrange, for example many CD horn designs pattern match the woofer around 800 Hz. So you can have signal at 800 Hz being modulated by information at 40 Hz, but if your box is a BR box the woofer will be moving less at 40 Hz and hence less distortion. So I'm not saying it's horrible to plug your ports, but there are tradeoffs.

And there are also speakers that have multiple ports with only some intended to be blocked, this changes the tuning frequency of the port(s), which has an effect on the low end rolloff, this can be used to linearize room response but doesn't change the speaker from ported to sealed. There are tradeoffs in this approach, namely increasing the tuning frequency makes it more likely for the speaker to get a signal below the tuning frequency, which will cause more excursion vs a lower tuning frequency in the same situation.
 
Last edited:
Feb 8, 2011
23,259
970
405
Vancouver Island, B.C. Canada
#95
View attachment 60662 I started playing Lansche 4.1 (sealed speaker) with two 18 inch Scaena sealed subwoofer(120lb , Kevlar/Carbon composite cones) about 2 hours ago.

Wow, it is kind of magic with clean and deep bass and enormous dynamics and wider deeper soundstage.

Go for Scaena 18 inch subwoofers.

You will not regret it.
Those are fantastic wood looking speakers. And I like the subs style.
Your speakers are deep (22"?), lots of internal volume and they have their larger woofers on the side; they must be full range (22Hz +/-2dB?).

You must be into Orchestral Classical music? Some recommendations with very low bass?
Are you also into synthesizer music, that too can go very low.
 
Likes: thomask

sbo6

Well-Known Member
May 19, 2014
924
71
85
Round Rock, TX
#96
Thanks for the feedback. What I know is - I wouldn't have stuffed the ports had there been excessive cone excursion at any frequency versus ported. And I haven't seen that in either of my mains - Vivids or Ushers. Maybe I'm not driving it hard enough or low enough, maybe there is more leakage via the ports than I know when stuffed? However from a frequency perspective 30Hz is pretty low (Vivids spec'd at ~20KHz - 29Hz I believe with 0 DB down) and volume ~90DB. FYR - the woofer moved ~1/2" and the Xmax = 2" I believe.

Also, can you help answer my last question: Also, curious if there was risk to plug ports why would companies like B&W, Axiom, etc. provide them? Would there be something permissible in the design to allow both configurations (less aggressive port tuning or?)
 

DaveC

Industry Expert
Nov 16, 2014
2,907
777
180
#97
Thanks for the feedback. What I know is - I wouldn't have stuffed the ports had there been excessive cone excursion at any frequency versus ported. And I haven't seen that in either of my mains - Vivids or Ushers. Maybe I'm not driving it hard enough or low enough, maybe there is more leakage via the ports than I know when stuffed? However from a frequency perspective 30Hz is pretty low (Vivids spec'd at ~20KHz - 29Hz I believe with 0 DB down) and volume ~90DB. FYR - the woofer moved ~1/2" and the Xmax = 2" I believe.

Also, can you help answer my last question: Also, curious if there was risk to plug ports why would companies like B&W, Axiom, etc. provide them? Would there be something permissible in the design to allow both configurations (less aggressive port tuning or?)

There's risk in overpowering any driver in any design. BR is simply more efficient so you get more SPL capability out of the same driver, so are less likely to hit it's limits, the driver will have less excursion playing the same SPLs. Sealed is only "risky" as far as it's lower SPL limits, but every speaker has it's limits. If the BR speaker has tuning frequency too high that's more "risky" vs a sealed design in many ways.

You are correct this only matters when playing at higher SPLs relative to what the system is capable of. Any speaker simulation will tell you exactly how much excursion your speaker will have in both scenarios, so you can download some free software, play with it and understand what's going on, probably in about 20 minutes or so. You can also look at volume, stuffing, T/S parameters and why they are different sealed vs ported, etc.

edit: The plugs provided will also change the bass rolloff to something more appropriate for smaller rooms, so the reduction in SPL capability won't matter as much in that situation.
 
Last edited:

Robh3606

Well-Known Member
Aug 25, 2010
1,042
57
145
Destiny
#98
No, I don't need to run more sims thank you very much! And the suggestion is insulting and condescending. Great way to argue a point! ;)

The evidence for what I said is right there in the article sb06 linked. Look at the excursion at 45 Hz. I'm not talking about adding eq, I have no idea where you got that from.

And the sentence I bolded is just plain wrong, assuming a full range signal. (edit: define "excessive". If the ported setup is at xmax then sealing it will cause it to exceed xmax at the same SPL, which is excessive) Again, the evidence is in the simulation in the link sb06 posted. I'm having a hard time wrapping my head around how this isn't extremely obvious... Everyone knows ported boxes are more efficient! To argue otherwise is ridiculous. Who needs to run more sims? Lol...

Dave nobody sets up a reflex enclosure at X Max the example is obviously with power applied up near the drivers limits. You won't be anywhere near X max under any normal listening levels. I think you are jumping to conclusions. I will post sims later at reasonable power levels and the driver will not go to X max.

Rob :)
 
Last edited:

DaveC

Industry Expert
Nov 16, 2014
2,907
777
180
#99
Dave nobody sets up a reflex enclosure at X Max the example is obviously with power applied up near the drivers limits. I think you are jumping to conclusions. I will post sims later.

Rob :)
You can post anything you want but I don't have endless time to argue about the very basics of speaker design.
 

sbo6

Well-Known Member
May 19, 2014
924
71
85
Round Rock, TX
There's risk in overpowering any driver in any design. BR is simply more efficient so you get more SPL capability out of the same driver, so are less likely to hit it's limits, the driver will have less excursion playing the same SPLs. Sealed is only "risky" as far as it's lower SPL limits, but every speaker has it's limits. If the BR speaker has tuning frequency too high that's more "risky" vs a sealed design in many ways.

You are correct this only matters when playing at higher SPLs relative to what the system is capable of. Any speaker simulation will tell you exactly how much excursion your speaker will have in both scenarios, so you can download some free software, play with it and understand what's going on, probably in about 20 minutes or so. You can also look at volume, stuffing, T/S parameters and why they are different sealed vs ported, etc.

edit: The plugs provided will also change the bass rolloff to something more appropriate for smaller rooms, so the reduction in SPL capability won't matter as much in that situation.
Thanks for the feedback. IME sealed speakers and subwoofers' drivers should be designed to meet specifications and that's what I've seen with SVS and JL for example in sealed designs. So yes there's risk in overpowering any driver, there's risk in damaging a car engine if I exceed red line, there's risk in every situation, the key is to design to meet specs and as an end user don't abuse.

In terms of the plugs, my point in calling it out was - if your statement is true WRT excursion, this would be a risky proposition for compaines like B&W, one of the largest Hi end speaker manufacturers in the world. As such, I trust their engineering and port / sealed application. So based on my real - world observations and measurements + plug availability from one of the top mfrs in the world I would surmise there is minimal risk to plug ports under normal operating conditions.
 

About us

  • What’s Best Forum is THE forum for high-end audio, product reviews, advice and sharing experiences on the best of everything else. A place where audiophiles and audio companies discuss existing and new audio products, music servers, music streamers and computer audio, digital to audio converters, turntables, phono stages, cartridges, reel to reel, speakers, headphones, tube amplifiers and solid state amplification. Founded in 2010 What's Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals we enjoy learning about new things and meeting new people and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing