Sealed Loudspeakers and Ported Subwoofers?

sbo6

Well-Known Member
May 19, 2014
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Round Rock, TX
#41
I admit half baiting you into this question because I wasn't expecting an answer that would be legit.

This isn't true in the way you think it would be. Ports are slightly out of phase with the driver that is feeding them to begin with. Can you hear it? Actually no, you hear numerous things but not the phase part. First you must understand that a driver is out of phase with itself constantly. Every frequency moves the driver a different amount because the size of the frequency is different. Because of this the frequencies cannot have the exact same phase, since the sound is originating from different points. To listen to a speaker of any kind is to hear varying phase.

What you're hearing is modes, caused by overlapping phase, but you aren't actually hearing the phase itself - you may be hearing the character of the ported subwoofer as well. This will happen with any subwoofer. Obviously using a crossover to reduce the overlap helps but this isn't specific to ported or any other form, it's source/amplifier dependent. When you adjust a subwoofer's phase (amp/preamp/crossover) you aren't perfectly aligning it to the mains to have same phase (no such thing), not in any way what-so-ever, you're simply getting to a mode/node point that is least offensive so that it sounds right.

And ported speakers don't always have a bump, but you do see it often. There is no specific reason why they would have to have a bump - I've seen lots that roll of very gradual.



Well, it's not true so...
Getting deeper into theory hear :)
First, WRT ports being "slightly OOP" primarily depends on the placement of the port, not only the mechanics and the resulting OOP sound as it escapes the port. So there is no definitive amount to quantify "slightly".

Second, just because a bass driver (in our case) is reproducing hundreds of frequencies which are OOP they are all time aligned relative to the driver. And while there may be modes as you call out, it's the speaker designer's job to assess and engineer the driver, xover and cabinet to avoid such audible challenges. Coaxials have a problem mitigating such issues.

Third, WRT, "What you're hearing is modes, caused by overlapping phase, but you aren't actually hearing the phase itself", how else would you hear phase anomalies other than cancellations or augmentations at overlapping frequencies?

Finally, WRT, "When you adjust a subwoofer's phase (amp/preamp/crossover) you aren't perfectly aligning it to the mains to have same phase (no such thing), not in any way what-so-ever, you're simply getting to a mode/node point that is least offensive so that it sounds right."

Yes and no. When you adjust a subwoofer's phase you can almost perfectly align to the same phase as the mains if the sub(s) proximity is aligned to the mains (like done with tower designs with separate bass / sub columns). However, this often times exacerbates room modes by injecting even more bass from essentially the same location.

Your second point about , "You're simply getting to a mode/node point that is least offensive so that it sounds right." I wouldn't say this is quite accurate. Your mains' bass rolls off (sealed or ported), ideally you want to roll in your sub to avoid that audible roll off and continue to provide subterranean bass (we all know this). By adjusting the subwoofer phase you are looking to align the phase response of the sub to the mains at the critical mains' rolloff frequency to fill that low freq trough while being mindful of room modes exacerbated by mains and sub placement. With everything in audio, it's all a compromise.

Also, almost no room permits, "perfect phase alignment". Sounds are constantly interacting exacerbating and attenuating frequencies, that argument isn't only indicative of bass frequencies. It's also simply part of nature.
 
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sbo6

Well-Known Member
May 19, 2014
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84
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Round Rock, TX
#42
It's a similar situation, and it would depend on the crossover slopes. But if you main speakers go down that low, then do you really need a sub. In general, I would say, use ported subs with ported main speakers from the same manufacturer (a la Wilson) who knows what he's doing and makes an effort to design with integration in mind; or go sealed all around, and avoid too much overlap. This mixing that I see many doing - including myself - is really tough to marry.
The difference is - When trying to integrate subs with ported speakers you are now contending with 2 locations of sound - the woofer and the port.

Also, There's no reason to believe that mixing brands = better bass due to some manufacturer's "secret sauce" in their products, hogwash. Are you saying that if I buy moderately priced speakers, say Polk, that the best integration and sound with be with a cheap Polk sub versus a Rel, JLA, Wilson, Magico?
 

sbo6

Well-Known Member
May 19, 2014
938
84
85
Round Rock, TX
#43
One of the implications of the higher power required to get equivalent SPL & -3 dB point out of a sealed box is, the amp and woofer have to work harder and correspondingly heat up more. A hot woofer motor + a hot amp + a compact enclosure can result in a short, exciting life for the amp.
True, but a) Depending on the subwoofer design the frequency where this occurs may be quite low and b) ideally more than 1 subwoofer should be employed to smooth out room mode effects.

Net is - there are + and - to sealed versus ported. In our modest - sized rooms with no escape from boundaries ported subs yield output at several (OOP) locations which make it difficult to integrate with often employed ported mains which have the same issue (actually worse given limited placement choices). So a common setup with 2 subs may have 8 low frequency output sources (4 subs, 4 mains) - what's a room mode to do but jump or shrink! :)
 

ack

VIP/Donor & WBF Founding Member
May 6, 2010
5,918
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Boston, MA
#44
The difference is - When trying to integrate subs with ported speakers you are now contending with 2 locations of sound - the woofer and the port.

Also, There's no reason to believe that mixing brands = better bass due to some manufacturer's "secret sauce" in their products, hogwash. Are you saying that if I buy moderately priced speakers, say Polk, that the best integration and sound with be with a cheap Polk sub versus a Rel, JLA, Wilson, Magico?
I said: "who knows what he's doing and makes an effort to design with integration in mind". Short of that, it's fair game. Don't over-generalize
 

sbo6

Well-Known Member
May 19, 2014
938
84
85
Round Rock, TX
#45
I said: "who knows what he's doing and makes an effort to design with integration in mind". Short of that, it's fair game. Don't over-generalize
Fair enough, thanks.
 
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Jan 29, 2012
1,548
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#46
How many budget speakers do you know employ sealed cabinet designs? Customers love bass, everyone wants 'full range". Stick a port in the back (usually) at the most beneficial diameter and depth based on the speakers' design and you achieve another 10+ Hz of low frequency output. Sealed, not so easy.
Sorry but this is a ridiculous argument. Both my Seiko and Omega watches have automatic movements, am I to assume that automatic movements are cheap?
 

sbo6

Well-Known Member
May 19, 2014
938
84
85
Round Rock, TX
#47
Apples and oranges. Automatic movement was all that was available before electric watches and some companies still employ self - winding to a) never have to deal with a battery and / or b) for nostalgia's sake.

My question remains - How many budget speakers employ sealed designs?
 
Jan 29, 2012
1,548
678
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#48
Apples and oranges. Automatic movement was all that was available before electric watches and some companies still employ self - winding to a) never have to deal with a battery and / or b) for nostalgia's sake.

My question remains - How many budget speakers employ sealed designs?
The majority of inexpensive home theater speakers and computer audio speaker I see on Amazon is sealed. Most pro audio speakers are sealed. AR speakers were all sealed.

I can give many more examples.
 

Robh3606

Well-Known Member
Aug 25, 2010
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Destiny
#49
The difference is - When trying to integrate subs with ported speakers you are now contending with 2 locations of sound - the woofer and the port.

Also, There's no reason to believe that mixing brands = better bass due to some manufacturer's "secret sauce" in their products, hogwash. Are you saying that if I buy moderately priced speakers, say Polk, that the best integration and sound with be with a cheap Polk sub versus a Rel, JLA, Wilson, Magico?
The distance between the port and the driver is insignificant.

Rob :)
 

Robh3606

Well-Known Member
Aug 25, 2010
1,042
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Destiny
#52
Older ones yes, but many of the self powered ones are sealed. The point is, the argument that designers use ports as a cost saving move is laughable.
Well actually it's not. It depends on how you look at it. For that same FR over the same bandwidth you get more bang for your buck using reflex enclosures. You don't have to waste amplifier power making up for the sealed subwoofers roll-off. You can also use a driver that doesn't have to put up with up to 12db of EQ so less expense there as well. So you are actually are using the bass drivers more efficiently using reflex enclosures.

As far as self powered being sealed I did a search on the JBL Pro page and couldn't find a sealed powered subwoofer. They were all bass reflex which makes sense in a Pro application. That included portable music and installed systems. The cinema stuff is always either ported or horn loaded.

Rob :)
 
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sbo6

Well-Known Member
May 19, 2014
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84
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Round Rock, TX
#53
The distance between the port and the driver is insignificant.

Rob :)
Based on what? the wavelength argument? And if the distance doesn't matter why do some manufacturers like Wilson permit plugging the port to be front or rear ported? From and measurement perspective I can tell you there certainly is a difference.
 
May 30, 2010
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#54
Based on what? the wavelength argument? And if the distance doesn't matter why do some manufacturers like Wilson permit plugging the port to be front or rear ported? From and measurement perspective I can tell you there certainly is a difference.
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.
 

sbo6

Well-Known Member
May 19, 2014
938
84
85
Round Rock, TX
#55
The majority of inexpensive home theater speakers and computer audio speaker I see on Amazon is sealed. Most pro audio speakers are sealed. AR speakers were all sealed.

I can give many more examples.

First off, here's the irony in your AR statement - Acoustic Research pioneered the "bass reflex speaker" via using a port. So no, not only were they not all sealed but they pioneered the ported design with the famous AR-1. Also, WRT monitors, sorry your statement again is simply not true. From Amazon's top selling studio monitors:


Presonus Eris - ported : https://www.amazon.com/PreSonus-Eri...coding=UTF8&psc=1&refRID=R4V5T4ATG7BKATW54Z39
Mackie CR-3- ported: https://www.amazon.com/Mackie-Studi...coding=UTF8&psc=1&refRID=R4V5T4ATG7BKATW54Z39
JBL Professional 1 - ported: https://www.amazon.com/JBL-Professi...coding=UTF8&psc=1&refRID=R4V5T4ATG7BKATW54Z39
KRK RP5: ported: https://www.amazon.com/KRK-Professi...coding=UTF8&psc=1&refRID=R4V5T4ATG7BKATW54Z39
JBL Ppro 305 Mk II: ported: https://www.amazon.com/JBL-Professi...coding=UTF8&psc=1&refRID=R4V5T4ATG7BKATW54Z39

The remaining top 10 and beyond sellers are derivations off the monitors above (difference color, different size bass driver, etc and are all ported. I can go on and on but I already know the answer.
 

sbo6

Well-Known Member
May 19, 2014
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84
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Round Rock, TX
#56
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?
 

Robh3606

Well-Known Member
Aug 25, 2010
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Destiny
#57
Based on what? the wavelength argument? And if the distance doesn't matter why do some manufacturers like Wilson permit plugging the port to be front or rear ported? From and measurement perspective I can tell you there certainly is a difference.
Yes wavelength and if understand your point correctly any system sealed or reflex that uses multiple woofers such as Magico or Revel and so on would be more difficult to integrate because or the multiple bass source room issues. So a Revel Salon would have 3 woofers and a port so 4 and a Magico M3 would have 3. Is this correct??

The only reason I can see to plug a front port to use a rear is to attenuate and HF component of the cabinet back waves contribution to the room.

Can you post some measurements so I can see??

I am not buying it I have 6 15" woofers in my HT set-up that are all ported on the back or sides of the cabinets depending on the install so 12 sound sources?? I should have a dogs breakfast for integration. I don't

Rob :)
 
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sbo6

Well-Known Member
May 19, 2014
938
84
85
Round Rock, TX
#58
Older ones yes, but many of the self powered ones are sealed. The point is, the argument that designers use ports as a cost saving move is laughable.
You clearly don't understand basic speaker design and ROI.
 

Folsom

VIP/Donor
Oct 26, 2015
4,408
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#59
Getting deeper into theory hear :)
First, WRT ports being "slightly OOP" primarily depends on the placement of the port, not only the mechanics and the resulting OOP sound as it escapes the port. So there is no definitive amount to quantify "slightly".

Actually the phase of a port is 90 degree behind the driver.

Second, just because a bass driver (in our case) is reproducing hundreds of frequencies which are OOP they are all time aligned relative to the driver. And while there may be modes as you call out, it's the speaker designer's job to assess and engineer the driver, xover and cabinet to avoid such audible challenges. Coaxials have a problem mitigating such issues.

Time alignment? Time alignment is phase, too. Time alignment is basically a marketing term since even midwoofer isn't time aligned with itself consistently. What matters is polar response, dispersion, lobing, etc - many of which benefit from what appears like physical time alignment.


No speaker designer on earth can correct every room from the design of a speaker except by switching to headphone making.

Third, WRT, "What you're hearing is modes, caused by overlapping phase, but you aren't actually hearing the phase itself", how else would you hear phase anomalies other than cancellations or augmentations at overlapping frequencies?

If phase decreases continually overall as frequency climbs it'll sound weird and unpleasant. But also if phase is screwy enough it'll come across as garble. I've never seen a speaker be that bad before though. In general people love fairly moderate level distortion speakers all day long. They like amps without low distortion, too.

Finally, WRT, "When you adjust a subwoofer's phase (amp/preamp/crossover) you aren't perfectly aligning it to the mains to have same phase (no such thing), not in any way what-so-ever, you're simply getting to a mode/node point that is least offensive so that it sounds right."

Yes and no. When you adjust a subwoofer's phase you can almost perfectly align to the same phase as the mains if the sub(s) proximity is aligned to the mains (like done with tower designs with separate bass / sub columns). However, this often times exacerbates room modes by injecting even more bass from essentially the same location.

You have to bypass the phase adjustment portion to get completely "aligned". Basically no amps do that. So even if you "align" it so it overlaps (and makes more modes) it's still lagging behind the main speaker because of the way the electronics work.


Your second point about , "You're simply getting to a mode/node point that is least offensive so that it sounds right." I wouldn't say this is quite accurate. Your mains' bass rolls off (sealed or ported), ideally you want to roll in your sub to avoid that audible roll off and continue to provide subterranean bass (we all know this). By adjusting the subwoofer phase you are looking to align the phase response of the sub to the mains at the critical mains' rolloff frequency to fill that low freq trough while being mindful of room modes exacerbated by mains and sub placement. With everything in audio, it's all a compromise.

Also, almost no room permits, "perfect phase alignment". Sounds are constantly interacting exacerbating and attenuating frequencies, that argument isn't only indicative of bass frequencies. It's also simply part of nature.
See above ^
 

sbo6

Well-Known Member
May 19, 2014
938
84
85
Round Rock, TX
#60
Yes wavelength and if understand your point correctly any system sealed or reflex that uses multiple woofers such as Magico or Revel and so on would be more difficult to integrate because or the multiple bass source room issues. So a Revel Salon would have 3 woofers and a port so 4 and a Magico M3 would have 3. Is this correct??

The only reason I can see to plug a front port to use a rear is to attenuate and HF component of the cabinet back waves contribution to the room.

Can you post some measurements so I can see??

I am not buying it I have 6 15 woofers in my HT set-up that are all ported on the back or sides of the cabinets depending on the install so 12 sound sources?? I should have a dogs breakfast for integration. I don't

Rob :)
As with most things in life, the devil is in the details :)

Having a speaker with multiple woofers mounted in a front baffle (very common) and in phase should pose no additional phase issues (in and of itself and driver to driver), unlike a port. So it's not the number of sources, it's the location of such sources and the phase of each source.

The problem with ports is that while they extend bass to lower frequencies, if you want to integrate a sub(s) you now have to contend with the main woofer(s) and now a port OOP with the speaker itself often at the back of the speaker further exacerbating the issue. The best solution is the original employed by M&K (I think) which was the first sub / sat system designed to roll off the sats, roll in the sub(s) and have very minimum frequency overlap. That's what the JLA CR1 does.

In my setup with side firing woofers and side firing ports right behind the woofers, I have the ports plugged up making integration much easier and sonically better. If my room was 2x the Cu ft, I'd probably leave them unplugged. Companies like B&W (I believe) and Kef even provide foam to plug the ports should one chose to.
 

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