Sealed Loudspeakers and Ported Subwoofers?

[Folsom]

You clearly don't understand basic speaker design and ROI.

Do you have any idea how many 15" drivers Jeff would need to get the same sensitivity and output? You have to BURN sensitivity off in the crossover to get that even if you greatly increase the box size, and multiply the amount of drivers to return sensitivity. His speakers are already like having two shipping containers pointed up...

 

[sbo6]

Do you have any idea how many 15" drivers Jeff would need to get the same sensitivity and output? You have to BURN sensitivity off in the crossover to get that even if you greatly increase the box size, and multiply the amount of drivers to return sensitivity. His speakers are already like having two shipping containers pointed up...

And those extra drivers - cost $$! My point.

 

[jeff1225]

You clearly don't understand basic speaker design and ROI.

And you do? Nothing you've said is relevant and your logic is ridiculous

Since you're such and expert, why do you tell is EXACTLY how Wilson saves money making a ported speaker.

 

[Folsom]

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.

So your argument is you can't mix them unless you use a line level crossover? That's what everything you said amounts to...

Why not plug the speaker port and go from there is a plate amp? or cross the plate amp harder (like Ack wants to do)?

The frequencies that a port acts in are very low so for example whether it comes out the front or back is more likely to determine whether you hear port noise or not than anything else since the frequencies are so long they wrap around the speaker anyways.

I'm not wanting to be rude, but think maybe you should consider relaxing instead of trying to come across like you know everything about this subject some of us deal with as a job.

 

[Folsom]

And those extra drivers - cost $$! My point.

The only argument I have for/against porting is damping qualities of what the speaker needs to sound correct. After that sometimes the room/multiple speaker application determines some of what's possible. But I have plenty of arguments against bad ported designs!

If your a speaker seller what would be wrong with a bigger more expensive speaker that yields more income for you? The complication is not everyone wants a dedicated airplane hanger to house their stereo. It's not a cost problem, it's a space problem.

 

[Robh3606]

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.

That's why almost all subs have a phase control to address that issue. Thanks for the clarification on the other drivers had me scratching my head. Still would like to see measurements to see just how significant any summing issues end up being.

"First off, here's the irony in your AR statement - Acoustic Research pioneered the "bass reflex speaker" via using a port."

AR pioneered Acoustic suspension speakers which are sealed.

https://en.wikipedia.org/wiki/Acoustic_Research

https://en.wikipedia.org/wiki/Edgar_Villchur

Rob

 

[sbo6]

And you do? Nothing you've said is relevant and your logic is ridiculous

Since you're such and expert, why do you tell is EXACTLY how Wilson saves money making a ported speaker.

First I am no expert, but i do have basic speaker design understanding, an engineering background, fundamental experience in studio environments and some good experience integrating about a dozen subwoofers over close to as many systems.

Please explain to me what's not relevant, I've been nothing if not on topic.

As for Wilson, irrespective of cost porting their speakers is a design choice. It also has the side benefit of producing deep bass for less $ than a sealed design. Magico goes the other route and ports. Both are essentially cost - no - object speakers so ported or sealed it doesn't matter.

 

[Robh3606]

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.

Look up the JBL L212 system did it back in 1977 Far as I know it's the oldest

http://www.lansingheritage.org/html/jbl/specs/home-speakers/1977-l212.htm

 

[sbo6]

That's why almost all subs have a phase control to address that issue. Thanks for the clarification on the other drivers had me scratching my head. Still would like to see measurements to see just how significant any summing issues end up being.

"First off, here's the irony in your AR statement - Acoustic Research pioneered the "bass reflex speaker" via using a port."

AR pioneered Acoustic suspension speakers which are sealed.

https://en.wikipedia.org/wiki/Acoustic_Research

https://en.wikipedia.org/wiki/Edgar_Villchur

Rob

"The state-of-the-art at the time of AR's invention was the bass reflex speaker, which boosted bass response for a given amount of cone travel by directing sound energy from the rear of the speaker cone through a port in the cabinet "tuned" for reinforcement of the direct signal from the front of the cone by the signal from the rear of the cone. " Same link, you must have skipped it. ;-)

 

[sbo6]

Look up the JBL L212 system did it back in 1977 Far as I know it's the oldest

http://www.lansingheritage.org/html/jbl/specs/home-speakers/1977-l212.htm

I think M&K beat JBL to the punch. https://mksound.com/about-mk/

 

[Duke LeJeune]

"The state-of-the-art at the time of AR's invention was the bass reflex speaker, which boosted bass response for a given amount of cone travel by directing sound energy from the rear of the speaker cone through a port in the cabinet "tuned" for reinforcement of the direct signal from the front of the cone by the signal from the rear of the cone. " Same link, you must have skipped it. ;-)

I think you are mis-reading that sentence.

At the time of AR's invention - which was the Acoustic Suspension enclosure - the bass reflex system was the current state-of-the-art.

 

[Robh3606]

The state-of-the-art at the time of AR's invention was the bass reflex speaker, which boosted bass response for a given amount of cone travel by directing sound energy from the rear of the speaker cone through a port in the cabinet "tuned" for reinforcement of the direct signal from the front of the cone by the signal from the rear of the cone. " Same link, you must have skipped it. ;-)

LOL are you new to this?? Did you look at my links?? Don't know where you got that but it is flat out wrong. Well just goes to show no real substitute for hands on.

Hello Duke thanks for the clarification! I missed that and just replied to his posting LOL welcome to the fray!

Rob

 

[sbo6]

That's why almost all subs have a phase control to address that issue. Thanks for the clarification on the other drivers had me scratching my head. Still would like to see measurements to see just how significant any summing issues end up being.

"First off, here's the irony in your AR statement - Acoustic Research pioneered the "bass reflex speaker" via using a port."

AR pioneered Acoustic suspension speakers which are sealed.

https://en.wikipedia.org/wiki/Acoustic_Research

https://en.wikipedia.org/wiki/Edgar_Villchur

Rob

Yes, but I think you're missing the point, Rob. The speakers' bass sources (drives and port(s)) in and of themselves are OOP, so it's more challenging to integrate. Add the fact that the port commonly fires out the back and closer to a wall (boundary) further exacerbates room modes, complicates integration with a sub(s) and delivers plain muddy albeit more plentiful bass.

 

[sbo6]

I think you are mis-reading that sentence.

At the time of AR's invention - which was the Acoustic Suspension enclosure - the bass reflex system was the current state-of-the-art.

Ah, thanks for catching that Duke.

 

[jeff1225]

First I am no expert, but i do have basic speaker design understanding, an engineering background, fundamental experience in studio environments and some good experience integrating about a dozen subwoofers over close to as many systems.

Please explain to me what's not relevant, I've been nothing if not on topic.

As for Wilson, irrespective of cost porting their speakers is a design choice. It also has the side benefit of producing deep bass for less $ than a sealed design. Magico goes the other route and ports. Both are essentially cost - no - object speakers so ported or sealed it doesn't matter.

Perfect. It's the non-answer i was expecting.

 

[sbo6]

LOL are you new to this?? Did you look at my links?? Don't know where you got that but it is flat out wrong. Well just goes to show no real substitute for hands on.

Hello Duke thanks for the clarification! I missed that and just replied to his posting LOL welcome to the fray!

Rob

Congrats, you are right! Go treat yourself to a cookie!

 

[Duke LeJeune]

...ideally more than 1 subwoofer should be employed to smooth out room mode effects.

Agreed. I was talking about single subwoofers to avoid going off on a tangent. I manufacture a four-sub system called The Swarm, so I'm invested in the idea of using more than one subwoofer to smooth out room modal effects.

The speakers' bass sources (drives and port(s)) in and of themselves are OOP, so it's more challenging to integrate. Add the fact that the port commonly fires out the back and closer to a wall (boundary) further exacerbates room modes, complicates integration with a sub(s) and delivers plain muddy albeit more plentiful bass.

To a certain extent the phase and location differences of driver & port serve the same ends - smoothing out room modes - as does a distributed multisub system.

At low frequencies de-correlation is highly desirable (according to Geddes and Toole). A highly correlated sound field at low frequencies would exhibit large room-induced peaks and dips. A highly de-correlated sound field at low frequencies would be much smoother.

Frequency response smoothness is apparently what matters the most to the ears at low frequencies. This is predicted by the Fletcher-Munson equal-loudness curves, which bunch up south of 100 Hz, such that a 5 dB change at 40 Hz is subjectively comparable to a 10 dB change at 1 kHz.

 

[sbo6]

Perfect. It's the non-answer i was expecting.

Think we're done here...

 

[Folsom]

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.

 

[sbo6]

Agreed. I was talking about single subwoofers to avoid going off on a tangent. I manufacture a four-sub system called The Swarm, so I'm invested in the idea of using more than one subwoofer to smooth out room modal effects.

Thanks, interestingly I have a 4 sub setup in my room. Not the swarm, but certainly a multi - sub system.

The phase and location differences of driver & port serve the same ends - smoothing out room modes - as does a distributed multisub system.

Agreed, but the problem with many speakers is - they are commonly placed near the front wall boundary and with a rear port exacerbate room modes. I understand some design speakers with that understanding but many do not. that in and of itself makes smoothing low frequencies more challenging.

At low frequencies de-correlation is highly desirable (according to Geddes and Toole). A highly correlated sound field at low frequencies would exhibit large room-induced peaks and dips. A highly de-correlated sound field at low frequencies would be much smoother.

Frequency response smoothness is apparently what matters the most to the ears at low frequencies. This is predicted by the Fletcher-Munson equal-loudness curves, which bunch up south of 100 Hz, such that a 5 dB change at 40 Hz is subjectively comparable to a 10 dB change at 1 kHz.

Replies above in bold. Also, WRT Fletcher - Munson - agree again. I try to emulate the equal loudness curve in my system which I have found to yield the most audibly linear bass.