Sealed Loudspeakers and Ported Subwoofers?

Robh3606

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You can post anything you want but I don't have endless time to argue about the very basics of speaker design.
Who's being condescending now? Look you made statement that plugging a reflex port will damage the driver by making it go to X Max. This not the case under normal drive levels. Do you agree or disagree?

Rob :]
 

DaveC

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Nov 16, 2014
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Who's being condescending now? Look you made statement that plugging a reflex port will damage the driver by making it go to X Max. This not the case under normal drive levels. Do you agree or disagree?

Rob :]
"Normal Drive Levels" and "Excessive" have broadly interpretable meanings. I'm not into playing word games.

And you're misquoting me. I never said that "plugging a reflex port will damage the driver...".

So yeah, thanks but no thanks! I already know what's going to happen here and let's just skip it. You're going to post sims with the same power input that will show no differences, but at the same SPL there will be, especially as we get closer to reaching the driver's limit. Ok, done, next...
 

thomask

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Dec 9, 2018
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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.
Yes Lansche 4.1 is a full range speaker down to 22hz.
But it still benefit from top quality subwoofer.

I am playing all kind of music.

I used to be classical music afficiado.

But now I play all kind of rock, fusion like "The Wall" of Pink Floyd.

I will go into the effect of Scaena subwoofer in more detail, In Scaena thread.
 
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sbo6

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Getting back to Ron's question WRT ported subs and sealed speakers I agree with most of what treitz3 stated after Ron's question. Which is to say sealed speakers + sealed subs I think is the best way to go. However, I'd be remiss if I didn't state that I heard Wilson XLFs with 2 Thor's Hammers (ported + ported) sound quite exceptional in a moderately large sized room (about 18' x 25' x 10'). And so if your room is large enough I think any speaker / sub config can work and it becomes more about the quality of the components as integration becomes less challenging.
 

Robh3606

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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.
And you're misquoting me. I never said that "plugging a reflex port will damage the driver...".

Really???

"So yeah, thanks but no thanks! I already know what's going to happen here and let's just skip it. You're going to post sims with the same power input that will show no differences, but at the same SPL there will be, especially as we get closer to reaching the driver's limit. Ok, done, next... "

I am not intellectually dishonest unlike some who know who they are.


Rob :)
 
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sbo6

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treitz3

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Gentlemen, this has gone on long enough. Do not attack a member of this forum or throw personal jabs on this thread or any others. We are better than this and it is not constructive whatsoever. Please discuss the technical merits of the thread and not the poster.

Thank you.

Tom
 

DaveC

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Nov 16, 2014
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Getting back to Ron's question WRT ported subs and sealed speakers I agree with most of what treitz3 stated after Ron's question. Which is to say sealed speakers + sealed subs I think is the best way to go. However, I'd be remiss if I didn't state that I heard Wilson XLFs with 2 Thor's Hammers (ported + ported) sound quite exceptional in a moderately large sized room (about 18' x 25' x 10'). And so if your room is large enough I think any speaker / sub config can work and it becomes more about the quality of the components as integration becomes less challenging.
I agree and would go with sealed subs if I was matching to sealed speakers because they sound similar and I think it would be easier integrate them to sound as one.

As was mentioned the port's output might be spaced differently vs the cone, so a ported sub with such a design would have a 2nd source of sound with a different output vs the cone. If you look at a Thor's Hammer you'll notice the ports are close enough to the drivers the sub's output can be considered as-one, perhaps this is most important with ported subs than the fact they are ported vs sealed? If the Thor's Hammer had rear-firing ports the rear port's output would load the room differently vs the pic below.

 

Robh3606

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Here are the simulations for the same driver in the same volume at the same power levels. One bass reflex the other sealed. To convert the bass reflex to sealed you just plug the port. From the simulations which are at 10 watts 25 watts 50 watts and 100 watts the sealed box limits the maximum driver excursion at each power level which was the point of the referenced article. I consider typical levels at between 10 and 25 watts. Red is bass flex and Orange is sealed. This driver max power input is 100 watts.

So the premise that blocking a reflex port will damage the driver by changing the driver loading from bass reflex to sealed and make it exceed the X Max is not correct. It will actually limit the excursion.

Top graph SPL bottom Excursion in mm

Rob :) 10 watts.jpg 25 watts.jpg 50 watts.jpg 100 watts.jpg
 
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Folsom

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Also if you increase the box size the bump will go away, if it stays just move the tuning a little lower. You can make it as smooth as you want. Although the bump is less than 3db so it's not important.
 

Duke LeJeune

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So where does this leave us with integrating ported subwoofers with sealed full range speakers? :D
This will all just be one person's opinion.

Imo all you really need be concerned with is getting a good blend in the frequency response domain.

At low frequencies, the phase response of a loudspeaker system only matters to the extent that it affects the in-room frequency response. This is because the ear has very poor time-domain resolution at low frequencies. The frequency response is what matters most, and the room has a very large effect on the frequency response of the mains and of the sub(s) at low frequencies.

So we are blending “mains + their room interactions” with “subs + their room interactions”. Whether the mains or subs are sealed or ported may affect how much knob-twiddling you end up doing to dial in a really good blend, but ime the basic process is the same and the end goal is the same regardless.

In other words, assuming suitable equipment, I don't see any significant hurdles to integrating ported subs with sealed mains or vice-versa.

By way of example, the subwoofer system I sell has multiple pluggable ports and whether some, none, or all of the ports are open makes no difference in the setup procedure, and may or may not make a small difference in the control settings. (And I have happy clients who have successfully paired this sub system with sealed, ported, dipole, transmission line, and horn-loaded main speakers.) Often clients experiment with plugging or unplugging one or more ports AFTER the initial set-up is complete, and/or reversing the polarity of one of the four subwoofer units. Sometimes a bit of subsequent tweaking of the controls is called for, but not always. (The woofers I use have enough linear excursion so that's not an issue in normal use.)

For those drawn to the nerdier side of things: At low frequencies speakers + room = a “minimum phase” system, which means that the frequency response tracks the time-domain response. Thus a bump in the frequency response corresponds with a longer decay time. So we might ask this question: When we hear the bump are we hearing the frequency response problem, or the time domain problem, or both? Well, research indicates that what we are hearing is the frequency response problem; that the time-domain aspect is barely audible at best.

One of the studies is relevant to a discussion of sealed vs ported boxes: Group delay in the range generated by a ported box was synthesized without correspondingly affecting the frequency response. It was found to be barely audible on test tones designed to reveal its presence, and inaudible on program material. The implication is that the perceptual differences between sealed and vented enclosures are at the most barely audible once their frequency responses have been matched. I don't claim this to be a comprehensive analysis of the situation, but I think it tells most of the story.

* * * *

In my opinion, differences in the in-room bass that people have noticed between ports facing the wall and ports facing the room have more to do with speaker/room interaction (in this case primarily boundary reinforcement) than with the resulting path length differences, which amount to small fractions of a wavelength.
 
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sbo6

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Thanks Rob, that is how I understood it and what my simple 30Hz sin wave test showed (eyeballing excursion of course). The sealed cabinet restricts (limits?) the cone excursion and higher SPL.

Also, what app is that?
 

sbo6

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May 19, 2014
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At low frequencies speakers + room = a “minimum phase” system, which means that the frequency response tracks the time-domain response. A bump in the frequency response corresponds with a longer decay time. So we might ask this question: When we hear the bump are we hearing the frequency response problem, or the time domain problem, or both? Well, research indicates that what we are hearing is the frequency response problem; that the time-domain aspect is barely audible at best.
IME it depends on how long the decay is. If I pull the bass traps out of my room and measure the decay time at moderate - higher SPLs it's visible and clearly audible in a negative way.
 
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DaveC

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Here are the simulations for the same driver in the same volume at the same power levels. One bass reflex the other sealed. To convert the bass reflex to sealed you just plug the port. From the simulations which are at 10 watts 25 watts 50 watts and 100 watts the sealed box limits the maximum driver excursion at each power level which was the point of the referenced article. I consider typical levels at between 10 and 25 watts. Red is bass flex and Orange is sealed. This driver max power input is 100 watts.

So the premise that blocking a reflex port will damage the driver by changing the driver loading from bass reflex to sealed and make it exceed the X Max is not correct. It will actually limit the excursion.

Top graph SPL bottom Excursion in mm

Rob :)

You need same SPL, not the same power input.

BR isn't used below tuning frequency.

The whole "premise" you completely took out of context. You're basically trying to argue a BR isn't more effecient vs a sealed design, and you're just wrong.

But hey, rig the results just to make a point and try to make yourself look better. Your behavior is ridiculous. None of this is up for debate, if you don't understand the basics this isn't the place to argue it anyways, I'm not interested and don't want to spend the time or effort on this ridiculousness.
 

Duke LeJeune

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Jul 22, 2013
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If I pull the bass traps out of my room and measure the decay time at moderate - higher SPLs it's visible and clearly audible in a negative way.
YESSS!!!

The inter-connectedness of the frequency response and the time-domain response at low frequencies implies that when we improve one, we have simultaneously improved the other! So we can approach the situation from either direction and we are addressing the same problem.

Bass traps directly improve the time-domain response which therefore improves the in-room frequency response.

A distributed multi-sub system directly improves the in-room frequency response which therefore improves the time-domain response.
 
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DaveC

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Nov 16, 2014
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Thanks Rob, that is how I understood it and what my simple 30Hz sin wave test showed (eyeballing excursion of course). The sealed cabinet restricts (limits?) the cone excursion and higher SPL.

Also, what app is that?

It absolutely does NOT show that.

His own graphs show significantly less excursion around the tuning frequency. At same SPL, which is most important, the differences are larger.
 

DaveC

Industry Expert
Nov 16, 2014
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IME it depends on how long the decay is. If I pull the bass traps out of my room and measure the decay time at moderate - higher SPLs it's visible and clearly audible in a negative way.
Nevermind, I misunderstood for a minute... :)

That is definitely the case, long decay muddies up the rest of the music.
 
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