Sealed speakers VS ported

[Duke]

If I just plonk a speaker down in my small living room , will a sealed or ported design suit me better. I've got a grand to spend on speakers.

Are you talking about a pair of speakers, or a single subwoofer?

Imo there are too many variables in play for "sealed vs ported" to predict which speaker will suit your better.

Would stuffing a port make a speaker the same as a sealed design ?

Blocking the port with an airtight plug transforms a well-designed ported box into an overdamped sealed box.

Stuffing a port with a material which resists but does not block airflow transforms a ported box into an "aperiodic" or "pressure relief" box, and again probably an overdamped one. This approach can be problematic from an excursion-limited power-handling standpoint, as the woofer is relatively unprotected from over-excursion by bass signals.

In my opinion, "amp + speakers + room = a system within a system". So there may be room and amplifier combinations for which either one or the other of the above modifications to a ported box makes sense. If a ported box speaker is boomy in your room and/or with your amplifier, then plugging the port may result in a better overall result. For instance a boomy ported bass cab in a boomy room driven by a tube amp will almost certainly sound better with the port plugged. However the same cab (with or without the same amp) will probably sound better with the port open if you're doing an outdoor gig.

Or do ported designs have a specially specc'ed driver ?

Yes the woofer specs are different; in particular, woofers optimized for ported designs usually have more powerful motors than woofers optimized for sealed designs (this shows up as a lower Qes number). Imo this is a hidden advantage of a vented box, at least if we're talking about two-way speakers, as ime the more powerful motor results in better midrange articulation.

Vented boxes offer the designer more degrees of freedom than sealed boxes do. Imo a vented box can be optimized for accuracy rather than for deepest loudest bass (and most impressive specs), with the net result being competitive with a good sealed box as far as articulation in the bass region, and possibly superior to the sealed box in the midrange region, if this is a two-way loudspeaker.

 

[restorer-john]

Imo this is a hidden advantage of a vented box, at least if we're talking about two-way speakers, as ime the more powerful motor results in better midrange articulation.

Vented boxes offer the designer more degrees of freedom than sealed boxes do. Imo a vented box can be optimized for accuracy rather than for deepest loudest bass (and most impressive specs), with the net result being competitive with a good sealed box as far as articulation in the bass region, and possibly superior to the sealed box in the midrange region, if this is a two-way loudspeaker.

Is " better midrange articulation" a term for less IM from LF VC excursion modulating the mids...

I say, bring back the midrange drivers.

 

[Duke]

Is " better midrange articulation" a term for less IM from LF VC excursion modulating the mids...

I can't say for sure what the dominant effect is if we're comparing otherwise similar speakers. To me it seems related to motor-strength-to-moving-mass ratio, however that is just an observed correlation which does not necessarily imply causation.

I say, bring back the midrange drivers.

If we're talking about conventional cone-n-dome speakers, in general I tend to agree, but imo it depends on the specifics.

 

[fineMen]

I can't say for sure what the dominant effect is if we're comparing otherwise similar speakers. To me it seems related to motor-strength-to-moving-mass ratio, however that is just an observed correlation which does not necessarily imply causation.

A well saturated magnet system was, back in the day, an alternative to copper sleeves over the magnet's pole. The low mass would decrease the current needed to accelerate the cone, and by that reduce the counter magnetization in the motor aka inductance.

Such general rules are more or less obsolete once Klippel did his first strike with the laser monitoring the cone's movement for a deeper analysis beyond Thiele/Small and distortion measurement.

Again, to suffocate a ported design is throwing away half the money. Presumably people understand this language

 

[Streamc]

Does anyone know who makes a good sealed standmount nowadays ?

KLH5

 

[Owl]

Just curious, does the direction of the port really matter. Front, Rear or down?. I guess the answer is, it depends on the room.

 

[puppet]

Just curious, does the direction of the port really matter. Front, Rear or down?. I guess the answer is, it depends on the room.

If you design a loudspeaker enclosure that will have a less than optimal port size and or length then positioning the port to the rear or bottom may work out better as far as noise/space constraints are concerned.

 

[tuga]

Passive radiators are much better than ports, because they keep the pieces of lego, random toys and critters out of your speakers.

Found some tea biscuits once...

 

[Duke]

Just curious, does the direction of the port really matter. Front, Rear or down?. I guess the answer is, it depends on the room.

There are different schools of thought as to what matters. I prefer rear-facing ports such that any coloration which emerges from them at least has to travel a bit further. A down-facing port would accomplish the same thing, but I also like to make it easy for the user to plug ports in case that improves the in-room bass quantity at low frequencies, which makes rear-facing ports generally more user-friendly than downward-facing ports. But if there is no other way to shoehorn adequate port length into the enclosure, then downward-facing makes the most sense.

That being said, quite a few excellent designs use forward-facing ports with no noticeable ill effects.

Found some tea biscuits once...

My first DIY speakers were transmission lines with removable side panels for access to the internal stuffing for adjustments. One time when I took the side panel off I found a handful of corn inside. We lived on a farm and apparently a mouse was stealing corn from the barn and carrying it to the house to hide in my transmission-line speaker in my upstairs bedroom!

After the corn was removed, that speaker seemed a bit less... organic...

;^)

Anyway I installed netting and that seemed to do the trick.

 

[YSDR]

Sealed enclosures are said to reproduce transients more accurately...

But that's just the theory. In reality a good ported box can have better transient/impulse response than a good sealed. The reason is the air in a sealed loudspeaker box have a non-linear behaviour, while it is less so in the ported one, because the latter acts as a vent (hence vented) to quickly equalize the inside-outside air pressure change and the port resonance (the tuning) dampens the cone movement too.
Below is my realworld example, the vented box tuning around the driver's Fs, the sealed version is the same box and woofer, just the ports are closed, creating a Qtc=0,5 (aka critically damped) sealed box, the measurements they took place outdoors.

Sealed:

Ported:

As we can see, the negative and positiv impulse swing after the initial positive peak is larger with the sealed box. The ported decays longer but that decay-swing (from approx 20 to 45 ms) is very low in level, plus the frequency responses was not equalized to the same response. If I had done so, the closed box would probably have performed even worse.

 

[tuga]

But that's just the theory. In reality a good ported box can have better transient/impulse response than a good sealed. The reason is the air in a sealed loudspeaker box have a non-linear behaviour, whereas the ported have not, because the latter acts as a vent (hence vented) to quickly equalize the inside-outside air pressure change and the port resonance (the tuning) dampens the cone movement too.
Below is my realworld example, the vented box tuning around the driver's Fs, the sealed version is the same box and woofer, just the ports are closed, creating a Qtc=0,5 (aka critically damped) sealed box, the measurements are done outdoors.

Sealed:
View attachment 237383

Ported:

View attachment 237384

As we can see, the negative and positiv impulse swing after the initial positive peak is larger with the sealed box. The ported decays longer but the swing is very low in level.

Can you show just the first 30ms?
The sealed cabinet seems to settle quicker.

I have found that bass reproduced by ports tuned above 30-35Hz sound too coloured, lacking tonal differentiation around the resonant frequency and also lacking clarity (for want of a better word) but maybe I haven't listened to the best specimens.

 

[voodooless]

plus the frequency responses was not equalized to the same response.

That basically invalidates the whole test. The impulse response is a transformation of the frequency and phase response. So if the frequency response is different, so is the impulse response. The slower decay can just be a function of that.

 

[YSDR]

The sealed cabinet seems to settle quicker.

It settles quicker (as I said too), because the frequency response of the sealed box starts to roll-off earlier, but the first negative and positive high level swing is larger (not in time but in level) with the sealed, but according to theory it should be the other way around.

 

[YSDR]

That basically invalidates the whole test. The impulse response is a transformation of the frequency and phase response. So if the frequency response is different, so is the impulse response. The slower decay can just be a function of that.

As I said, just check the first 10 ms, not the decay. If it would EQ-ed to the same, the settling time would be the same (or probably worse in the case of the sealed) but the 0-10 ms would be worse for the sealed, it is worse even if not EQ-ed.

 

[voodooless]

As I said, just check the first 10 ms, not the decay.

The first 10ms look exactly the same. That’s
Roughly upto 100 Hz? Anything going on after will define < 100 Hz.

 

[Frgirard]

Gentlemen, for a forum that claims to speak science, use math and physics and not salt shaker and turmeric.

 

[voodooless]

Gentlemen, for a forum that claims to speak science, use math and physics and not salt shaker and turmeric.

Well, why not stop whining and be an exemplary member then…?

 

[Ricardojoa]

Does the seal alignment (damping factor) affects the impulse response? Does the port tuning have any effects on the impulse response?

 

[voodooless]

Does the seal alignment (damping factor) affects the impulse response? Does the port tuning have any effects on the impulse response?

Obviously everything does. It’s a transformation of frequency and phase response, so any change in any of these will alter the impulse.

 

[Frgirard]

Well, why not stop whining and be an exemplary member then…?

no whining, I'm laughing. you put on voodoo as soon as you can.
Physics and mathematics? have you or haven't you?