Are passive radiator monitors true superior to ported, or are there any cons?

[abdo123]

We don't see that a lot though, especially not on cheaper designs. Who wants to hide apparent woofers?

True, I hope Purifi makes an 8-inch passive radiator for their 8-inch woofer, that would be a beast om na te streven.

Just look at the compression performance of the March Audio Sointuva, Almost the same as the D&D 8C with two 8-inch subwoofers.

Edit: It's arguably better than the D&D 8C

 

[voodooless]

Edit: It's arguably better than the D&D 8C

I guess that one has some electronic limiting going on.

 

[abdo123]

I guess that one has some electronic limiting going on.

Nope, they confirmed that they don't limit the speakers at all.

I don't think it's necessary either since it's not a ported design. (However i would argue some limiting from 100Hz up is necessary).

 

[MarkS]

Passive radiators are always technicaly worse than good slot-ported or port designs.

No, there are tradeoffs. Ports have resonances up into the midrange. IMO these are more deleterious to the sound than a slight increase in bass distortion.

Plus, we also have to decide what we're holding fixed when doing the comparison. Price is one possibility, size is another. This is not just a "sales room" effect, some of us actually want smaller, lighter speakers if possible, and are willing to pay more for that.

 

[MAB]

The cabinet volume difference isn’t really that much. Usually it’s about the same as a reflex alignment. Reflex just adds the port volume. What you do need though, is more surface area. You needs at least a passive radiator with twice the SD of the active driver, preferably 3x. All these PR’s need to go somewhere..

Ports have their own issues. For a smaller speaker, a large enough port is mostly fine. For low tuning, a port can quickly be very long and large. Taking up considerable volume and are prone to resonances. In those cases a few massive PR’s can really work very well.

Yeah, passive radiator gives on paper a very idealized port response minus the port resonance and problems. And not more distortion, unless you don't take into account the massive excursion you get from the passive radiators, which is solved with 2x or more radiators!

The thing about passive radiators is they typically will be tuned with higher moving mass than the driver they are paired with, by a large margin. For instance, a Seas L26ROY active subwoofer driver has moving mass of 118 grams, the matching SL26R passive is 273 grams. A single passive will walk the subwoofer all over the room if driven near resonance, making a heck of a racket from the suspension and the box and the rattling. Adding a second passive or a bigger passive will certainly reduce the excursion but the additional mass is large (~200 grams of additional mass per passive in the case of the SL26R). The problem is so easily solved by pairs on opposite sides of the cabinet. And it seems like so many passives for sale are not doing the work to deal with the few problems that passives introduce. Instead we have these little cubes with high mechanical noise, distortion, and resonances.

 

[sarumbear]

Passive radiators are always technicaly worse than good slot-ported or port designs.
The distortion is higher with passive radiators. The only advantage is that you can shrink the cabinet and get the same -3 dB point in the bass , compared to a ported design.

Not true. If you argue you have to show us why, technically.

 

[MAB]

Not true. If you argue you have to show us why, technically.

Agreed.

 

[MAB]

Passive radiators are always technicaly worse than good slot-ported or port designs.
The distortion is higher with passive radiators. The only advantage is that you can shrink the cabinet and get the same -3 dB point in the bass , compared to a ported design.
This is a serious salespoint in a store, more important than really good sound.
The price for shrinking the cabinet and using a passive radiator are always: higher distortion and somewhat unarticulated bass, compared to good closed boxes and ported ones.

In 2022 you see a lot of designs with passive radiators from lots of companies.
I always stay away from those.

I agree with your fourth statement... Yes a passive radiator in a shrunken cabinet is a recipe for bad results, and elevated distortion.
But you shouldn't extend this to passive radiators in general. Passives solve issues with ported designs with a wide range of tuning and do so with manageable tradeoffs, like cost of the hardware. The results of a good passive radiator implementation are awesome, and not as you generalize.

 

[Dinesh Menon]

I know it's an old thread, still wished to draw our FMs attention to the humble Polk T50 Floor standing speakers with 2 passive radiators, which measured well in Amir Sir's test.
Is it a good buy even today ?

 

[MAB]

I know it's an old thread, still wished to draw our FMs attention to the humble Polk T50 Floor standing speakers with 2 passive radiators, which measured well in Amir Sir's test.
Is it a good buy even today ?

Those are (IMHO) very good budget speakers.
The passive radiators do provide bass extension that most speakers at this price point can't match.
Polk has been doing passive radiators since ages ago. It's an achievement just getting a floor stander with two passives at this price that sounds good!
I might have an issue with the 1kHz peak. If it is resonance, then it is there to stay. That being said, not may speakers at this price combine so many good attributes.

 

[dfuller]

Turns out passives actually have steeper roll-off than vented cabinets, which means greater group delay and somewhat worse transient behavior. Whether or not this is audible is another question, but it's certainly the case that it exists.

In a ported design you have a 4th order roll-off - driver compliance + driver mass + port air slug mass + cabinet air spring. In a passive it's fifth order - driver compliance + driver mass + cabinet air spring + radiator compliance + radiator mass.