[legion1capone]

What is the advantage to Passive Radiators? I see them on smaller subs more than larger subs. What is there job exactly and how do they work?


Some subs that use passive radiators:

http://www.salksound.com/SongSub.shtml

http://www.definitivetech.com/Produc...ubeSeries.aspx

 

[mojomike]

They operate very much like a port in that they are tuned to vibrate at and around a specific frequency. One advantage over a port is that they take up much less space. Where a deeply tuned port need a lot of length, the passive driver just needs weight added to tune it. That way you can achieve a deep tune using a fairly small box.

 

[flickhtguru]

Personally I like passive radiators. IMO they have the some of the benefits and characteristics of both a sealed and a ported speaker. From my experience if the active driver and passive radiators are tuned correctly you get that punch in the chest feeling when the bass hits hard. They have the low bass extention and efficiency of a ported sub but they have the quickness and punch of a sealed sub.

 

[lennon_68]

They effectively work exactly as a port would. The advantage is (as mojomike explained) that they take up less space. This can be crucial in a small enclosure or when tuning low - in a small box you may not have room for a port - to tune low requires a longer port which may not be feasable. Yes you could make the port a smaller area so the length wouldn't be a problem but then you run into problems with port compression and chuffing which is the other big advantage - they don't chuff. However, although they won't chuff/compress like a port they do have mechanical limits that will compress and bottom like a driver so it's not all a free lunch. The main reason they aren't used in many designs is generally a port will be just as effective for basically no extra cost (or very little cost) whereas PR's can add significantly to the cost.

 

[mojomike]



Quote:
Originally Posted by flickhtguru /forum/post/18167940


Personally I like passive radiators. IMO they have the some of the benefits and characteristics of both a sealed and a ported speaker. From my experience if the active driver and passive radiators are tuned correctly you get that punch in the chest feeling when the bass hits hard. They have the low bass extention and efficiency of a ported sub but they have the quickness and punch of a sealed sub.

There is nothing inherent about a passive radiator sub design that makes it any more like a sealed sub than like a ported sub. A sub with a passive radiator is neither inherently quicker or punchier than a sub with a port.

 

[flickhtguru]

Like I said it was that way with my experience. Maybe the ported speakers I listened to were crap and the ones with passive radiators were good ones. Depending how much weight and how tight you have the passive radiators tuned makes them tighter(puchy) or boomy/muddy(loose). I'm not trying to argue, this was just what I noticed.

 

[Hi Def Fan]



Quote:
Originally Posted by flickhtguru /forum/post/18168995


Like I said it was that way with my experience. Maybe the ported speakers I listened to were crap and the ones with passive radiators were good ones. Depending how much weight and how tight you have the passive radiators tuned makes them tighter(puchy) or boomy/muddy(loose). I'm not trying to argue, this was just what I noticed.

No, you're right actually. Given we're talking two speakers of equal quality, the one with passive radiator vs open tuned port would keep cone movement tighter.


These radiators are passive, but they are nowhere near being open air like a ported speaker. They aren't just tuned properly in size and stiffness, their passiveness has to be tuned just right to keep the air management so that they push out when the driver retracts, and vise versa, while still being passive vs sealed. No matter how you cut it that means tighter driver cone management.


Definitive Technology, one of the best speaker makers in a small home theater size, has designed their latest ProCinema 600 series with passive radiators in all the satellites and the sub. Everyone that's reviewed them be it customers or review sites/magazines have noticed better, fuller sound from this new design over the previous 60 series, and the passive radiators are the main design change.

 

[Funk Audio]



Quote:
Originally Posted by Hi Def Fan /forum/post/21791423


No, you're right actually. Given we're talking two speakers of equal quality, the one with passive radiator vs open tuned port would keep cone movement tighter.

Not exactly correct either, yes given the same power the active drivers' excursion will be less in most cases but this is not due to better "control" but due to efficiency loss around tuning due to the losses associated with the stiffness of the passive radiators suspension.


The main reason passive radiator designs often sound more like sealed, is due to the fact that in almost every case passive radiators are used to give a lower tuning than would otherwise be possible, and it is this lower tuning that gives it that sealed "sound". This is because the farther above the tuning frequency the more it behaves like a sealed enclosure, so if your tuning is low enough by the time you get into the mid/upper bass frequencies, where our ears are more sensitive to distortion and ringing, it is essentially acting sealed and will sound like sealed. There are many other factors involved in "sound quality" and "punch" than simply ported/passive/sealed, properly designed they can all sound very good, also badly designed can make any alignment sound bad. Sealed is the easiest to get "right" and is why often has the distinction of being the best. Passive radiator is also reasonably easy to get "right", ported can be trickier as it can be physically difficult to design the enclosure to be "right" and work from a construction standpoint, and often compromises are made in the design to make it buildable, however it has the most potential to have equal sound quality to the other alignments with the most low end efficiency, and therefore provide the most for the money.

 

[Hi Def Fan]



Quote:
Originally Posted by Funky Waves /forum/post/21791654


Not exactly correct either, yes given the same power the active drivers’ excursion will be less in most cases but this is not due to better "control" but due to efficiency loss around tuning due to the losses associated with the stiffness of the passive radiators suspension.

First off I said quality, not power. One cannot equate power with quality of construction. Secondly I was referring to the dampening of the cone, not merely how much excursion it has. The extent of excursion has nothing to do with how precisely it's forward and back movement is controlled. That kind of control is never going to be possible with a mere port design. In port design cone control is specifically up to the driver design, there's no assistance from the enclosure.

Quote:
The main reason passive radiator designs often sound more like sealed, is due to the fact that in almost every case passive radiators are used to give a lower tuning than would otherwise be possible, and it is this lower tuning that gives it that sealed "sound".

Again, when we're talking "sealed" sound, we're talking cone control, vs flapping uncontrollably in an open enclosure. Let's not confuse frequency of tuning with control of the enclosure's gas management, the two are entirely different things.


I'll skip quoting any part of your last paragraph and just say that your having said many factors attribute to sound quality is the obvious. Where you miss the obvious however and somewhat contradict yourself is where you say ports and the proper tuning and fitting of them is the hardest, yet the best bang for the buck.


Indeed port tuning is not simple, nor is even port fitting in some cabinets. This is why you see SO many crappy sounding speakers that just have little holes and short tubes in them, that offer ever so slightly lower frequency, at the expense of sound quality. I don't call that best bang for buck. In reality it's the illusion of bang for buck a lot of consumers become victims of.


I have spoken with some pretty good subwoofer cabinet designers and I do know a bit about gas management in speaker cabinets. The Definitive Technology tech I spoke to also describes the benefits and function of passive radiators pretty much the same as I have here. Sorry, but I have to disagree with you.

 

[jjackkrash]

^^^ I know one pretty good subwoofer cabinet designer you've spoken to--at least electronically--and he posted just above you.

http://www.funkaudio.ca/Custom_Gallery.html

 

[Hi Def Fan]

Doesn't mean a whole lot really. "Pretty good" is relative to one's success, and I don't even see anything but over priced ported enclosures, nor is it as well known a brand as they make it out to be. Looks to be still in the start up stage. You Google that name and you get one of 3 or 4 sites, including one that redirects you.


The vague and even contradictory terms he uses leaves me even more skeptical. In reality the internet is full of people trying to use forums to launch their business. Doesn't mean they succeed at it, and if he was as successful as he makes it sound, he wouldn't need to be glomming onto forums to get customers.


They make light of "big box stores", yet contradict that resistance to volume sales by trying to make themselves sound like they have a vast global consumer base. Yet where is their name seen even in smaller volume high end audio stores? None that I've seen in the US. Sounds a lot like snake oil to me.


You know when you see someone talk as if they prioritize basic build quality of speakers using cabinet material like aluminum, it's more about a gimmicky fashion statement than bang for the buck sound quality. How he could even mention bang for the buck in his post above is a bit absurd really.

 

[ccotenj]

^^^


do a bit of browsing around in the subwoofer forum... your eyes may be opened a bit...

 

[Theresa]

I have two subs with passive radiators. By my experience and everything reliable I've read they are no different (apart from losses with the passive radiator) from ported except not requiring a bulky port taking up space in the enclosure.

 

[Mupi]

I understand that the radiator is tuned to some frequency, but what is making those frequencies. If the woofer is capable of making those frequencies then why bother with a radiator. So my question is what is driving the radiator. Is it still the woofer but the woofer is not capable of high output at those low frequencies and so the radiator adds to the output?

 

[Theresa]

Its called "passive" for a reason. It substitutes the mass of a cone for the mass of air in a tuned vent.

 

[Mupi]

I get all that but where is the frequency coming from that causes it to vibrate? Is it still produced by the woofer and the radiator just adds to the low output of the woofer as it is tuned to resonate at that frequency?


BTW my earlier question was not in response to your post. If was a general question.

 

[Mupi]

I guess I get it. My assumption was indeed correct.

http://www.humanspeakers.com/whatis/PR.htm

 

[polizzio]

Mupi,


The passive radiator moves because of air pressure fluctuations within the sealed enclosure, like a diaphragm, caused by the movements of the active driver cone (the one with a magnet and powered).

Think how pressures within the speaker enclosure vary and differ while operating a sealed or ported cabinet if you were to measure with a very sensitive device, capable of measuring fractions of a pound of pressure, capable of measuring say 1/25th of 1 psig.


Think of it this way. At first, high fidelity speakers were sealed, then came along the bright idea to port the cabinet to boost acoustic output (generate sound from both surfaces of the driver cone. Passive radiators do similar, but with a slightly different twist (some degree of dampening possible). Vented or PR rely upon driver cone rear surface movements/radiating area to generate additional sound, the need to create more sound output from a given power level and cone radiating area. Sealed generate sound from the front face of the driver cone, vented and PR rely upon or "play" both sides of the driver cone to create output. Hence why ported subs "sound" more dramatic. And reason why a ported or PR cabinet can never be as sonically accurate as a sealed. Ported or PR rely upon "ringing" or secondary movements to generate additional sound. Quantity at the cost of accuracy. You want highly accurate bass output, get sealed enclosure driver surface area, multiple units, multiple drivers, more amplification power.

Some people don't care for sealed sub sound characteristics, they prefer exaggerated versus accurate. They want more BOOM, it impresses family and friends, see my room vibrate wildly.

 

[Theresa]

Not entirely correct. I assure you my subs don't "ring." There is much snake oil in the discussion of what the benefits of sealed subs are. Its been discussed ad nauseum.

 

[mojomike]



Quote:
Originally Posted by Hi Def Fan /forum/post/21793153


Doesn't mean a whole lot really. "Pretty good" is relative to one's success, and I don't even see anything but over priced ported enclosures, nor is it as well known a brand as they make it out to be. Looks to be still in the start up stage. You Google that name and you get one of 3 or 4 sites, including one that redirects you.


The vague and even contradictory terms he uses leaves me even more skeptical. In reality the internet is full of people trying to use forums to launch their business. Doesn't mean they succeed at it, and if he was as successful as he makes it sound, he wouldn't need to be glomming onto forums to get customers.


They make light of "big box stores", yet contradict that resistance to volume sales by trying to make themselves sound like they have a vast global consumer base. Yet where is their name seen even in smaller volume high end audio stores? None that I've seen in the US. Sounds a lot like snake oil to me.


You know when you see someone talk as if they prioritize basic build quality of speakers using cabinet material like aluminum, it's more about a gimmicky fashion statement than bang for the buck sound quality. How he could even mention bang for the buck in his post above is a bit absurd really.

I hope you realize that you you are arguing with a guy (Nathan) who builds subs that leave anything Deftech has ever produced in the dust. Deftech subs are middle-of-the-road at best. They never meet their ridiculous, exaggerated, over the top specifications. Nathan is the guy than many hard-core enthusiasts turn to when they get bored with certain so-so performing subs such as Deftechs. If you want to keep that argument going, you're just going to wind up looking silly.