One would almost think a passive radiator would cancel out the sound of the active by creating an opposite frequency, but instead it enhances it. This is interesting, I didn't know about this, it's good to learn. Ty.
A port _is_ essentially a passive radiator, the air column inside it is the 'cone' and the air cushion in the box is the suspension. The actual passive radiator does the same thing, but differently. Both resonate in a certain frequency band, where it adds up to the active drivers' output. Above that, their inertia blocks the out-of-phase sound coming from the active driver's back. Below tuning though, the waveforms will be out of phase, leading to no noteworthy output. That's why both resonator box designs act as a higher order filter, while a sealed box rolls off less abruptly, with 2nd order characteristics.
Not entirely correct. It would be more accurate to say that they are both Hermaholtz resinators. The slope is not exactly the same, the passive radiators has a slightly steeper roll off than a port.
@@DodgyBrothersEngineering Yes, the PR rolls off with (I think) 30dB/Oct, while the port rolls off with 24dB/Oct. But their working principle is pretty much the same.
@@DodgyBrothersEngineering Well, my main point was, if you want to understand the physics behind the port, it's very helpful to know about the PR first - it's way easier to learn about mass and suspension when present as, well, mass and suspension instead of just air in both cases. Of course both port and PR come with their own quirks design challenges, but today with design software, you can actually design a decent enclosure while still believing a port is just an "air tube to relieve pressure from the cabinet", as many people actually seem to think. Knowledge of the actual physics behind it don't really matter there anymore.
@@westelaudio943 agree, modern software can advise you on things like port air velocity. Which is where most ported designs come undone. I tend to think of PRs as an expensive port alternative that removes a lot of the guess work.
I think passive radiators are the clear winner in small enclosures, where you either need something the width of a drinking straw that can't pass air properly, or coiled up like the intestinal tract, taking up most of the room in the box.
It rings like a bell driven by a rubber band attached to your woofer. After a few cycles of a bass note it catches up and rings at nearly full amplitude. All those frequency response plots you see where the port or passive radiator makes nice low bass. That is where you get to with a continuous tone playing forever. The transient response is what the woofer does on its own without the radiator, because the radiator takes time to get going. Funny how that is never talked about. When the bass note ends, it rings a few more cycles. Play a fast attack plucked bass note, or drum beat that by its nature is a sinewave that starts suddenly and then has an exponential decay, and a passive radiator will compress the leading edge or that attack and compress the peak at the start of the note, and will catching up with the signal after a few cycles. If the note decays quickly, the ringing of the radiator may extend the note a bit as it always has a decay that is defined by it's Q. So passive radiators can create bass, late, with crushed attack, and as such do not reproduce the bass with high fidelity. If you are looking to extend the bass and don't care about fidelity, go for it. Otherwise, just add a second woofer and do a little EQ in the low end.
Thanks, makes total sense. I'll avoid them. Thinking about it that way makes me think they're best for things like bluetooth speakers where size and power are big limitations.
I'd say it depends on the weight and damping characteristics. A small heavy passive radiator will probably swing the longest. A nice big lightweight one like on the back of a Klipsch Forte series speaker, will probably do this less. The best is a sealed horn loaded system, where a compression wave is concentrated and amplified down the horn, and it also takes energy out of the speaker cone, so it stops resonating more quickly - functioning like an aperiodic membrane but with improved efficiency. This is really where "fast" bass comes from. To those who say there is no such thing as a "fast" subwoofer and it's simply that lower notes have longer time periods, the effect is not measured over a single cycle but over several - like blowing into a bottle, it continues to ring for a while. I did have a pair of second hand KEF speakers where the bass did sound fairly baggy like this, though the passive radiators were similar size to the woofers. It is better to have bigger passive radiators that couple to the air better and don't store so much internal energy due to the lower excursion, and also don't run out of excursion and limit themselves as quickly. The other thing a passive radiator will have is a big suckout at its own free air resonance. A port doesn't have its own free air resonance, or it tends towards zero. Although this is usually well below where you should be high passing, you might miss out on a bit of low bass that got through the filter. I have heard from a video review of a certain brand of speakers, that another problem with them is at very low volumes, the rubber membrane can be a bit rigid towards moving at all, so you need to turn them up a bit more than a ported to really "wake up" the bass reinforcement, or else they can sound a bit lacking in low end, as if you just had a sealed box. My opinion is that they have a certain size range of enclosures where they are superior to ported, but then as you get bigger, ported starts to win - losing its disadvantages of the port filling most of the box, or not being able to get the ports wide enough to pass air properly without the tuning frequency getting ridiculously high. I'd say it's rare to see passive radiator designs in PA speakers because the speakers are in the size range where you lose the disadvantages of ports and gain all the advantages.
I have looked around Parts Express and I do not see any Kits or Washers to be used as weights for tuning the passive radiator. Are we supposed to know the thread size and just go down to Home Depot and buy Body Washers and spacers? Then weight the whole assembly out piece by piece? Buy the correct size bolt to go with it? Im just asking. I am very willing to do all this if its really the way it gets done. WinISD Pro is very easy to use and understand. There may be a few hick-ups in the beginning but you can watch one or more usually short YT Videos and get a leg up. WinISD will will give you the info neccessary to get a correct box size, give the info you need to add or subtract weights. Adding weights will cause your Xmax to increase on your passives so you need to find the happy medium for your goals. More watts pushed thru the speaker the more travel you will have at a given frequency. Once you get into the ballpark with your tuning you can then use a Rew tuning and some DSP for the easy way out like me. :D
@@PartsExpressOfficial Thanks for the reply. I wasnt sure if it would get answered. Some of your Passives do come with a nice set of Weighted Discs most do not. 5mm hole in the Passives. Tuning can be sensitive down to a half-ounce so maybe buy some smaller washers to go along with the larger ones so you can fine tune. Thanks again.
Hi, is it possible to "tune" the passive radiators of a jbl charge 5? I want to have a deeper bass. I read about lil weights on the backside of the radiators, but im not Sure if this already works
No. People talk about the phase of the PR, but that talk is often misleading. At low frequencies the PR is the main source of sound output, and at high frequencies the active driver is the main source of sound. So the PR is not producing sound that is interfering with the active driver.
Cool. Your DS315-PR 12" are working great with the DSA315-12 woofers. In addition to the basics, I'd like a more technical explanation of the phase relationship between the active and passive woofer. A LOT of people say the radiator is out of phase, which I believe in inaccurate. There's a lot of wrong and misleading info out there!
Hmm. Maybe because you are driving it way harder than its supposed to be driven with trash bass heavy music while in a mode that removes all dsp and protection to the drivers? Idk man, idk...
Nope. A disconnected speaker has a damper aka a spider that has more rigidity. Some passive radiators have spiders to help with cone alignment but for the passive radiator to work properly it must have as little resistance as possible. The goal is to have as little resistance as possible but the proper mass to equal the desired tuning.
Slow bass. A passive radiator does nothing when the woofer starts moving at the start of a bass note. So you don't get anything out of it to start with. After a few cycles of the bass note it gets pumped up and starts moving such that the woofer is no longer moving. Yeah, that happens. So it rings like a bell during that bass note. When the note ends, the passive radiator keeps going for a few more cycles. That's blurry bass. Just say no to ports and passive radiators if you want clean fast bass. To get the same amount of bass, just add a second woofer or move up a size. Then EQ the low bass to bring it up.
I think larger lighter passive radiators generally ring less, but an infinite baffle with a long foam stuffed tunnel on the other end will ring the least - at the cost of efficiency. A fully sized front loaded horn will do well too - due to the air pressure mating improving efficiency, but also drawing energy from the moving cone more quickly in a way that it stops resonating quickly. The room you are in can ring too, and that is often the worst offender of the lot!
One would almost think a passive radiator would cancel out the sound of the active by creating an opposite frequency, but instead it enhances it. This is interesting, I didn't know about this, it's good to learn. Ty.
I wondered what a passive radiator did so I came to you.
A port _is_ essentially a passive radiator, the air column inside it is the 'cone' and the air cushion in the box is the suspension. The actual passive radiator does the same thing, but differently. Both resonate in a certain frequency band, where it adds up to the active drivers' output. Above that, their inertia blocks the out-of-phase sound coming from the active driver's back.
Below tuning though, the waveforms will be out of phase, leading to no noteworthy output. That's why both resonator box designs act as a higher order filter, while a sealed box rolls off less abruptly, with 2nd order characteristics.
Not entirely correct. It would be more accurate to say that they are both Hermaholtz resinators. The slope is not exactly the same, the passive radiators has a slightly steeper roll off than a port.
@@DodgyBrothersEngineering
Yes, the PR rolls off with (I think) 30dB/Oct, while the port rolls off with 24dB/Oct.
But their working principle is pretty much the same.
@@westelaudio943 I would go as far as saying they work "roughly" the same. A different way to achieve an approximate same desired end result.
@@DodgyBrothersEngineering
Well, my main point was, if you want to understand the physics behind the port, it's very helpful to know about the PR first - it's way easier to learn about mass and suspension when present as, well, mass and suspension instead of just air in both cases. Of course both port and PR come with their own quirks design challenges, but today with design software, you can actually design a decent enclosure while still believing a port is just an "air tube to relieve pressure from the cabinet", as many people actually seem to think. Knowledge of the actual physics behind it don't really matter there anymore.
@@westelaudio943 agree, modern software can advise you on things like port air velocity. Which is where most ported designs come undone. I tend to think of PRs as an expensive port alternative that removes a lot of the guess work.
I think passive radiators are the clear winner in small enclosures, where you either need something the width of a drinking straw that can't pass air properly, or coiled up like the intestinal tract, taking up most of the room in the box.
Getting that 7inch epique passive for a portable Bluetooth build today. Can't wait to see how it performs with the 5.5 driver.
How big passive radiator I can use for 10” woofer?
Thank you!
It rings like a bell driven by a rubber band attached to your woofer. After a few cycles of a bass note it catches up and rings at nearly full amplitude. All those frequency response plots you see where the port or passive radiator makes nice low bass. That is where you get to with a continuous tone playing forever. The transient response is what the woofer does on its own without the radiator, because the radiator takes time to get going. Funny how that is never talked about. When the bass note ends, it rings a few more cycles. Play a fast attack plucked bass note, or drum beat that by its nature is a sinewave that starts suddenly and then has an exponential decay, and a passive radiator will compress the leading edge or that attack and compress the peak at the start of the note, and will catching up with the signal after a few cycles. If the note decays quickly, the ringing of the radiator may extend the note a bit as it always has a decay that is defined by it's Q. So passive radiators can create bass, late, with crushed attack, and as such do not reproduce the bass with high fidelity. If you are looking to extend the bass and don't care about fidelity, go for it. Otherwise, just add a second woofer and do a little EQ in the low end.
Thanks, makes total sense. I'll avoid them. Thinking about it that way makes me think they're best for things like bluetooth speakers where size and power are big limitations.
Very nice observation. How about both a second woofer and some DSP, together :D.
Weird because the RSW-10 utilizes a passive radiator and that is one of the most accurate and best sounding subs you can come across.
I'd say it depends on the weight and damping characteristics. A small heavy passive radiator will probably swing the longest. A nice big lightweight one like on the back of a Klipsch Forte series speaker, will probably do this less. The best is a sealed horn loaded system, where a compression wave is concentrated and amplified down the horn, and it also takes energy out of the speaker cone, so it stops resonating more quickly - functioning like an aperiodic membrane but with improved efficiency. This is really where "fast" bass comes from. To those who say there is no such thing as a "fast" subwoofer and it's simply that lower notes have longer time periods, the effect is not measured over a single cycle but over several - like blowing into a bottle, it continues to ring for a while. I did have a pair of second hand KEF speakers where the bass did sound fairly baggy like this, though the passive radiators were similar size to the woofers. It is better to have bigger passive radiators that couple to the air better and don't store so much internal energy due to the lower excursion, and also don't run out of excursion and limit themselves as quickly.
The other thing a passive radiator will have is a big suckout at its own free air resonance. A port doesn't have its own free air resonance, or it tends towards zero. Although this is usually well below where you should be high passing, you might miss out on a bit of low bass that got through the filter.
I have heard from a video review of a certain brand of speakers, that another problem with them is at very low volumes, the rubber membrane can be a bit rigid towards moving at all, so you need to turn them up a bit more than a ported to really "wake up" the bass reinforcement, or else they can sound a bit lacking in low end, as if you just had a sealed box.
My opinion is that they have a certain size range of enclosures where they are superior to ported, but then as you get bigger, ported starts to win - losing its disadvantages of the port filling most of the box, or not being able to get the ports wide enough to pass air properly without the tuning frequency getting ridiculously high. I'd say it's rare to see passive radiator designs in PA speakers because the speakers are in the size range where you lose the disadvantages of ports and gain all the advantages.
PROPS for the best thumbnail!!! +
hi my question is for the Creative T3 sub : it has 3 x 6.5" woofers so are all active or some passive? i dun have it on hand atm so i can't check
Sorry stupid question but why not using another active speaker instead of a passive radiator? Sound should be better so its only about costs?
Watch the video, he tells you why.
To drive another speaker, you need another amplifier.
Passive radiation for small port designs, but what difference makes when having a sealed port.
That thumbnail 😂
But with no magnet how the do magic 😂
thank you
I have looked around Parts Express and I do not see any Kits or Washers to be used as weights for tuning the passive radiator. Are we supposed to know the thread size and just go down to Home Depot and buy Body Washers and spacers? Then weight the whole assembly out piece by piece? Buy the correct size bolt to go with it? Im just asking. I am very willing to do all this if its really the way it gets done.
WinISD Pro is very easy to use and understand. There may be a few hick-ups in the beginning but you can watch one or more usually short YT Videos and get a leg up. WinISD will will give you the info neccessary to get a correct box size, give the info you need to add or subtract weights. Adding weights will cause your Xmax to increase on your passives so you need to find the happy medium for your goals. More watts pushed thru the speaker the more travel you will have at a given frequency. Once you get into the ballpark with your tuning you can then use a Rew tuning and some DSP for the easy way out like me. :D
Correct, you can just buy washers from Home Depot, though each PR usually come with a few to start off. You can use those for size comparison.
@@PartsExpressOfficial Thanks for the reply. I wasnt sure if it would get answered. Some of your Passives do come with a nice set of Weighted Discs most do not. 5mm hole in the Passives. Tuning can be sensitive down to a half-ounce so maybe buy some smaller washers to go along with the larger ones so you can fine tune. Thanks again.
Hi, is it possible to "tune" the passive radiators of a jbl charge 5?
I want to have a deeper bass.
I read about lil weights on the backside of the radiators, but im not Sure if this already works
Check out our resource on passive radiators! Here is a direct link:
pulse.ly/wroqn7jzlw
You might want to reconsider that thumbnail image… 😅
Hell no it's awesome! He's like "Passive radiators, how do they work?!?"
Why?
@robbielex that video cracks me up 😂
"Its a older meme sir, but it checks out"
Wait till those Juggalo's see it.
Thankyou bro
do passive radiators color the sound?
No. People talk about the phase of the PR, but that talk is often misleading. At low frequencies the PR is the main source of sound output, and at high frequencies the active driver is the main source of sound. So the PR is not producing sound that is interfering with the active driver.
Cool. Your DS315-PR 12" are working great with the DSA315-12 woofers. In addition to the basics, I'd like a more technical explanation of the phase relationship between the active and passive woofer. A LOT of people say the radiator is out of phase, which I believe in inaccurate. There's a lot of wrong and misleading info out there!
passive radiators of jbl keeps ripping when in low frequency
Hmm. Maybe because you are driving it way harder than its supposed to be driven with trash bass heavy music while in a mode that removes all dsp and protection to the drivers? Idk man, idk...
That awkward moment when someone on the internet explains to you that passive does not mean active. 😑
It's a driver that radiates passively. ;)
Maybe it should be called an indirect radiator?
Who dosent love a small box. Problem is god put a tongue on the passive radiator.
I accidentally turned on my jbl low frequency in max volume is WAS AMAZING AND SCARY IS WAS A FLIP 5 I was like OMG IT WORRKSSSS
huh? no reference to drone cone? or did i miss it? i'm not watching it again.😂
Does the science behind it mention the manufacturer making twice as much money
So basically it's a speaker not hooked up but looks like it works yes
O and if it is hooked up the polls would have to be switched
Nope. A disconnected speaker has a damper aka a spider that has more rigidity. Some passive radiators have spiders to help with cone alignment but for the passive radiator to work properly it must have as little resistance as possible. The goal is to have as little resistance as possible but the proper mass to equal the desired tuning.
Are you gonna explain how they work with your fancy science bullshit, na dawg I believe in miracles.
Slow bass. A passive radiator does nothing when the woofer starts moving at the start of a bass note. So you don't get anything out of it to start with. After a few cycles of the bass note it gets pumped up and starts moving such that the woofer is no longer moving. Yeah, that happens. So it rings like a bell during that bass note. When the note ends, the passive radiator keeps going for a few more cycles. That's blurry bass. Just say no to ports and passive radiators if you want clean fast bass. To get the same amount of bass, just add a second woofer or move up a size. Then EQ the low bass to bring it up.
I think larger lighter passive radiators generally ring less, but an infinite baffle with a long foam stuffed tunnel on the other end will ring the least - at the cost of efficiency. A fully sized front loaded horn will do well too - due to the air pressure mating improving efficiency, but also drawing energy from the moving cone more quickly in a way that it stops resonating quickly.
The room you are in can ring too, and that is often the worst offender of the lot!
I’m gonna stick to ported. Easier to get loud more windy and if you build it right it should hit just about any note you want
I believe in miracles. ✨🤡🤡✨
Who smoked all my dope
I was talking to myself
Wheres shaggy2dope whoop whoop