How to Design, build and Tune a Passive Radiator

This is everything you need to know about a passive radiator. In this video I show you how to tell if a passive radiator will work with your project, how to tune it properly and even show you the size box you should design. Basically everything you need to know about passive radiators.
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[@soniclab-cnc]

Been building lots of passive radiator designs last few years... It really opens up possibilities for smaller box builds. No more chasing port length- box size- tuning round and round. If you've designed many ported boxes you know what I mean. lol. I use Bass Box Pro for my passive radiator designs. Predictions from bass box are spot on with my measurements so I trust it.

[@Toid]

Great point! I completely agree with you as well

[@rcs5573]

Have you ever had any chance to use Eminence Designer? I want to build one but I usually use Eminence Designer. I was wondering if it is any good.

[@soniclab-cnc]

@@rcs5573 I haven't used it in years. I was using an early release back in the day. I actually used it to design a bunch of double 18" PA subs. The software was free from Eminence since we bought 24 subs. It was version 1.0 or something...they have updated it since. I don't think it did passive radiator or 6th order bandpass. It's more suited for PA builds I guess.

[@danrussell9357]

Great video - I enjoyed the passive radiator calculations because there is not a lot of content on the topic. I liked the transitions between slides and appreciate the effort put into editing.

[@Toid]

Thank you Dan! I hope you can make it this Friday to the Patreon zoom. It’d be fun to catch up.

[@brianboro5278]

Yes! The math was great.

[@DIYhyfy]

Class is in session!

[@Toid]

🍎📏📐

[@moisesbeltran2612]

The Bad thing about using only 1 passive radiator is, the speaker jumps around, having 2 opposing passive radiators cancels the vibrations.

[@computerfreak696]

That depends on where you place the passive radiator. If you place it on the opposite side of the woofer, then the vibrations are cancelled as well

[@athenazoey5093]

What is really the point? You want less vibrations so for clean sound resonance right? ???

[@brianboro5278]

Great video. I really appreciate your DIY instructional videos!

[@Toid]

Thanks Brian! It was great talking to you this past year at the Speaker Design Competition

[@gprojectnoob4779]

So ive built hundereds if not a 1000 boxes over the last 40 years and always has this design concept in my head along with some modified versions of this. A 2 chamber box with both chambers sealed. Woofer on the front baffle like normal and on the inside wall mount a passive way stiffer then the woofer so the higher the LF excursion the more the inner passive moves. So the internal volume/compliance changes depending how much the woofer moves or how much it can move the passive.

[@DonnieMulligan]

Great Stuff! Very Helpful! Keep it up!

[@Toid]

Thanks Donnie! Keep up the great content on your channel!

[@MetroidChild]

If you only want one passive you need to bulk up the weight in order to get an equivalent Q factor, this means vibrations get even worse, although it works well if you aim the single PR towards the floor (makes it act like a bass shaker). In a car this doesn't matter as much, just tie box down so it doesn't move. Regular air ports also have two major advantages if you don't have size constraints, air is free unlike PRs, and you can stuff air ports to alter how the sub behaves, say if you bring the sub indoors and outdoors a lot.

[@Pentenfi]

Best video on the topic so far. Great information for beginners. Just to add, one could also talk about methods to compute and tune a PR if one doesn't have a complete data set for the PR. Anyways, I like PR builds as they provide so much more freedom for the designer

[@cotandiet6096]

Thank you so much for sharing.

[@mcjonner]

Hey toid! Would you consider doing a video using a cheap aiyima amp to power a diy sub? They just released one that is powerful with their upgradeable power supplies and can be used bridged. - $100. There's a video of someone who built one of your sets of speakers also built a sub and used a cheap 2.1 Chinese amp to power the set of speakers and said it worked great as the speakers were very efficient. That made me wonder what one of those amps can really do specially if you have an avr with bass management and dirac or audyssey to further eq it. Super cheap alternative, at least to complete the build and could upgrade later if wanted.

[@Toid]

Maybe. I need to get a better test setup to accurately test amplifier wattage.

[@mcjonner]

​@@Toid diyhyfy released a video 4 days ago using a cheap amp on a diy sub. He just recently did your jtr inspired speakers and powers those with the same amp, pretty impressive.

[@Toid]

@@mcjonner yeah he is killing it. If you check my live videos, you’ll see I had him on a few weeks ago and we talked about all his projects. He’s a great guy and I have been trying to help him out where I can. He did a beautiful job on the Audience 212.

[@thenotoriousrvh6091]

Good stuff ! Always learn something from you 😁

[@Toid]

THat is always my hope. Thanks RVH!

[@niharadawade4442]

Very helpful! thank u Nick!

[@Toid]

Glad it was helpful!

[@NinO12752]

Hey Toid! I started a watching your videos this week and I find them very detailed and easy to understand. This got me into looking deeper to build my own Sub and Speaker next year. And as I was looking through soundsimport (parts express isn’t an option in the EU) I was wondering, would it be possible for you to do an video about the different tweeter (ribbon, dome, planar, horn) variations and their best uses? Haven’t found (or haven’t looked deeper) those kind of video. Greetings from Germany and keep up the good work

[@Toid]

I’ll definitely add that to my list of video ideas. I appreciate it. If you did find the content useful, I do ask that you use my affiliate links. I am affiliated with sound imports. It’s no cost to you, but it does help out the channel so I can create more videos like this. I do think your video ID is a good idea and I do want to do it. But I’m not sure when I’ll get to it.

[@NinO12752]

@@Toidthanks for your reply! I will use the Link to support you, no worries. It’s good to hear you like the idea even if unsure when to do it, that’s enough for me and was worth taking the time asking the question!

[@Dev_Everything]

How does a passive radiator not act as an out of phase sub woofer cancelling out the wave? This has always been a mystery to me.

[@datdudeinred]

That's because a passive rad doesn't have any polarity switch as no power, & it can be placed facing any side of the box & will work the same unlike a powered 2nd driver which either be dual opposed (in this case polarity is reversed for 2nd driver) or push pull (like m&k, perlisten subs) in which case it's more like a passive rad but powered & the entire sys is thus sealed. So the passive rad gets sucked in when powered driver moves out & visa versa. So it's not canceling out anything. Also there's another way to put a powered 2nd driver facing in opposite direction & cancel out front driver but both are placed in seperate boxes that's called cardioid arrangement (which is a whole other can of worms) just FYI. Ps - this is my understanding not saying that's correct ans or analogy. But from my extensive research this seems almost perfect ans for your question.

[@Dev_Everything]

@@datdudeinred You said it yourself. When the sub moves out (+) then it sucks the passive radiator in (-). How is this not out of phase? If I wire 2 subs like this then it will certainly cancel each other out. Why would it matter if one has a VC and one does not.

[@SamFirthDesigner]

Hey Toid, I've an idea for you - what about using a driver with a motor, but then adding some variable resistance across the terminals of said passive driver to tune its behavior? Thanks for the vid!

[@soniclab-cnc]

Interesting idea, but then you are paying for two drivers and possibly added components.. Adding weight is very simple and requires much less expensive drivers. I like the theory but it sounds highly impracticable if not impossible. That would make it an active passive radiator ? lol

[@Stan_the_Belgian]

A tube is cheaper

[@MrWoodstock35]

Great content right here! I can feel your stuff getting faster and better edited. The different transitions are distracting though. Just cut between you and the computer without all the diamonds and blinds and stuff.

[@Toid]

Appreciate it!

[@gerardvoughnfaust4167]

two radiator i think can do like 6th order bandpass. driver in between, two radiator in each side of the driver

[@lorenpedro]

Designing design!

[@user-uk8fo5ol4q]

Hello can i ask what is better for you between thin or thick passive radiator when it comes to good sounding?

[@kevinchapin3291]

What about the 18 inch radiator.

[@TheFloridaBikeVlogger]

dumb question. if you were gifted an old speaker cabinet and the woofer is still good but the bottom passive radiators are gone except just the frame, could you just have them rebuilt? basically uncle passed away and I kept the old audio system he had and right before he died he had the woofer refoamed but the bottom speakers were said to be passive radiators but all that was left was just the frame, should I even bother or is there away to rebuild them? am I making sense lol I am so confused but I just dont want to throw these away as it sounds somewhat decent or at least to me I think it sounds better than what my sound bar was giving me. any insight would be appreciated.

[@rawsonte]

Can a passive radiator be too big? Know there more to it than that, where not want to tune too low pushing excursion of active driver too much

[@anandshah71]

I have some cheap old but working subwoofers that have 12mm xmax can I use it as a passive radiator

[@andrewmcmillan8110]

Slaps M12

[@dakken74]

If you are using 2 woofers,,,do you do the measurements for 1 and then double?

[@Toid]

Yes

[@dakken74]

@@Toid thank you for the quick reply. I have one more question if you don't mind. If the resonant frequency of the PR is lower than that of the driver, can the PR reach it's resonant frequency? Say the driver is 50hz and the PR 22hz.

[@wandersonuhuu5902]

Meu querido..você pode me ajudar?estou com um projeto com um woffer da partybox300 da jbl de 6,5 polegadas e um radiador passivo de 8 polegadas,qual a litragem ideal para que eu consiga um fs de 55 hetz?

[@12Vencedor]

i want to pair the tangband w5 subwoofer with the epique 150 radiator. it seeems to have the double volume displacement. but whatever i try in winisd i cant get an f3 of 32hz like i have in my ported setup... can anybody help?

[@robindas1207]

nicee

[@prometheusjae6532]

Hey can anyone help me , I want one 12 in my suburban truck , but a real high wattage one , like , the ds18 12 inch 4000 rms hooligan sub .. wat passive radiator can I put wit it that can hit real in the high 20s hz range ???

[@andreseduardoandradecardoz6113]

First comment

[@Toid]

Dang that was fast!

[@andreseduardoandradecardoz6113]

​@@Toid ​ First time I do that but I saw the opportunity and couldn't pass it 😂

[@Toid]

@@andreseduardoandradecardoz6113 haha! I get that completely! Who knows, maybe you’ll be first next time as well 😁

[@ulamss5]

Those are comically expensive radiators lol

[@Toid]

They really are. most of the cost on those passive radiators are the baskets. WHat most people don't realize is that the passive radiator that is designed for the subwoofer, is actually the same driver missing the motor structure. That is one of the reasons some passive radiators are more than others.

[@scottaberdonian7374]

No need to show face too often. Just program interface, please. :) Yeah radiators selling isn't great :) Thank you for video

[@scottaberdonian7374]

And leave transitions away. hahaha . The simpler is better!

[@thomasschafer7268]

Remember that a 12" woofer needs a 15" passiv radiator in comparison to its area.

[@Toid]

That’s not accurate. The size of your passive radiator is going to be directly dependent on your tuning, wattage, enclosure and volume displacement. That’s what the video was all about.

[@SamFirthDesigner]

Good reply

[@DavidJohnson69-qq2bo]

Can 2 PR’s be in a push-pull confirmation (on opposite sides of the enclosure), or should they both be mounted on the same side of the cabinet with each other? Thanx! Great video. Your new subscriber!