PDA

View Full Version : I haz passive radiators.



TaylorFade
07-11-2012, 09:33 PM
Eff ports.

Still dialing it in, but just so you guys know how super easy and awesome it is to figure up moving mass for tuning a PR, here's the "Quick and easy" version of the formula.

http://i848.photobucket.com/albums/ab45/taylorfade/f89e063d.jpg

Anyway... here's the sexiness. It's moving some ****. Currently running that Tantric HD 10 on a 4k @ 5 :)

http://i848.photobucket.com/albums/ab45/taylorfade/05d9fa37.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/a39e6e9d.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/03c68aa9.jpg

R34P3R
07-11-2012, 09:36 PM
I've always wanted to use a pr. Is it possible to blow them? Like over excurt them and damage soft parts? How are they sounding?

EDIT:Oh and your sub is upside down :p:

splwj47
07-11-2012, 09:37 PM
whats the point of a PR?

Dirtrider4eva
07-11-2012, 09:40 PM
Play output the sub can't exactly handle well.

TaylorFade
07-11-2012, 09:42 PM
I've always wanted to use a pr. Is it possible to blow them? Like over excurt them and damage soft parts? How are they sounding?

EDIT:Oh and your sub is upside down :p:

I seriously doubt it if your system is designed correctly. That's one of the reasons behind having at least double the Sd or double the excursion for your passives.


whats the point of a PR?

No port noise, crap ton of "port area" without having to snake a huge port around in the box, smaller box because you don't have to account for port displacement.

Basically... all the advantages of a vented alignment without any of the downsides.

There are only two disadvantages of a PR... they rolloff faster below tuning... and the cost. That's it.

RAM_Designs
07-11-2012, 09:43 PM
Which PR's are those? They look similar enough to my old Assassins...might want to get one or two. I know AE had some 15" and 18" PR's for pretty cheap, but IIRC they were not adjustable.

TaylorFade
07-11-2012, 09:50 PM
Which PR's are those? They look similar enough to my old Assassins...might want to get one or two. I know AE had some 15" and 18" PR's for pretty cheap, but IIRC they were not adjustable.

These were custom built for me by Tantric like, yesterday. Just don't have the stickers yet. Murph said he wasn't going to take credit for them until I got them dialed in and wrecking ****. Lol.

kushy_dreams
07-11-2012, 10:20 PM
So thats really just a woofer minus the motor and coil and you add/subtract mass in place of where the coil would be to "tune"?

RAM_Designs
07-11-2012, 10:23 PM
So thats really just a woofer minus the motor and coil and you add/subtract mass in place of where the coil would be to "tune"?

Yes, it works just like a port. Except in this case the relationship between the box volume, cone area of the PR, and moving mass of the PR will affect the tuning frequency that you end up with.

supermaxx123
07-11-2012, 10:25 PM
I'd love to run passives but ports are sooo much cheaper.

RAM_Designs
07-11-2012, 10:30 PM
I'd love to run passives but ports are sooo much cheaper.

I had some of the TC Sounds VMP's years ago when they were having a sale(Maybe 6 years ago?). I sold them right before TC decided to jack all their prices up... :(

TaylorFade
07-11-2012, 10:33 PM
I'd love to run passives but ports are sooo much cheaper.

I hear ya. They're not cheap. But my very picky and specific set of needs/wants for that stupid little build was giving me fits trying to do a port.

Plus, I've been wanting to do PR's for a while.

supermaxx123
07-11-2012, 10:46 PM
I hear ya. They're not cheap. But my very picky and specific set of needs/wants for that stupid little build was giving me fits trying to do a port.

Plus, I've been wanting to do PR's for a while.

Keeping space costs money! One of these days I'll justify spending the money on passives... Nice build BTW.

TaylorFade
07-11-2012, 11:21 PM
Keeping space costs money! One of these days I'll justify spending the money on passives... Nice build BTW.

Thanks, man. I haven't built a "sealed" box in forever. I was like... "Wait... thats it?"

hispls
07-12-2012, 12:00 AM
I have some PR's here that I've been sitting on for years. Always meant to make a box for them. Very useful if you want to tune low in a small volume.

TaylorFade
07-12-2012, 12:08 AM
I have some PR's here that I've been sitting on for years. Always meant to make a box for them. Very useful if you want to tune low in a small volume.

That's my whole M-O in my daily. I very, very rarely have more than 2 cubes in my trunk and tuning for < 2cubes daily is a pain in my ***.

The one thing I ran into with this one is because of the baffle space required and the depth I wanted, the box turned out huge. I had to eat up a ton of airspace with big *** 45's in the corners. It's actually still too big for my liking. A redesign may be in order, but I haven't given up on this one yet.

ThatChevyGuy
07-12-2012, 01:40 PM
why 45s in the corners?

Get some vids bro, i bet it sounds good.

safiend
07-12-2012, 02:19 PM
Very clean!

quackhead
07-12-2012, 02:20 PM
I want to say Thank you. Passives are one of the most overlooked designs...and always have been in car audios. Now, SHOW ME THE #'s ALREADY...bro.

quackhead
07-12-2012, 02:39 PM
Yes, it works just like a port. Except in this case the relationship between the box volume, cone area of the PR, and moving mass of the PR will affect the tuning frequency that you end up with.

I always though the function of adding/subtracting weight was to tune the Mms of the PR as close to the MMs of the Subwoofer as possible..as you said, the idea is to have the PR replicate the inward stroke to produce sound just like a port. I may be mistaken, but doesn't a properly tuned PR setup actually give the same output as a ported design, but across the whole response curve instead of a specific frequency?

quackhead
07-12-2012, 02:42 PM
I think the result of the more output in the lower octaves is due to the added cone area

quackhead
07-12-2012, 02:58 PM
hmm..maybe I am wrong on some things...I don't know much about them anyways..here is a good read. - HUMAN Speakers: What is a passive radiator? (http://www.humanspeakers.com/whatis/PR.htm)

ThatChevyGuy
07-12-2012, 04:39 PM
you can also tune them to lower fs not just to match your sub i think

quackhead
07-12-2012, 07:04 PM
you can also tune them to lower fs not just to match your sub i think

yea..I read that...I left my last posts just to just to say, "oops, i was wrong"..I am real curious of the outcome on TaylorFade this little project.

Bettr n' Revrse
07-12-2012, 07:10 PM
Dont PR's need to be a little bigger then the sub our using? Such as a 12" PR for a 10" sub?

wenn_du_weinst
07-12-2012, 07:20 PM
I seriously doubt it if your system is designed correctly. That's one of the reasons behind having at least double the Sd or double the excursion for your passives.



No port noise, crap ton of "port area" without having to snake a huge port around in the box, smaller box because you don't have to account for port displacement.

Basically... all the advantages of a vented alignment without any of the downsides.

There are only two disadvantages of a PR... they rolloff faster below tuning... and the cost. That's it.
pr also have lag ;)

ThatChevyGuy
07-12-2012, 07:21 PM
i had a 10 with a 15 pr (actually just a blown sub with the magnet removed LOL if that counts) Dropped deep as hell for a sealed 10

TaylorFade
07-12-2012, 08:51 PM
yea..I read that...I left my last posts just to just to say, "oops, i was wrong"..I am real curious of the outcome on TaylorFade this little project.

Jury is still out since it's only been a few days. Still not low enough, but I hadn't anticipated the PR's needing to break in so it's getting lower and louder by the day. It's doing some good work, but it aint' happy on the low note of "Rack City."


Dont PR's need to be a little bigger then the sub our using? Such as a 12" PR for a 10" sub?

It's possible if that 12 has enough throw.

Rule of thumb at a minimum is double cone area or double the throw. e.g.- (1) 10" sub with 20mm of xmax and (2) 10" PR's with at least 10mm of throw or (1) 10" sub with 10mm and (1) 10" PR with at least 20mm.

From what I understand, you can use upwards of 8x the cone area.

wenn_du_weinst
07-12-2012, 08:52 PM
passive radiator size is install dependent, much like port area.

R34P3R
07-12-2012, 09:11 PM
From what I understand, you can use upwards of 8x the cone area.
Lol, SA8 with 18" pr.

Bettr n' Revrse
07-13-2012, 05:49 AM
Hmmmm Id like to try them but Id need to do more reading to figure out how they work...

murph
07-13-2012, 06:03 AM
Hmmmm Id like to try them but Id need to do more reading to figure out how they work...

You add weight to them hence raising or lowering the tuning. Depending on how much power you are running and the size of the woofer(s) tells you the size and how many you will need. Typically you go up one size of the size of the sub you are using a pr with.

Bettr n' Revrse
07-13-2012, 06:05 AM
You add weight to them hence raising or lowering the tuning. Depending on how much power you are running and the size of the woofer(s) tells you the size and how many you will need. Typically you go up one size of the size of the sub you are using a pr with.

Easy enough... Im not sure what Ill be running though at the moment..

rebelfromva
07-13-2012, 06:12 AM
this is very interesting... would like to see a video

murph
07-13-2012, 06:19 AM
Near the end he shows it in action.

http://www.youtube.com/watch?v=9jZBMtXw5to

this is very interesting... would like to see a video

rebelfromva
07-13-2012, 06:25 AM
Near the end he shows it in action.

http://www.youtube.com/watch?v=9jZBMtXw5to

this would be good for my trunk as it being small already but the need to keep some space too. Where would one find a pr?

murph
07-13-2012, 06:29 AM
this would be good for my trunk as it being small already but the need to keep some space too. Where would one find a pr?

Here Passive Radiators Allow You to Easily Tune Your Subwoofer Enclosure When a Port Tube Won't Work. Variable Mass Passive Radiators from TC Sounds and Dayton Audio! (http://www.parts-express.com/wizards/searchResults.cfm?srchExt=Cat&srchCat=527) or PSI also sells them.

quackhead
07-13-2012, 12:45 PM
Exodus Audio PR-21, 21" Passive Subwoofer Radiator for TC sounds, Dayton Audio | eBay (http://www.ebay.com/itm/Exodus-Audio-PR-21-21-Passive-Subwoofer-Radiator-TC-sounds-Dayton-Audio-/170875664962?pt=Speakers_Subwoofers&hash=item27c8fbba42)

The_Grimy_One
07-13-2012, 12:51 PM
I wanna run passives and save some space! If I am running a single 15, I would need to do an 18 passive?

gckless
08-05-2012, 12:41 AM
I have been thinkin about a PR design for a little while, but they are definitely not as popular as either sealed or ported. There's not too many PR's out there. The VMP's look nice, but expensive! And I haven't seen any others with any kind of decent specs as those.

Anyway, how did you figure out box dimensions? What kind oof internal space did you use, as compared to what was suggested or required for those 8's in a ported box? From what I have seen, a PR box would be almost the exact same internal volume, and it's only smaller because you don't need to add the dimensions of the port, correct?

But your box looks awesome! Kudos on that.