# got the bug again..passive radiator boxes?



## Lycancatt (Apr 11, 2010)

I understand them, I've just naver had one and want to. tell me about your successes, failures, fancy secrets..just looking for ideas and to hear pros/cons from people who've built these.


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## sq2k1 (Oct 31, 2015)

I am also interested in this topic as I have never heard or seen one in person.


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## Lycancatt (Apr 11, 2010)

everything I've modeled with help from friends has looked absolutely horrible, doesn't go low, even with adding a ton of mass to the passives. for now, I'm trying a bandpass box tuned stupid low since I don't need anything above 40 hz and basicly want to move lots of air.


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## Holmz (Jul 12, 2017)

Lycancatt said:


> everything I've modeled with help from friends has looked absolutely horrible, doesn't go low, even with adding a ton of mass to the passives. for now, I'm trying a bandpass box tuned stupid low since I don't need anything above 40 hz and basicly want to move lots of air.


Any update on this?
I am leaning towards a passive.


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## Focused4door (Aug 15, 2015)

Lycancatt said:


> everything I've modeled with help from friends has looked absolutely horrible, doesn't go low, even with adding a ton of mass to the passives. for now, I'm trying a bandpass box tuned stupid low since I don't need anything above 40 hz and basicly want to move lots of air.


I would at least model an extended bass shelf, it is likely as good or better than a bandpass for what you want to do. The box will be huge, but that will help get the really long port in it.

WinISD can model an extended bass shelf, so quick and easy to do.

EDIT, just realized this thread was brought back from the dead.


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## Lycancatt (Apr 11, 2010)

ended up with a 4.5 cubic ft bandpass for a 15 with an f3 at 22 hz..not built but planned and driver is bought.


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## Holmz (Jul 12, 2017)

Focused4door said:


> I would at least model an extended bass shelf, it is likely as good or better than a bandpass for what you want to do. The box will be huge, but that will help get the really long port in it.
> 
> WinISD can model an extended bass shelf, so quick and easy to do.


What is there for a Mac (OSX) or Linux?

For me I have room for a box, ~6" x 18" x 48"... so a pancake shape of a box, which sort of makes a port a problem. But ~2 cubic feet with thickness of wood factored in.


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## Focused4door (Aug 15, 2015)

Holmz said:


> What is there for a Mac (OSX) or Linux?
> 
> For me I have room for a box, ~6" x 18" x 48"... so a pancake shape of a box, which sort of makes a port a problem. But ~2 cubic feet with thickness of wood factored in.


No idea about Mac or Linux, but do you have Excel?

The Subwoofer DIY Page has formulas and Excel spreadsheets


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## Holmz (Jul 12, 2017)

Focused4door said:


> No idea about Mac or Linux, but do you have Excel?
> 
> The Subwoofer DIY Page has formulas and Excel spreadsheets


I did not see any excel sheets, but I can take a crack at coding up the math.

The basic questions and statements are:
1) (sites say)... a ported is better than a sealed for extending the frequency range lower.
2) (sites say)... that a passive is better than a ported as there is no port noise issues.
3) ... passive radiators may not have good transient response 
4) ... just use sealed as cabin gain extends the low frequency base enough

And then other people say:
5) don't run a passive just a ported enclosure
6) just use a BSE (which does make some sense to me)

Other than cost of the radiator, it seems easier than ports and flanges and extra box volume for the port(s)... and the box size seems smaller.
But no one seems to consider using a passive radiator. Is that tradition or some decent reason?


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## 04quadcab (Dec 31, 2017)

I think the cost of the passive radiator is probably the main factor. It's just cheaper to use MDF to make a slot port. Passive radiators start to make sense when you have a tight space, and you can't sacrifice room folding a port up Inside the Box.

The other thing to remember, as a general rule of thumb for passive radiators, the passive must be capable of moving twice the air as the active. So if you have one 10 inch sub with a 10mm x max you will need 2 passives each with a 10mm x max. Or you will need to go with a smaller sub mated with a larger passive with a longer throw. So again you start running into the cost constraints.

Personally, I love the idea of experimenting with these things it seems like something fun and different. I'm pretty sure that my next home theater build is going to use passive radiators. The plan is to eventually upgrade the 10's in my truck and then use those drivers in my home theater. The drivers are scuffed up a bit from rubbing against the underside of the backseat, so I will aim them down and then mount passive radiators firing forward. I would also love to see you 6 order bandpass using passive radiators instead of ports. That would be different.

Sent from my Pixel XL using Tapatalk


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## mrexcitement (Jan 23, 2019)

I know this is an old thread but i have experience with a dual Dayton RSS265HO-4 and dual Dayton RSS265-PR (passive radiator) setup.

The Dayton passives have double the cone travel of there active counterparts so only one passive per active driver is needed.

I designed and built this for the car , i have both active drivers on one side with one passive in the middle and the other passive directly opposite on the other side of the box.

It is one of the cleanest tightest subwoofers i have heard in the car , no boominess just good clean bass and goes very loud and low , definitely an SQ setup but also is able to produce high SPL , the box net volume is about 40 Litres , so relatively small , which was my main goal.

I am feeding this 1200W RMS from an Alpine PDX-M12 amplifier.

This was my first experience with passive radiators and i was extremely impressed with the outcome .


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## 04quadcab (Dec 31, 2017)

mrexcitement said:


> 40 Litres


That is about 1.4 cuft, I don't even know if i can fit 4 cones on a box that small.

Thanks for your input, I am trying to figure out a way to get good sound in an under-seat box and I might give this a try.


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## captainbuff (Mar 11, 2017)

Holmz said:


> But no one seems to consider using a passive radiator. Is that tradition or some decent reason?


This is an old post but I can offer something that may be of some use...my old home theater was an Omni-Mirage 5.1 with floor standing speakers. The floor standers had two active and four passive. With a Denon amp and a Velodyne sub it sounded really nice and kicked ass.
However...fast forward around 12 years...
There is nothing physically wrong with any of the speakers (including a center and two surrounds). I am quite certain they would all play very well...they just need to have the rubber surround replaced as it has cracked on all of them.
They have seen plenty of use so I am not lamenting the fact that they have worn out. What is ridiculous is that each floor stander has 6 drivers that all need the rubber done...
I don't know how to do it myself and was quoted around $80 per driver I think. 
If they were just a more normal 'active driver design' then I would likely just get a pro to do it. Having to replace 12 rubber surrounds on just two floor standers means they have been sitting in storage for years. The five speakers were around $5k back then...probably a little more because I remember the Velodyne sub was $1,100...so they weren't rubbish gear either.
PITA. I'd love to set them up in my living room...but no dice.


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## Holmz (Jul 12, 2017)

captainbuff said:


> This is an old post but I can offer something that may be of some use...my old home theater was an Omni-Mirage 5.1 with floor standing speakers. The floor standers had two active and four passive. With a Denon amp and a Velodyne sub it sounded really nice and kicked ass.
> However...fast forward around 12 years...
> There is nothing physically wrong with any of the speakers (including a center and two surrounds). I am quite certain they would all play very well...they just need to have the rubber surround replaced as it has cracked on all of them.
> They have seen plenty of use so I am not lamenting the fact that they have worn out. What is ridiculous is that each floor stander has 6 drivers that all need the rubber done...
> ...


If they have a re-rubber kit, then just have a go at one...
You have nothing to loose as they are junk with out them... "so have a go, to get a go", and HG would say.


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## captainbuff (Mar 11, 2017)

Holmz said:


> If they have a re-rubber kit, then just have a go at one...
> You have nothing to loose as they are junk with out them... "so have a go, to get a go", and HG would say.


Yeah 100% agreed...to be honest just rolling through the forums I saw this post and it reminded me of them.
Like i said though...'they are on the list'! The bloody list just keeps getting longer every day...


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