Passive radiatior question

[BJ The Man 10+ year member]

I would like to do a passive radiator setup with my 10L7 considering i have no room for a ported box.

Where can i find the materials to do this?

What are some pros and cons? (other than the fact that the radiator will make it louder)

thanks.

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[audioholic 5,000+ posts]

A PR system will react much like a ported box. For simplicity's sake, you can refer to ported systems' frequency characteristics versus enclosure tuning to get a good idea what you would be experiencing from your PR.

Pro's are increased efficiency of the system, again much like a ported system. A pro specific to PR systems would be saved space by lacking the necessary volume for a port. The cons would be similar to ported systems, a less linear response usually, exaggerated response near tuning, etc. A con specific to PR's versus ported would be the added cost of the passive radiator itself, versus a free or almost free port, obviously.

Materials you will need would include the passive radiator of your choice, and all the other common box building materials.

 

[BJ The Man 10+ year member]

for a single 10L7 in .8CF sealed would i want to 8inch PR's or should i make a new box.

 

[Freelander 10+ year member]

Here is a 10" Passive Radiator

 

[Freelander 10+ year member]

Most passive setups I've seen use the same size radiator as the sub itself. Not sure if you can use smaller radiators or not.

 

[Immacomputer 10+ year member]

You don't want to use a smaller amount of displacement on the PR as you might damage it due to over excursion around tuning. You should look into two 10" PRs firing in opposite directions (to keep the enclosure from being moved by the mass of the radiators) as they should work for that sub.

 

[BJ The Man 10+ year member]

well because of the side of the box i would have them on would two or 3 8's work. im looking at the daytons that were posted earlier

 

[Kyle_Keating 10+ year member]

pr's are displacement limited while ports are velocity limited

this is simply because ports dont have a suspension linear limitation, but rather a friction linear limitation, non-linear drag against the port is the catalytic for distortion for ports while non-linear suspension travel is that for passives. There is also a resonance issue with ports that tends to occur in higher frequencies. This is a bit more complex, but it can show up in impedance and frequency response measurements.

a 5"round port might be about the same as a 15" passive radiator at around 2" peak to peak. The port can do about 10" peak to peak before serious compression... yes the air in ports move just like woofers //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif So its easy to compare ports to pr's once you know how far each can move before distortion. One thing surprising about ports is that the higher they are tuned, the faster the air moves and the more drag there is.... for PR's the lower the tuning, the more they move and the more the suspension get stressed.

often times, it is difficult to get a big port in a small box. The tuning of the port depends on the length and area or the port with the volume of the box, the pr is much more heavily dependent on the mass of the pr itself, the box is pretty minor. So if you have a high BL driver and a small box, a PR is very ideal from a size perspective.

 

[BJ The Man 10+ year member]

so when adding and subtracting weights from it im doing what?

 

[audioholic 5,000+ posts]

so when adding and subtracting weights from it im doing what?

Adjusting its tuning frequency.

 

[BJ The Man 10+ year member]

ok then i guess im going with 2 8's

 

[Kyle_Keating 10+ year member]

ok then i guess im going with 2 8's

bigger is better, two 10's would be better for your sub.

 

[BJ The Man 10+ year member]

i dont have room for that and i cant build another box so ill just tune the 8's low and hope it works out

 

[azimuth 5,000+ posts]

bigger is better, two 10's would be better for your sub.

wouldn't using 2 10" radiators defeat the purpose of smaller box size? unless it's possible to point them + sub in 3 different directions.