is there anything bad about using passive radiators? for the sound i am trying to get i think i either need to have a wall or open space for my subs (no trunk). i am not so much concerned with spl or sq i want my car to have a lot of impact and with the limited space that i have 4 15's wouldnt fit into my trunk with adequate airspace.

If you want impact, a PR is not the way you need to go.

what are passive radiators used for? and which the way to go?

the reason i asked was because i decided to go with 2 15 axis with passive radiators. when i spoke to thilo at tc sounds he told me that adding pr would give me more bass and act as a 3rd and 4th woofer. so if that is true how will this not help me?

No it doesnt act as a 3rd or 4th woofer, PR's act as a port, that really isn't there.

You need to have twice as much Sd with a a PR as the woofer..so 1 15" woofer, needs 2 15" pr's.

sd? and a member made a comment but didnt elaborate. what route would i need to go to get more impact?

sd?

Surface area of the cone, roughly.

what route would i need to go to get more impact?

Try a higher-tuned enclosure...

Ported, tuned to 38hz.

so what should i be tuning to 38hz? does it matter? 2 15's 2 18's or whatever? or r we still talking about pr's. cause i thought that wasnt what u were recommending. or 2 15 tc sounds.

but i thought more cone area was what moved more air and gives u more movement inside the car. so if it improves cone area it would create more impact inside the car right? i dont mean to keep bothering you but when someone who is supposed to be the creator of a line tells me one thing and i am then told he was wrong it just confuses me more.

If you want impact, a PR is not the way you need to go.

I'm curious, how do you figure?

Thilo didn't steer you wrong.

A passive radiator alignment is almost identicle to a standard 4th order vented alignment (regular ported box) with slight variations in response around the passive radiator Fs.

The only real disadvatage to a passive radiator is cost, but since you already bought them, you are good to go.

They have many advantages, to include- Lower tuning than possible in a small size box vs. ported, better behavior below tuning (helps woofers keep from unloading), no port resonance and increased mechanical noise suppression.

The passive radiators do not need to have 2 times the Sd of the drivers you are using, but they should have roughly 2x the displacement capability of the active driver, and if you look closely at the parameters, they usually have a lot more stroke than the active driver. More than likely Thilo reccomended the correct passives to go with your woofers, they probably have a lot more Xsus than the Axis woofers have Xmax.

All you have to figure out is your box size and tuning, again a passive radiator set-up will have roughly the same response curve above tuning as a standard 4th order vented. There are online calculators that will tell you how much mass you will need to add to get the desired tuning. If you need help, I am sure there are plenty of people here who can help.

Don't worry, you have the right stuff, you just have to figure out how to use it correctly... I have known Thilo for a long time, he knows what he is doing.

ok. just a slight correction. havent bought anything yet. so are you saying that i can make a 4th order vented box and sound the same as having the pr's? and all that u said i am a newbie at all of this. so i understood none of it. i am looking for the right setup for the sound i want and it seems like i need more cone area opposed to a box or pr's. so when he told me they acted as 3rd and 4th woofers that was what i wanted to hear.

i dunno. all of this and i dont feel like i am getting anywhere. i will be patient though. still looking at the hcca's and the btl. i will make a decision in a couple of weeks.

OK, here is a simple explanation. (I thought you already had the passives and subs???)

Passive radiator alignments and 4th order vented alignments have rougly the same output. Passive radiator is more expensive, usually more complex and easier to mess up. When Thilo told you they acted like a 3rd and 4th woofer, he was just trying to explain it in a way you could easily understand... And yes, the passives do augment the output of the box, just like a port does... It is just a different approach that gives you similar results.

You can get just as loud with a port as a passive radiator and vise-versa. Judging by your posts, I would reccomend straight forward 4th order ported.

Also, slow down and try and be a little more articulate in your posts (questions)... You will get better responses that way.

-Mike

Edited June 9, 200817 yr by 95Honda

ok. thanks.

-Mike