Passive Radiators

[murph 10+ year member]

I want to know the purpose of these, the benefits and any other details.

Click to read more...

 

[goingdef 10+ year member]

had some home audio ones YEARS ago the box only had a 6.5" woofer but coupled with a 10" passive had an amazing amount of output, and if your wondering I thought it couldnt be doing all that much either until I removed it from the situation and was amazingly disappointed in the 6.5 alone. From what I could tell it just moved equal/opposite of the "powered" driver but I know there are ones now a days that can be tuned to your liking.

 

[winkychevelle 10+ year member]

they act just like a port they can be tuned by changing the weight added to the cone.

they save airspace since they arent very deep and allow you more design flexibility.

general rule of thumb is if you have a 10" sub u need a 12" radiator but this is not always necessary as long as the radiator can displace the same amount of air or more than the sub which is why boston's radiators are the same size as the speakers they are matched with.

personal experience they work good for smaller systems up to about the 145db range after that i cant say ive ever seen a passive radiator system get louder than that.

biggest downside to the radiators is generally their price

 

[murph 10+ year member]

they act just like a port they can be tuned by changing the weight added to the cone.
they save airspace since they arent very deep and allow you more design flexibility.

general rule of thumb is if you have a 10" sub u need a 12" radiator but this is not always necessary as long as the radiator can displace the same amount of air or more than the sub which is why boston's radiators are the same size as the speakers they are matched with.

personal experience they work good for smaller systems up to about the 145db range after that i cant say ive ever seen a passive radiator system get louder than that.

biggest downside to the radiators is generally their price

So say you have a 12inch subwoofer and you get a 15inch radiator would the output be higher with the radiator specifically on the lows.

 

[winkychevelle 10+ year member]

say you have a 12 inch sub and u get a 12 inch radiator with equal xmax and then you get a 15inch radiator with 3/4 xmax is the sound going to be different of they are both tuned to say 34hz?

quick answer is no

the passive radiator is going to displace the exact same amout of air as the sub driving it.

the reason people recommend larger radiators is because they dont have to excurt as much to equal the same displacement as the sub driving it and generally lower x-max radiators are cheaper

you would tune a radiator just like a port but instead of adding port length u add weight

 

[murph 10+ year member]

ttt

 

[RAM_Designs 5,000+ posts]

A simple google search will give you a lot of answers, and even in depth explanations/formulas for figuring out tuning and such.

 

[wenn_du_weinst 10+ year member]

only benefit to passive radiators is saving space.

 

[murph 10+ year member]

From my readings a passive radiator greatly extends the frequency response of the woofers. Is there any output achieved by the radiator itself or is the only purpose of it frequency control?

 

[wenn_du_weinst 10+ year member]

it's exactly like a port, nothing more nothing less. I can't believe people in this hobby don't know how a port works.

 

[murph 10+ year member]

it's exactly like a port, nothing more nothing less. I can't believe people in this hobby don't know how a port works.

I know how a port works and from what I have been reading it says it achieves greater response.

 

[winkychevelle 10+ year member]

it doesnt do anything more than a port does ports are actually more flexible in the install but passives are easy to mount and tune