Dayton Titanic with passive radiator ?

[jeeracing]

Hi,
I have build a subwoofer with a Dayton titanic 10" , around 35-36 liters with a 3x10 port. it sound really great but I have a big probleme of air flow sound in the port.

I can't put a bigger port because I have not much space in the box,
I try also sealed it but it sound not as much loud and deep for me.

My other option is tu put a passive radiator but I never work with it, I dont know how to tune it too. I find the CSS ARP 12 for example, I dont know if it will make a good match with the Titanic and with the box volume.

well, If somebody have an option for me it will be great to know.

thank you everybody.

[event horizon]

To tune a passive radiator all you need to do is add or subtract mass to get the desired resonance (of the PR, equivalent to the ports). The thing is it's not as easy as it sounds due to the Qms of the passive radiator. In a reflex enclosure the air is the mass (in the ports) & it doesn't have any "mechanical Q".

You'll need a single passive radiator which is at least 2 times the bass driver area with the same excursion, or possibly the same area with at least 2 times the excursion.

As you have found with ports, the more area & the lower the air velocity the more linear it'll sound (less distortion). You'll get a better sounding & responsive sub by going kind of OTT with the passive radiators. I'd suggest that 3 times the swept volume that the driver can move would be quite nice indeed

It'll get expensive though...

[Cokewithlime]

As event horizon mentioned, you will need 2x+ the swept volume of the Dayton titanic 10" sub - you could go with a minimum of 2 of these Dayton 12" PR (three would better) which is another alternative to the CSS PRs

The other option is to go with a larger port - you don't have to have all of the port inside the enclosure for it to operate correctly - if you don't mind the look of have some of the port external to the box this could also work for you.

[bear]

If you go with two PRs it is best to have them symmetric - as in identical placements on opposing walls. Even stacked on the same wall can cause them to not run in phase at certain frequencies.

In reality the pressure in the box is not what you might imagine - it is not even at all - the suspension of the PR is doing the job of linearizing the nodal pressures that appear to move with frequency across the rear surface of the wall, and therefore across the PR's rear surface.

So, these pressure (and anti-pressure) nodes may or may not appear along a single wall identically WRT frequency...

[j.michael droke]

Hi there: Have you considered using two ports to get more area and reduce each ports length. This will reduce the velocity in each port. Also multiple ports of the same diameter should be spaced some distance apart. ( reference Vance Dickerson's book "Loudspeaker Design Cookbook", 7ed, page 74, and figure 2.39 through 2.41)
...regards, Michael

[jeeracing]

thanks evenybody.

I have make some calculation and if I enlarge my port tube to 4" it will be 23" long. even if its a double 3" port. it's way to long for me.

[j.michael droke]

Originally Posted by jeeracing

thanks evenybody.

I have made some calculations....even if its a double 3" port, it's way to long for me.

Hi there Jee: I ran your 35.5L Titanic sub project through a box program
(LCD Design Suite7) and found the following:
2 vents @ 2-5/8 inches D x 13.9 inches long ( area +53%),
2-vents @ 2-1/2 inches D x 12.6 inches long ( area +39%),
2 vents @ 2-1/4 inches D x 10.0 inches long ( area +12.5%)
Hope you keep the community informed of your progress and listening results,

regards, Michael