re xxx 12" with ae passive radiator

[dennis09x 10+ year member]

You really need to download WinISD Pro Alpha. It will give you one more piece of info that I think you're overlooking and that is PR excursion. I think that you might find that you don't have enough vertical surface area on your box to mount enough passive radiators to keep from stroking them all out. The more power you run, the higher the tuning, the larger the driver the more swept volume you need from your PRs to keep from damaging them. This is one of the main reasons that you don't see PRs used in car audio systems that much. Building a port is just easier most of the time.
You must have the PR mounted on a vertical surface for it to work correctly. if you can't fit it on one, you can't use a PR.

K ill give it a try.

 

[dennis09x 10+ year member]

Sh!t your right, im getting like a 3 inch excursion when the sucker only has 2" p-p. Even with 2 of the PR's im still almost hitting that high. jesus, this is braindead. Looks like ill have to go back to thee ol port cause i dont have enough space for 2 PR's

 

[helotaxi 5,000+ posts]

Now you see why they aren't used when high power and output are part of the equation.

 

[dennis09x 10+ year member]

Now you see why they aren't used when high power and output are part of the equation.

good call, good call... thanks for the help guys, ill have to look more into this once i get home stereo happening. This power is to much for these poor little PR's. time for some good ol 4" pvc x 2

 

[John_E_Janowitz 10+ year member]

Now you see why they aren't used when high power and output are part of the equation.

Actually, this is usually the time when PR's ARE used. IF you can't fit adequate PR's in the enclosure, there is most likely no way you'd be able to fit an adequate port in. To keep distortion to an inaudible level and vent velocity low enough you want to keep the velocity below 10m/s. This typically means a huge port.

For example in 3 cubic foot, a pair of 15" PR's with 1500grams each tune to right about 20hz. With up to 1000W input with an AV12, you won't run out of excursion on the PR's, meaning no port compression, no vent noise, no bottoming, etc. Now technically a port that would have the same tuning and mass of air in the port equal to that of the PR's, would be 18" diameter and 600" long. Obviously that isn't realistic. We do need to determine what diameter is required to meet the goals for vent velocity though. In this case an 8" diameter vent, 114" long will keep vent velocity to 14m/s at 1000W input, already into the audible distortion, compression range. A 6" diameter vent is 62" long and vent velocity then goes up to 25m/s where you are getting much more into audible distortion, vent noise, and compression.

A 4" vent, 26" long with 1000W input puts vent velocity over 56m/s. To keep vent velocity to 10m/s means only 35W input power with the single 4" port. Again, the pair of 15" PR's have no compression, no vent noise, and no audible distortion added with the full 1000W input.

Here is the direct link to the PR FAQ for anyone looking for it who cant' find it on our site.

http://www.aespeakers.com/PRFAQ.php

John

 

[John_E_Janowitz 10+ year member]

Sh!t your right, im getting like a 3 inch excursion when the sucker only has 2" p-p. Even with 2 of the PR's im still almost hitting that high. jesus, this is braindead. Looks like ill have to go back to thee ol port cause i dont have enough space for 2 PR's

If you're adding a second PR, your excursion is going to be cut exactly in half. If you're running out of excursion on the PR's that easily though, you are likely just tuning too high. Do you have parameters for the woofer you can post here?

John

 

[dennis09x 10+ year member]

12"

Mounting Depth - 12.75"

Mounting Hole Diameter - 11.5"

Overall Diameter - 13"

Bolt Hole Circle - 12.25"

Motor Width - 10.5"

Motor Depth - 5"

Basket Depth - 7.75"

Displacement - 0.24 cu. ft.

Weight - 72 lbs.

XXX SERIES

T/S Parameters

12"

Electrical Q Value -Qes: 0.46

Mechanical Q Value -Qms: 3.29

Total Speaker Q Value -Qts: 0.404

Free Air Resonance -Fs: 21.00 Hz

Equivalent Compliance -Vas: 74.0 liters

One-Way, Linear Excursion -Xmax: 54 mm

Efficiency -SPL 1W/1m: 83.76 dB SPL

Effective Piston Area -Sd: 480 cm^2

DC Resistance -Re: 4.2 ohm

Nominal Impedance -Znom: Dual 2 ohm

Thermal Power Handling -Pe: 2000 W

Force Factor -Bl: 18.16

I think i might be tuning to high, which is probably my problem

 

[helotaxi 5,000+ posts]

John, he's going for a typical SPLish setup with a mid 30's tuning. Not the right place for a PR based on everything I know.

I'm the kind of person that would actually like a PR setup since I'm not looking for a peaky SPL type alignment and I don't usually run a ton of power. The current subs I'm playing around with want less than a cubic foot each tuned to 25ish Hz. THAT's a hard port to fit. Problem you run into with a setup like that if you are trying to run high power is that there isn't enough surface area on the box to get enough PRs on there.

 

[helotaxi 5,000+ posts]

One more thing to consider is what port velocities you would see with a given setup with actual applied power and within what frequency range you actually use. Most people aren't really going to care that port velocity would be high with an actual 1000W at 20hz for the simple reason that they never send a signal with significant 20hz content to their sub. Totally different story if you're talking home theater, but for car audio you can get away with some things based on normal program material.

 

[dennis09x 10+ year member]

It too bad, i would have liked the ability to tune 22-35 or so. Just so I had the flexibility to do so on a whim. I gotta see how i will enjoy my 33 hz set-up first. If i end up disliking it, i will probably have to go the route of multiple PR's and re-configure my box.

Im at school right now and can't get winISD, but what weight would i need from 2 15" ae PR's to tune to 33 hz in a 3.14ft^3 box? and john, do those 400 g PR's have the ability to have mass added to them?