Passive Radiator Help

[mrazandrewm]

Awesome!

I do have a question about the excursion on the PSI PRs. I modeled the SA8V2 and PSI's 10" PR in WINISD Pro, but at slightly more wattage to the woofer, the PR's cone excursion surpasses 1/2 of the total usable excursion. Would it be alright to run the PR slightly past 1/2 it's total usable excursion? I guesstimated the forward motion is half of the total usable excursion. Is that wrong of me to assume that?

Is that at tuning? I don't remember how WinISD defines it, but it sounds like that would be correct. You should probably make sure though. Because if that's the case, you need more PR.

The SA8v2

Sd=201sq.cm. (just took Sd of DC's 8", couldn't find it on the SA)

Xmax=1.6cm

Vd=321.6cc

PSI 10" PR

Sd=320sq.cm.

Xmax=3.2cm

Vd=1024cc

Ratio is 3.18x the Vd in your PR. You should be absolutely fine with that.

It's also doing it to the PSI 8" SW.

So with your math the 10" PR from PSI would be fine and I don't need to worry about the excursion on the program? I can post a few pics if that'll help...

[gckless]

Awesome!

I do have a question about the excursion on the PSI PRs. I modeled the SA8V2 and PSI's 10" PR in WINISD Pro, but at slightly more wattage to the woofer, the PR's cone excursion surpasses 1/2 of the total usable excursion. Would it be alright to run the PR slightly past 1/2 it's total usable excursion? I guesstimated the forward motion is half of the total usable excursion. Is that wrong of me to assume that?

Is that at tuning? I don't remember how WinISD defines it, but it sounds like that would be correct. You should probably make sure though. Because if that's the case, you need more PR.

The SA8v2

Sd=201sq.cm. (just took Sd of DC's 8", couldn't find it on the SA)

Xmax=1.6cm

Vd=321.6cc

PSI 10" PR

Sd=320sq.cm.

Xmax=3.2cm

Vd=1024cc

Ratio is 3.18x the Vd in your PR. You should be absolutely fine with that.

It's also doing it to the PSI 8" SW.

So with your math the 10" PR from PSI would be fine and I don't need to worry about the excursion on the program? I can post a few pics if that'll help...

Yep. Because Xmax is so much greater in the PR (just verify with Dave that it's in fact 32mm one-way travel), your Vd is much higher. I had like 1.43x the PR over my powered drivers, and I would reach mechanical limits under high power around tuning. With double that, I'm pretty sure you'll be fine.

Another thing you have to worry about is the weight you will need to add. If you're adding too much (2lbs or more) it's gonna be rough on your suspension. To find weight, here's a rough estimate:

- Find the length of an aero port for your desired tuning and the same size as your PR (10" in this case).

- Find the port volume (Sd x L). Convert this to cubic meters.

- Find the mass (density of air (1.225kg/cubic meters) x port volume)

And remember that's total, including the weight of the PR itself.

This might help also: http://mobileaudioforum.com/forum/showthread.php?6351-Passive-Radiators-and-You

[boom50cal]

passive radiators are so cool. so one could build use a single 12 inch sub and build with 2 passive 12 radiators?

curious to see what the output of a single 12 ported vs a single 12 with the correct passive radiator setup would be.

[gckless]

passive radiators are so cool. so one could build use a single 12 inch sub and build with 2 passive 12 radiators?

curious to see what the output of a single 12 ported vs a single 12 with the correct passive radiator setup would be.

Read the thread man

But basically you're concerned with Vd (volume displaced), which is Sd times Xmax. So can't really say for sure if one quantity of a certain size will work, since that's only part of the equation.

Output is damn near the same. You lose a little SPL with the PRs simply because of lossy transfer function, but I don't think it's as much as everyone thinks. I have yet to test that though. Hopefully TFade is working on that right now.

If it helps at all, I was doing about a 147 with my pair of 15's on about 3k with dual 18" PRs. And I couldn't really run that full tilt either.

[mrazandrewm]

passive radiators are so cool. so one could build use a single 12 inch sub and build with 2 passive 12 radiators?

curious to see what the output of a single 12 ported vs a single 12 with the correct passive radiator setup would be.

Read the thread man

But basically you're concerned with Vd (volume displaced), which is Sd times Xmax. So can't really say for sure if one quantity of a certain size will work, since that's only part of the equation.

Output is damn near the same. You lose a little SPL with the PRs simply because of lossy transfer function, but I don't think it's as much as everyone thinks. I have yet to test that though. Hopefully TFade is working on that right now.

If it helps at all, I was doing about a 147 with my pair of 15's on about 3k with dual 18" PRs. And I couldn't really run that full tilt either.

I read your article on here as well as the link you gave me. I do have a concern though. If I ran the PSI-8 with the PSI 10" PR, that would give me a VD ratio of about 2:1 (2 being PR and 1 being PSI- . If (and when) I hear back from Dave at PSI, I'll ask him the questions I had on here.

Back to the equation please...

- Find the length of an aero port for your desired tuning and the same size as your PR (10" in this case). What do you mean same size as my PR? Change the aero port size to 10"?

- Find the port volume (Sd x L). Convert this to cubic meters.

- Find the mass (density of air (1.225kg/cubic meters) x port volume)

And remember that's total, including the weight of the PR itself.

So the PR has a Mms of 176g. Do I have to subtract that from the weight I need to achieve the tuning frequency that I want? What if that weight is larger than what the equation calls for?

[gckless]

passive radiators are so cool. so one could build use a single 12 inch sub and build with 2 passive 12 radiators?

curious to see what the output of a single 12 ported vs a single 12 with the correct passive radiator setup would be.

Read the thread man

But basically you're concerned with Vd (volume displaced), which is Sd times Xmax. So can't really say for sure if one quantity of a certain size will work, since that's only part of the equation.

Output is damn near the same. You lose a little SPL with the PRs simply because of lossy transfer function, but I don't think it's as much as everyone thinks. I have yet to test that though. Hopefully TFade is working on that right now.

If it helps at all, I was doing about a 147 with my pair of 15's on about 3k with dual 18" PRs. And I couldn't really run that full tilt either.

I read your article on here as well as the link you gave me. I do have a concern though. If I ran the PSI-8 with the PSI 10" PR, that would give me a VD ratio of about 2:1 (2 being PR and 1 being PSI- . If (and when) I hear back from Dave at PSI, I'll ask him the questions I had on here.

Back to the equation please...

- Find the length of an aero port for your desired tuning and the same size as your PR (10" in this case). What do you mean same size as my PR? Change the aero port size to 10"?

- Find the port volume (Sd x L). Convert this to cubic meters.

- Find the mass (density of air (1.225kg/cubic meters) x port volume)

And remember that's total, including the weight of the PR itself.

So the PR has a Mms of 176g. Do I have to subtract that from the weight I need to achieve the tuning frequency that I want? What if that weight is larger than what the equation calls for?

Ah, 24mm of Xmax in the PSI 8". Talk with him, see what he says. Also, what will your orientation be and where is this going to be in your vehicle?

For the equation, yes.

[boom50cal]

passive radiators are so cool. so one could build use a single 12 inch sub and build with 2 passive 12 radiators?

curious to see what the output of a single 12 ported vs a single 12 with the correct passive radiator setup would be.

Read the thread man

But basically you're concerned with Vd (volume displaced), which is Sd times Xmax. So can't really say for sure if one quantity of a certain size will work, since that's only part of the equation.

Output is damn near the same. You lose a little SPL with the PRs simply because of lossy transfer function, but I don't think it's as much as everyone thinks. I have yet to test that though. Hopefully TFade is working on that right now.

If it helps at all, I was doing about a 147 with my pair of 15's on about 3k with dual 18" PRs. And I couldn't really run that full tilt either.

hmmm. Murhpy is getting an email tomorrow morning then.

[mrazandrewm]

passive radiators are so cool. so one could build use a single 12 inch sub and build with 2 passive 12 radiators?

curious to see what the output of a single 12 ported vs a single 12 with the correct passive radiator setup would be.

Read the thread man

But basically you're concerned with Vd (volume displaced), which is Sd times Xmax. So can't really say for sure if one quantity of a certain size will work, since that's only part of the equation.

Output is damn near the same. You lose a little SPL with the PRs simply because of lossy transfer function, but I don't think it's as much as everyone thinks. I have yet to test that though. Hopefully TFade is working on that right now.

If it helps at all, I was doing about a 147 with my pair of 15's on about 3k with dual 18" PRs. And I couldn't really run that full tilt either.

I read your article on here as well as the link you gave me. I do have a concern though. If I ran the PSI-8 with the PSI 10" PR, that would give me a VD ratio of about 2:1 (2 being PR and 1 being PSI- . If (and when) I hear back from Dave at PSI, I'll ask him the questions I had on here.

Back to the equation please...

- Find the length of an aero port for your desired tuning and the same size as your PR (10" in this case). What do you mean same size as my PR? Change the aero port size to 10"?

- Find the port volume (Sd x L). Convert this to cubic meters.

- Find the mass (density of air (1.225kg/cubic meters) x port volume)

And remember that's total, including the weight of the PR itself.

So the PR has a Mms of 176g. Do I have to subtract that from the weight I need to achieve the tuning frequency that I want? What if that weight is larger than what the equation calls for?

Ah, 24mm of Xmax in the PSI 8". Talk with him, see what he says. Also, what will your orientation be and where is this going to be in your vehicle?

For the equation, yes.

Subwoofer and PR firing up under my read bench in my f150. I'll have the bench raised to accommodate the enclosure as well.

I'll figure out what the added weight needs to be and then I'll ask more questions (if I have any). Thanks.

[mrazandrewm]

Have not heard back from Dave yet (from PSI). However, it looks like I'll need to use the 12" PR for the PSI 8" subwoofer (gives me room to add another one down the road).

[mrazandrewm]

Alright. So I decided on the 12" Passive Radiator. Now I don't know what subwoofer to get. Option 1) PSI-8 on 650w RMS. Option 2) SA8V2 on 1000w RMS. Or option 3) Fi SSD 10 on 10002 RMS. All three will be in a 0.62 ft^3 tuned to 33 Hz. Here's a link to my photobucket of all three (together) in WinISD Pro: <iframe width="480" height="360" src="http://s1379.photobucket.com/user/mrazandrewm/embed/slideshow/"></iframe>