What do you think of these 4th designs?

[Real96SS]

So I am trying to put together a 4th order for my 2 PSI P3 18's and this is my first one. I have 2 designs.The first one is the one I would like to use but I'm thinking it may have loading issues due to the placement of the port. Plus with that design I can build inside the drain rails in the bed.The second design seems perfect.The only thing is with that design I would have to build my max width 50" and then height would be around 20" and then have to come in to clear the drains and then up the full 22". Not hard but I would like to be able to just go straight up. Either way what do you guys think.

Edited June 11, 2012 by Real96SS

[quakecitystudio]

If I may suggest,

I feel like there isn't enough back spacing in the rear chambers for each woofer, in both designs.

For the first design, I'd remove the short wall of the port, and move the subwoofer wall up towards the port opening. Make sure the port area equals the surface area of the subs.

For the second design, I'd change it up, so there's three chambers, two large ones and one small one in the middle. The two subs would face each other firing into the smaller chamber. It goes "large chamber" ported small chamber "large chamber. But make sure that the small chamber is big enough to be able to remove a sub.

[Real96SS]

If I may suggest, I feel like there isn't enough back spacing in the rear chambers for each woofer, in both designs. For the first design, I'd remove the short wall of the port, and move the subwoofer wall up towards the port opening. Make sure the port area equals the surface area of the subs. For the second design, I'd change it up, so there's three chambers, two large ones and one small one in the middle. The two subs would face each other firing into the smaller chamber. It goes "large chamber" ported small chamber "large chamber. But make sure that the small chamber is big enough to be able to remove a sub.

I'm just going to say...............WTF ARE YOU TALKING ABOUT KOBE BRYANT!!! LOL. You have to have watched Kobe's the system on youtube to find that funny. You honestly confused me.If you can show me what your talking about. As for the back spacing i dont think that should matter if the subs have the correct amount of space. I would like to see what your talking about so I can better understand what your telling me.This is my first 4th order design so excuse me for not knowing.

[bassface]

Port length looks pretty short to me, the one im building called for 110 square inches at 22.5" length. But mine is only for 2 13.5" inch subs.

Edited June 12, 2012 by bassface

[quakecitystudio]

That's fine, I see alot of guys do 4th order bandpass with the rear chambers being smaller than the chamber that they are firing in. Your subs would be mounted in sealed chambers right? I looked back at your screen shots and you did a calculation for the sealed chambers and one for the ported chambers. Your port is tuned to 49.58 hz?

Do you know what your sealed chambers are tuned to? I know that when you have larger sealed chambers the tuned frequency is lower. I once did a sealed box for 2 12s at 5.4 cu.ft. and the frequency was around 23hz.

[Real96SS]

Port length looks pretty short to me, the one im building called for 110 square inches at 22.5" length. But mine is only for 2 13.5" inch subs.

I don't know what your looking at but thats 285 square inches of port area. I think your think your port had to be longer because of what you were tuning too. The length of the port adjust your tuning and I'm guessing your box was tuned low were as this one ported side will be tuned around 49hz.

That's fine, I see alot of guys do 4th order bandpass with the rear chambers being smaller than the chamber that they are firing in. Your subs would be mounted in sealed chambers right? I looked back at your screen shots and you did a calculation for the sealed chambers and one for the ported chambers. Your port is tuned to 49.58 hz? Do you know what your sealed chambers are tuned to? I know that when you have larger sealed chambers the tuned frequency is lower. I once did a sealed box for 2 12s at 5.4 cu.ft. and the frequency was around 23hz.

They will be mounted into the sealed chambers.Port tuning as of now is 49hz because when researching before everything pointed to tuning the ported side high around 40-55hz. I dont think you can tune a sealed box.Now depending on the size could make it sound different but I haven't seen a calculator for that. I'm actually going to downsize the sealed section to be around 2^3ft after displacement due to the power I will be giving the subs.

[stroupe79]

the first one looks like it would have loading issues where 1 sub would be blowing against the port wall and the other 1 would not...

the 2nd design looks more like the 4th's I am used to seeing...

[Real96SS]

the first one looks like it would have loading issues where 1 sub would be blowing against the port wall and the other 1 would not...

the 2nd design looks more like the 4th's I am used to seeing...

Yeah thats what I thought about the first one. The only reason I designed it like that was to try and keep the port on the drivers side since I have been told thats the best place if you compete. Don't know how much of a difference it makes but the second design is what Im sitting on right now. Im going to shrink it down a little for better handling of the power but thats about it.

[jroo]

If I am looking at this correctly, you have roughly 3 cub sealed playing into 13 cube ported with close to 300 square inches of port. I also see that you might have a higher tuning frequency like almost 55. From what I know about 4ths, that will be loud as piss but peaky as hell. I am also not sure how low it will play with the sealed section being that small compared to the ported side.

[Ddub847]

y is your sealed section so small