Four Type-R 12's Box build questions/help please

[REH]

Alright fellas, I'm working on coming up with an enclosure for four SWR-1222D's. I want to do a removable/changeable port to be able to adjust tuning on it so I'm probably going to do a square port instead of a center slot on this box. I will be feeding them 2.4kw (In a perfect world without any rise, voltage drop, etc) But they'll be on an old RE Audio VLD-3DE so I'm factoring them @ 600rms each at 1 ohm nominal.

I have a couple of questions as I proceed with the Torres calc's and paper scribbles and I figured I should just start a thread and hope that some of the knowledge on here can chime in and give some advice as I go along.

Box will be for (4) Type-R 12's (SWR-1222D models).

My old box I had for two of them worked fantastic at 4cu.ft net/32hz with 58sq in of port. (16H 38W 19D, 4x14.5" 30 long port if I remember right) on the same amp @ 2 ohms.

~~~~Questions for the new box I want to build~~~~

-Port area-

How much port area should I aim for? Like I said above my box for 2 of them was 58 square inches of port and worked great. Do I need to double that and aim for around 116? Or would smaller area be fine on a square port with rounded ends?

-Net volume -

Old box was 4ft net for two of these subwoofers on 1.2k and performed well. Should I double it and aim for 8 cubic feet net from doubling subwoofers and power? Or should I aim slightly smaller and go in the 7-7.5 net range? Would there be a *noticable* difference in output between for example a 7 cubic ft net, vs an 8 net enclosure?

-Port to rear hatch-

I know the old rule for distance from port to any wall is to stay equal distance as the smallest measurement of the port. (example being a 4"x14.5 port, keep at least 4" away from the wall). Is this still the general standing rule? Or on larger ports, say a 10x10 square.. I staying 10" from the wall necessary or could it be tightened up a little bit without issues?

Thanks in advance guys.

[Joe X]

If you are having space problems you could do 3 6" round ports.

[REH]

If you are having space problems you could do 3 6" round ports.

Space is definitely a factor, but not completely limiting. I thought about the multiple smaller ports, but I wanted to check in with some of you experienced guys on the port area factors. Three 6" would be 84 inches of port, Would that give any noise with sonotubes and be plenty of area? You're actually the one who gave me the dimensions and sketch up for my previous box with 58 inches of port for the 2 subs, which from that is why I was expecting to have to double the area for four of them.

I'm really open to anything port wise, but I'm trying to make sure that I can initially tune it low and have the net and port area needed to perform well at a tune of 30-32, and then be able to swap out ports and have a higher tune if I ever wanted to do any metering etc. That's why I was considering the square removable port idea like Steve has on his box. However, I know that can easily be done the same with round ports mounted onto a panel. So my major concern was with the needed port area. What would you recommend for area? I know you just said the three 6" for round's, but what about squares/slots and area?

[Joe X]

Double net volume and port area will work on the same or similar tuning and power, the 3 6" round ports I would recommend using flared ports like PSP, you will not have any noise like that, you should also bear in mind that change tuning means a different port size which in turn change net volume for a given gross volume unless the port is fully external, you have to bear in mind those things before coming up with a spec.

[REH]

Double net volume and port area will work on the same or similar tuning and power, the 3 6" round ports I would recommend using flared ports like PSP, you will not have any noise like that, you should also bear in mind that change tuning means a different port size which in turn change net volume for a given gross volume unless the port is fully external, you have to bear in mind those things before coming up with a spec.

Okay, I think I'll give the 6" aero's a shot. Does this look right to you? The 28" depth gives me 6" from the ports to the rear hatch.

~When making aeros out of PVC the port length in torres is the total end to end length after flaring correct? As in if you took your made port and laid it next to a yard stick after bending I would need it to be 20" at that point right?

~Would you recommend putting the 3 ports horizontal side by side at the bottom of the box, or vertical up the center?

Also, I will be doing internal bracing and putting a flush mount baffle onto it but I'm not worried about adding the baffle to the Torres measurements. That'll be done afterwards.

[fecupe2001]

8-10 c/f and 3 6" aeros is just insane for almost any decent 12" sub when you use 4 of them, that same box on my explorer was burping 154 @ 45 hz using 4 dd 2512s

[REH]

Went to Lowes yesterday to pick up MDF and PVC, but they were out of 6" PVC... so, I played with numbers some more in Torres last night and came up with this one. 99 square inches of port, I know isn't "ideal" but I think that it should be fine for some type R's. What do you guys think? I have ran 2 of these subs in a 4cf net with 54 inches of port and had no noise, currently in a box with 58 inches and obviously no noise as well.

[Triticum Agricolam]

I think those specs look fine. Your port velocity is still reasonable with 2400 watts of input power. That box looks like a winner to me.

[REH]

I think those specs look fine. Your port velocity is still reasonable with 2400 watts of input power. That box looks like a winner to me.

Thanks for taking a look for me, I'll give this one a go.