need advice for dual front fire 18" - AVS Forum
DIY Speakers and Subs > need advice for dual front fire 18"
Seppelrator's Avatar Seppelrator 06:13 PM 04-09-2013
Hi currently I´m building my new home theatre and decided to go diy to get more performance for my money.
Thinking of a dual front fire design.
I never did this before so your help is much appreciated.

Use is only HT and my goal is about 15Hz.
After what I read 18" Dayton HO would be good way to go?!

Most likely 2 8ft³ cabinets so 4x18" daytons or is this way to much for my room? 14x11x7ft but open to one side. Does sombody know a simple design for this?

What amp would suit this project best? Was thinking of two EP4000 or Inuke or one of these china FP14000/10000q?

Thanks for your advice.

Jay1's Avatar Jay1 06:22 PM 04-09-2013
8ft3 will not be suitable for a pair of 18s tuned to 15hz. That will work for a sealed pair... How big is the open area to your room?
Seppelrator's Avatar Seppelrator 06:36 PM 04-09-2013
Here is a quick drawing:


Jay1's Avatar Jay1 07:29 PM 04-09-2013
Your subs are going to attempt to pressurize that entire area. You might be better off with 4 subs, 2 front 2 rear, but of course you might not be able to place them in the rear (depending on your room setup).

8ft3 is a good size for a single driver ported sub tuned low, and there's a few drivers that will work well in such an alignment. You will need something like a miniDSP to act as a high pass filter. If you decide on sealed subs, you will also need something like a miniDSP to EQ the response flat.
Seppelrator's Avatar Seppelrator 08:15 PM 04-09-2013
Thanks for your help.
I think sealed would be better for my room as it is not that big or just 2 ported subs?

2 single subs in the rear could be a little difficult because of the limited space between my couch and the walls (about 22" each side). Not the best placement, is it?
Sibuna's Avatar Sibuna 09:00 PM 04-09-2013
you could build 2 dual opposed boxes and place them up front, you still get 4 drivers that way and it may be easier for you to place them. Gorilla83 built 4 dual opposed but i heard them when he only had 2 running, his space is similar in size and shape and they had no issues filling the space

his thread - he used the Dayton 18s

http://www.avsforum.com/t/1435795/first-diy-project-for-a-guy-looking-to-upgrade-multiple-sealed-18s
Seppelrator's Avatar Seppelrator 09:07 AM 04-10-2013
Yes dual opposed would be possible too but I would prefer the look of 2 drivers in the front.
Would I loose performance if I go this way?
Thanks
mastermaybe's Avatar mastermaybe 09:21 AM 04-10-2013
This is what I did:



Loads of output to 15hz in a 3500^3 area.

James
Seppelrator's Avatar Seppelrator 05:53 PM 04-10-2013
Hi James,
this is exactly what I want to buid. Would you be so kind and give me more information of your subs?
Thanks
Dank1209's Avatar Dank1209 07:27 PM 04-10-2013
Sepp. Click on his name then profile then threads started. It's called 72 hrs $1000 bucks ....that's James build thread iirc
Bill Fitzmaurice's Avatar Bill Fitzmaurice 08:20 PM 04-10-2013
Quote:
Originally Posted by Seppelrator View Post

Yes dual opposed would be possible too but I would prefer the look of 2 drivers in the front. Would I loose performance if I go this way?
You would. Dual 18s will create a lot of motive force, and what will move is the sub. Either go with four singles or if you must have duals make them dual opposed, which cancels that motive force. I'd do singles, the more subs you have and the wider you spread them apart the smoother the in room response.
mastermaybe's Avatar mastermaybe 09:19 AM 04-11-2013
^ Yes, I suppose all being equal front facing is not ideal, but I've yet to see mine move a centimeter on a hardwood floor with rubber feet- the cabinet itself feels pretty inert as well. I suppose a 160lb cabinet and sensible feet help in the movement dept.

James
Bill Fitzmaurice's Avatar Bill Fitzmaurice 01:52 PM 04-11-2013
Quote:
Originally Posted by mastermaybe View Post

^ Yes, I suppose all being equal front facing is not ideal, but I've yet to see mine move a centimeter on a hardwood floor with rubber feet- the cabinet itself feels pretty inert as well. I suppose a 160lb cabinet and sensible feet help in the movement dept.
Keeping the volume reasonable doesn't hurt either. But not everyone does so.
noah katz's Avatar noah katz 03:05 PM 04-11-2013
re enough volume for ported, even if it's not enough to be optimal, you can still get more output capability if you have the power for it.
Seppelrator's Avatar Seppelrator 06:14 PM 04-11-2013
I work in the states this week so I just picked up a Cerwin Vega CV5000 for 700$.
I think I can not to wrong with this amp. Still not sure if single or dual front or dual opp or even ported like Noah suggested.
The looks of a dual front sub would be awesome but only if the the performance loss is not too big.?
noah katz's Avatar noah katz 12:47 PM 04-12-2013
Quote:
Originally Posted by Seppelrator View Post

Still not sure if single or dual front or dual opp or even ported like Noah suggested.

Just to be clear, I was suggesting that it *might* be viable; use a modeling program to investigate.
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