How big can i make my box before i blow my sub? (1 Viewer)

[matt steele]

THINKING OF GETTING:
I am thinking about getting a dayton tit 15" and the dayton 1000rms amp to go with it for home theater use.

LARGE ROOM:
This will be in a large room 13' across and about 40' long. The room is split in the middle with a half wall divider. This wall does not seal off the room. It only goes half way up to the ceiling and does not go all the way across the room. I'm not sure if this will help make the room smaller to the sub or not.

QUESTIONS:
I am wondering:
a. What size box i should build?
b. What frequency i should tune the box to?

This sub will be 90% home theater and 10% music.

I am a little worried that the amp may end up blowing the sub as the sub is rated at 800rms and the amp at 1000rms.

Tthe sub will be in a down firing position. Am i correct is assuming this could cause the sub to bottom out or blow easier because of the cone sag in this configuration?

So how easy / likely will it be to blow the sub? What would be a suitable box and tunning frequency that might limit my chances of blowing the sub and also give really low bass at high levels?


I already have a dayton tit 15" sub with a dayton 500 rms amp powering it. It is in a 5cuft box tunned fairly high at about 23hz. This sub does not get loud enough for my liking in this room. It is for this reason i have decided to go with the bigger amp. Should i expect better bass for the HT with more power bigger box and lower tuning frequency?

 

[Robert_J]

Answers:
a. Have you modeled the sub using any of the free subwoofer design software that's available? Unibox (my favorite) and WinISD Pro are the two most popular.
b. That depends on the size of the box you can live with, the extension that you want and how the sub models in the software.

All things being equal, doubling the input power will at best give you a 3db increase in output. Since not all things in speaker design are linear, you won't get your full 3db increase. Lowering the tuning frequency will actually hurt your output. You are trading output for extension. If it isn't loud enough for you, then you need a more efficient sub, more subs or both.

-Robert

 

[matt steele]

Thanks for the help.

Yes i have modeled the sub with winISD Pro.

In terms of box size i can go with anything from 5cuft to 9cuft taking into account the port displacement etc.

The worry that i am having with the Dayton titanic and the 1000rms amp is just what you said, the sub is going way past its mechanical limits at certain frequencies.

This has led me to two conclusions much like what you have suggested to me. Add more subs! They are as follows.

____________________________________________
IDEA 1:
Use two Dayton titaniums running off of a behringer amp ep-2500. But it seems if i am getting an amp with this much power i should get some bigger subs that can take it? Still need to be around the $200 mark.

In this configuration i would have two subs in a 9cuft box. The port would have a bend in it which i don't like, but if i take corner correction into account it shouldn't matter.

I still have the same issue of it not working because of the impedance being wrong.

Can anyone suggest an alternative subwoofer that is of the same price and quality? I really cant go much more than $220 per sub but if i have to up to $300


__________________________
IDEA 3:
Running 4 15" Daytona Infinite Baffle subs / or some other Ib sub. With a behringer amp ep-2500. I can either put this in a room that is 114cuft or a room that is 1576cuft. I think i need to go with the larger room.

This is the configuration that i am leaning towards as i have heard a lot of good things about infinite baffle. I have some questions / concerns about it however.

The other subs im considering are: (4 of whatever sub i decide on)

Exodus Tempest X15 - $185
Mach 5 Audio IXL 18.4 - $250
Mach 5 Audio MJ-18 - $116
Ficaraudio SSD18 - $239
Dayton IB385 15 - $115


Price is a bit of an issue since i am getting 4 subs instead of just 2.
The MJ-18 is the cheapest but its relatively small xmax is making me dislike it.

I'm really not sure if i will do better with the Mach 5 Audio IXL 18.4 or the Ficaraudio SSD18. any suggestions?

I am leaning towards the Mach 5 Audio IXL 18.4. I am from Canada and im hoping that by skiping customs and crap they will be cheapest. Of course i dont know that the subs can even be ordered from canada? Anyone know this?

 

[Robert_J]

Idea 1:
What is a Dayton titanium? I've never heard of them and I am a frequent customer of Parts Express.

Unfortunately, the EP-2500 is too much of an amp. I modeled 2 15" Dayton RS HO's in an 8cf box tuned to 16 hz using 1 6" port. The subs reached xmax at 31hz. If you back off the amp's gain, then you are sacrificing your output.

What is wrong with the impedance? The Behringer will drive a 2 ohm load or higher in stereo or a 4 ohm load or higher in bridged mode.

Try modeling a pair of ED 16Ov.2's in an 8cf box. 6" port tuned to 16 hz. The EP-2500 will put out a healthy 800w/channel at 20hz when driving a 2 ohm load so that's what I use to model the pair. I'm seeing well over 120db. Port speed is a little higher than I want. An 8" port may be better but you would have to make your own flares.

Idea 2:
Did you skip this?

Idea 3:
This is the path I'm taking. I have wood cut but I have to wait until the temp reaches 55 degrees before I can start gluing. There's one sub driver you missed. The Fi IB driver. It's $220 shipped. You have to order it by e-mailing IB at ficaraudio dot com. I mentioned this in a few other threads here as well as links to reviews of them.

If you are in Canada, then the Mach 5 is you best choice. Order them directly from Mark and you will save on customs fees. I bet that it would be difficult to tell the difference between the Fi and XL subs when mounted.

-Robert

 

[matt steele]

Sorry I made a lot of changes to this post as i continued to read and learn more. So i made some typos.

I meant typos:
- Dayton TITANIC is what i meant, not titanium
- I scraped idea two. It was an IB with only two drivers. I have since learned that I think I want to have 4 drivers for IB.
- I just learned about the behringer. The not working with the subs came from trying to get a dayton plate amp to work with the subs.


It sounds like if they will all sound very similar then the Mach 5 is the way to go because they will probably turn out much cheaper.


This question may be stupid since i don't know a lot about IB as of yet...

What should i expect the difference in bass sound and feel to be like with the ported box design versus the Ib design with the mach 5's?

 

[Robert_J]

The best description I've read has been "effortless". There's a post in the Speaker and Sub section where a guy wants the "ultimate" sub. I mentioned DIY and IB, even linking to a review of the Fi subs.

And the Mach5 18's can be ported - link

-Robert