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Time for an upgrade. Want as low as possible in as little space as possible.

 

Bronze Member
Username: Arnotjie

Post Number: 36
Registered: Apr-10
Okay, well. I've been running my FIRST system for a couple of months, and already I wish I spent more on the first go. Currently I have 2 Polk audio DB12's with 4ohm SVC's. They are in a sealed box of around 1.7-1.8 cubic feet. For my amp I have an Option Audio (rebadged sound magus apperntly) OAK 1200. Its rated at 700W RMS @ 2 ohm (what I'm currently running) and 1200W RMS @ 1 Ohm. I don't have any electrical upgrades at the moment, but I have connected a voltmeter to the car, and it seems to be okay. It stays above 13.7 volts even at full volume (for me anyway). But I will be doing the big 3 when I upgrade the subs.

Okay, so what I want in the out of the new system:
1. It has to be able to really hit the low notes, below 30Hz. That is probably the most important thing, and the most disappointing thing about my current set up.

2. I'm pretty happy with how loud my current set up is, so as long as it's not a downgrade in that department, it should be fine. (I won't complain if it is louder though)

3. I would like if the frequency response isn't too peaky at anything above 35Hz, and for it to extend to at least 150Hz, as I'm only running 4inch speakers.


Restrictions:
1. I want to use the amp I have, so 1200 @ 1ohm or 700@ 2ohm

2. Maximum enclosure volume would be 5 cubic feet, but i would prefer to keep it below 4.

3. Maximum mounting depth is about 200mm

4. I live in Australia. We have most brands available: JL, Eclipse, Polk, Boston, Etc. However, We don't get any USA exclusive brands like Fi, Sundown, SSA, etc... This is not really a restriction, But shipping costs wil be pretty high, so Fi would not necessarily be chaper than JL for example. (just thought it might be usefull information).

As for the subs, It can be 4 8's, 2 12's, 1 15, sealed, ported, etc. It can be any combination, as long as it fits the restrictions. Price isn't too much of a factor, but obviously, the cheaper the better.

I would really appreciate your help, and thanks in advance.
 

Silver Member
Username: Alonzoub

Post Number: 262
Registered: Apr-10
This may not be tooo much help as i am about to go to sleep so i didnt put a TON of thought into it... But if you are happy with loudness, I would simply build a professionally designed ported enclosure that can extend below 30hz. Use the money u saved to buy a better front stage that can extend flat down to maybe 70hz. That way you arent tasking your subs with such a large range of signal (20hz - 150hz is nearly 3 octaves).

If i have time tommorow ill see if i can come up with some rough specs for a nice ported box.
 

Silver Member
Username: Lord_huggington

Ontario Canada

Post Number: 461
Registered: Oct-10
X2.

Port your subs @ 25-30 Hz, not only will they be louder, they'll extend much lower too. A sealed box, for most subs, makes them roll off way earlier than ported (IE - 50 Hz, then -12dB @ 30 Hz and so on, so ported would be +3dB @ 30? Hz).

We just did a thread like this, which was super long, so I'll tell you that the outcome was: the guy had the wrong (sealed) box!

PORT THEM BISHES!

A guy on here makes AMAZING boxes, his name is Dustin, his business is something like DLS designs. I can't remember. You'll see him here though.
 

Silver Member
Username: Lord_huggington

Ontario Canada

Post Number: 464
Registered: Oct-10
Dustin = bassman3.
 

Bronze Member
Username: Arnotjie

Post Number: 37
Registered: Apr-10
Okay. Well, thanks a lot for the input. I have been thinking I might try that out, and see how it goes. It won't be too expensive if I do it myself, so if I still want to upgrade afterwards it would only be about $50 in wood wasted. But if I am happy with it, it will save me a lot.

I think I read the thread you are talking about:https://www.ecoustics.com/electronics/forum/car-audio/691463.html ?

What program was used to model the frequency response? And where can I find it? I would like to see how a ported box would compare to a sealed box on that. And I'm guessing that program will be able to give you the perfect enclosure volume, port diameter, and length as well?

As for the enclosure. I would love to have a professionally built box. but I'm guessing shipping for a 4+ cubic foot box would be insane? Or is there some way of sending it through cheaply?

Thanks a lot.
 

Silver Member
Username: Joe1234

Post Number: 461
Registered: May-09
The software is WinISD:

http://www.linearteam.dk/default.aspx?pageid=winisd

Have fun with it!!
 

Silver Member
Username: Lord_huggington

Ontario Canada

Post Number: 468
Registered: Oct-10
Winisd is not fun lol. It won't tell you perfect things, it'll show you what you think is perfect compared to what else you think is. Cabin gain effects a lot of stuff, including xmax, so plots are really just a rough estimate. The best thing is experience. Some people can look at a sub, look at the T/S real quick, and just know what box to build.

Standard shipping, like USPS, is pretty cheap. You'd spend like $350 for all the bells & whistles, shipped.
 

Silver Member
Username: Joe1234

Post Number: 466
Registered: May-09
Ok, just to give you an idea of where you are, take a look:

Upload

Your sealed 1.8 cuft is performing like in the yellow curve with a laughable F3 = 50Hz so no real bass there.

A big ported enclosure would perform like the green curve and would be as loud as a sealed enclosure on 1500W RMS power. Specifically 5.58ft3@28.5Hz will give you deep bass of F3 = 27.6Hz. for two db124s.

Your amp fits those speakers perfectly on power.

Play with the software, I think you can shrink that box to 4 cubes without loosing much bottom end. Read the other thread or the software help if you have questions, I think it's all there.
 

Bronze Member
Username: Arnotjie

Post Number: 38
Registered: Apr-10
Wow. I had no idea it was that bad. By just listening to it, I would've predicted F3 to be around 40Hz at the worst. I didn't think it would make THAT much of a difference going with a ported enclosure, so I am really excited to hear what it'll sound like. I'll have a bit of a play with winisd (well try to at least, haha) and see how much I can shrink that enclosure, because that volume is probably internal, and before sub and port displacement, am I right?

Is there any way to predict cabin gian? If I had the total volume of the cabin and maybe LxWxH and placement of the subs, for example?

Lord Huggington. $350 shipped to Australia? Because if that is the case, I would definitely consider it!

Thanks for all the replies!
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