View Full Version : Subwoofer questions
03-20-2007, 06:03 PM
Ok, First Things first. I had bought the Polk DB212 Subwoofers in the ported enclosure for $429 dollars. I had them working since early january and a few days ago one of my subs was either on its way to blowing or something else, perhaps water from my trunk, and it kept popping. only one, my bass bost is at 70% and my gain was at 55%ish and i was wondering why it might have messed up. i went back and got a new set and now have them breaking in again and I would like to know how to prevent this.
Also do you think getting the polk SR type sub thats 600 watts rms would be louder and hit harder?
I also have my subs facing the trunk roof and angled toward the driver and it really doesnt shake my mirror s much at all unless the trunk is open, i was thinking of making a new box so they can both have more room in the box and face the driver at a 90 degree angle. does anyone think that thiss will cause more shake in my car our loudness?
03-20-2007, 09:36 PM
Your problem is the bass boost.... set that to zero, and then readjust your gains. You are placing a tremendous strain on your amplifier, this can end up with another blown sub (s).
Here useful link that has the information you need...
03-20-2007, 11:28 PM
Yup. Kill the bass boost AND drop the gain to below 55%.
03-21-2007, 04:27 PM
And fire the subs backwards towards the license plate ;) . Bass sounding much louder with the trunk open leads me to believe you've got a whole mess of cancellation going on. Experimenting with sub box positioning will go a long way to reducing cancellation.
To answer another question, the SR subs should be a nice improvement over the dbs. The db 212-2 enclosure hits pretty hard and sounds fairly good, but a pair of SR124s properly powered should hit harder, sound better (and cost more to accomplish that).
edit: Also curious- exactly what amp are you using to power the db212-2? When you mention you've had the woofers blow, I can't help but think you'd be better off using a subsonic filter to keep the lowest of the low out of the db's response.
03-21-2007, 09:11 PM
the amp i use is a ma audio hk100d 800 watt rms @ 2 ohms. so idk
03-22-2007, 05:48 AM
the amp i use is a ma audio hk100d 800 watt rms @ 2 ohms. so idk
This one? http://www.sonicelectronix.com/item_3474.html
If so, use the gains sensibly (find an online tutorial if you're not 100% sure) and definitely try out the subsonic filter set @ 20hz- it'll keep your subs from over-excursion trying to play below 20hz (and probably extend their lifespan)...very important with ported enclosures such as your db212-2, not so critical if you run a sealed setup.
Go easy on the bass boost too. Those subs are loud as hell properly powered (not necessarily a bad thing), and turning boost into the mix might well get you more output, but also gets you more distortion lower on the volume dial (and drives your amp into clipping far easier than an un-boosted signal). Clipping that amplifier will send far more than rated power to each sub and will do some damage to your replacement subs too ;) .
03-22-2007, 08:47 AM
yes that is my amp the HK-1000D class x amp and i bought it from sonic. i suually had my ssf at half, i thought havng it at 50z ment anything below that wouldnt play but im still a newb sort of. i got a tutorial and im adjusting my gains later today with an AC voltage meter. I hope this will help with alot of soundwave cancelation going on in my trunk, i will also get dynamat when i can afford it... probably when i get my taxes back.
03-22-2007, 05:14 PM
yes that is my amp the HK-1000D class x amp and i bought it from sonic. i suually had my ssf at half, i thought havng it at 50z ment anything below that wouldnt play but im still a newb sort of. i got a tutorial and im adjusting my gains later today with an AC voltage meter. I hope this will help with alot of soundwave cancelation going on in my .trunk, i will also get dynamat when i can afford it... probably when i get my taxes back.
Proper gain levels won't help any with cancellation, but it'll do a lot as far as not toasting more subs. It just ensures that you don't have maximum power reached at your amplifier too soon on the volume dial (and a clipped signal should you increase the volume further after your amp has reached maximum output).
Your amp is actually overpowering your two subs...not necessarily bad unless your gains are set high- use a lower gain setting and you'll have headroom. Use too high a gain setting (along with bass boost) and you'll send the subs more that rated power, and when you clip the signal the subs could even see more than double their rated power (and a dirty, distorted signal) which makes short work of the subs, causing thermal damage.
Think of gain levels, bass boost, LPF settings and subsonic filters as a balancing act that will either get the most out of your equipment (if set properly) or burn up your subs prematurely (if not).
As far as ssf, I'd have to download a copy of your manual to know what that means.
LPF, or low pass filter (I'm trying to condense your multiple threads that are kinda on the same subject) is a crossover that allows the low frequencies to "pass" to your subwoofer. You'll probably want to set this between 50 and 80 hz...experiment and see where it sounds best.
A subsonic filter basically cuts the lowest frequency output to keep your subs from:
a) trying to reproduce frequencies outside the range of human hearing (like below 20hz) that actually take a lot of your amplifier's power to reproduce anyway
b) trying to reproduce the lowest frequencies below your enclosure's tuned frequency (really important with ported enclosures), which causes the subs to lose control (over-excursion) and bottom out, risking mechanical damage.
A HPF (mostly of concern on full range frequencies) is a High Pass Filter, which does as the name suggests- lets the highs pass to the appropriate full range speakers.
I'm glad you got a gain setting tutorial...also read up on clipping, cancellation, proper tuning for a ported enclosure- the internet is a wonderful thing in this regard ;) .
Like they said above, lose the bass boost, try standing the box up so the subs aim towards the back of the trunk and see how that is.
SR woofers could be louder, but not in a box that size. One SR12 ported needs almost as much space as that db212 box. It would be about that loud, depending on the port. Two would be much louder, but would eat up a ton of space- almost double your box.
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