/ Register

Advantages Of 2 Sealed 12s Over A Ported 12

Discussion in 'General Car Audio Discussions' started by TheSSG, Jan 6, 2004.

  1. TheSSG

    TheSSG Full Member

    I just got an E-mail from ED, and the 12Os are on sale for $165, which would make 2 $330. This now makes them a viable alternative to my planned A12/15 or Brahma 12. I know adding a second woofer gives you a 3dB increase, but I know porting a sub also adds 3dBs. So, as I see it, the only real advantage of going with 2 12Os would be I would have sealed, with the output of ported. The only thing is, a 12A, or Brahma 12, because of their Xmax, will have close displacement. These will go into my CRX HF, but because of security issues, they will be going under my cargo cover, limiting my vertical height to 14", so the only way I could use a 15" would be to aim it directly into the cover, causing horrible vibration. So, box size is limited, but not by too much. If I did a dual chambered sealed box for the 12Os, I could give each ~2 cu. ft., giving me the .707 QTC. What else I am unsure of is if 2 sealed drivers will be able to play as low a a ported driver, with similar output. I'm not really going for SPL, mostly SQ, but some days I like to play it loud. i'm just curious as to anyone else's thoughts.
     
    TheSSG, Jan 6, 2004
    #1
  2. ScottS

    ScottS Full Member

    acorrdeing to my plot of this it seems that the b 12 in a ported box at 2 cubes tuned to 25 hz will not only be louder than the two 12 0's but have all most the same sounding roll off with more output


    Scott Stoner
     
    ScottS, Jan 6, 2004
    #2
  3. peter_euro

    peter_euro Full Member

    I do not know much but it is my understanding that if you want SQ, you go with sealed box... :rolleyes:
    And advantage of having 2 subs ported or sealed, regardless... you get to double the power... I hope you are not trying to say that the 3dB advantage refers to one ported vs. 2 sealed... I would think doubling the power plus more cone area would be worth more than 3 dB... :) But I would agree that the 3dB of ported SINGLE over sealed SINGLE would be likely... But what do I know? :(
     
    peter_euro, Jan 6, 2004
    #3
  4. ScottS

    ScottS Full Member

    actually the first section is quite wrong i know plent of sq competitors who run ported. Actually sound quite nice.


    besides that we do not know if he has double the power he has not mentioned anything of this quite yet. Not to mention that the brahma is dual 2 ohm so 4 ohm or 1 ohm mono is achieveable with out ruining the integrity of the sub. Looks like in most cases the Brahma is looking louder than both 12o's givin the same box only the single brahma is ported. Also given the same power. Another thing you have to look as is power compression in which plotting doesnt show up.
     
    ScottS, Jan 6, 2004
    #4
  5. peter_euro

    peter_euro Full Member

    actually the first section is quite wrong i know plent of sq competitors who run ported. Actually sound quite nice.


    besides that we do not know if he has double the power he has not mentioned anything of this quite yet. Not to mention that the brahma is dual 2 ohm so 4 ohm or 1 ohm mono is achieveable with out ruining the integrity of the sub. Looks like in most cases the Brahma is looking louder than both 12o's givin the same box only the single brahma is ported. Also given the same power. Another thing you have to look as is power compression in which plotting doesnt show up. [/b][/quote]
    I am not a sub expert, I was simply referring to my experience auditioning different types of port noise that I witnessed... I am sure you can have a very clean sounding ported box but seems to me that everyone I know tells me it is much easier to get nice sounding sealed box than ported... From what I see, and hear, nice sounding sealed boxes are more common than ported but I am sure there are exceptions... If you look at FR curves for sealed vs. ported, the sealed usually yields much smoother curve than ported (I know curves do not mean much but still...)

    And the exact volume to get the ports right is sometimes pretty hard to figure out.... :rolleyes: So I do not think I am that totally wrong... After all, it is all in design and execution of that design... If you are competing or have a clue, it is one thing, if you rely on your local install shop or just being a novice, a sealed box is a much better bet to get nice bass...
     
    peter_euro, Jan 6, 2004
    #5
  6. TheSSG

    TheSSG Full Member

    I was referring to a 3dB gain from porting a single driver. So, if I take a sealed B12, and port it, +3dBs. Now, if I take a 12O, nad add another (w/ equal power), I will get +3dBs. I have a Tsunami 1100dB. If I get a A12/b12, I will have 1100watts. Because of limiting factors of teh 12O, if I get on, the 12O.44, it will be 2ohms, and get 550 watts. If I get 2 12Os, I can wire tehm into 1100, giving them each 550 watts. Thus the 3dB gain. Now, if I have a 12A/b12 w/ 1100 watts, and port it, I will get +3dBs. I know if I do a low tune, (28 or 30hz), I can get a SQ ported box. But I'm just not sure if 2 sealed 12s will have equal lowend output, though I've heard the 12Os can play quite low.

    I'm fairly confident in my box building abilities too. Sealed would be easier, and so I could make a REALLY nice sealed box, as sealed boxes are braindead. The only problem I have with calculating port length is that I get different lengths from different sources(one answer from an equation, different answers from programs, and different programs give different lengths).
     
    TheSSG, Jan 6, 2004
    #6
  7. peter_euro

    peter_euro Full Member

    There is actually a way of using just one voice coil on DVC, Geo gets the credit again, LOL, it is called RDO and you can read up about it on Adire Audio website in tech section... I am betting on this because I will be running 2 Brahma 15 in a sealed box and wired into 1 Ohm... I am betting that the bottom extension will be more than sufficient and with 2400 watts, plenty loud... ;)

    And I can built a box too but trying to get the tuning right, LOL, just like you... basically trial and error... My last creation, 7th order BP made me so miserable... Much easier with sealed box and plenty of power... :p
     
    peter_euro, Jan 6, 2004
    #7
  8. TheSSG

    TheSSG Full Member

    That's what gets me wondering. I could always do a single higher excursion 12, or even a 15A, and that would probably work well. The 15 appeals to me especially because the increased displacement will mean less distortion. Only problem I have then is I'd have to aim the sub up, for security purposes, and then I'd have mad rattling...but a 12 may cause rattling of the cover as it is. ANd because of the Xmax advantage, a 12A or Brahma 12, sealed, would have pretty close displacement at ful excursion. The B12/12A have a good 10mm Xmax more, and would have twice the power. That's why I'm thinking a low tuned Brahma 12 may be the best route.

    I did read the thing about the RDO, which was neat. Luckily my amp puts out max power at 1ohm, and all the single setup subs I'm looking at are dual 2ohm.
     
    TheSSG, Jan 6, 2004
    #8
  9. peter_euro

    peter_euro Full Member

    Lucky for me, the RDO lets me get the 1 Ohm load from 2 15s...:) Also, the power rating should be reduced by 25% in RDO which is perfect for me since 25% reduction from 1600 watts gives exactly 1200 watts.... :D I am betting that the 2 15s will be better than 4 12s I am getting rid off... :rolleyes:
     
    peter_euro, Jan 6, 2004
    #9
  10. TheSSG

    TheSSG Full Member

    What in the World do you drive? That's a lotta space. I have a CRX, but no tinted windows, and I don't really want them tinted, so I have limited space :( I wonder if i could use a bunch of deadener onthe cover.... If I can figure out a way to keep it all relatively hidden, and keep the cover from hopping all over, i'd prefer to get a 15. 2 15s, I hate you :p
     
    TheSSG, Jan 6, 2004
    #10
  11. peter_euro

    peter_euro Full Member

    peter_euro, Jan 6, 2004
    #11
  12. TalNLnky

    TalNLnky Full Member

    RDO is cool, BUT!!!! if he's worried about volume (db's) is a bad choice since you loose 3dB in efficiency.

    with that said.... Ported can sound wonderful, In fact, for most subs, if they CAN go ported and SQ is desired, i'd go ported all the way due to the lower distortion/lower excursion/keeps bl high. The trick to getting Ported to sound good is Tuning Low... get that group delay down, along with keeping the Frequency response nice... with a bit of a rolloff.

    Now, the cool thing about the brahma , is that you can throw them in sealed boxes, and they won't distort like normal subs will after they reach a certain excursion.... The brahma in a sealed box is just MASS SQ.... keeps it nice and responsive, but without distortion.... but... if you want good volume, you gotta go ported just like any other sub.
     
    TalNLnky, Jan 7, 2004
    #12