Not happy with my system at all.

Discussion in 'OT Technology' started by speedricer, Jan 20, 2004.

  1. speedricer

    speedricer Go SpeedRicer Gooooo

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    Ok In my cavalier I took out the back seat and built a box that is 3cu. ft. per sub with a 2"x12" vent that is 14" long. In the box I have 2 15" Xtant a1544's. (not the a1544a) and for an amp I have a Ultra Liniar UL400HC. I have the subs wired up to 1 ohm (at one ohm the amp puts out 1200 watts rms, subs are only supposed to take 500 watts rms) I have the gain on the amp turned just a little more than half way up. The bass is just so so. But it's not as loud as I would like it to be.
    So I want louder. I don't want to spend another grand on the system so what could I do? Thinking of maybe getting 2 15" solo-baric L5's. But I Don't know.
    Is this amp an ok amp?
     
  2. 04

    04 Guest

    Did you change your mind or something?

    Anways, if those two Xtant's arent enough, you are going to want at least 2 15" L5's like you said.

    Tell me this, is your vision blurred when you turn it up right now?

    Also, make sure the wiring polarity is the same for both woofers.
     
  3. speedricer

    speedricer Go SpeedRicer Gooooo

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    Yeah they are wired good.
    and At first I felt like my vision was blurred. But I got used to it quick.
    I want more.
    And yeah was thinking about 2 of the L5's
     
  4. speedricer

    speedricer Go SpeedRicer Gooooo

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    Sometimes I think It would have been better to have built a sealed box.
     
  5. speedricer

    speedricer Go SpeedRicer Gooooo

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    What 15" subs would you recomend that would work in my box i've already built.
     
  6. 04

    04 Guest

    That would almost certainly make it less loud than it is now :confused:
     
  7. speedricer

    speedricer Go SpeedRicer Gooooo

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    I'm thinking about maybe buying 2 more of them and just making a wall.
    I really didn't want to have to make a wall. But I'm really not happy with the setup.
    Took it to a guy I know that has a system with 2 12" JLaudio W7's in a RSX. He has them running off a mono RF punch amp. It puts out like 1500 watts RMS (don't know model number) But anyways he knows his stuff pretty good. Well he tried to tune my system he messed with the crossover for a long time and said he didn't like the cross over on the amp. So we hooked up some kicker Line drive he had and it did make a difference But still not loud enough for my taste. I know alot of people think I'm crazy for wanting it louder around here. I just think if i'm going to spend alot of money on a system I want to be happy with it.
     
  8. GSteg

    GSteg Member

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    If you don't care much about sound quality, get a (or 2) subwoofers that will peak easily. To the human ears, peakier frequency response will get us thinking that it's "louder".

    Right now, RE has 2 15" HC for only $300+shipping. They are heavy though, so expect your car's rear end to sag a bit more. :big grin:

    3.0 cubic feet each is alright for those HCs, but I'm sure you'll get a much cleaner output than the xtants and possibly get louder. But try to ask RE if they can sell you the dual 4ohm so you can retain your 1 ohm load at the amp.

    OORR....

    Get a single DD9515 and put it in a 6.0 cubic feet ported box tuned to 35hz and behold! Vented box+high BL peak=boom boom.

    but maybe you lost some of your hearings? At high volume level, people don't get "used" to it, they lose hearing. Eventually, your ears will poop out.
     
  9. GSteg

    GSteg Member

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    and also, i'm not sure why the crossover would change the SPL on the system. They are used to attenuate frequencies. If your amp's xover is bad, then it wouldn't decrease SPL.

    As long as the gain is set properly, a line driver isn't going to help, unless all you did was add a line driver and left the gain right where it is, in that case, it's basically the same thing if you turned up the gain a bit w/out the line driver.

    In anycase, I think it's your hearing. If not, maybe bass is escaping your car? Try sound deadening the car yet? Panel resonanting can make your mind think that you're getting less bass, well because thats how our minds work. LOL.
     
  10. 04

    04 Guest

    Actually, the BL does not change when you change the alignment of the enclosure.

    BL is simply the length of wire immersed in the magnetic field.
     
  11. GSteg

    GSteg Member

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    what i'm refering to was put a subwoofer with a high BL peak value into a vented box and play the sub near the tuning freq' and you'll get a nasty peak. Sorry if i didn't make myself clear enough.

    Now if i were to put vented box=high BL, then i guess you can stomp on me ;)
     
  12. 04

    04 Guest

    Um, but a woofer with a high BL would also have a low QES. If that is the case, the magnitude of the resonant peak would be less than that of a woofer with a low BL and high QES.

    A high Q system has a large amount of energy stored at resonance, and a low Q system has a less amount of energy stored at resonance. This extra energy allows the woofer to "ring" and be more peaky.

    If you have Winisd, model a high BL speaker that has a low QES value and a given box size and tuning. Then, do another project with the same driver, but this time with a large amount of series resistance. This would decrease the damping, which would in turn increase the energy stored at resonance, and will make the driver peak much more at resonance. Try it out, you may be surprised ;)
     
  13. 04

    04 Guest

    Wait, are you talking about that specific driver peaking more, or two drivers being compared? :confused:
     
  14. GSteg

    GSteg Member

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    Maybe the term BL is used too generally here. Maybe we should just refer to Qes as motor force instead of BL as BL value can change so easily with Re that its basically meaningless.

    But as you know, in a vented box, at the tuning freq, the driver is stalled by a high pressure. So a subwoofer with a lot of motor force would be more wiser than a subwoofer with less motor force (assuming everything else is constant) in terms of output right at that frequency.

    That's why I suggested the DD9515 as it has a narrow BL curve (coils wired in parallel). Would be great for near-tuning frequencies. Since we hear peaks, we generally think its louder.
     
  15. 04

    04 Guest

    But Qes does not refer to motor force...

    BL doesnt change at all unless something like say the driver heating up.

    What you aren't realizing is that a motor with a ton of strength will start and stop "on a dime" so to speak. There is no overshoot, because the motor has such high control over the diaphram. In a low BL, high Q system, however, you get more overshoot because there is less restoring force on the driver, allowing it to move further. If you had a driver with like 40 N/A's of BL (im generalizing here), it wouldnt be able to produce any bass because it's rolloff would be so steep because the motor would have such a high restoring force.

    Ok first you were talking about a high BL, now you are saying the DD's is narrow? That means completely two different things. A narrow curve would indicate that its flux is "contained" in a small area, and the magnetic gap is somewhat short. A wide curve would indicate that the flux is not as contained in such a small space, BUT a speaker with a wide curve could have the same BL as a speaker with a narrow one.
     
  16. GSteg

    GSteg Member

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    But Qes is a better indication of motor force than BL is. We can change the value of BL to double of what it is simply by wiring the coils in series, but that will not change the actual motor force of the subwoofer.

    Its true that too much Motor force will suffer the SQ of the driver, but we're talking loudness here, so with a BL (again, not in series) of around 25 N/A, it'll be fine. The DD9515 doesn't sound that bad. And since it has a low Qes, we can bet it's more efficient and is a perfect candidate for a vented box. We're just talking about the daily street booming bass. Now if we're talking about all-out SQ, then I do agree.

    And as for the stop and go thing, it's more of an inductance relating issue than BL. As you know, the cone moves when there is current passing though the coil, so the cone will only move as fast as the signal can get through the coil. But i'm sure you've known this for a while already.

    And I said the DD9515 has a narrow BL curve, as in bandwidth, not the peak Value. So obviously we're not seeing things eye to eye
     
    Last edited: Jan 25, 2004
  17. 04

    04 Guest

    I see where you are coming from saying BL is a bad indicator of motor force and that QES would be better. BUT, the calculation for QES also includes the compliance of the driver in it's equation. So if you take two different drivers with the same BL, but different stiffness in suspensions, you will have different values for each.

    Are you talking about him building an enclosure to be a "one note wonder" that peaks terribly and has an extremely narrow bandwidth peak? Like what they use at a SPL competition? If so, then I agree with you, a high BL driver would work great, BUT that would make a terrible system for listening to music of ANY kind :confused: I mean, even the bass heads I wouldnt think would like the sound of that, right? Even rap has a somewhat wide range of bass notes, and if the song he plays back doesnt have a note that corresponds with the huge peak, the bass won't sound all that great.

    As far as inductance goes, yes I know that the lower inductance, the better. But I was not refering to the transient response of the woofer, sorry if I wasn't clear on that. What I was refering to was the fact taht a low Q system will have a narrow bandwidth and consequently it will sound faster due to what your ear "thinks" it hears, remove a lot of the low frequency amplitude, and the bass will sound "tighter" as many percieve tightness to be higher frequency bass.

    I understand what you are saying about the DD's BL though, you are just saying it has a narrow X vs. BL. You are also saying that the driver's BL while the system is still linear is high, right?
     

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