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New Tweeter hookup question

Discussion in 'Gen 2 Prius Audio and Electronics' started by dgstan, Jun 28, 2006.

  1. dgstan

    dgstan Member

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    Sorry for the ignorant question, but I've gotten a new set of speakers for the front doors (6 1/2" and tweeters). The set came with crossovers, but since there are separate wires for the mids and tweets, I assume there's a built in crossover in the amp. Anyway, when using the crossovers, the sound is horrible. Without the crossovers, the sound is great. The tweeters sound a little shrill, so I want to install a 10uf cap.

    My question is: Do I install the cap across the tweeter terminals or in line on the positive wire?
     
  2. GeoGeek

    GeoGeek Member

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    <div class='quotetop'>QUOTE(dgstan @ Jun 28 2006, 05:33 PM) [snapback]278237[/snapback]</div>
    Go to this website: http://www.bcae1.com/passxovr.htm
    Here you can see what the effective cross-over frequency will be based
    on your tweeters impedance and using different capacitor values.
    If your tweet is 4ohms and you're using a 10uF cap, frequencies will roll off
    below 6.7kHz....not sure that's really what you're after based on what you described.
    The site will also show you the series vs. parallel wiring scheme for the cap.

    You definately want to make sure that you are feeding full range signal into your aftermarket
    component crossover.....if I'm not mistaken, the JBL option stereo has separate outputs (for the fronts)
    for the tweets & mid-bass drivers (the rears may be full range , based on what I've read).
    Anyway, if the signal coming from the JBL amp is actively crossed over in the amp, that would explain
    why it sounds like crap (because you're feeding the aftermarket passive crossover already crossed over
    signal....not good).

    My car has the base stereo and I took the signal coming into the front tweeter (which comes in full range but then gets stepped-down at the tweet with a cap) and used it as the input for my aftermarket passive crossover.....that setup sounds great.

    Are you going to be using an aftermarket amplifier?
    If so, it may be a moot point....in that case you'll need to get low-level input for your amp (a topic that's been covered here on PC in other posts), then run the full range output of your aftermarket amp
    into the crossovers for your new front components.

    Enough rambling.....hope I've answered your question.

    Regards,
    Matt
     
  3. H2OSkier

    H2OSkier Member

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    You would have to combine those two signals to create a full range signal. There are a number of products that will do this but to my knowledge these are used to feed another amp. JBL is coming out with a new product that will have a built in amp but that is limited to 20 watts per channel. If you google "signal summing" you'll find a bit of reading to bring yourself up to speed.

    Ken
     
  4. Presto

    Presto Has his homepage set to PC

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    The rears are full range. Tap into those outputs for your crossovers.
     
  5. H2OSkier

    H2OSkier Member

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    If you tap into the rears what happens to the BT and Nav that comes out the drivers side speaker ? Also wouldn't you lose the fader control ?

    Ken
     
  6. dgstan

    dgstan Member

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    <div class='quotetop'>QUOTE(GeoGeek @ Jun 29 2006, 05:58 AM) [snapback]278523[/snapback]</div>
    Thanks for the info. I'm a little confused, though. Why do you say the 10uF is the wrong range? Are you saying I should use a 4.7? The 10uF looks to rolloff right about where you want it do, no?

    If the factory amp has a built-in Xover, the cap at the tweeter should not be necessary (so, basically, I'm filtering the signal twice). However, I feel the tweeters are too loud. Elsewhere, it's been said that wiring the cap in parallel would reduce the signal going to the tweeter. Is this true? If not, how would one go about doing this? I understand that simply lowering the treble on the MFD would accomplish somewhat the same thing, but that would affect the rear tweeters as well. They are (for the time being anyway) still stock.

    No, I'm not going to change from the factory amp.

    Thanks for everyone's comments and sorry for all the neophyte questions...
     
  7. GeoGeek

    GeoGeek Member

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    <div class='quotetop'>QUOTE(dgstan @ Jun 29 2006, 05:22 PM) [snapback]278798[/snapback]</div>
    Okay, let's start over.
    From your post, it sounds like what you're after is some attenuation (toning down) of the output
    coming from your aftermarket tweeter. One way to achieve this is to place a resistor
    in line between the crossover and the tweet (not a capacitor). A capacitor is typically used in instances
    where you're running full range signal to a speaker that can really only reproduce the high end frequencies
    efficiently (like a tweeter), the effect is to "filter" out low range frequencies and let the tweeter focus
    on reproducing high end frequencies cleanly.

    In your case, the aftermarket crossovers for your component speakers are expecting to be receiving full range signal (in applications where you're not using a subwoofer), but you only have the crossed over output
    coming from your factory amp. If you hook up either the tweeter leads or the mid-bass leads to the input of your aftermarket crossovers you're only sending it part of the frequency range.....thus the crappy sound.
    When you bypass the aftermarket crossover and send the leads straight to the new tweets & mid-bass speakers, then you're basically using the crossover parameters set up in the factory amp for the factory speakers....which, if I'm not mistaken, have some bizzare impedances, like 6ohms or something.....when you hook up your new drivers (which, I assume, are both 4 ohms) you get mismatched output between the
    two....again, crappy "shrill" sound.

    As I see it, you've got three options:
    1.) Take the other posters advice and use the full range signal going to the rear speakers and use that as input for the front speakers new aftrmarket crossovers. Then you could take the amp's output for the fronts
    and redirect it to the rears....you could make this switch at the amp to avoid having to re-run wires all over the place....although you may be stuck running an extra set of wires to the rear tweets.
    2.) Adjust the line levels & impedances of the signal currently going to the front speakers using a combination of resistors, capacitors, & coils to "re-condition" the signal to more closely reproduce the
    signal the aftermarket tweet & midbass are expecting to see (from the crossovers you're not using).
    This is a more cumbersome route, in my opinion.
    3.) Use a line level adaptor to reduce the output fron the factory amp to line level, which you can use as
    input for an aftermarket amp....whose signal you can run straight out to your new aftermarket crossovers & component speakers.....This option, of course, means buying a new amp.

    Hope this helps.
    Cheers,
    Matt
     
  8. dgstan

    dgstan Member

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    <div class='quotetop'>QUOTE(GeoGeek @ Jun 29 2006, 07:05 PM) [snapback]278917[/snapback]</div>
    First, thanks again for you patient and detailed response. Second, I need to say that the new speakers really sound great (provided I don't use the crossovers). They are worlds better than the stock setup. The tweeters just sound a little over-driven. I'm probably nitpicking and no doubt my ears are unfamiliar with real highs. I'll give it some time to get used to it. I've got a long road trip this weekend to dial them in.

    I was hoping there was an easy way to adjust the signal to the front tweeters only. I did find this website which details a simple attenuation circuit using two resistors.

    http://www.mhsoft.nl/spk_calc.asp#att

    However, the resistor values specified are not standard "Radio Shack' values and I'm afraid that rounding them to the nearest available value would be self-defeating.

    The thing I don't understand, however, is with all these Prius owners swapping out their speakers and tweeters, how come I haven't seen anyone else has raise this issue? Very few people are replacing the factory amp. This leads me to believe I'm a little too critical.

    I'll report back next week on my longer-term impressions.

    Again, thanks for your help,

    DGStan
     
  9. GeoGeek

    GeoGeek Member

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    <div class='quotetop'>QUOTE(dgstan @ Jun 30 2006, 12:25 AM) [snapback]278963[/snapback]</div>
    DGStan,
    No problem.....glad I could help.
    I used to work as a car audio installer while I was in college...so I'm used to just going by the
    old shop and grabbing what I need (component wise)....guess it makes sense that Radio Shack
    doesn't have what you're looking for. If you're going to go for the resistor solution, you can probably
    get what you're looking for at a high-end custom car audio shop (i.e. not Circuit City/Best Buy).
    There's probably also numerous on-line sites you could purchase them through.

    On your other comment, I think that many of us out here who've upgraded to components
    either did so in conjunction with adding an aftermarket amplifier or did so on a non-JBL system, or both.
    Some may even have done the front/rear inputs swap.

    I too am going for a long road trip this weekend and will get lots of enjoyment out of the upgraded
    Prius sound system (not to mention the light fuel bill!)

    Have a great weekend,
    Matt
     
  10. klamut

    klamut New Member

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    <div class='quotetop'>QUOTE(dgstan @ Jun 30 2006, 12:25 AM) [snapback]278963[/snapback]</div>
    To lower the treble on the tweeters, maybe yours have the 3db boost feature that some Infinity Kappa speakers have, if so then on the crossover or the woofer Infinity put a switch or dial to turn on/off the 3db treble boost. Check the manufacturer's installation instructions to see if your's have the feature.

    I too am puzzled that no one else has raised the issue of continued poor sound despite replacing the speakers. Note that I'm not an audiophile or very picky about my stereo systems, if I can hear a problem with this Prius sound system then everyone will.

    In my case, a 2005 non-JBL head unit, I replaced the fronts with Infinity Kappa 60.7cs and rears with Kappa 62.7i and that's all I changed, no extra amplifier or subwoofer.

    My system now sounds like some main instruments have almost disappeared or faded to the background, some others are more prominent and overall many familiar songs lack the "presence" I'm used to hearing from decades of listening to them on many other systems.

    I'm stuck: I don't know if it's because the Kappa's are 2ohm impedance vs the stock speakers' 4 ohms or whether the head unit is just plain garbage, or some other explanation.
    I've read online that many head units can handle 2 or 4 ohm speaker impedance but have no way of knowing if the non-JBL head unit can. If I had this to do over I'd buy 4 ohm speakers, not 2ohm for this 4 ohm head unit.

    Has anyone else had similar problems and what was the solution? is the problem the 2 ohm speakers? the head unit itself?
     
  11. bsd43

    bsd43 Member

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    klamut, you sure your speakers are not wired out-of-phase?
     
  12. klamut

    klamut New Member

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    <div class='quotetop'>QUOTE(bsd43 @ Jul 4 2006, 02:57 PM) [snapback]281077[/snapback]</div>
    I followed Sparky's speaker replacement guide, it has a wiring diagram showing polarities for the non-JBL head unit. I tried to be very careful and double-checked the polarity after connecting each speaker. I sometimes wonder if one of the crossovers are defective with reversed polarity.

    What are the symptoms of out-of-phase speakers?