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JBL Speaker Upgrade - Wiring Problem

Discussion in 'Gen 2 Prius Audio and Electronics' started by richinlou, Jan 19, 2010.

  1. richinlou

    richinlou New Member

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    I replaced my JBL speakers (4 woofers/4 tweeters [unpluged the dashtop midrange]) with Alpine SPS-600C speakers. I attached the new speakers to the existing speaker wiring harness for each speaker. The results were a disaster - initially sound (very poor quality) came from each speaker but when I rasied the volume, the tweeters screetched terribly (and continued after I turned off the radio) and the woofers were barely audible. I did not drive the new speakers off the woofers (as per the instructions). Before I humble myself and resort to admiting my failures to a local car audio shop, can anyone provide some guidance? Also, I do not want to loose my bluetooth capabilities as referenced in other posts. Any and all help would be greatly appreciated! Thanks.
     
  2. ursle

    ursle Gas miser

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    Reversing polarity wouldn't do that, if you replaced 4 ohm speakers with 8 ohm speakers they shouldn't squeal, you must've grounded your signal somewhere.
     
  3. KK6PD

    KK6PD _ . _ . / _ _ . _

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    Well if you had just wired the wrong polarity, that would result in phase cancelation. The squealing was the JBL amp protesting the wrong inpedance being hooked up to it, did you check as to what the existing speakers were marked as far as impedance in ohms. I do not think they are just 4 or 8 ohms.... and as for not following instructions..... you feel bad enough, I wont bang on you for that!!!

    The tweeter crossover and lo/midrange speaker are in parallel, with their crossover cap present a unique impedance to the JBL amp. That squeal you heard was the amp protesting the fact the impedance was way off.

    I would restore ALL the OLD SPEAKERS to the way it was... then power up the radio and make sure the amp is still working, and is not blown. Then if the speakers are not marked with the impedance rating, take an Ohm Meter and measure what they are... then buy speakers with the same impedance... or else replace the JBL power amp with one that will handle the 4 or 8 ohm speakers. What ever you do, DO NOT PLUG SPEAKERS IN OR OUT WITH POWER ON!!! The tweeters will blow if you unplug the other speaker in the set!!!!

    Good Luck, let us know what you find, and please read and follow ALL instructions!
     
  4. richinlou

    richinlou New Member

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    Thanks all! I humbled myself and went to a local auto audio shop yesterday and they simply removed the Alpine cross-overs between woofer & tweeter and everything is working fine and the new speakers are quite an improvement over the JBLs. Because the JBLs were 2 ohm and the Alpine's are 4 ohms they said I'd loose 50% of my volume. While I never paid any attention to the number value of the volume with the radio on, I am hard pressed to notice any decrease in volume capacity. Luckily, I didn't loose my Bluetooth and/or any of the controls on the steering wheel. I learned my lesson (and my limitations!). Thanks once again for your help.
     
  5. austingreen

    austingreen Senior Member

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    Just an fyi -

    amps will usually produce at most 50% more power for 2 ohm versus 4 ohm speakers. The way our hearing works, it takes four times as much sonic power to sound twice as loud. So going from 2ohms to 4ohms will sound at least 80% as loud if the speakers have the same efficiency.

    One thing you may want to check is if the jbl amp may be sending your tweeters lower frequencies than they are designed for. You may want to put a high pass filter (that crossover or just a capacitor) to protect the speakers. If this is the case you may be missing out on some mid range. I'm not sure the crossover frequency in the amp or for your tweeters.

    Those speakers can not produce some of the low end bass. Sound will be improved with a subwoofer.



     
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  6. richinlou

    richinlou New Member

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    I suspect that you are correct in your assessment that I would benefit from a high pass filter for each tweeter. While the sound is currently "acceptable," I have the tone contols for the high end diminished as much as possible, the midrange diminished somewhat, and the bass boosted to max (with marginal bass response at best). Alpine's technical support staff recommended a 4.5Khtz filter. Once I figure-out where I can purchase them, I think the simplist thing to do is to use capacitors and place them inline on the (+) speaker wire for each tweeter.
     
  7. richinlou

    richinlou New Member

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    UPDATE ... After having the speakers wired by my local auto stereo guys, I've learned a few things worth sharing:

    First, the crossover(s) for the front door woofers and tweeters is built into the JBL amplifier (which explains why the shop did not put them in-line with those speakers). HOWEVER, the Alpine crossovers between the woofers and tweeters in the rear door panels were used.

    MOST IMPORTANTLY, I was subsequently able to dramatically improve my bass response by wrapping self-adhesive foam insulataion (3/4" x 3/4", purchased at hardware store) all the way around the edge of each woofer where it protrudes from the inside metal door panel. This gave a positive seal with the plastic rings molded into the interior of the door panels. The profile of the Alpine's was just under 1/4" lower than the stock speakers and this created an air space between the speakers and the molded rings in the door panels. It seems that lots of bass was lost in this gap between the speakers and the door panels. I also used 1/8" strips of Gorilla Tape to wrap all the way around the foam where it attaches to the speaker to ensure a long-lasting fit.

    Now that this saga is over and done with, I'm very pleased with the results. I lost very little in volume going from 2ohm to 4ohm (again, thanks to AustinGreen for all his help understanding this minimal loss!), and I'd conservatively say that for the total $300 I spent, I improved the audio by a factor of 3.
     
  8. Grayson73

    Grayson73 Junior Member

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    Did you end up using the high pass filter?