wiring two speakers in series

Discussion in 'Car Audio, Electronics & Security' started by Chuck71RS, Mar 25, 2019.

  1. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    Thinking about installing a third pair of speakers under the dash grill (6x9 under package tray, 4" lower-front door panel). Want to fill the car with more sound and something from the front of me and above the door speakers would do so. Very little stereo from the dash so more like a center channel. I get good stereo from the 4" in the lower door panel. The system has a filter for the door panel speakers to block frequencies below 400hz

    Will test with the 4" two-way door speakers under the dash grill. If the results are good, will get either a pair of 3 1/2" or tweeters. With the 4" two-way in the lower door, I think tweeters would be a good addition but will wait till the sound test.

    Would power the dash speakers with the same amp that powers the door speakers. (Package tray speakers have a separate amp). Series wiring two speakers (both 4 ohms) on the same channel will double impedance but power drop is not a corresponding half reduction. Series is safer then parallel.

    Each amp channel is 35rms at 0.5% thd. Tweeters I looked at would have db of 93-97 at 2 watts so not much power needed for volume

    A fader would be needed to balance the door and dash speakers. Don't know how this would be done but since it is in series would a fader be needed for the left pair and one for the right pair?

    Where and how to install a fader in the wiring?
     
    Last edited: Mar 25, 2019
  2. dave@ztech

    dave@ztech Veteran Member Lifetime Gold Member

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  3. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

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    While you can wire a tweeter to the 4", you need to do it in parallel and not series. On the channels of the amplifier connected to the 4" up front, at 400Hz and up the amplifier is seeing 4 ohms. If you were to now add a tweeter with a passive crossover on it and let's say it's crossed over at 3KHz, now the amplifier will see 4 ohms from 400Hz up to3KHz and then 2 ohms from 3KHz and up. The amplifier unless it is of some really junk design, should easily handle this setup.
    You didn't state how the 4" are getting crossed over at 400Hz and it can be done two ways. Electronic or passive crossover. If you are using an electronic crossover in the amplifier, then a second pair of 3.5" or 4" full range could be wired in either series or parallel to the existing 4" and now they will all play from 400Hz and up BUT if you are using a passive crossover on the existing 4" and then add in series a second set of 3.5" or 4", this now changes the impedance for the passive crossover and now the speakers are crossed over at a different frequency.

    https://www.the12volt.com/caraudio/passive-crossover-calculator.asp

    Jim
     
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  4. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    The stereo has a separate eq unit from the receiver. The eq has a fader for front and rear speakers. The eq splits the incoming signal from the receiver to the two amps (one for the front pair and the other for the rear pair).

    The 400hz filter is a built in switch on the eq (1986 Kenwood) and for only the amp powering the front speakers (4" in the lower door panel).
    A modern head unit sends the signal to the eq which splits it to two amps (1986 Kenwood - one front and one rear). The eq has a sliding front-rear fader
     
  5. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    To balance the door speakers and the dash, use an attenuator. Called it a fader because I did not remember the name attenuator. I remember a few basics but little experience

    Series or Parallel: Isn't series safer then parallel?
    ***Parallel can result in impedance drop to an unsafe. I know that is the theory but I have no idea how much drop I would have or when it becomes unsafe
    ***Series will increase impedance which will reduce power (but don't know how much)

    Installing an attenuator will depend how the speakers are wired?
    *** series: a single stereo attenuator on neg wire coming off the lf-rt door speakers . Or two mono, one on the neg wire of each door speaker
    *** parallel: a single stereo on the + wire coming off the amp for both dash speakers. Or two mono, one one the + wire coming off the amp for each dash speaker
     
  6. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    You could wire the small center speakers (left and right) to be powered off the head unit rather than the amp, assuming the speaker outputs are available and you are using the preamp outputs to the amps. They won't be quite as loud as the amped door speakers, but they will fill the sound hole, and work with your fader.
     
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  7. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    Interesting idea. The preamp outputs are being used for the amps. Don't know if the head unit amp can be used at the same time. The stereo is not available to try right now. The Pioneer manual does not cover this question. Will call Pioneer
     
  8. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

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    I have not seen anything in the operating menu or any type of chassis mounted switch on the Pioneer radio's to turn off the built in power of the radio. It seems to me Alpine did that a few years ago and I think on that was to basically cut down on the heat generated by the radio while in the dash.
    The problem with using let's say the front amplified outputs of the radio and the front pre-amp outputs to an external amplifier is no way to really control them independently through the radio controls.
    Jim
     
  9. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    Could volume for the dash speakers be controlled with a mono attenuator between each Pioneer amp pos output and the pos terminal on each dash speaker? But since this is an amplified output, would a potentiometer be needed?
     
  10. xten

    xten Veteran Member

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    Yes it's possible. That's how my dash speakers are hooked up.
     

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