car audio high pass issue

Discussion in 'General Electronics Chat' started by carguy, Apr 7, 2007.

  1. carguy

    Thread Starter New Member

    Apr 7, 2007
    5
    0
    I am trying to post a question and it will not allow me to do so.

    My Q-
    I have a couple of amps in my car
    The amp driving the cabin is set to flat
    the rear speakers have bass blockers
    the front speakers are component w/crossover network

    I am still getting a little distortion from the front stage

    Q- what effect will it have if i set the amp high pass as well as the bass blockers and crossovers

    effectively running 2 highpass filters in series

    Hardware
    Alpine cda-7838 head unit
    Kenwood 7202 920watt 2 channel amp
    Kenwood 7202 920watt 2 channel amp
    Sony explode 400watt 12" subwoofer (1200watt max)
    Q-logic bandpass box
    Polk db5250 5.25" component speakers 100watt continuous (200watt max)
    Polk db691 6x9 triaxial 100watt continuous (300 watt max)
    Pyle 6 farad digital capacitor

    thanks in advance
    David Lundquist
    gigalanman@msn.com
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    With all that amplification I'd be surprised if there wasn't "a little distortion". The usual method of debugging a problem is to divide and conquor. If you can find out which pathway is introducing the distortion you will have some chance of fixing the problem. I think it is unlikely that introducing more components will solve the problem.
     
  3. carguy

    Thread Starter New Member

    Apr 7, 2007
    5
    0
    I was more concerned about how the 2 high pass in series would effect the load impeadance or the cross over frequency points.

    would the cross over frequency points increase twofold?
    example they are currently 200Hz , would they then be @ 400Hz?

    and the load...currently @ 2 ohms
    how would that effect the load impeadance - important due to amp stability
    (not stable under 2 ohm load)

    thank you in advance
    David Lundquist
    gigalanman@msn.com
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    Is it your impression that you are hearing crossover distortion as opposed to distortion introduced by excessive gain aka clipping or limiting?
     
  5. carguy

    Thread Starter New Member

    Apr 7, 2007
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    0
    I believe the front right midwoofer cone rattles on occaision so I am assuming
    the factory component crossover network is crossed over to high.
    being that I have alot of mid bass and highs i am attempting to crossover (filter)the front @ a higher frequency.unfortunatley I dont have the x-over specs from PolkAudio as it is "trade secret" information.

    I would like to try using the amplifiers highpass filter in conjuntion with the x-over ,but have concerns about causing a drop below 2 ohms.

    I am not an electronics guy - I thought it would be better to ask someone who understands the theory.

    I am curious what result ,in load impeadance ,running 2 filters in series would have on the load to the amp due to resistance change.

    I know the r1*r2/r1+r2 parallel resistance equation and with my limited knowledge have wired a 2 ohm load to the amp.
    will placing an additional filter (cap w/resister) in series on the positive lead
    effect the total load (ohms)
    thanks
     
  6. carguy

    Thread Starter New Member

    Apr 7, 2007
    5
    0
    I apoligize - not crossed over "to high " I ment crossed over to low
    thanks
     
  7. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    hello carguy,

    before i can give a sensible answer to your query, let me clarify an issue which seems to bother you.

    are we talking here of a power amp high pass filter in series to your PolkAudio x-over?

    you have not mentioned at what audio level you're playing your system

    another thing you said you have a 400+w per channel kenwood driving a 100w midrange?

    moz
     
  8. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    Filters are normally considered "linear" components and the response of two "linear" components is "linear". I understand the difference between crossover distortion in the power output stage of a push-pull amp but I'm less clear about distortion that may be introduced by the passive crossover networks placed between the amplifier output and the speaker.

    Because I know of no useful purpose for a non-linear filter, I'm going to hazard a guess and say that the problem is in the amp or the mechanical mounting of the components. No combination of "linear" components can produce a non-linear effect such as distortion.
     
  9. carguy

    Thread Starter New Member

    Apr 7, 2007
    5
    0
    thank you papa bravo , I have switched the leads on the speakers front and back and the distorting speaker is now in the back.

    you are correct, 1 channel on 1 amp is creating the failure
    I will replace the amp.
    thanks
     
  10. penman1964

    New Member

    May 22, 2007
    2
    0
    it is probably wattage distortion so turn up the high pass filter till the distortion is gone. i have a 4 channel 480 w. amp with ch. a to sub, bridged with low filtered @ 32 hz and ch. b, high filtered with 2 - 8 in. mids at 100 hz and up and hadf to turn down the gains to about half volume so it doesnt have distortion at high volume. so putting 2 high filters in series will basiclly make the tweeters.
    hope this helps
     
  11. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    Its probably your ear drums beating against your skull.......
     
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