car audio high pass issue

Thread Starter

carguy

Joined Apr 7, 2007
5
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
 

Papabravo

Joined Feb 24, 2006
14,393
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.
 

Thread Starter

carguy

Joined Apr 7, 2007
5
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
 

Papabravo

Joined Feb 24, 2006
14,393
Is it your impression that you are hearing crossover distortion as opposed to distortion introduced by excessive gain aka clipping or limiting?
 

Thread Starter

carguy

Joined Apr 7, 2007
5
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
 

mozikluv

Joined Jan 22, 2004
1,437
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
 

Papabravo

Joined Feb 24, 2006
14,393
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.
 

Thread Starter

carguy

Joined Apr 7, 2007
5
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
 
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
 
Top