to the audio/electrical junkies

[etlsport]

lately ive noticed my audio system has been "clipping" very lightly, ive adjusted my input levels on the amp (everything from the head unit is RCA to the amp, 4 surround and 2 sub channels) to cure the problem and its ok for a while then it will start to clip sometimes and then stop again randomly.. all on the same drive, but theres no alternator whine at all

im wondering if the RCA voltage isnt consistent because my monitor will occasionally cut out for 5-10 seconds every 30 minutes and just say "no signal" (i have a head unit that plays cds/dvds and a separate monitor connected via yellow RCA)

whats the best way to check the voltage? can i just disconnect the RCA from the amp and bridge the gap with an ohm meter? or any other ideas about what could be causing it

[Gussie2000]

Hi etlsport..

Reviewing your question & the descriptions of the problem with your audio sys what could be possibly happening is that one of input chips is over heating & is about to say go go bye bye........:o

When the input chips go above the regular temp the processor unit as safety precaution shuts down the entire system to prevent a major damage.

Now,i'll highly suggest you to have the head unit checked by an certified tech.

If you are familiar with an multimeter tester you can check the current fluctuation drawn one the + 12 cable,the ground cable,the remote cable & continuos yellow cable for any sudden high/low current draw.

Now if this only happens when you raise the volume & play your head unit for long periods of times have in consideration that the inner side of the dash board retains huges amount of heat from the engine compartment,worse if the heater is on,the laser lens begins to fail while playing your CD's,the head unit's chassis temp goes high tough.

By the way,check the wiring harness,RCA cables & connectors for any cooked insulator;Another thing you can do is play the head unit outer the dash & use your finger tips to test the temp at the heat dissipator shield,if the temp is quite high then focus on that issue.

Hope those tips are helpfull ;)

[etlsport]

the head unit never turns itself off.. on 1-2 days when the temps were like 10-15 deg audio would cut out but as soon as the vx was warmed up that went away

the clipping im talking about sounds a bit like static but with a rhythmic pattern

[Gussie2000]

Ok,so since there's no sign of potencial damage you should check the wiring harness.
But i got one question ....

Is this noise audible when you playing Cd's or the radio stations ?

[etlsport]

nope its very faint.. you cant hear it except between songs or when the sound is turned down to a 2-3 setting (normal listening volume is 10, highest ive ever gone is 20, max on the unit is 30) sometimes im not even sure that im hearing it until i cut power to the head unit and i hear the silence, if i turn the input level on the amp up it gets louder

[mdwyer]

Is this a relatively new amp? Say, within the last eight years or so? I hadn't heard of any audio equipment being impacted, but I have had other consumer electronics die from bad capacitors. Wikipedia calls it "Capacitor plague".

A conventional multimeter might not read well. I think you need one of those "True RMS" ones to get accurate readings with AC signals. I'm not sure, though. I'm the wrong kind of techie. :)

Finally, I have heard a tick-tick-tick sound coming from a car before, that sounded a lot like a CD skipping. We were at about 13,000ft, and an electrical storm came over. We were bleeding static out of the air through the antennas. Each 'tick' was a spark jumping to ground.

[Gussie2000]

Ok,try this one.....

Turn on the CD player with the ignition key in ACC position,go ahead & play CD and/or radio station,keep the a/c heater off
If so far you don't hear that noise then turn on the a/c heater.

If you still don't hear any thing then turn on the parking lights,if nothing is heard keep going by turnning on the head lights.

Jump inside & close the doors,if nothing is heard open the door;What we looking is for any possible open/shorts in the electrical system

If you hear that noise at this point then is more likely something related to ground connection,check all grounds for any loops

But if this noise is only audible when the VX's engine is running you can drive by any audio/auto shop and search for some weird electrical issue,can't be a big deal,possible is an draw of electromagnetic field waves.

As how i said,if you are familiar with an multimeter tester go ahead a check the speaker's wiring ohm/voltage.

Apply the same step with the RCA cables & subwoofers wires,Check all wiring related to the audio/video system.:)

[etlsport]

only get the sound while driving and even then its still occasional 95% of the time its not even there at idle, seems to be just low speeds (but not in park or neutal) , but could be because at high speeds wind noise drowns it out.... doesnt come from the subs at all, only the surround speakers

yea its a new amp, purchased new in november or december

my new thinking is its probably got to do with the fact that my head unit is located directly above the ECM, so RCA cables come out behind that, then go down and run down the center of the passenger footwell to avoid any source of interference, they are too long so they do loop, probably 1 foot in diameter and then cross at a 90 degree angle before continuing to the amp.. its really not a huge issue.. just a minor annoyance after putting much time and effort into my sound system, i was hoping to fix it before the new components go in (fiberglassing new tweeter pods started today ;Db;)

[tom4bren]

Eric,

Does the amp drive all of the speakers or just the sub? It sounds like the midrange speakers might be driven with bass. A crossover network may solve the problem or even a simple high pass filter.

Tom

[etlsport]

yea its a 5 channel amp, have a high pass filter on the fronts and not sure whats on the rears but its on a "rear speakers" setting

[Gussie2000]

I now believe that what you have been dealing with is a electro magnetic feed back waves.

The ECM it self emits those waves but since the RCA cables are quite close & carries the signal processed by the head unit they might have being "receiving" those waves from the ECM.

Try to place those RCA cables on the opposite side,if you have the means $$$$$$ have those cables upgraded,the twisted or braided RCA cables works better for this kind of situations.

Hope this one works for you buddy :)

[etlsport]

heh theres no way to avoid the ECM with my head units location.. the RCAs are already plenty upgraded, they are the upper level rockford fosgate wires, twisted w/ a woven outer shield

im thinking what i will do is run new power and ground wires in and out of the head unit and hopefully that will help.. if not i guess i'll just have to deal with it

[mdwyer]

One more thing: If it isn't the ECM, there are some other solutions. Ham radio geeks have got all kinds of ways of cleaning up interference. My friend totally shielded his coil-over-plugs. I haven't noticed any problems with my own, though.

Anyway, this link (http://www.k0bg.com/ignition.html) might give you some ideas.

[etlsport]

messing around with the wires ive pinned down the culprit.. the sound is gone completely when i disconnect the RCA in for the sub, changing the input level on the sub channel doesnt seem to affect it. would the fact that the 4 surround speakers are 4 ohm and the subs are wired in parallel to be equivalent 2 ohms?

[Hotsauce]

Try subs in series for 8 ohm load. You might also be getting feedback through the RCA's. Try a groundloop isolator on the sub inputs.

John C.

[Gussie2000]

Whenever you remove the power supply from your audio system to replace RCA cable,amps,speakers,etc it's very important to be aware that you shouldn't not plug the RCA cable to the amps prior to turn on the system.

These is the following steps

After the installation is done have all the amps level adjusters to the minimun level, i mean all of them,same apply to the head unit.

Place the key on ACC & turn on the head unit,after a few seconds check the amps led to make sure they are on & running.
Recheck all the ground cables for any loose nut,this is very important.

Turn off the head unit;Plug one of the subs input RCA cables,then turn on the head unit & rise the volume little by little,if possible have someone with you to adjust the amp levels at the time you controling the head unit.

Repeat this step until you've complete connected all the input cables to the amp.

When you had all the RCAs connected run the head unit for a while,then beging to adjust the EQ levels on the head unit's volume no more than 60 % of his power,after you had this one sorted go to the amps,with the volume at 60 % or less adjust the levels until you begin to hear distorsion.

If you amps come with high/low level inputs have them positioned accordingly
especially if you running the speakers & subs on the same amp.personally i don't recommend that,i rather run one amp for the speakers & another amp for the subs,don;t forget to add an capacitor 1.5 farads or higher.

Why i don't recommend running all the speakers & subs on the same amp /

well,the amp has more tendency to over heat & if it fails & go go bye bye you'll run off of music completly
Another tip to have in consideration is the amps,subs & speakers impendancy.
For example :
If you decide to go running with 1000 watt subs at 4 ohms look for a amp at the same impendance spitting no more than 950 watt,the RMS is also very important,if the amp's RMS is 500 watt please make sure the sub holds on that amount or more RMS,more likely for precaution & peace of mind :o

If speakers is what we talking about i rather run new wiring instead of touching the factory wiring to run the new speakers,yes is more job tought,but it pays its self.
I suggest that because when we decide to upgrade the audio sys the factory wiring isn't the one that fullly fits the new speakers specs & that takes away performance from your audio sys.

Dynamat the vehicule is a key for better & clear sound,and because the VX's interior is acoustic it's highly recommended to have this one done,that helps to hear the music quite high without turning the volume quite high :p

When adjusting the sub & speakers use the balance & fader levels to better adjust the sound,since the left side speakers are closer to the driver than the right side ones balancing the sound can definetly helps to get the best sound by just slightly adjusting this one over the left;The fader control level can be use to have the rear speakers spitting more than the front ones because the cargo/rear passenger area has more dimensions that the front/driver-passenger so you can have the music coming better from the rear & even from to right to left

[etlsport]

yea, i should clarify my setup right now...

in all the stock locations i have 2 ways that are 60 watts RMS at 4 ohms
2 subs that are 150 watts RMS at 4 ohms wired in parallel so they are effectively 2 ohms

amp puts out
50x4 at 4 ohms to stock locations
300x1 at 2 ohms to the subs

all wires have been upgraded to 14 ga monster cable
wires to the subs are 12ga monster cable

twisted pair rockford fosgate signal wires from the head unit run completely separately of any other wires except for the ECM directly below the head unit

head unit uses stock power input with a noise filter on it and is grounded directly to the firewall

4 ga stinger power wire to amp
4 ga stinger ground wire (about 12" grounded under drivers seat bracket, sanded the paint off)

150 SF dynamat on floor and doors