Stereo "Pop"

[UNHCLL]

Group,

I've been struggling with a problem with my stereo since installing a new aftermarket amplifier.

The stereo now has a "pop" through the speakers when transitioning on/off the throttle. I've moved all the speaker wires away from the main battery cable. I've various grounding locations for the amp & the headunit. Moving RCA cables and speaker wires have not made any changes.

The noise only occurs with transition on/off throttle. It did subside when the alternator belt is loosened.

Has anyone else suffered this issue? This was not present when previously running all the speakers directly off the headunit.


Any help is appreciated!
-Chris

[m3guru]

maybe your wiring is running rich? :lostme:

[UweM3]

over sensitive amp? faulty amp?
Can you borrow another amp?
Have you got one of these capacitor thingies to buffer the batterie?

[Lionel]

Group,

I've been struggling with a problem with my stereo since installing a new aftermarket amplifier.

The stereo now has a "pop" through the speakers when transitioning on/off the throttle. I've moved all the speaker wires away from the main battery cable. I've various grounding locations for the amp & the headunit. Moving RCA cables and speaker wires have not made any changes.

The noise only occurs with transition on/off throttle. It did subside when the alternator belt is loosened.

Has anyone else suffered this issue? This was not present when previously running all the speakers directly off the headunit.


Any help is appreciated!
-Chris

Need more info to determine source. I did have it originally but ditched it with a heavier ground. As mentioned it may also be be the internal circuits of the amp but to me it sounds more like poor grounding or feedback.

FYI, what I mean in poor grounding is it may be in a bad spot or ground wire to small or just to thin a gauge.

Do you also have a slight of faint reving noise at high volume?

By the way with amps and caps it usually better to have one spot with a good ground than multiple spots. Head unit is a different story.

L.
Let us know what other info and symtoms you have and we'll try an help isolate the problem.

[UNHCLL]

over sensitive amp? faulty amp?
Can you borrow another amp?
Have you got one of these capacitor thingies to buffer the batterie?

Need more info to determine source. I did have it originally but ditched it with a heavier ground. As mentioned it may also be be the internal circuits of the amp but to me it sounds more like poor grounding or feedback.

FYI, what I mean in poor grounding is it may be in a bad spot or ground wire to small or just to thin a gauge.

Do you also have a slight of faint reving noise at high volume?

By the way with amps and caps it usually better to have one spot with a good ground than multiple spots. Head unit is a different story.

L.
Let us know what other info and symtoms you have and we'll try an help isolate the problem.

I've tried grounding the amp directly to the ground terminal on the battery, on the body next to the battery, and above the rear shock tower. None of these have alleviated the issue. There is no cap or additional power supply/monitoring item in the car. Both ground and power cables are 4 gauge.

Using Shielded RCA's, run up the drivers side of the car, and before that I had them running up the center(transmission tunnel) of the car. This did not change anything.

I have not had the chance to try and install another amp to check if the issue is isolated to this specific amp. Amp is brand new, and has only been in use for ~6 weeks. Boston Acoustics GT-40.


I do get a small amount of whine in the higher rev's... more noticeably so when added load on the electrical system (IE: headlights on).

[UweM3]

Boston Acoustics GT-40! That's a good quality amp, I am surprised to hear about your problems. Have you contacted Boston Acoustics direct with your problem?
Everything else in your install is looking fine to me. Long long time ago when I was still into stereo I remember using an inline suppressor, but that was only required with cheap amps.

[JOEBMW]

I would look into two things....

Ground Loop Isolators: http://www.radioshack.com/product/in...ductId=2062214

Also, how do you have the amp remote power ?When does the amp turn on? If you have the amp turn on before the radio sends out a signal (even a 0 zero signal) then you will get noise because the input is floating without the radio on.

[Lionel]

With out seeing or hearing its hard to say whats the cause but not impossible, so we'll have to factor out some items.

The ground should be bare metal and to the chasis, the battery terminal is usually the worst place, as you'll get feedback from everything else in the car including the alt (whine). Try and avoid grounding directly to the battery.

The RCA's are fine(location wise) as long as you don't run them parallel with the battery lead on the right side of the car. The left side is always best for the RCA, remote(1 volt) and your front left speaker when all is amped from the back-forward. The channel under the sill is the best spot to run wire(to me). The tunnel shouldn't be an issue either but never tried that in this car.

You said you have shielded RCA's thats good as bad one's will allow amplification of the alt noise. thats why most use the twisted cable type RCA's. the twisting of the cable will filter out most noises. Check which do you have and if you have the old black straight wire ones they may be suspect for the whiney noise but not the pop.

The Pop can be a few things here.

1-Grounding, point or size wire. Just so you know the same gauge in as out is a starting point rule of thumb. for most its enough for some it may not be enough if its a bad spot or over 18 inches from your amp. When noise comes in some use a heavier grounding wire to eliminate the problem.

As an example, I have two 4 gauge wires on each amp, I have 2 amps. I'm tyed to the wheel chok on the left side. It may be bad spot so I used heavier wire. For my buddy's E30 M3 I used single 4 gauge leads from each amp to the rear tower locations and they where enough, there is zero feedback. Also very short distance.

2-Everything is starting up cold(Simultaneously as Joe explained)A cap, line isolator or a line supressor will def help eliminate that. As Joe already mentioned.

3-sometimes a bad line from your head unit. This can be checked by changing line ouputs to another line on the head to the amp in question. For say if your sub is acting up and you know the rear channel is fine, use that line to check the sub line. Just don't switch lines while the system is on.

Hard to pin down to one single thing without being there, but trying to help.

Also more reading info for you.

http://www.caraudiobook.com/car_audi...leshooting.htm

L.

[UNHCLL]

Boston Acoustics GT-40! That's a good quality amp, I am surprised to hear about your problems. Have you contacted Boston Acoustics direct with your problem?
Everything else in your install is looking fine to me. Long long time ago when I was still into stereo I remember using an inline suppressor, but that was only required with cheap amps.

I have not contacted BA yet, but may shortly to see if perhaps the power control/processor(?) inside the amp is bad.

I would look into two things....

Ground Loop Isolators: http://www.radioshack.com/product/in...ductId=2062214

Also, how do you have the amp remote power ?When does the amp turn on? If you have the amp turn on before the radio sends out a signal (even a 0 zero signal) then you will get noise because the input is floating without the radio on.

Amp is triggered off the Remote turn on from the headunit directly.
I have not tried the ground loop isolators.

I have also discovered that if I turn the audio volume all the way down to zero, I do not get any feedback/pop through the speakers. This has led me to believe that the issue lies with the amps output/power signals, and NOT the wiring to the speakers picking up electrical interference.


Thanks for the suggestions guys!
-Chris

[UNHCLL]

The ground should be bare metal and to the chasis, the battery terminal is usually the worst place, as you'll get feedback from everything else in the car including the alt (whine). Try and avoid grounding directly to the battery.

I will try relocating the ground location yet again. I've tried to avoid drilling/screwing new holes into the car to get new ground locations thus far.

The RCA's are fine(location wise) as long as you don't run them parallel with the battery lead on the right side of the car. The left side is always best for the RCA, remote(1 volt) and your front left speaker when all is amped from the back-forward. The channel under the sill is the best spot to run wire(to me). The tunnel shouldn't be an issue either but never tried that in this car.

You said you have shielded RCA's thats good as bad one's will allow amplification of the alt noise. thats why most use the twisted cable type RCA's. the twisting of the cable will filter out most noises. Check which do you have and if you have the old black straight wire ones they may be suspect for the whiney noise but not the pop.

I've swapped RCA's between the twisted, shielded, and old school black straight. No change. I even ran the RCA's out the trunk, through the drivers window, and direct to the headunit. No change.

1-Grounding, point or size wire. Just so you know the same gauge in as out is a starting point rule of thumb. for most its enough for some it may not be enough if its a bad spot or over 18 inches from your amp. When noise comes in some use a heavier grounding wire to eliminate the problem.

4 GA in and out. 60A fuse on the positive lead. I've tried running dual ground straps from the amp (2 connection points on the amp) without success.

2-Everything is starting up cold(Simultaneously as Joe explained)A cap, line isolator or a line supressor will def help eliminate that. As Joe already mentioned.

This would only cause the "pop" issue on initial startup, correct? I am getting this on every on/off throttle application while driving.

3-sometimes a bad line from your head unit. This can be checked by changing line ouputs to another line on the head to the amp in question. For say if your sub is acting up and you know the rear channel is fine, use that line to check the sub line. Just don't switch lines while the system is on.

If I'm understanding this correctly, then I've already done this. I've isolated the RCA's to 1 single set at a time (F, R, S) and still had the same issue.

http://www.caraudiobook.com/car_audi...leshooting.htm

L.

Thanks for the help and the link! I'll do some more reading and possibly look into the ground loop isolators.

If I can't resolve it within the next week or 2 using basic knowledge, I may send the amp back to be tested... or drop it off at a local audio specialist and have them figure it out.


-Chris

[Lionel]

We're getting warmer.

The wiring and RCA's will only help get rid of the noise or whine from the Alt, not the pop.

The pop is the amp turning on at the same time as your head unit. You mentioned the lines where checked so its not the head unit. With out the line supressor/ filter or cap it can do it every time you turn the head unit on or off. Yes, even while driving.

What we need to do is delay the amp turn on so its after your head unit or when everything is ready. This will avoid the pop. A line filter, suppressor or capcitor should do the trick. Electronic is best but you have to be very selective.

Personally never had the need for one but brother Chicco(on this board) understands the inner workings of these items better than I do.

Shoot him a PM if he doesn't chime in here.

I also have a source for further help, check your PM.

L.

[UNHCLL]

The pop is the amp turning on at the same time as your head unit. You mentioned the lines where checked so its not the head unit. With out the line supressor/ filter or cap it can do it every time you turn the head unit on or off. Yes, even while driving.

What we need to do is delay the amp turn on so its after your head unit or when everything is ready. This will avoid the pop. A line filter, suppressor or capcitor should do the trick. Electronic is best but you have to be very selective.

Lionel,

I think I may have confused you??
The pop does NOT occur when turning the stereo on/off.

It occurs litterally when you go from NO throttle input to ANY level of throttle input with the engine running, and ONLY when the engine is running. Basically, I would define it as occuring any time the Throttle Position switch is triggered from it's resting point (idle).

I can lightly tap the throttle pedal while rolling, out of gear and make the pop occur. Same thing when I let OFF the throttle from a constant state.

Does that make sense?

-Chris

[Chicco]

Hello:
Here is a quick fix below, of a Passive filter other than buying an Active filter. The only other thing is how much gain is turned up on the amp? You may want to lower it.

Relay turn-off pop is caused by components in the system turning off before the amplifier completely shuts off. In most cases, the component will be an EQ or signal processor. Usually adding a little turn-off delay to the offending processor can fix the problem. This allows the processor to turn off after the amplifier, preventing the pop. Many components have this feature built in, and it is adjustable. Check the manual to see if your component has this feature available. If not, you can build your own delay circuit with a diode and a capacitor. Add a 1N4004 diode in series with the processor's turn-on lead, striped side toward the unit. Then add a capacitor in parallel, the positive side of the cap connected to the striped side of the diode, the negative side of the cap to car chassis ground (not to the body of the radio or processor chassis). Experimenting with the capacitor value will give you just the right amount of delay before the EQ shuts off. You don't want the delay very long, just long enough to make sure the amp is off before the EQ powers down. Usually 220 - 1000uF is about right. Make sure that the cap is a polarized electrolytic, 16V or higher.

Regards,
Chicco

[UNHCLL]

Hello:
Here is a quick fix below, of a Passive filter other than buying an Active filter. The only other thing is how much gain is turned up on the amp? You may want to lower it.

Relay turn-off pop is caused by components in the system turning off before the amplifier completely shuts off. In most cases, the component will be an EQ or signal processor. Usually adding a little turn-off delay to the offending processor can fix the problem. This allows the processor to turn off after the amplifier, preventing the pop. Many components have this feature built in, and it is adjustable. Check the manual to see if your component has this feature available. If not, you can build your own delay circuit with a diode and a capacitor. Add a 1N4004 diode in series with the processor's turn-on lead, striped side toward the unit. Then add a capacitor in parallel, the positive side of the cap connected to the striped side of the diode, the negative side of the cap to car chassis ground (not to the body of the radio or processor chassis). Experimenting with the capacitor value will give you just the right amount of delay before the EQ shuts off. You don't want the delay very long, just long enough to make sure the amp is off before the EQ powers down. Usually 220 - 1000uF is about right. Make sure that the cap is a polarized electrolytic, 16V or higher.

Regards,
Chicco

Gain has been turned almost all the way down, no change.

The pop has no correlation whatsoever with powering on/off any of the components in the car, so I don't think the above is of any use... sorry Chicco!

-Chris

[Lionel]

Gain has been turned almost all the way down, no change.

The pop has no correlation whatsoever with powering on/off any of the components in the car, so I don't think the above is of any use... sorry Chicco!

-Chris

Wow, I did read into this wrong and so I am to blame for Chicco's response.

Sorry Chicco, my response may have mis lead yours , but we tried.

Down to amp-ground or amp internals and possibly sticky TPS, the sound may just be amplified and picked up as feedback with in the car.

Also don't forget the pm.

L.