CK5
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Alternator Whine Through Radio/Speakers...
- Thread starter PWagon
- Start date
Story of my life. Write a novel and leave out the most important part.
Remember a capacitor does not pass DC. So putting it inline with power or ground would stop the amp from working.
Instead, you put it across the power line as close to the amp as practical. You hook the positive lead of the capacitor to the hot wire, and the negative to the ground wire. Don't cut any wires, just strip them back and solder the capacitor leads across the wires.
In this case, I would not solder them at first. Just wrap them around the power leads a couple of times until you see if it works. You may have to try a couple of different capacitors.
One thing to know, capacitors are strange when you hook up more than one. If you hook two or more in series, the values divide instead of adding.
You have to hook them in parallel to get more capacitance.
In other words, if you hook two 1000mf capacitors end to end across the power line, you will be only hooking 500mf up. If you hook them both across the lines it will equal 2000mf.
As for the size, I pretty much pulled it out of the air.
Given the frequency of the noise we are trying to get rid of its reasonable. Plus its cheap.
You could bump it up to 6800mf for not too much more money.
https://www.alliedelec.com/rs-pro-7111539/70648293/
Capacitors of these sizes are acting as filters, but a boost capacitor might work better.
You can find them here:
http://www.techronics.com/Capacitors/1-2-Farad-Capacitors.html
Here is how they work. Big amps, say 2000 watts have to deliver massive amounts of current very fast, which means they have to be supplied with those currents at audio rates. So, you use big cable. I have seen amps with 2 gauge wire, while the starter on the same truck has 4!
While the 2 gauge will handle the current continuously with no problem, there is a problem. all conductors have resistance. The heavier the cable, the less the resistance. But conductors have something else. Inductance.
Not going into what that is, but it resists sudden changes in current. The faster the change, the more it resists.
So, even the massive cables cannot supply the current the amp needs as fast as it needs it.
The massive capacitors I linked to above act as super fast acting batteries. You mount them across the power line close to the amp. They charge up to the input voltage. When the amp calls for a sudden surge, it supplies it until the power line catches up.
Check in your area for an automotive sound shop. With any luck they will have some used big caps that they would let you try before you buy.
If you can't find any, I would try the cheap small ones first. I wish you were closer. I've got a few hundred caps of the smaller size laying around we could hook up and try real quick.
Remember a capacitor does not pass DC. So putting it inline with power or ground would stop the amp from working.
Instead, you put it across the power line as close to the amp as practical. You hook the positive lead of the capacitor to the hot wire, and the negative to the ground wire. Don't cut any wires, just strip them back and solder the capacitor leads across the wires.
In this case, I would not solder them at first. Just wrap them around the power leads a couple of times until you see if it works. You may have to try a couple of different capacitors.
One thing to know, capacitors are strange when you hook up more than one. If you hook two or more in series, the values divide instead of adding.
You have to hook them in parallel to get more capacitance.
In other words, if you hook two 1000mf capacitors end to end across the power line, you will be only hooking 500mf up. If you hook them both across the lines it will equal 2000mf.
As for the size, I pretty much pulled it out of the air.
Given the frequency of the noise we are trying to get rid of its reasonable. Plus its cheap.
You could bump it up to 6800mf for not too much more money.
https://www.alliedelec.com/rs-pro-7111539/70648293/
Capacitors of these sizes are acting as filters, but a boost capacitor might work better.
You can find them here:
http://www.techronics.com/Capacitors/1-2-Farad-Capacitors.html
Here is how they work. Big amps, say 2000 watts have to deliver massive amounts of current very fast, which means they have to be supplied with those currents at audio rates. So, you use big cable. I have seen amps with 2 gauge wire, while the starter on the same truck has 4!
While the 2 gauge will handle the current continuously with no problem, there is a problem. all conductors have resistance. The heavier the cable, the less the resistance. But conductors have something else. Inductance.
Not going into what that is, but it resists sudden changes in current. The faster the change, the more it resists.
So, even the massive cables cannot supply the current the amp needs as fast as it needs it.
The massive capacitors I linked to above act as super fast acting batteries. You mount them across the power line close to the amp. They charge up to the input voltage. When the amp calls for a sudden surge, it supplies it until the power line catches up.
Check in your area for an automotive sound shop. With any luck they will have some used big caps that they would let you try before you buy.
If you can't find any, I would try the cheap small ones first. I wish you were closer. I've got a few hundred caps of the smaller size laying around we could hook up and try real quick.
datmony
Registered Member
I have an inexpensive approach for you to pursue and that has worked for every stereo installation I have ever done. Take your power wire and ground wires for ALL components (deck, amp, etc etc, this even includes something like a cigarette lighter socket if you are running a phone off of that power that will hard wire into the deck) back directly to the battery. Completely eliminate the common ground aspect of the system and go directly to the battery. You can even run some test lines directly there and see if it solves it for you. Don't be surprised if it eliminates all of your issues.
I essentially did just that when I ran my new 4 gauge power & ground off the battery into the cab (along the passenger side). The amp and radio both get power from the 4 gauge wires, but get the key on power from the ignition so they don't stay on all the time.
datmony
Registered Member
Try to cut your wire for switched power. Hook that to the power distribution point you have for the amp. (the stereo will be constantly powered at that point obviously). See what happens. If your whine goes away at that point (wouldn't be shocked if it did immediately) then you know that the power coming from the switched source is the culprit. You can then look for a cleaner source of switched power, do some of the items folks have previously noted but just on that switched power source, or just leave it constantly powered and shut it off at the head unit versus with the key. If you still have noise then I would say that something is creating a secondary ground and pulling in noise from that. (stereo chassis, amp, something).
Are you pulling switched power out of the fuse box? They are notoriously noisy electrically speaking.....
Are you pulling switched power out of the fuse box? They are notoriously noisy electrically speaking.....
So with the amp running, unplugging the RCA cables stops the noise?
How about RCA cables still connected to head unit, but power/ground not connected to head unit? And what happens when you adjust the gain on the amp?
Just to be clear, this is only a head unit, right? Not a phone or ipod with an AUX or USB cable?
I had a similar situation a long time ago and couldn't break the ground loop noise, so I finally powered the head unit through a DC-DC converter, since I had one laying around. It's too bad car audio usually uses RCA cables instead of a balanced (i.e. differential) setup because sometimes you find head units or amps that tie the input (-) to power ground and it can be hard breaking the loop noise. Everybody talks about running power and signal separately, but that assumes crosstalk is the issue. For a loop issue, bringing the wires closer together will help, since the total area inside the loop is reduced.
Another idea...do you have the dash light circuit wired to the head unit (so the lights dim with the dash lights)?
How about RCA cables still connected to head unit, but power/ground not connected to head unit? And what happens when you adjust the gain on the amp?
Just to be clear, this is only a head unit, right? Not a phone or ipod with an AUX or USB cable?
I had a similar situation a long time ago and couldn't break the ground loop noise, so I finally powered the head unit through a DC-DC converter, since I had one laying around. It's too bad car audio usually uses RCA cables instead of a balanced (i.e. differential) setup because sometimes you find head units or amps that tie the input (-) to power ground and it can be hard breaking the loop noise. Everybody talks about running power and signal separately, but that assumes crosstalk is the issue. For a loop issue, bringing the wires closer together will help, since the total area inside the loop is reduced.
Another idea...do you have the dash light circuit wired to the head unit (so the lights dim with the dash lights)?
Check post 12. Looks like it is coming from the amp. He had already tried most of what I had suggested. I suspect the internal power supply has a problem, but i hope its fixable with an external filter cap across the power leads.
For all of the above, the outcome is expected. Of course the noise stops when the amp is off, it is the victim. Of course the noise stops with no alternator, it is the source. I didn't see a test with the amp on, but no input attached.
Try running a ground wire from the amp to the radio. I've read that this can be cause but a difference in current between the two devices.
Sometimes a low-quality component with poor power supply isolation will introduce noise.
Head unit, or amp.... it can be hard to convince people to move away from a brand / model that they really like but if the component isn't well designed, the noise will always be there and you will be stuck with "band aids" to try to fix it.
Find a different amp to try.... swapping one component at a time will quickly isolate if it's a bad/poor component.
-G
Well... I'm a little embarrassed to post this update, but I feel I should share with you all the root cause of my alternator whine through the amplified speakers. Ultimately the PICO (spelled right?) in my amp apparently was the culprit (or so I'm assuming). I reluctantly ordered a replacement amp, installed it, and the alternator noise went away. It's a bit embarrassing that I replaced grounds, power feeds, head units, and even an alternator, but I was hesitant to swap out the amp. Swapping out the amp would have been the easiest thing to do, right? I think several of you even suggested the amp, but I stubbornly did not until now. The amplifier was the culprit. Regardless, I appreciate all the suggestions and help on this thread. Thank you.
Problem solved, and valuable experience gained.
Nothing wrong with that.
-G
Nothing wrong with that.
-G
No need to be embarrassed. You pay good money for a new part, you expect it to work. Since it has a problem, but its new, then the most likely cause is something else. And on the bright side, you have upgraded lots of other stuff, which is always a good thing.
As for PICO, not sure what that is, unless you mean the name of the amp. I've used some of their RF amps in cable TV stuff, and many of them had internal power supply problems. But they are cheap, and usually work good, so when I buy one, I just go ahead and rework the power supply first.
Since the problem was probably in the amp's internal power supply, there is a good chance a capacitor would have fixed it, but its always better to have a part that works correctly instead of one that has to be "improved" to make it work right.
In my case, with the PICO amps, I can buy them for under $100 each, make them reliable with about $1.50 worth of parts, and they will do the job of a $350 amp. So I go the cheap route.......
As for PICO, not sure what that is, unless you mean the name of the amp. I've used some of their RF amps in cable TV stuff, and many of them had internal power supply problems. But they are cheap, and usually work good, so when I buy one, I just go ahead and rework the power supply first.
Since the problem was probably in the amp's internal power supply, there is a good chance a capacitor would have fixed it, but its always better to have a part that works correctly instead of one that has to be "improved" to make it work right.
In my case, with the PICO amps, I can buy them for under $100 each, make them reliable with about $1.50 worth of parts, and they will do the job of a $350 amp. So I go the cheap route.......
