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I get serious interference and a "whirring" radio noise from my aftermarket radio/cassette stereo. What can I do to fix this! It was suggested that the "Ground in a corvette" was unreliable and that this occured allot. I have checked all my wiring and the ground is at the dash brace next to the console? I would like to put in a whole new unit and CD changer, but if this is what to expect I don't know if its worth investing in. Let me know what you think, Thanks :D
You can get an RCA in-line noise filter and that may help you out. Also, on your new system, make sure you run power down one side of the car, and audio down the other side. Some shops just tape the audio and power wires together, and run them down one side. Sometimes that is the cause of the nasty alternator whine, but not always. Try the inline filter first and see how that helps out. I've got the same problem, and I went and bought a filter, I just haven't installed it yet. I'll let you know what happens .
I found a little help by cleaning the connections on the ground strap located on the antena plate under the rear fender. I took it loose, wire brushed all the connections and reattached - like I say it helped some - AM reception still isn't the greatest.
Mad--there is a way to get rid of radio noise. But it's not easy. I'm still fighting it. The ground is very important. Some say the battery acts as a natural filter, and taking your ground right at the negative post, will reduce the noise issues. This has not been my experience. I've tried a number of different filters, but have had no success.
The only thing I have not yet tried, but is a potential source of noise, is the antenna. Make sure your antenna is grounded.
I've become so frustrated with this noise pursuit, I've considered taking the car in to be sniffed for EMI.
Location: North Royalton, OH "Suppose you were an idiot... and suppose you were a member of Congress... But I repeat myself."
Re: How do I get rid of "Radio Noise" (madmaxgt)
I just installed a Kenwood aftermarket cassette deck and CD changer a week ago, and have not had any problems whatsoever. My power lead is the original yellow wire to the stock radio, my "always hot" wire for station memory and clock is directly to the fuse panel. My ground is the dash brace on the driver's side of the console. My amp is stuffed behind the passenger dash panel and its power is drawn directly from the battery with wiring under the center console. It is grounded to the dash support on the pasenger side. My speaker wires to the rear run down the passenger side. I do have ALL of my original ignition shielding on the car - think that might be making a difference? Not a whir or a buzz on any station or any interference with the CD changer or cassette player.
OK, this radio noise problem has to be defined more clearly, first off forgetabout AM radio reception....it's junk anyway...even IF everything is correct...
second off we need define the source of the noise....the ignition sounds like a lightening strike in an old AM radio ....a rapid cracking sound that varies with engine speed...and it very typical of AM radios....tune one around in your house, if you can find one anymore....listen to a short wave....that will get you a feel for the audio of the ignition interfearance.....if that's the nature of it, your dead....forgetaboutit...you need another front end....
now on the other hand, you can get a whine from the alternator, most typically affecting the power amp rather than signal source, but the head end can also contribute in a reduced manner....
so this alternator whine once again is in the design of the power amp...most cheap amps at say 15 watts/channel have the noise....and only thing you can do is go to Radio Shak and buy an interfearance filter kit, and pray it works well enough to enjoy, it may not...depending.....you can increase the capacity of the filter capacitor across the power line too, try connecting the grounds in differant ways....this will knock out about 90% of the problem....but still that reamining 10-% can be irritating as hell....
I have histerically found that input shielding the wire routing is not a problem source....but that's just ME, in my experiences.....
All higher power amps have what's known as a 'chopper' power supply, this by it very nature increases the voltage available at the speaker terminals, upping the power output available, and in it's operation will remove most if not all that alternator whine....
easiest way to check for alt whine would be to pull the regulator plug outof the alt when car is running, that will kill the alt output, then see if the whine is still there, as opposed to ignition....
just spending money on a stereo unfortunately does NOT guarantee quality of the unit, there are many poopiety unit out there, most built to a price, very damn few built/designed RIGHT.....sorry but this cuts across all brands....except McIntosh, if you can afford it...
I just went through this exercise on my 74. I have a fairly new alternator so wear wasn't a factor there. The stereo consists of 4 4 x 6 Blaupunct speakers in the front and a Bazooka sub in the back. This is powered by two Hi Comp amps rated at 135 watts each. The head unit is an older Blaupunct "Boston" receiver to which I have connected a 12 disc JVC CD changer and a graphic equalizer. All power was drawn directly from the battery and all grounds went directly to the frame in a common area. All stock ignition shielding is in place and the cockpit is completely insulated by aluminum foil faced insulation. I also had an inline noise suppressor on the antenna. I still had a significant problem with whine from the alternator. The way I cured it was to mount a noise suppressor directly connected to the alternator and one suppressor for the radio and another for the amps and CD player/equalizer. This eliminated all of the whine. The suppressor for the alternator is available from Ecklers and I also used the same type for the amplifiers and CD player/equalizer because of the current draw. I used an Accel RFI noise suppressor, which you can get from Jegs or Summit, to suppress noise to the head unit. More detail on the installation is available at my website. Hope this helps you out because that whine can drive you crazy. :crazy:
Re: How do I get rid of "Radio Noise" (78Vette-SA)
Here are the tips and tricks that I have used over the years.
1. Connect all the major power supplies & grounds right to the battery. Use a minimum of 10 gauge wiring. Installing a relay will allow your key to function normally while issolating the radio from the rest of the wiring in the car.
2. If you radio reception is really bad, especially on AM you need to replace your antenna cable, yes they do go bad.
Never put one of those cheap "noise filters" on the supply line to the stereo. A: It doesn't work. B: The resistance limits the output a lot.
Getting rid of noise is not that hard. Here are some key issues:
Positive feed should come directly from the battery. Use an inline, auto stereo, fuse close to the battery. 10 or 12 gauge wire is minimum.
Amp and headunit should feed off the same supply wire. Avoid crimp connectors at all costs. Solder or use a distribution block.
Ground should NOT go to the battery, but the frame. Birdcage usually works, but frame is preferred.
I have no ignition shielding and AM and FM is great. The shielding serves no purpose with modern ignition wires.
Run the power & ground away from other wires. Also run any low-level RCA wires away from anything else.
On mine, the factory loom is on the drivers side. The stereo power & ground goes along the tranny tunnel. RCS goes along the passenger side rocker.
You do need atleast some quality parts to make it work. If the amp says 300W for $29.95, don't hold your breath. It's junk.
However, sometimes even quality amps can have problems. I had a Rockford Punch 6A, and FM was unuaseable. Took a long time before I realized the switching power supply of the amp interfered. Forunately Rockford was great and replaced it with a Power 4a at no cost. They paid shipping back & forth, very friendly. This was even though I bought the amp off ebay. With the Power 4A, all noise went away.
You guys have many different opinions as how to approach the noise problem. The fact is you all probably went through this exercise and, if you were persistent, came up with a tolerable solution...hence your differing solutions.
Let me qualify myself before giving you the straight scoop. I'm an EE from RIT in Rochester NY. Before I started at RIT I worked as a home audio repair technician in Nashville Tenn. for 8 years. As a side duty I also installed high end car audio equipment for the "rich and Famous", (fancy cars). The systems normally cost in the range of $2000 - $6000. You get the idea. I had formal training in the art of eliminating audio noise in cars from Nakimichi as well as referencing other articles on the subject. I never had a car I couldn't tame using these simple techniques:
(GROUND LOOPS CAUSE NOISE!!!)
All power leads should come directly from the battery, ground and +12V. The gauge should be no less than 10awg (multi strand, 50 strand or more). Crimped ends are OK if you have the correct tool otherwise solder or a combination of both is a must. The idea is to make the ground cable have the least electrical resistance from the component to the battery.
Use the best audio cable (the cables with the RCA connectors on it) you can. If you make your own audio cables be sure you use top quality RCA connectors and double shielded cable. Solder all connections. These audio cables are potentially the worst contributor of noise to a system. They connect to all the audio components creating unavoidable ground loops. By making sure these are shielded to the max and making sure the ground cables from each component is large in comparison to the audio cable shielding, the effect will be negligible.
Each unit that requires power must have it's own ground connection. This means if you have a head unit, 2 amps, and an EQ you would require four separate ground wires from the battery (No cheating allowed).
Each unit must have only one ground connection. All amplifiers and auxiliary units (including the head unit) should be mounted in such a way as not to be grounded to the chassis via the mounting hardware. The head unit is a special case. Connecting the antenna will result in a secondary ground connection via the antenna shielding. The last thing to do after the installation is found to be noise free is to attach the antenna to determine what, if any, noise it contributes.
The routing of cables is important also. As a rule of thumb, keep all wiring, speaker wires and power cables especially, as far away from others as possible. Tach and ignition wiring is the worst (EMI everywhere!). Even keeping the power cables close to each other can result in cross coupling (noise) although it should be a low priority at first.
If after all that you still have noise problems, and if you followed the rules there should be very little noise if any, you can use the standard in-line noise filters (they do not degrade the operation in any way as long as the current need by the unit is considered when choosing the filter size.)
Follow these rules and you canít go wrong. Good luck.
Re: How do I get rid of "Radio Noise" (tangee-vette)
My prob is whine with cassette use only. FM and AM is fine. The pitch changes with the rpms. Would the in-line filter help this situation?
Can't hurt and will probaby help.
It will have the most effect if the head unit is powered and grounded directly from the battery as stated above using heavy wire and the filter also uses these same power\ground cables for its connections. The main power wire to the head unit is the only one that would need a filter. The ignition wire has very little current draw and therefore doesn't need filtering.
If you have other componets such as external amps, all bets are off until the system has been properly installed as stated above. Like I said, can't hurt. May as well try the easy stuff first.