I guess its a little OT, but the stereo in my 51 Chevy is acting weird. When the car is off it sounds amazing, but once I start the car it sounds very crackly. But it doesn't always do it, just most of the time. Here are the specs: pioneer head unit Boston acoustic 6 1/2 speakers front and back Fosgate subs Orion amps Monster cables The car has a 350 v8 with a new alternator and battery. It's carbureted with an HEI ignition. Why would it sound so bad when the car is running? The amp feed and constant power for the head unit are off the battery. The switched power is from the ignition switch, and ground is tied in with the windshield wiper ground. Any Ideas? Thanks!!
Antenna issue (radio) cheap Audio Cables (to amp) Mis Matched Spark Plugs/Coil Bad Ground (To amp, head unit, or both) Poor routing of audio power wiring, or audio cables or both Bad antenna ground any number of other issues up to and including a bad Head unit. Not likely the head unit, but a possibility, nonetheless. Also, Might want to clarify "Crackly" a little bit better. Maybe from ticking at RPM, or whining with RPM sensitivity, or just poor radio reception, or some other help.
A constant whine would more likely be the alternator...but you say it's not always present when running. Did your old alternator have anything the new one doesn't, like a condenser/capacitor wired to it?
It does it on any input, radio iPod cd etc. the old alternator is the same 3 wire mind I have now. All the audio wires are routed up the door post and A pillar. The power for the amp is along the floor. The sound is a crackle, Almost like a blown speaker, but I have tried different speakers and it's not that.
The list that Scottrod wrote pretty much covers everything, but I would add something to that list I ran into when I worked in the car audio/alarm field. Old ford trucks have the main power wire to the ignition switch routed above the radio. These trucks had the same symptoms that youre describing. We would cut the main power wire and re-route it to the floorboard as far away from the head unit as possible, fixed the problem every time. This may or may not help, but worth a try. I dont know where the main power in your car is; but in my 54, I believe it is run pretty close to where the radio is installed. If the main power to the switch is similar to the 54 you could possibly disconnect it at the switch and run a temporary wire away from the head unit to see if it helps. You would need to disconnect the other end also, leaving the original main power as just an extra dead wire while you try to figure it out. Also something to consider is the routing of the battery charging wire coming from the alternator, it may need to be re-routed also. Hope this helps.
Not to hijack the thread, but what are the thinnest gauge wires I can run from an overhead console unit to the speakers and power? I need to feed the whole lot down through a very small space in the chopped window pillar on a model A.
Depends on how loud you like your music. If it's just a normal low power stereo, you should be able to get by with #20 for power and #22 or possibly smaller for the speakers. The heavier the wire, the less voltage drop, and less chance for things to go wonky. I'd suggest wiring it up out of the car first, and make sure it works ok running from the battery before installing it.
Thanks. I guess I should also check on the existing gauges coming out of the back of the unit. Worse case, I could use thinner wires for only the 15" or so needed to drop down through the windshield post and clear the dash mount,larger gauge for the rest. However, then I have to count on my splices to be nearly perfect.
You said amps, do you have one on the midrange as well? It could easily be a bad ground on the amp or even the radio. Not sure how new your headunit is, but if it happens to be a DVD player, I wouldn't put it past Pioneer to have a signal noise issue. The Pioneer DVD players in the last few years have been pretty lousy, I'll never install one for a customer again. Not to argue with Squirrel, but I really don't recommend running anything less than 18 gauge for speaker wire, depending on how far and where you're running it of course. Just my $.02
He asked what he could get away with....you can get a decent amount of sound thru some rather skinny speaker wire, if you try.
Yeah, but it just seems to me like it's asking for trouble down the line, be it getting kinked in a door jam or being subjected to engine noise. That's just me though, I'm a bit of an audiophile. I tend to run 12 gauge for door speakers, but I'm also pumping 120RMS+ through each of them.
Well, here in the normal world, we can get away with using the crappy tiny wires they used to include with speakers. I only paid $3.99 for my HDMI cable, too
I only have 1 amp. its under the front seat. The Pioneer is about 4 years old. No DVD player. I have an Eclipse head unit I can swap in if need be.
Also... you want to make sure you run your power wires perpendicular (or a good distance apart) to your speaker/rca wires.... if you run them parallel they'll pick up feed too!! We always ran the power wire on the drivers side and the speaker wires on the passenger side, Most all the wiring that goes to the rear runs down the driver side. This was on new vehicles.
Clean up the grounding points and reattatch your wires. Don't ground anything on the wiper wiring. Run all your RCA inputs away from any power sources. Make sure that all your power sourced wires are on the opposite side of the floor. Install a capacitor/noise filter on the battery supply wire from the ign switch. Don't tie all your grounds together and don't directly ground the speaker wires. The neg. from the speakers will ground through the head unit leads they attach to. Best case to solder all connections. Your problem is a corrupted ground or interference. Since it only happens when the engine is running but doesn't change in pitch or volume most likely it is not ignition signals or amplified noise. That leaves your grounds or noise picked up by the cables. Some of the best speaker wire made is cat 5 muti-stranded cable. Home audiophiles use it for high end vacuum tube amps. It works well for most uses except driving woofers. Also regular twin zip cord [your extension cords] works good too.
What value should the capacitor be for the noise filter? I have a bunch of caps laying around from building tube amps. Seems like a cap to ground would act like an amplifier filter cap.
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