Audio Cutting Out
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Joined: Mar 2016
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From: Scottsdale Arizona
Audio Cutting Out
I have a 1968 C3 with a 283 small block. I installed a new radio (old Panasonic worked well, but was beat-up). Now the audio of my radio plays perfectly when the engine is off (same for MP3) but when the engine is running, the audio cuts in and out a lot (same for MP3). I installed first a new RetroSound and then (thinking the radio was bad) a Classic Car Stereos "Corvette" Radio. Same problem with both radios installed! Problem is not AM/FM related as the MP3 also cuts in and out. I replaced the old distributor with a new HEI, no change in the problem. All spark plug wires have been replaced as well. I went so far as to double ground the radio chassis and all ground wires. Then, I wired the radio directly to the battery (both + and -). Nothing has changed the problem. There is no interference noise at all, just the audio cutting in and out. And, again, it is only when the engine is running. HELP!
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From: Southlake, TX
Le Mans Master
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
If it's (radio) not loosing power- lights turning off- but just audio output- not dependent on the source and two different headunits- you need to check your speakers.
The new radios you describe can't see ( or rather don't like) a ground on the audio output- or a "common" ground between the front & rear speakers.
If it is happening at low volume- then's it more than likely the wiring- at higher volume- could be the speakers-tensile leads hitting the basket or metal frame of the car- maybe even a bad voice coil.
I'd disconnect the speakers and try one at a time- and see what happens.
Richard
The new radios you describe can't see ( or rather don't like) a ground on the audio output- or a "common" ground between the front & rear speakers.
If it is happening at low volume- then's it more than likely the wiring- at higher volume- could be the speakers-tensile leads hitting the basket or metal frame of the car- maybe even a bad voice coil.
I'd disconnect the speakers and try one at a time- and see what happens.
Richard
Le Mans Master
Joined: Mar 2001
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From: Lincoln, CA
I was having an issue when I step on the brakes the stereo would turn off.
I complete redid the wiring to address the issue. Ran Power and ground directly to the battery. Also ran the accessory power to the battery.
The yellow wire then connects to a relay which get it's signal from the factory accessory wire. This solved all my issues.
I complete redid the wiring to address the issue. Ran Power and ground directly to the battery. Also ran the accessory power to the battery.
The yellow wire then connects to a relay which get it's signal from the factory accessory wire. This solved all my issues.
Team Owner
Joined: Jan 2006
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From: Crossville TN
C3 speaker are grounded to chassis ground at [-] terminals. For most modern amps/heads, the speaker wires are NOT grounded to the chassis; they are just [+] and [-] wires coming from the amp/head.
I suspect that is where you are having your problem. Or, as mentioned above, you got power from the stock power wire and it does not have enough current carrying capability for bass with the new system. Try turning the volume and bass levels down and drive the car again. If the same thing happens, it does not have to do with the power supply wire. If you do not have the same problem, run power directly from battery or BATT connector on the fuse panel, with a fuse built into that wiring.
I suspect that is where you are having your problem. Or, as mentioned above, you got power from the stock power wire and it does not have enough current carrying capability for bass with the new system. Try turning the volume and bass levels down and drive the car again. If the same thing happens, it does not have to do with the power supply wire. If you do not have the same problem, run power directly from battery or BATT connector on the fuse panel, with a fuse built into that wiring.
Le Mans Master
Joined: May 2003
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From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Guys- he's wired to the battery...he needs to check the speakers....
Last edited by Richard454; Aug 30, 2016 at 12:13 AM.
Cruising
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I struggled for several months with this topic until I finally managed to solve it. My two old radios (Blaupunkt and Kenwood) never had a issue, but the Retrosound unit was cutting out the audio every few seconds.
The things I did try which helped:
*Make clean 12Volt ignition switched power source by relay from battery power (as described in the Retrosound troubleshooting manual)
*Install ferrite core to USB cable at the point where it enters the radio housing
This made the radio work most of the time, however at idle and with the car at operating temp, I still had intermittent audio cutting out.
Final solution suggested by Retrosound was to retard the HEI ignition timing from 14 degree advance to 10 degree (to reduce spark gap between rotor and cap @ HEI).
This worked but the car idled like crap and was low on power.
So I choose to install the display extension kit from Retrosound and put the headunit behind the seats into the storage compartment - away from the HEI distrubutor RF-noise. Now I can use 14 degree advance AND listen to the radio all day without audio cutting out.
Maybe you are lucky and get away with a new rotor, cap, coil, spark plug wires, ignition shieldiing and spark plugs gapped @0.35".
The things I did try which helped:
*Make clean 12Volt ignition switched power source by relay from battery power (as described in the Retrosound troubleshooting manual)
*Install ferrite core to USB cable at the point where it enters the radio housing
This made the radio work most of the time, however at idle and with the car at operating temp, I still had intermittent audio cutting out.
Final solution suggested by Retrosound was to retard the HEI ignition timing from 14 degree advance to 10 degree (to reduce spark gap between rotor and cap @ HEI).
This worked but the car idled like crap and was low on power.
So I choose to install the display extension kit from Retrosound and put the headunit behind the seats into the storage compartment - away from the HEI distrubutor RF-noise. Now I can use 14 degree advance AND listen to the radio all day without audio cutting out.
Maybe you are lucky and get away with a new rotor, cap, coil, spark plug wires, ignition shieldiing and spark plugs gapped @0.35".
Thread Starter
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Joined: Mar 2016
Posts: 86
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From: Scottsdale Arizona
Thanks for your suggestions on this. I will institute your ideas if my fix ends up failing ...
I have found a solution that seems to have worked. Oddly, it was not due to any type of RF interference. It appears that the voltage fluctuates just enough in these old cars that modern (sensitive) radios will cut out. They can't handle the fluctuations well. In my car's case, I have a voltage fluctuation that drops from the needed 12V to 13.6V. That was causing my new radio's audio to cut out when the previous older (less sensitive) radio worked well.
The fix? My sound technician made me an in-line resistor board with 10 diodes that mitigates the fractional voltage drop that is occurring and viola, problem solved!
I have found a solution that seems to have worked. Oddly, it was not due to any type of RF interference. It appears that the voltage fluctuates just enough in these old cars that modern (sensitive) radios will cut out. They can't handle the fluctuations well. In my car's case, I have a voltage fluctuation that drops from the needed 12V to 13.6V. That was causing my new radio's audio to cut out when the previous older (less sensitive) radio worked well.
The fix? My sound technician made me an in-line resistor board with 10 diodes that mitigates the fractional voltage drop that is occurring and viola, problem solved!
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Melting Slicks
Joined: Mar 2005
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From: Midlothian VA
Possible bad fuse - fuse wire can break from the end of the cap but still touch yielding a complete circuit until it either gets hot and pulls away from the cap OR (possibly in your case) is wiggled away from the cap due to vibration (engine/road). Had one like this - tested fine with a ohm meter every time. But finally I pulled it out and the cap simply slipped off.
New fuse solved my problem.
New fuse solved my problem.