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AM to AM Radio Upgrade
https://slantsix.org/forum/viewtopic.php?t=48935		 Page 1 of 1
Author:  FrankRaso [ Tue May 29, 2012 8:21 am ]
Post subject:  AM to AM Radio Upgrade
The original AM radio in my 65 Barracuda needs a rebuild or a least a good cleaning. I think money would be better spent sending it Tayman Electrical (or someone like him) for an AM/FM conversion.

However, I haven't quite decided on how best to install additional speakers and an MP3 player so I'm looking for a cheaper and quicker upgrade for the time-being. I noticed that my 1973 Dart also has an AM radio with similar physical configuration. Last night, I tried it out and it seems to fit nicely, including the faceplate. The most obvious external difference is that my 73 radio has black push buttons while my 65 radio has chrome. A less obvious difference is that the numbers are placed higher on the display of the 73 radio, which may make them a bit harder to read. At least the red (power) and orange (lights) wires on the 73 radio correspond nicely with my underdash wiring.

There is a slight difference in the speaker wiring and I thought I would check a few things before powering it up:
  • The speaker leads for my 73 radio have green (female terminal) and black (male terminal) wires. Does the green wire (positive?) connect to the larger spade terminal on my speaker?
  • What should the resistance of my speaker be (across the terminals) for the radio to work properly?
Author:  Mroldfart2u [ Tue May 29, 2012 9:04 am ]
Post subject:  Re: AM to AM Radio Upgrade
Quote:

There is a slight difference in the speaker wiring and I thought I would check a few things before powering it up:
  • The speaker leads for my 73 radio have green (female terminal) and black (male terminal) wires. Does the green wire (positive?) connect to the larger spade terminal on my speaker?
  • What should the resistance of my speaker be (across the terminals) for the radio to work properly?
Yes that SHOULD be correct... Larger of the 2 is normally positive. A way to test and be for CERTAIN can be done. But the speaker needs to be out of vehicle so you can see the cone. If needed I will post it... USUALLY earlier OEM car radios are rated for 8ohm speakers. You can check this with an multi meter set to ohms... It will read 6 ohms or so for an 8 ohm speaker (due to impedance and resistance values thats what it comes out to) and if its a 4 ohm speaker will register about 3 ohms.... Hope this helps...
Author:  FrankRaso [ Tue May 29, 2012 9:51 am ]
Post subject: 
I'd rather not pull the speaker if I can avoid it. Is there an obvious difference in sound if the speaker is hooked up backwards?
Author:  Mroldfart2u [ Tue May 29, 2012 10:13 am ]
Post subject: 
Quote:
I'd rather not pull the speaker if I can avoid it. Is there an obvious difference in sound if the speaker is hooked up backwards?
No... and to be truthful i have never seen any damage done to OEM styled radios by hooking the speaker up 'backwards'.... Maybe a true audiophile could decern the difference in sound but I cant...
Author:  KBB_of_TMC [ Tue May 29, 2012 10:56 am ]
Post subject: 
The '65 baracuda the Tidewater Mopar Club restored a few years ago was missing its original radio & speaker. We put in a new AM/FM/CD (after welding up and recutting the mangled hole in the steel dash) and found that a 6x8" 8ohm speaker up front fit just fine (protecting it with stretched black cloth) and its mate & cover fit the rear defroster hole perfectly (we were missing the rear defroster anyway). We also put a direct-fit electronic voltage regulator in place of the old electromechanical unit. Most of the other Mopars the club has restored required an odd size speaker under the dash; that one was the exception. Sometimes we could get a custom stereo underdash speaker; 2 smaller speakers mounted on a plate to match the original mounting.

Some of the original speakers I've seen had one side obviously grounded, but all the aftermarket ones I've seen have the coil isolated from ground, so polarity doesn't matter except for the relative phasing between speakers.
Author:  FrankRaso [ Tue May 29, 2012 11:31 am ]
Post subject: 
I did a quick search and found that the difference is that cone of the speaker pushes OUT with correct polarity and pulls IN with reversed polarity if a 1.5V battery is momentarily connected to the terminals (+ to + and - to -).

It probably doesn't make any difference with a mono-speaker but reversed polarity with one of a pair of stereo speakers could cause poor sound from sound wave cancellation.
Author:  emsvitil [ Tue May 29, 2012 12:24 pm ]
Post subject: 
Quote:
I did a quick search and found that the difference is that cone of the speaker pushes OUT with correct polarity and pulls IN with reversed polarity if a 1.5V battery is momentarily connected to the terminals (+ to + and - to -).

It probably doesn't make any difference with a mono-speaker but reversed polarity with one of a pair of stereo speakers could cause poor sound from sound wave cancellation.
Mono doesn't matter.

Stereo doesn't matter if both are wrong or both are correct.

Cancellation is possible if 1 is wrong and 1 is correct.
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