Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
I just installed my factory AM/FM radio in my convertible. When I got the car there was an aftermarket stereo installed and a set of modern 6x9 speakers. As mentioned by a fellow Docker, and by George at the radio shop where I had the radio fixed, modern car speakers are 4-ohms. The amp in the radio was designed for use with 8-ohm speakers; 4-ohm speakers are hard on the transistors and will eventually damage them.
I temporarily hooked the radio to one of these 4-ohm speakers. Even at low volume there is noticeable distortion, so after a quick test I turned it off.
I'm not keen on soldering resistors in series with the 4-ohm speakers. This ought to work, but half the amp output will be wasted as heat instead of sound, so I'd have to crank-up the volume twice as loud. Installing an amp to isolate the radio from the speakers would be an option, but there is added complexity due to the design of the fader control. George said that he'll be getting some OEM-style 8-ohm speakers in about 3 weeks, and they'll be $35 each.
I have options, but they all involve more time/money/waiting. I guess I'm just frustrated.
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
Thanks for the tip, Snotty!
Anybody know what dimensions the factory speakers should be? Something tells me they should be 4x10 but I'm not sure. Do they bolt right in or should there be mounting ears on the ends? Some !tape replaced the factory dash spkr with (poorly fitted) aftermarket 6x9 before I got the car. The FSM is not helpful, it's hard to climb under the dash of my hardtop with the console, and the other two cars are at my parents' house.
Thanks, Mike <span class='smallblacktext'>[ Edited Fri Jun 08 2007, 08:31AM ]</span>
Joined: Sun Feb 26 2006, 08:46PM
Location: Kingston,Ontario
Posts: 5622
Mike i have even better source---Princess Auto.6X9 for the rear is like $6.99!! Depending on store locations some may stock the front speaker,too. When they are installed,who's gonna know?? Plus they will have that "factory" sound LOL! For the Dockers south of the border,Princess Auto is a large Canadian chain for car and tool junkies alike. <span class='smallblacktext'>[ Edited Fri Jun 08 2007, 08:31AM ]</span>
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
I thought about Princess Auto but assumed all their speakers would be 4-ohms. Do they have 8-ohm speakers? I did find a way to mount a 6x9 under the dash in the front so that would be okay too. <span class='smallblacktext'>[ Edited Fri Jun 08 2007, 08:33AM ]</span>
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
Well if you're planning to use the factory radio, the amplifier will not tolerate a 4-ohm speaker, which is what all modern automotive speakers are.
Another option would be to get two very small (3" diameter?) 4-ohm speakers, make a plate to mount them on that will fit the factory opening, and wire them in series so the total resistance is 8-ohms.
Princess Auto surplus section shows two-way 30W RMS 4-ohm speakers, 3.5" $10, 4" $13 (CDN$). I think this is my new favorite plan.
Mike
<span class='smallblacktext'>[ Edited Fri Jun 08 2007, 08:50AM ]</span>
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
Radio Shack in Canada was sold to Circuit City, and all the stores were rebranded as "The Source". I doubt I'd find anything that still has a Radio Shack or Tandy brand name on it. Can't hurt to ask though. There's a "The Source" store in a stripmall close to me that's been around for a long time, so may have old stock.
Thanks for the link, Rust Hole. The info in the tech section already came in handy. It confirmed that a 4-ohm speaker should measure approx 4-ohms DC resistance with a multimeter, and an 8-ohm speaker about 8-ohms DC resistance. They also warned that many vendors of speakers advertising "4/8 ohms compatible" are actually just 4-ohm speakers, and not suitable for use with old radios.
Princess Auto had some speakers in stock that said "4/8 ohms compatible" so I bought a couple. I cut a small hole in the back of one of the packages so I could test with my multimeter. Sure enough, it measured 4-ohms exactly. Back to the store they will go!
Oh yeah, I'm still wondering, does anybody know what dimensions the factory speakers should be? 4x10? 5x7?