Speaker ohms

Does anyone know what the speakers' resistance rating should be for the factory AM/FM/casette in an '88 Cavalier? It's nothing fancy and probably has somewhere around 3 watts/channel.
It works good enough for what I use it for, but the rear 6X9's are missing. I actually have several 6X9's lying around but the ohms ratings marked on them vary from 4 ohms, to 10. The radio itself doesn't have any recommended speaker ohms listed on it. I could take a front one out but they don't come out too easily -- I figured this is probably pretty common knowlege for the guys in here -- like they're pretty much all 4 ohms or something. Or is there even much difference what ohms speaker you run -- 4, 10, etc -- as long as they're not some really high resistance? What would be the consequences of running speakers of different resistance than this low-power amp was intended for?
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radio, lower ohm speakers could destroy your radio.
--
Clive

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On Sun, 3 May 2009 18:44:35 -0700, snipped-for-privacy@webtv.net (James Goforth) wrote:

Probably 4 ohms. But that is a WAG, based on experience. Issue is power, with low performance audio equipment, the maximum voltage for the speakers is about 12 volts, so 12 volts at 4 ohms is 3 watts. Slightly better performance equipment uses about 24 volts (by bridging circuits) giving about 6 watts. Any more, and the equipment must have an inverter to convert the low battery voltage to a high (about 40 to 80 volts) voltage.
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Almost all car audio speakers made today are 4 ohm. Unless you start talking about subwoofers, which can range from 4 ohms to 1 ohm. Anything over 4 ohms is going to require more power from the amplifier, anything less than 4 ohms, unless the amplifier is capable of outputting 2 or less ohms, or is 2 channel bridgeable, is going to cause overheating. Especially on a factory '88 GM cassette deck, trying to drive a speaker at less than a 4 ohm load is going to cause damage to the internal amplifier.
Sharky
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James Goforth wrote:

GM's are typically 10 ohm for standard amp and speakers.
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Paul wrote:

Yes! In the '87 thru '89 models, Chevvy, Pontiac, Olds and 'vette (except for the Bose systems) all used 10 ohm speakers.
If you can't find any inexpensive 10 ohm speakers in the current market, you might hook a couple of 4 ohm speakers in series for each 10 ohm speaker you're replacing. That gives 8 ohms which won't seriously 'overload' the radio's amp. (Don't any of the hot-dog audiophiles come at me with a 'poor damping factor' argument.)
Important note. That vintage of GM sound system used speakers that weren't grounded. If one of the "new" speaker terminals is grounded to the speaker frame, you'll wipe out the radio.
-- pj
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