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Thread: Radio- speaker question

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    Default Radio- speaker question

    I have a 73Z with the orginal radio. As you know it only has one speaker hooked up in the back. I was wondering if I can hook a 2nd speaker up to the radio. I want to add a 2nd speaker in the back on the other side. Will this work and how would I wire it?

    I don't want to add a different sound system just the 2nd speaker.

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    you will need to put a cross over transformer in before the speakers to ballance the impeadence at the output of the radio, works like a splitter if you will. I would also reccommend you replace the original speaker with a new set of speakers to insure the speakers are ballanced as well.

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    Agreed. Don't simply hook up two speakers to the stock radio, you can (will?) damage the radio. Extra circuitry as described by the previous post is required.

    As for using better speakers back there instead fo the very rudimentary stock unit, you need to use a fairly shallow depth speaker. I used a pair of poly-cone 5 1/4" Kenwoods in mine. Don't worry about co-axial speakers with separate tweeters and such - the stock radio doesn't have the ability to make those sound much better than a single-cone.
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    Thanks, Can I get a cross over transformer at say Radio shack?

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    Don't OVER complicate the simplest of issues. You do NOT need the additional circuitry if you do things right.

    This has been covered before, has been done NUMEROUS times, and the answer is really bone simple. It's all in the wiring of the TWO (again TWO) speakers. Instead of Series wiring, you wire in parallel, this changes the load on the radio properly.

    Bottom line, use TWO 8 ohm speakers, Monaural, 5-1/4" (Ideally should be 5-1/8", but good luck finding that), and no more than a 10 watt rating is more than sufficient. Wire them in parallel, i.e. + to + on each speaker and - to - then the OEM wiring direct to one of the speaker terminals.

    See these 3 other posts:
    http://www.classiczcars.com/forums/showthread.php?28953

    http://www.classiczcars.com/forums/s...arallel+series

    http://www.classiczcars.com/forums/s...arallel+series

    Don't expect Blaupunkt type of sound, but more along the line of the "free" el-cheapo give away radio you can score out of a gumball machine... just a tad louder. The OEM radio had 3.5W of power with a THD of 10% into a 4 ohm speaker with a very light magnet... as yoiu can imagine, it's by no means the equivalent of an iPod.

    Don't turn the volume all the way up (even with just ONE speaker) and you'll be fine. I've had this setup in my car for the last 10 years and have always been able to enjoy "stereo"...

    FWIW
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    This is all correct, I assumed the stock speaker was an 8 ohm, my bad.
    Last edited by 5thhorsemann; 10-21-2011 at 10:40 AM.

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    Thanks

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    I am having a problem finding 8 ohm speakers They all seem to be 4 ohm. Advise?

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    Not trying to be "cute" but... keep looking?

    Radio Shack, your local Audio Shop, Wal-Mart, just to name a few places. I've even found 5-1/4" speakers in hardware stores, Lowe's, Home Depot, True Value, Ace, again, you just started today.


    But don't, as in DO NOT hook up two 4 ohm's in series or parallel as that will more than likely cause problems.

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    Crutchfield? Critchfield? Something like that.............

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    You can connect 2 4-ohm speakers in series. This will result in an 8-ohm load which will not damage the radio. It will reduce the total power output but the acoustic output of 2 speakers is better and will offset it some.

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    Speakers are inductive loads, not resistive loads, the speakers will sound like crap in series, you need the crossover to run two 4 ohm speakers and get any kind of sound quality.

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    Beerman, read the WHOLE post and you'll see why your answer... while technically correct, if the question were just, how can you equate an 8ohm speaker with two 4 ohm speakers, is TOTALLY WRONG for this application. (And some audiophiles will still discuss the HOW you connect in series as being important not only in circuit but also in acoustic response.)

    In this case, your "fix" is actually the WORST thing you can do for that radio. You're essentially DOUBLING the speaker rating.

    We're dealing with a 40+ year old radio that used technology and components probably 50 or so years old by now, with ratings of 4 Watt, 10% THD, and designed to use ONE 4 ohm speaker.

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    Checked today, Radio shack. Car Toys, Wallmart. and another local stereo shop. The only 8 ohm speakers avail are woofers all of the others are 4 ohm. So What do I have to do to use 4 ohm speakers?

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    Last edited by EScanlon; 10-22-2011 at 04:28 PM.
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    I agree that a series connection is not ideal but since 8-ohm speakers don't seem to common any longer it is a workable option. It will not hurt the radio. The worst problem will be the decoupling of each speaker from the output of the power amp and therefor soft bass. Does that really matter here?

    Another option is using a 4-ohm resistor in series with each 4-ohm speaker and then paralleing the pair, resulting in a 4-ohm load on the radio. The bass will still suffer a bit however.

    A better solution might be using a "booster" amp that is designed to be driven by the speaker output of the radio. This will present a suitable load to the radio and isolate the radio from the speakers allowing the possability of more power and tolerance to a 2-ohm load. The booster amp could easily be hidden under a seat or in the dash to preserve the factory look.
    Last edited by beermanpete; 10-22-2011 at 11:58 PM.

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    Once again, the radio is designed to supply an INDUCTIVE LOAD. The crossover is an inductive load that modifies the output to support multiple inductive loads, they cost like $20.00 and are the size of a pack of cigarettes. Doing things rite the first time saves time and money, and in this case the original radio.

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    Quote Originally Posted by 5thhorsemann View Post
    Once again, the radio is designed to supply an INDUCTIVE LOAD. The crossover is an inductive load that modifies the output to support multiple inductive loads, they cost like $20.00 and are the size of a pack of cigarettes. Doing things rite the first time saves time and money, and in this case the original radio.
    Not exactly. The radio is designed to tolerate a reactive load. How does connecting the speakers in series change the load to a non-inductive or non-reactive load?

    The "crossover" is not a crossover anyhow, it is a transformer which matches the impedance of the load to the source. When transformers are used in their linear range (as it would be for this application) they will not add or subtract any reactance, the reactance of the load is simply presented to the source in its normal form but with the magnitude altered according to the transformer's turns ratio.

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    Quote Originally Posted by beermanpete View Post
    Not exactly. The radio is designed to tolerate a reactive load. How does connecting the speakers in series change the load to a non-inductive or non-reactive load?

    The "crossover" is not a crossover anyhow, it is a transformer which matches the impedance of the load to the source. When transformers are used in their linear range (as it would be for this application) they will not add or subtract any reactance, the reactance of the load is simply presented to the source in its normal form but with the magnitude altered according to the transformer's turns ratio.
    Wa-WHAT? It's caled a "CROSOVER" because it "crosses over" the load. The transformer keeps the inductive load "stable" when highs and lows of music signal pass through the coils of the speakers. That little resistor you see on the back of the speaker is there to compensate for heat buildup in the coil of said speaker, in parallel, to provide for the reactive inbalance.

    If you take two 8 ohm inductive loads in parallel, they effectively form one inductive load of of under 4 ohms, depending on signal intensity and strength, not like a set of resistive loads which will devide themselves in half over the circut. If you place succesive inductive loads in series the resistance will degrade with each load as the magnitute of the power source deminishes through the previous load or device. This is the reason you can not wire unregulated alternators (AC generators) in parallel or series. The back feed voltages become circuit fatal to the individual devices over time. Of course all this depends on the intensity of the power generated, again we are talking 4 watts. We are however talking a 40 some odd year old radio that will be a PITA to replace.

    Buy the C/O and be happy.
    Last edited by 5thhorsemann; 10-23-2011 at 06:30 PM.

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    I think beerman's onto something. Feed the output of the radio into both the L and R channels of a booster/equalizer doobob. Here's the thing: SOME of them have pseudo surround -- basically a button you can hit to introduce some very minor reverb that will give the sound some pseudo-stereo "presence." You can output to 4 speakers (2 up under the dash). Because you're not actually loading the radio (much), the sound will be somewhat less crappy/distorted than if you were driving a speaker. Yeah, that's what I'd do (if preserving the original radio is important, that is).
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    I like the sound of that. If I hook the radio up to an equalizer, speakers into the input, I can then hook up two 4 ohm speakers to the output of the equalizer. And just to be sure this would not hurt the radio?

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    As long as the equalizer accepts an amplified input signal, it would work.

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    In Case anyone's interested I did find 8ohm speakers check out these sites
    http://www.turnswitch.com/speakers.htm
    http://www.skycraftsurplus.com/5-14r...vespeaker.aspx I bought the cheap one. Thanks to everyone for the help. Escalon, I appreciate your input.

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    Like Escanlon said, yes, it will work fine. In fact it will work better than just a speaker.

    Look for an equalizer/amplifier with "surround sound" effects, like this preamplifier has:

    http://notebooknerds.com/sony-xdp-u5...-audio-system/

    That will give the monaural sound a certain "liveliness" that will simulate stereo/quad. And THAT is probably as much as you can make out of a low-power monaural output.

    (Just to be clear, you need an amp, not a pre-amp, so you have to keep looking. This unit won't do what you need. I just has the effects you need.)
    Last edited by FastWoman; 10-25-2011 at 08:23 PM.
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