tweeter speaker power?

Discussion in 'General Electronics Chat' started by sdowney717, Oct 11, 2012.

  1. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    I am repairing some old speakers. Each one has 3 speakers in the case.
    One is the lower range 3.5 inch
    Another is mid range? 2 inch across
    third is a tiny tweeter about 3/4 inch across.

    they look just like this, 4 ohm 200 watt rating Phase III.
    I painted mine walnut color.
    http://www.ebay.com/itm/PHASE-III-M...pt=Vintage_Electronics_R2&hash=item53e9adc5d5

    Anyway the midsized 2 inch speakers have failed due to corrosion and paper cones rotted.

    I was thinking of replacing with these 2 inch unites which I bought.
    http://www.ebay.com/itm/Two-Unites-...er_MP3_Player_Accessories&hash=item257652929b

    Do you think they will substitute ok?
    How does the power rating come in here?
    These ebay speaker look identical, same sized ceramic magnet.
    One of the original 2 inch speakers also has a broken coil wire, and that wire is extremely fine. They did not use braided copper to connect to the cone, just tiny wire from coil direct to the solder lug. I dont see how that tiny wire could carry much power. That wire corroded and broke.
    The original speaker is also completely sealed, no slots on backside.
    The Ebay speakers are more standard with the braid and slotted open steel housing.

    These Phase III speakers have a single bipolar capacitor in series with the negative wire of both tweeter and midrange speaker. The polarity is also reversed from the woofer and the other two.

    Here they are painted. One is missing its 2 inch speaker. The other one I repaired the 2 inch speaker.
    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Oct 11, 2012
  2. Audioguru

    New Member

    Dec 20, 2007
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    The poor quality speakers you found are extremely cheap when new. The 3.5" driver is too small to be a woofer.
    With a 10W to 20W amplifier then the average power is 1W to 2W so they will survive. Of course they will also survive a 100W amplifier if the volume control is turned down.

    The E-Bay 2" speaker is junk but it might work in the cheapo speaker system.
     
  3. sdowney717

    Thread Starter Member

    Jul 18, 2012
    385
    13
    Thanks was thinking they would. These speakers are in the boat. Boat is a sedan cruiser. They sound ok for my purposes. Reason I got into them is I started hearing a rattle sound which turned out to be rust rattling inside the speaker behind the sealed cone.
    One advantage is these are small enough to not get in the way nor be too obtrusive. I have them mounted overhead near the front salon windows. They dont get wet.

    Is there a mini speaker system that has really great sound? something similar size wise.
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    Years ago, RadioShack sold a speaker called the Minimus 7. It had a 4" long throw woofer with a REAL rubber surround and a REAL dome tweeter. It produced 60Hz to 20kHz well and sounded great. It was rated for 40 Whats but the woofer was stamped 5 Watts.

    I had some in my car and some at home. With a 70W amplifier they survived for years before they burnt out.

    Now I have some cheap speakers like yours except the woofers are 4". They are the rear speakers on my home sound system. The much larger front speakers provide most of the sound and these little speakers provide midrange sounds in the back.

    A few months ago I bought a powered speaker system for the small TV in my computer room. It costed $25.00 and sounds great. It has one 5" woofer and two satellite speakers each with two 2" tweeters.
     
  5. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    13
    If I got these
    http://www.ebay.com/itm/Pair-of-2-M...63?pt=Speakers_Subwoofers&hash=item43a7fd01c3

    how would they be wired up?
    Would you use the same bipolar capacitor circuit OR would you join these directly to the input wires as the mini woofer is?

    The way they are wired now is one leg of the tweeter and one leg of the midrange are joined. Then this wire has the bipolar capacitor returning back to the amplifier input negative. Other leg of the midrange and tweeter return back to the amplifier input positive. Mini woof is just wired to amplifier inputs. Also the polarity on the woofer is reversed compared to the midrange and tweeter.


    http://www.bcae1.com/passxovr.htm
    http://www.bcae1.com/capspkr.htm
    reading here you want to block the lower frequencies use the capacitor in series with the speaker.
     
    Last edited: Oct 11, 2012
  6. Audioguru

    New Member

    Dec 20, 2007
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    The new midrange speaker looks good. But its power is rated in phoney "peak" whats instead of real continuous RMS Watts. They say 10 Watts RMS so it might survive continuous 3W. It has low sensitivity but the cheapo tiny "woofer" and tweeter might also have low sensitivity so might be a good match.

    Of course it needs a capacitor in series to block low frequencies.
     
  7. sdowney717

    Thread Starter Member

    Jul 18, 2012
    385
    13
    If you have the low frequencies being blocked by the capacitor, then is the power somewhat dissipated going into the mid and tweeters? If true then it would be less of an issue. I had second thoughts about the other ones I got saying they were only 1/2 watt then perhaps burning up.
    However I wonder is the wattage determined by the gauge of the coil winding?
    The original midrange speakers, those coils the wire was fine as a hair shaft. So could not be very much power but still worked ok for years.

    Wont higher wattage speakers take more power to make the sound. So then the radio will have to turn up the volume put more energy into the speaker?
    I tend to think higher wattage speakers allow for higher volume sound output. Another possible problem, what if the little woofers wont play as well with these better midrange speakers. Meaning the same volume level from the radio with the better midrange speakers will make the midrange quieter than they should sound compared to the original setup.
     
  8. Audioguru

    New Member

    Dec 20, 2007
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    If a capacitor blocks low frequencies then the low frequency power does not go into the midrange and tweeter drivers. Instead all the low frequency power goes into the woofer.

    The power rating of a speaker is determined by the guage of the wire in the coil before it gets too hot and in the amount of movement (excursion) that can occur before damage.

    Higher wattage speakers are better so most of their spec's are better than cheap low power speakers.
    More power means it can play louder when it is fed more power if the sensitivity is the same or is more. A high power speaker does not "take" more power, instead it plays the amount of power it is fed but it is not destroyed by more power (up to its power rating).

    Usually a better speaker is more sensitive so it plays louder than a cheaper speaker.

    I suspect that the cheap little woofers have the same poor sensitivity as the new midrange speakers.
     
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