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  • Noitoen
    replied
    From China they mark the goods to sell in Europe with the CE sign drawn a little different and they say, when inquired tha this mean China Export. Maybe 700 W RMS also means something like Real Music Spoiling or S##t

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  • Guest's Avatar
    Guest replied
    Originally posted by 754 View Post
    Why wouldn't you run wires from the theater system, to the garage, then another set of speakers, use the B speakers switch.
    Probably better sound. Yes, I know you need to be able to control the volume..
    I used to run up to about 90 watts when listening to vinyl after work. My big speaker were not hooked up..
    It's really only setup to watch TV/Movies. And if the kids are in there watching SpongeBob or something, I don't want to hear it while I'm in the garage.

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  • 754
    replied
    Why wouldn't you run wires from the theater system, to the garage, then another set of speakers, use the B speakers switch.
    Probably better sound. Yes, I know you need to be able to control the volume..
    I used to run up to about 90 watts when listening to vinyl after work. My big speaker were not hooked up..

    Leave a comment:


  • Seastar
    replied
    It's obvious from the preceding posts that this is a machining forum and not an electronics or audio forum.
    As said before----
    Listen to Jerry!
    He is correct!
    Bill

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  • J Tiers
    replied
    Originally posted by PStechPaul View Post
    Consider what is needed for 720 watts into 8 ohm speaker load. P = E^2/R, so E = sqrt(5600) = 74.8 Volts. RMS. So for a sine wave that is 210 volts P-P. I doubt the power supply has voltage aywhere near that. Maybe if you put eight 8 ohm speakers in parallel, for a load of 1 ohm. Then 700 watts can be 26 volts RMS or 74 volts P-P. That would be 27 amps. I suppose a stereo system with four 8 ohm speakers on each, or a quadraphonic system with 4 ohms on each output, might be possible.

    Actually, true power of about 10 watts is very loud for a typical room or a car. Hundreds of watts are only needed for large outdoor venues like Woodstock, or for car audio competitions.
    You have, for one thing, forgotten speaker efficiency, which is particularly low for small speakers. Small speakers tend to have poor coupling to the air at low frequencies, which is where the power tends to be.

    Big difference between acoustic watts, and electrical watts. Acoustic watts are "volume velocity", and the speaker has to translate electric watts into a mass of air moving. Fairly easy for high frequencies, where wavelengths are small, but hard for low frequencies, where wavelength is quite large, and a lot of air must be moved for significant acoustic power.. At 200hz,wavelength is already 5 feet, much larger than a speaker cone.

    The most efficient speakers tend to be horn type speakers. They act as an "acoustic transformer", matching the impedance of the air to the speaker cone. They are also quite large if they work at low frequency, approaching a wavelength in diameter for good performance. Speaker cones of normal size are not well coupled to the air.

    Then also, you have totally forgotten the dynamics of music. An average level of 10 watts requires a power capability of many hundreds of watts, in order to reasonably cleanly reproduce peaks. Peaks may be 30 to 100 times more power than the average level. If you fail to reproduce the peaks, music sounds distorted and obnoxious.

    For small sized speakers, low efficiency is normal, and amplifier wattage is used to compensate.

    If the LG folks are obeying the rules, their power claims are OK. They are not unreasonable, Class-D makes high power cheap and small.

    As for the wire size.... A design decision, the effects of which are dependent on wire length. The speaker itself has a voice coil wound with very small wire. Obviously the wire length to the speaker has resistance which wastes a certain proportionof the total available power.

    20 gauge wire has about an ohm per 100 feet of length, so a 50 foot length of 20 gauge speaker wire would be an ohm. I suspect the wire to either of the "mid-high" speakers is no longer than perhaps 20 feet, so perhaps as much as 0.4 ohm resistance. The voice coil of a 3 ohm speaker often has a resistance of 2.5 ohms, so it is the largest actual resistance in the circuit, with the largest losses and wasted power.
    Last edited by J Tiers; 11-30-2017, 10:55 AM.

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  • RichR
    replied
    Originally posted by PStechPaul View Post
    Consider what is needed for 720 watts into 8 ohm speaker load. P = E^2/R, so E = sqrt(5600) = 74.8 Volts. RMS. So for a sine wave that is 210 volts P-P. I doubt the power supply has voltage aywhere near that. Maybe if you put eight 8 ohm speakers in parallel, for a load of 1 ohm. Then 700 watts can be 26 volts RMS or 74 volts P-P. That would be 27 amps. I suppose a stereo system with four 8 ohm speakers on each, or a quadraphonic system with 4 ohms on each output, might be possible.

    Actually, true power of about 10 watts is very loud for a typical room or a car. Hundreds of watts are only needed for large outdoor venues like Woodstock, or for car audio competitions.
    If you look at the specifications, they claim Front Speaker Output of 230W x 2 and Subwoofer output of 240W for a total of 700W. So at 230W
    and the 3 Ohm speakers claimed in reply #27 you're at about 26 Volts RMS.
    Last edited by RichR; 11-30-2017, 11:32 AM. Reason: Spelling

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  • Guest's Avatar
    Guest replied
    My dedicated home theater has four Marantz MM7025 which together provide 8x 140W channels. I'm only using 7 of those 140w channels for the center/2xleft/2xRight rear and side surround speakers. I also have two 12" subs at <= 200hz each powered with their own 200W amp. I had to install a 20A dedicated circuit. She's definitely lots of fun, but definitely over kill as we typically don't need to drive her more than 20% to get the most earth shaking, spine tingling, hair raising, goose-bump exploding experience you can imagine.







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  • Forestgnome
    replied
    My Carver is 650w/ch rms. Yes, there is such a thing as rms watts. The input power consumption is specified as 1500w at full power. Must be pre-CE rating system. I'd bet good money this stereo can't stand up to mine in a bass contest.

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  • wierdscience
    replied
    Come on man,go full AVE on it and show us what's inside!

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  • Guest's Avatar
    Guest replied
    Originally posted by PStechPaul View Post
    Consider what is needed for 720 watts into 8 ohm speaker load. P = E^2/R, so E = sqrt(5600) = 74.8 Volts. RMS. So for a sine wave that is 210 volts P-P. I doubt the power supply has voltage aywhere near that. Maybe if you put eight 8 ohm speakers in parallel, for a load of 1 ohm. Then 700 watts can be 26 volts RMS or 74 volts P-P. That would be 27 amps. I suppose a stereo system with four 8 ohm speakers on each, or a quadraphonic system with 4 ohms on each output, might be possible.

    Actually, true power of about 10 watts is very loud for a typical room or a car. Hundreds of watts are only needed for large outdoor venues like Woodstock, or for car audio competitions.
    I forgot to mention the speakers said 3 ohms on the back. I was a little surprised by that and the tiny gauge speaker wires.

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  • Hopefuldave
    replied
    I was dragged out a few years ago by the Students Next Door (I had the car...) to see Dillinja with the Valve Sound System - 30kw of *VALVE* amplified Drum n' Bass, trouser-flapping bass and earplugs handed out on the door The equipment racks were quite impressive, and they didn't need the heating turned on in the hall...

    Dave H. (the other one)

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  • tomato coupe
    replied
    Originally posted by PStechPaul View Post
    Actually, true power of about 10 watts is very loud for a typical room or a car.
    Yep.

    Hundreds of watts are only needed for large outdoor venues like Woodstock, or for car audio competitions.
    The original Woodstock sound system was around 12,000 W. The Grateful Dead's "wall of sound" was more than double that.

    Leave a comment:


  • PStechPaul
    replied
    Consider what is needed for 720 watts into 8 ohm speaker load. P = E^2/R, so E = sqrt(5600) = 74.8 Volts. RMS. So for a sine wave that is 210 volts P-P. I doubt the power supply has voltage aywhere near that. Maybe if you put eight 8 ohm speakers in parallel, for a load of 1 ohm. Then 700 watts can be 26 volts RMS or 74 volts P-P. That would be 27 amps. I suppose a stereo system with four 8 ohm speakers on each, or a quadraphonic system with 4 ohms on each output, might be possible.

    Actually, true power of about 10 watts is very loud for a typical room or a car. Hundreds of watts are only needed for large outdoor venues like Woodstock, or for car audio competitions.

    Leave a comment:


  • 754
    replied
    I am not getting one..
    Guess I am just going to be stuck with my Sansui BA 3000 and CA 3000 amp set..
    I will suffer through it.
    I suspect one of my transformers weighs more than the speakers in the pic.

    Leave a comment:


  • Paul Alciatore
    replied
    Yea, and go to the lumber yard and find a piece of lumber that measures an actual 2" x 4". Or a piece of plywood that is actually 3/4" or 1/2" thick.

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