max watts per channel UMBP?

Discussion in 'MacBook Pro' started by Kronie, Apr 29, 2009.

  1. Kronie macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #1
    Can anyone tell me how many watts per channel my macbook pro can push out through the audio card and the 1/8th jack?

    I'm going to wire up two JBL rear surrounds as laptop speakers. There 50 watts continuous and 300 watts peak. 8ohms.

    I should be fine, right?
     
  2. Skika macrumors 68030

    Joined:
    Mar 11, 2009
    #2
    i am not sure but i think the macbook only outputs the sound that is not amplified. I think you will need an amplifier.
     
  3. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #3
    I called Apple they told me 10 to 15 watts per channel. I'll try it and see what it sounds like.
     
  4. Teej guy macrumors 6502a

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    Aug 6, 2007
    #4
    The audio out jack is just an un-amplified line-level output...I doubt the information they gave you is correct.

    Maybe they misunderstood the question...maybe I'm wrong, who knows.
     
  5. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #5
    It HAS to be amplified. How does it push the speakers in a pair of headphones or a small pair of laptop speakers? I'm sure the whatever signal gets pushed to the MBP speakers also gets pushed to the 1/8th jack. Well, really that's just a guess. Here is to hoping.
     
  6. Consultant macrumors G5

    Consultant

    Joined:
    Jun 27, 2007
    #6
    LOL. Headphone outputs cannot drive real speakers without amplifiers.

    You need an amplifier for those speakers you have.

    Some good ones are:
    - Onkyo
    - Harmon kardon
     
  7. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #7
    I have an Onkyo and yes its a great amp, I stream music to it downstairs.
    The ones I'm going to try using are NOT big speakers there small rear surrounds that I'm not using downstairs.

    If the MBP is truly 15 watts per channel, I might be OK. Ill let you know how it turns out......

    Well let me just say this works perfect!! It sounds sweet!! Surprising bass for 4" woofers. I actually had to tone the bass down in the EQ it was distorting the speakers.

    I don't know what that 1/8th jack pushes for watts but it HAS to more than 15. It has to. If I crank both the volume in Itunes and OSX its actually too loud. It pushes these JBL's with no problems:

    [​IMG]
     
  8. The General macrumors 601

    Joined:
    Jul 7, 2006
    #8
    Hahaha, that's the amp that powers the laptop's built-in speakers. The headphone jack puts out enough to drive headphones, maybe little tiny speakers ...

    The reason you can hear sound coming out of those speakers is it either:

    1. Travels through this Onkyo you say you have and gets amplified.

    or

    2. The speakers have built-in amplifiers.
     
  9. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #9
    Neither.

    I'm telling you the mini jack is amplified and by quite a bit.
     
  10. sycho macrumors 6502a

    sycho

    Joined:
    Oct 7, 2006
    #10
    It wasn't the speakers distorting, it was the lineout amplifier that was distorting. Everyone else is correct in saying that it is only meant for line out or for headphones. It is probably only about 1V output RMS, 1V through 8ohms is 125mA (V/I=A), which in total would be about 125mW (V*A=P). Add on top of that that the output isn't really meant to drive low impedance loads and you have got a whole bunch of problems.

    Basically, you are being very foolish to use the un-amplified output to directly drive speakers.
     
  11. The General macrumors 601

    Joined:
    Jul 7, 2006
    #11
    LOL, I don't know what to tell you, man. You're just wrong. You're not correct. The headphone jack is not powering your speakers to a point where they're "too loud" ... it's not happening.

    The speakers are powered, or you don't realize you have them plugged into your Onkyo.
     
  12. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #12
    So, what would be my "whole bunch of problems"?

    I ask because this really sounds great in my office.....but I don't want to blow anything on my laptop.

    What about a some type of headphone amp?
     
  13. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #13
    Well, your right. I guess my my amp that's two floors down in the living room is powering the satellites in my office upstairs. I'm glad you could clear that up for me.
     
  14. The General macrumors 601

    Joined:
    Jul 7, 2006
    #14
    Then the speakers are powered. What is the model number of your speakers? And what kind of cable did you use to plug them into your headphone jack?
     
  15. J the Ninja macrumors 68000

    Joined:
    Jul 14, 2008
    #15
    Does anybody even make passive speakers that use 1/8in jack to connect to the power amp? If he can plug them into his headphone jack without cutting off the end of a cable, they are almost certainly self-powered.
     
  16. sycho macrumors 6502a

    sycho

    Joined:
    Oct 7, 2006
    #16
    How about some sort of amplifier in general? Just goto a thrift store and buy a stereo amplifier, the sound will be much better then. Like I said, the line-out is not meant for driving low impedance loads, that is why you had all that distortion when the bass was up.

    The speakers are not powered. There would enough voltage output to make it audible, but not before the line-out was clipping.
     
  17. The General macrumors 601

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    Jul 7, 2006
    #17
    He said with the volume all the way up it's "too loud" ... now, unless he has ridiculously sensitive hearing, there's no way it would get anywhere near "too loud."
     
  18. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #18
    Well, I called apple and talked to two different tech's that couldn't tell me the headphones jack output. They did say that running the speakers will not in any way hurt my MBP, which is all I care about really. They said "go for it".

    I guess it could possibly hurt the speakers? As long as nothing is distorted things should be fine. The line out may NOT be meant to drive unpowered speakers....but it is and its working great. I understand that's not what Apple had in mind but with a quick adjustment in the EQ it sounds just fine.
     
  19. The General macrumors 601

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    Jul 7, 2006
    #19
    HELLO, SIR. WHAT CABLE ARE YOU PLUGGING THEM IN WITH? ALSO, MAY I HAVE THE MODEL NUMBER OF YOUR SPEAKERS? THANK YOU.
     
  20. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #20
    There JBL E10. Rear surrounds.

    I'm telling you NOT POWERED.

    See for yourself. go buy one of these:

    [​IMG]

    And cut the RCA ends off. Separate the wires and wire into some small speakers. (make sure you dont mix up + and -)
    What's that you hear? Sound? From the headphone line out? No way!
     
  21. Teej guy macrumors 6502a

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    Aug 6, 2007
    #21
    Must be quite the little headphone amp in there.
     
  22. Kronie thread starter macrumors 6502a

    Kronie

    Joined:
    Dec 4, 2008
    #22
    I was surprised it works as well as it does. BUT I'm a little cautious about it.

    So with a little searching, I FINALLY found what I was looking for, which is this, USB stereo amp.

    Its perfect for what I need. Hopefully I doesn't sound like crap, but for $18 I'm willing to chance it.
     

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