I think my iPad burned my Amplifier's Speakers

Discussion in 'Digital Audio' started by Alvi, Dec 7, 2014.

  1. Alvi macrumors 65816

    Alvi

    Joined:
    Oct 31, 2008
    Location:
    Mars
    #1
    So I was listening to music on my amplifier through my iPad while it was charging and I noticed a buzzing sound while it was plugged in so I disconnected the charger for a while. Later on the 5% battery left warning appeared and when I plugged it in I could only hear the woofers. So I guess the drivers died.

    Any thoughts?
    Am I an idiot or is my iPad, my iPad's Charger, my amplifier or my speakers crap?

    Amplifier: Denon PMA520
    Speakers: Boston Acoustics CS 260 II
    iPad Air 2 with stock charger and cable
     
  2. cycledance Suspended

    Joined:
    Oct 15, 2010
    #2
    hmm...that's scary. sorry for that.

    how did you connect the ipad to the amp exactly?
     
  3. Alvi thread starter macrumors 65816

    Alvi

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    #3
    Through a 3.5mm Jack to RCA cable
     
  4. localoid macrumors 68020

    localoid

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    #4
    If you crank your speaker's amp up to "11" and run a really hot signal into the amp's input you can easily drive the amp into clipping as it tries to put out more power than its capable of. Often times the result will be fried tweeters since most of the excess, clipped energy is in the high frequency range. Tweeter usually can't handle much power and they fry easier than woofers will.
     
  5. cycledance Suspended

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    Oct 15, 2010
    #5
    i doubt he cranked it to 11. and what's a hot signal?

    i just checked the amp goes to 70 watt.
    the speakers max is 250 watt.
     
  6. cRuNcHiE, Dec 7, 2014
    Last edited: Dec 7, 2014

    cRuNcHiE macrumors 6502a

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    Jan 2, 2007
    #6
    If you plugged it in while your amp was on, its possible the POP from connecting blew your tweeters. If you're lucky they may have a temporary fuse, but I doubt it.


    You shouldn't plug anything into an amp while the amp is turned on for this exact reason. Same goes for plugging guitars into guitar amp etc.

    Also, are you using a genuine apple charger?

    If i were you, i'd get an airport express which supports airplay, then you can use it's analogue output to your amp, or if you had an amp that supports digital inputs you can use an optical cable with the airport express.

    Either way you won't get a buzz while charging your iPad, no noise when plugging in charger, and you won't be tethered to anything either.
     
  7. Alvi thread starter macrumors 65816

    Alvi

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    Mars
    #7
    I just looked to the clipping thing. Might be possible but I didn't really listen to music with a super high volume and I didn't set any gain or any bass boost.

    Thanks for looking into that, I should have posted those details too.
    The volume was actually at 60% max.

    There was no "POP", I plugged in the iPad's charger while the iPad was already playing music into the Amp.

    Yes, it is the one that came with it.

    I actually had one a while ago but my house is quite big and old, it's walls are almost 60 cm thick and the signal was quite sucky in our bedrooms so I ended up selling the thing. I wish Apple sold something like an apple TV but just for audio.
     
  8. localoid, Dec 7, 2014
    Last edited: Dec 7, 2014

    localoid macrumors 68020

    localoid

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    #8
    A amp rated @ 70 watts driven into clipping can produced 200% or more of the amp's rated power which is sent as a nasty, clipped square-wave to the speakers. Speakers rated at "250 watts" means it's rated for momentary peaks of up to 250 watts, e.g., you can easily fry them with much less power if it's continuous, even for a few seconds. JBL's technical note on the nature of amplifier power gives more detailed info.

    Hot = Near or above the input's rated max power level on the amp. In other words you can overdrive your amp's input driving it into clipping as well.


    LOL. You can't get an accurate idea of percentage of power the amp is actually putting out from the volume control setting. You'd need a power level meter that actually measures the amp's output to get an accurate idea of what how many watts your amp is actually putting out, and you'd need a meter that's able to measure peak and average levels.


    Excellent point. I've watched (and heard) guys blow speakers in PA systems, guitar amps, etc. plugging stuff in many times over the years.
     
  9. blueroom macrumors 603

    blueroom

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    Location:
    Toronto, Canada
    #9
    D-Link DCH-M225
     
  10. cycledance Suspended

    Joined:
    Oct 15, 2010
    #10
    i think i am starting to understand what happened.

    60% on the amp is high. the amp was a bit weak for the speakers. it distorted the low power headphone signal. the amp clipped. the tweeters couldn't take that. they also might not have liked the continuous power of the 60%.

    i still think the the power supply of the ipad must have "leaked" its energy into the amp. and the denon amp should have had a fuse.

    on the boston speaker website it says: Recommended Amplifier 15 – 250 watts.

    isn't something wrong with that?
     
  11. Alvi thread starter macrumors 65816

    Alvi

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    #11
    OMG Thanks for the suggestion! I will get one as soon as I fix my speakers. :D

    There are a lot of things that are wrong, first of all why the heck does the iPad leak energy into stuff? In a normal situation, plugging and unplugging your iPad from it's charger shouldn't affect it's audio output at all and if so, why didn't the amp stop this from happening.

    On the other hand I really don't know much about amp to speaker power ratios, I got these as a bundle for Black Friday and both of them had decent reviews and a good price. Just out of curiosity would be the ideal speakers for this amp?
     
  12. rnodern macrumors newbie

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    Nov 29, 2014
    Location:
    Manila, Philippines
    #12
    They're 8 ohm speakers, yeah? And 8 ohm output? This is really strange. 3.5" and rca plugs do not carry charge. Also, your amp would cop damage before the speakers. I might suggest that they may not, or may have not been wired correctly at some point. Look for the fuses on your amp. I suggest looking at these before replacing speakers.
     
  13. ChrisA, Dec 24, 2014
    Last edited: Dec 24, 2014

    ChrisA macrumors G4

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    Location:
    Redondo Beach, California
    #13

    The above is like the case. Those ratings are total BS and are written by marking people. I seriously doubt he has either 250W speakers or an amp that can output 70W. Both numbers are likely grossly exaggerated.

    What happens with audio gear is it clips and distorts and it's the harmonics from this that blows the speakers.

    It should be repairable but you need some minimum of skill and equipment to fix it. I'll need to test each of the drivers separately and then work trough the crossover. The parts are replaceable.

    You said the volume was at 60%. That was the problem. unless you are playing at a sports stadium keep the volume control way down at the 30% level at most.

    It's counter intuitive but an under powered amplifier can actually damage speaks quicker then a more powerful amp. The reason is the smaller amp goes into clipping and distortion faster. Just don't let that Denon amp go over about 25%, that is 4 on a 10 scale. An amp that is driven to clip send a "TON" of high frequency power to the speakers and blows the tweeters
     
  14. Alvi, Dec 25, 2014
    Last edited: Dec 25, 2014

    Alvi thread starter macrumors 65816

    Alvi

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    #14
    Man :( this is complicated, I guess I should've researched before getting this "Bundle" which is clearly incompatible. I am also considering getting some smaller, more compatible speakers to go with the amp and maybe get another one for this big ones.

    Any speaker suggestions for less than 300-500$ a pair?

    The Amp's channels are 45W at 8 ohms and 70W at 4 ohms
     
  15. Fzang, Dec 25, 2014
    Last edited: Dec 25, 2014

    Fzang macrumors 65816

    Fzang

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    Jun 15, 2013
    #15
    A pair of active Rokits for as high as your budget allows. Skip the amp monster completely.

    I suspect they may be a wee bit pricier than just "bookshelf speakers", but the chances of them blowing up should be significantly reduced.
     
  16. Alvi thread starter macrumors 65816

    Alvi

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    #16
    Why should I skip the amp? I mean, the speaker burning scene won't happen again if I am careful enough, I'm sending both the speakers and the amp to get checked by the manufacturer in January anyway. (they're brand new)

    I keep trying to figure out what use I should give to those huge 250W speakers and also to that 45W per channel amp. As far as I understood on the internetz matching the amp power with the speaker power is a safe bet to avoid clipping.

    But I can't find any amps that have such power, did I get something wrong? I also saw some power amplifiers but they're ridiculously expensive, like 5 times more than the actual speakers, what should I do?
    What's the ideal amp for those speakers and what's the ideal speaker for my current amp?
     
  17. Fzang, Dec 25, 2014
    Last edited: Dec 25, 2014

    Fzang macrumors 65816

    Fzang

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    #17
    Have you checked the fuse? Also was the iPad playing at maximum volume? How are you testing your speakers now? With the same iPad and the same cable setup? Maybe a different setup to double-check?

    For compatibility :eek:
     
  18. Alvi thread starter macrumors 65816

    Alvi

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    #18
    My plan getting these things was to actually move away from pre-made solutions like those, I prefer upgradeability. If I were to be practical I'd just fill my home with Sonos speakers or what not.
    Edit: I also want to use a turntable.
     

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