Thinkings about an audio amp project

Discussion in 'The Projects Forum' started by stupidlogic, Jan 12, 2011.

  1. stupidlogic

    Thread Starter Member

    Aug 10, 2010
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    Okay, I'm in an electronics class and a circuits lab this semester and will be dealing a lot with amplifiers, circuit analysis/construction, and the like.

    Well, my amp for my 5.1 speaker system is dead and was thinking about trying to design an amp to run them.

    Here's what I have figured out so far:
    I need 6 power amplifiers @ appropriate levels for each speaker
    I need a lowpass filter for the sub-woofer amps
    I need 5 highpass filters for other amps

    I also need the impedance and power ratings of each speaker.


    Now, I'm just looking for any input from more experienced people and/or links to information and resources on building something like this.

    I think it will be a fun project where I can learn something. Thanks in advance for any helpful input.
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. wayneh

    Expert

    Sep 9, 2010
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    FWIW, a modern AVR treats all channels (5 or 7, not including the LFE channel) equally - all amps are the same. The TOTAL power of all amps combined should be limited by the power supply, for economic reasons. That is, the rated power of each channel, times the number of channels, should exceed what the supply can deliver. That's not a technical requirement, just a recognition that a good design gets the most out of the most expensive component. It's very unlikely you'd ever drive all channels at peak power, so it's cheaper to over-spec each channel and under-spec the power supply.
     
  4. Wendy

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    Mar 24, 2008
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  5. gootee

    Senior Member

    Apr 24, 2007
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  6. stupidlogic

    Thread Starter Member

    Aug 10, 2010
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    This all very good information and I appreciate it. I will be going over it and doing more research in the coming week(s). The only thing is that (not that I've done much research yet), but my satellite speakers are 62W @ 8 Ohms. Most of the amps I've seen are in the 50W range. Can I find an amp that can drive a little higher then that or would I just be safer to keep it at 50W for my speakers' sake. I guess, I'm really just asking... How close can I get to 62W without damaging the speaker.

    Thank you again for the all the help!
     
  7. Audioguru

    New Member

    Dec 20, 2007
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    The difference in sound level between 50W and 62W is so small that nobody can hear it.
    Twice as much power makes the sound only a little louder, 10 times the power sounds twice as loud. 50 real Watts might blow up your speakers that might be rated for 62 Whats instead of 62 Watts.

    My computer speakers are fed 3.5 real Watts each and they are loud. In my car the 5 channels are driven with a total of 288 real Watts and they are only a little louder.
    The distances are almost the same.
     
  8. gootee

    Senior Member

    Apr 24, 2007
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    Ditto that.

    And if you try to drive them with anything close to their maximum rating, they will likely have a lot of distortion.

    You should probably also verify that 62 Watts isn't their PEAK rating, as seems to be a trend these days. If it's BIG SOUND you want, but still crystal clear, maybe think about adding a couple of Vandersteen 2ci, or the Kef 10x/y series, or even some huge Magneplanars. You can find pretty good prices for used ones, if you shop carefully and are a little bit patient. THEN you could think about using something capable of an honest 50 to 100 Watts average per channel.

    By the way, if you look at all of the sublinks at the national.com audio links I posted, you WILL find everything you might ever need, in terms of amplifiers you could build.

    But also keep in mind that for about the same price, and maybe even less, you could instead buy three really-good used Adcom GFA-545II dual power amps, or three NAD 2200 dual power amps, or similar. (But if you do that, you had BETTER have speakers that can handle the power, or they'll rip the motors right off of your tweeter cones.) A stack of three Luxman R-10xx series would be to-die-for, too.
     
    Last edited: Jan 15, 2011
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