Receiver power

Discussion in 'AV Receivers' started by charlie_kaf, May 26, 2004.

  1. charlie_kaf

    charlie_kaf Auditioning

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    My Dad just moved into a house that has built in speakers in 4 rooms (8 total speakers). All the wires for these speakers (8 pairs) are apparently connected into 2 pairs of wire that comes out in the equipment rack. So when you hook up these 2 pairs of wires all 8 speakers work (the volume can also be controlled by wall dials though).
    My question--My Dad would like to hook up a receiver so that he can play music/radio and then listen to it in different rooms--problem is that when we hooked up his old Sony amp it blew in about 5 minutes, I assume there is just too much draw on the amp. Can a regular amp (200 dollar range) be expected to run all these speakers connected together--or will it require a extensive setup split into zones--which will cause another problem because I have no idea where all the speaker wire ends terminate. Any advise would be appreciated. Thanks.
     
  2. Charles J P

    Charles J P Cinematographer

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    Well, that is interesting. I mean, if all of the speakers are wired together presenting an extremely low impedance (1 or 2 ohms or less) that would explain why the receiver blew, but if that's the case, what in the heck were the people that lived there before using? I mean, there arent any receivers that would go into 1 ohm but many amps wont either. Is it possible to split the speakers back out? Where they wired together before or did you/your dad do that. You're best bet for a whole house audio system is usually some kind of multi channel amp (I think wild west electronics.net sells a few) that go up to 12+ channels of power. You usually dont need a ton of wattage.
     
  3. ChrisLazarko

    ChrisLazarko Supporting Actor

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    Or you just get an reciever that could possibly power to sets of speaker such as A+B and a switch that can handle 12 outputs and has an input for A-B type recievers. Also, in the 200 dollar range, all the amps in recievers will be weak, and powering that many speakers, probbly having a lower impednce or whatever there is no way it will work. Especially a Sony, those are especially weak.
     
  4. Ted Lee

    Ted Lee Lead Actor

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    does he want to run all 8 at the same time or just be selective in which speakers are on?

    if it's the latter, another option is a speaker selector box ... the ones that have protection circuity built in. niles stuff is pretty good.

    http://www.nilesaudio.com/products/s...selectors.html

    you can usually find something similar in most b&m stores (bb, cc, gg, etc...)

    i don't know what would happen if you tried to run all 8 speakers through the niles box though. i assume it would shut down...but not sure.
     
  5. charlie_kaf

    charlie_kaf Auditioning

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    Thank you very much for the responses. I got some more information on how they are wired. There was an electrican over last night and he was in the attic looking at some other stuff so we had him check out how the speakers are hooked up. He said that they are all basically hooked up in parallel. 1 wire for the right channel and 1 for the left channel goes to 1 speaker then to the next and so on!!! So I may have to try to re-wire it. I'll keep you updated with any new info. Thanks again.
     
  6. CalvinCarr

    CalvinCarr Supporting Actor

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    If you want all of them driven at on time you can do it in series or in Parllel/series. What are you trying to acomplish?
     
  7. charlie_kaf

    charlie_kaf Auditioning

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    CalvinCarr
    Yea I would like to power them all at once but all the speakers are hooked up in parallel now. I believe that is what caused the original amp to blow--so as far as what I am trying to acomplish--I guess use all 8 speakers without blowing another amp. From reading your post it sounds like running in parallel is not such a bad thing? Is that correct?
     
  8. CalvinCarr

    CalvinCarr Supporting Actor

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    Parallel is a bad thing. It drops the impedance below the nominal level the reciever is able to handle. You hook them up in series or a series/parallel arrangement. Do you have seperate volume controls or do you want the same volume for all rooms?
     
  9. Aaron Gilbert

    Aaron Gilbert Second Unit

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    Charlie,

    Wiring in parellel is usually a good thing, yes, but has little benefit in your particular situation. Do you know if all these speakers are eight ohms nominally? Actually, you can find out fairly easily if you have a ohmmeter (analog or digital). Just measure the resistance at the wires where all speakers are joined together, where you'd connect to the receiver. If it measures about 1.5 ohms, then nominally you are looking at a two ohm impedance. That is quite low, but not impossible to drive. My Kenwood KM-X1000 will drive a two ohm load in stereo, and they can be found on eBay other other places occasionally for around $200. You'd of course need a receiver that has preamp outputs for the front L/R channels, or a preamp. Another option which may sound weird, but is doable, would be to use a car stereo amplifier. The vast majority of them are stable into two ohms in stereo mode, and some even into one ohm. You'd still need a receiver with preouts, the car stereo amp, and a 12-14V (13.8 is typical) power supply. You can get one that should have sufficient power for about $100, a 20A model should do the trick unless you really want to blast the system. I'd probably look for a good used low impedance capable home amp first, myself. Most Carver amps should be able to drive two ohms ok, as I think most mid to higher end Adcoms will, and no doubt a whole bunch of other brands.

    Of course, the cheapest and perhaps wisest long-term solution is going to be wiring in series, as has been suggested, or a series-parallel arrangement.

    Good luck!


    Aaron Gilbert
     
  10. charlie_kaf

    charlie_kaf Auditioning

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    Thanks alot for the info Aaron and Calvin I got some good ideas but it sounds like I will be getting in the celling to do some re-wireing.
    I just got this e-mail from my dad though:
    "Just bought a $200 tunner with a $30 service contract for 4 yrs---------------see if I can blow it up tonight "

    -who knows though, we might get lucky. I'll let you guys know how it turns out.
     
  11. Shiu

    Shiu Second Unit

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    Be careful! Typical ohmmeters measure resistance with a d.c. (battery) output. It measures resistance, not impedance. Impedance varies with frequency of the source, you cannot measure it with an ohmmeter. In fact, if you try one on a tiny cheap loudspeaker, you may damage the voice coil with the d.c.
     
  12. Aaron Gilbert

    Aaron Gilbert Second Unit

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    First off, you CANNOT damage a speaker by connecting an ohmmeter to it. Secondly, I'm aware of the difference between impedance and resistance. I wansn't suggesting that an ohmmeter will tell you the impedance of your speaker at a specific frequency, because it will not. What it will tell you is the DC resistance of the voil coil, and from that you can extrapolate the nominal impedance, because the DC resistance is approximately 75% of the nominal impedance.


    Aaron Gilbert
     
  13. Shiu

    Shiu Second Unit

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    OKay!
     

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