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Discussion in 'DIY Discussion' started by Soloist, Nov 7, 2011.

  1. Soloist

    Soloist In my lonely furrow

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    Hi. Your local fool here - I think I already know the answer to this but because I want it to be a different answer, I thought I'd better just check with those who really know!

    I have an AV amp (horrible buzzy thing) and my lovely Bow Wazoo. One room, one set-up, one pair of speakers to use for hi-fi and AV.

    Now, I could piggy-back the outputs to save me from unplugging/plugging each timr. With the unused amp switched off, would any damage occurr?

    Ta!

    Andrew
     
    Soloist, Nov 7, 2011
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  2. Soloist

    felix part-time Horta

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    DO you mean leaving both power amps connected to teh speaker and switching one off? If so it is a very bad idea and it wont work for long. The 'off' amp will look like a very strange load and the other amp is rather likely to damage it (output transistors will avalanche ie behave like zener diodes above a very few volts of AC - which in turn will kill the driver stage... )

    I beleive QED make or made a speaker switching box for this kind of use - it is or was fairly cheap , too :)
     
    felix, Nov 7, 2011
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  3. Soloist

    robert_cyrus

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    Can you use pre out for L and R from the a/v amp and feed the wazoo which would just treat it as another source? You'd have 2 volume controls to adjust but no switch which might best option.
     
    robert_cyrus, Nov 7, 2011
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  4. Soloist

    Soloist In my lonely furrow

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    Thanks Felix. I had dismissed the idea of a switching box but it does make sense and keeps it simple, as in all the best engineering solutions!
     
    Soloist, Nov 8, 2011
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  5. Soloist

    Soloist In my lonely furrow

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    Robert, many thanks for your thoughts. My girls are already confused enough about what comes from where, goes to where and so on. this would cause a complete meltdown! I think i'll go for the switching box....

    AB :)
     
    Soloist, Nov 8, 2011
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  6. Soloist

    speedy.steve

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    You can use 2 sets of double pole double throw light switches the type that you have in hall and landing.

    Each switch will have 2 outputs (ideal for +/- cable to speaker) and 4 inputs, One pair for one amp and the other pair for the other amp. Double this up and you cover both speakers.

    With all switches are thrown one way only one amp will be connected (the other amp will see open circuit so is best switched off). Throw the switches the other way and it's vice versa. Label them, simples, as the Meercats say :)

    As these switches are designed for AC they can easily carry the speaker juice - I used this system when I fed my Tannoy GRF's from my AV amp (made nice LH and RH speakers) and for Hifi fed them with my 20W Class A push pull valve amp. I could not hear any sound degradation with the switch in or out.

    If you play around with the switches in front of you and a multimeter it's easy to figure out how to connect them.
     
    speedy.steve, Nov 8, 2011
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  7. Soloist

    RobHolt Moderator

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    That's an excellent and very practical suggestion.
     
    RobHolt, Nov 8, 2011
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