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  1. #1

    test speaker switch box ??

    I purchased a speaker switching box so I may run different speakers in my house. I never use more than any two sets at any one time. I think it is responsible for frying my amp twice now. (internal speaker output blown i am told)
    How do I test this thing?.... my speakers are all ok... no shorts..
    any thoughts appreciated
    thanks

  2. #2
    Administrator Dave's Avatar
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    So you are running two sets of speakers at the same time? That's a potential problem. Basically you need to make sure the speakers' combined impedance matches the amp, otherwise damage may occur. Google "impedence matching" and you should find plenty of tutorials.
    Dave Owen
    MediaCollege.com

  3. #3
    well there is something i didnt know...........!!

  4. #4
    well i had a look, but frankly couldnt find anything I could understand..... all a bit over my head in electronics. But if indeed running more than one set of speakers thru the switching system is NOT to be done then that might indeed be the problem. How does that explain the tuners "A & B" speakers? apparently one can run two sets using that method yes?

    Quote
    Quote: Dave
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    So you are running two sets of speakers at the same time? That's a potential problem. Basically you need to make sure the speakers' combined impedance matches the amp, otherwise damage may occur. Google "impedence matching" and you should find plenty of tutorials.

  5. #5
    ... also, the folks that sold the speaker selector box said that you absolutely should be able to run as many sets of speakers as you choose...they said that is the whole point of the piece of equipment..... confused.

  6. #6
    Could you give any more information on the manf./model of your switch box? Also more explanation of your connection setup would be helpful in diagnosing the issue.

  7. #7
    it is a TC-25 5 way
    apparently they have had some issues.... wondering if it is just some "hidden" problem... as i originally posted i don't know how to test it really. I put an ohmeter across all the terminals and it displayed the same resistance accross all... but not sure if that is really telling me anything.

  8. #8
    I really need more info on the amplifier as well as the speakers you were connecting through the switch, and how they were all connected from amp -> switch -> speakers when the problem arose. Power ratings, impedance ratings, etc.

    Essentially, your amplifier channel outputs (assuming stereo L/R) are rated to drive a certain load impedance. It's usually screenprinted on the back of the amp by the output, if not check the manual. Typically it will be 4 - 8 ohms. Much less or more can potentially damage the amp. The speakers should also have an impedance, again typically 4 - 8 ohms, but could be higher. Looking at it this way, you can see that each amp channel output is really meant to be connected to one speaker at a time.

    If you connect multiple speakers to a single output at one time, the impedance that the amp sees will change, depending on how you connect them. This can either increase or decrease the impedance and result in damage to your amp outputs. If you pick your speaker impedances correctly, you may be able to get away with using two speakers connected at one time. With an A/B switch on the amp you might see in the user manual a statement to make sure the speaker impedances meet minimum values.

    Your switch (assuming wired as expected) is essentially doing just this, connecting one or more speakers to the output of the amp. With this 5-way switch, if you had all 5 buttons pressed it would be like connecting 5 speakers to one amp channel, and could easily blow your amp output. If your speaker impedances were not well suited for the amp, even using two rooms at a time could have caused the damage.

    It's also conceivable that the switch or wiring is flawed, and perhaps results in a short circuit connecting the amp channels together which can also blow the outputs.

    If you've tested that all of your speakers are in working order, you could use a multimeter's continuity checker to ensure that the input/outputs of the 5-way are indeed connected as labeled, and no shorts occur. If the switch seems fine, check your impedance ratings as I mentioned. If your speakers are in fact damaged, there could be a few other causes I haven't gotten into.

    To setup a multi-zone, multi-speaker system properly, you would really be better off using an appropriate amplifier rather than a passive switcher, perhaps something like this:

    http://www.bhphotovideo.com/c/produc...Amplifier.html

    Hope this helps

  9. #9
    thanks for your reply. A wealth of info...appreciated. I have taken the switching box out of the system for now as it is the only real suspect at this point. I have gotten mixed messages about it's correct use,,,some saying that it should be able to play any combination of speakers, however your argument makes more sense to me. The box was connected to my "A" output, and as you say, it would seem to be the same as potentially wiring all speakers to the same output, thereby overloading it. Using it to be able to play any one set of speakers seems a reasonable and covenient use of the item.

  10. #10
    Administrator Dave's Avatar
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    Nice reply SchwartzSound
    Dave Owen
    MediaCollege.com

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