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1 speaker, 2 outputs???

Discussion in 'Home Cinema Speakers' started by agw_01, Dec 11, 2002.

  1. agw_01

    agw_01
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    I am getting a Yamaha DSP-AX620 amplifier for christmas, and want to use my TEAC as the amplifier for my 10" sub woofer.

    My dad said something about being able to connect one speaker upto two outputs so that it doesn't damage the amp, but he isn't sure how to go about doing it.

    Does anybody know as I would rather not risk damaging anything.

    Thanks
     
  2. James45

    James45
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    what sub is it? you do know most subs are powered (ie have their own amplification onboard), can't see the point in using a seperate receiver for the sub in this case.
     
  3. agw_01

    agw_01
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    Sorry, I forgot to put that the amp was ripped out of a Cinema before it was pulled down.

    The sub doesn't have an amp, but it does have the word ACTIVE on the back of the magnet, so it must need an amp.

    I am going to take the line-level sub out from the yamaha amp into the TEAC and then plug the TEAC into the sub... i.e, the TEAC will be the subs amp.

    I don't know what make the sub is, as it doesn't have any branding on it. It will probably be crap, but I might as well use it while I have all the equipment :)
     
  4. James45

    James45
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    the TEAC will probably have massive amplification if it's from a proper cinema, watch the power levels as you could probably blow the sub with it very easily
     
  5. Nobber22

    Nobber22
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    I think he means the sub was ripped out of a cinema. The Teac is an older prologic reciever.

    agw_01: if the sub has a mains lead on it, it will have it's own internal amp and be active. If it just looks like a big speaker in a box, it is passive and will require all the power from the amp. Maybe the Teac isn't ballsy enough for the sub either? Under-drive it and you will damage the sub.
     
  6. agw_01

    agw_01
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    sorry, I meant to put that the sub was ripped out from a cinema. Sorry about that.

    The TEAC is just a standard stereo reciever... nothing special.

    The sub was previously my mates, but he gave it to me because he didn't need it. He also got one of his mates to build him a box for it (perfect size he said).

    The sub is active but it doesn't have an amp yet, thus the reason for me using the TEAC.

    Ive had the sub running through the TEAC before, when I set up a wannabe HTPC setup last week and it was ok, but with me getting this Yamaha amp and it having a proper sub-out I want to make full use out of its features.

    So, does anyone know how to connect one speaker upto two outputs so that it doesn't damage the amp?

    Also, nobber22, what do you mean by under drive it?

    Thanks
     
  7. GaryG

    GaryG
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    Technically, assuming your amp is a two channel amp and your speaker has a single voice coil, you connect the speaker across the two + terminals on the amp and invert the phase of one of the inputs on the amp and feed a mono signal to the inputs.

    Practically, unless you have a method of inverting the phase to one of the inputs and know that the impedance of the speaker is not going to draw a high current and blow the output transistors in your amp it's a bit risky, I would suggest you just use the one channel of your amp.
     
  8. agw_01

    agw_01
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    Cheers Gary. Originally I was going to plug the mono sub out from the Yamaha into the TEAC and then plug the sub into the corresponding speaker output on the TEAC.

    I was just wondering if there was another way to connect up one speaker to two outputs so that it wouldn't damage the TEAC amp, but I don't think I will be able to do that :(

    Ah well, I might not even use the sub... depends on what speakers I pick up on Saturday.

    Either Mission M73s or 702e's.

    Thanks again
     
  9. GaryG

    GaryG
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    Don't give up on the sub too quickly, all things beging equal a 10" driver is going to be able to reproduce bass better than a 6" driver. Although the TEAC has a modest output power, provided you don't listen in a large room at high volume levels it will probably be beneficial. Put the sub in a corner behind the main speakers (a corner with the longest walls is the best place to start to excite the maximum number of room modes) and adjust the sub volume to just add a little 'weight' to the Mission's. Don't expect it to shake the room, that's a little unrealistic with the TEAC and a driver with an unknown specification. If it's not to your liking then there's nothing lost, if you do like it and you're running out of steam with the TEAC then it's worth upgrading the amp. Let us know how you get on.
     
  10. Nobber22

    Nobber22
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    Under-driving a speaker means you are using an amp which is not powerful enough to move the cone(s) properly at a given volume. Therefore you will (and here my lack of technical knowledge may shine thru) cut off the peaks/troughs of the signal sent to the speaker and damage the voice coil. You don't just "blow" a speaker with too much power, too little is just as bad.

    There is a more technical explanation from the guys who know more about speaker impedence than me. Sorry. Do a search.

    The sub out on your new Yam 620 is designed to output bass to an active sub with a built-in sub (which yours doesn't have - yet?), so you could get around it by running another set of speaker cable from the fronts output on the Yam amp to the sub and set the fronts to large & bass output off. This will send all bass to fronts and thence onto the passive sub. Don't use the Teac at all.

    BUT, don't try this until someone else around here gives you the go-ahead!!! I am just speculating aloud here and may be wrong. The Yam has about 70 w RMS which is average power, so your sub may suck out more than you'd like. :(

    Personally I think passive subs for home cinema are a poor substitute for a nice active one. They drain power meant for other speakers while not adding a tight lowend to the sound. I know you are itching to try it out, but......;)
     
  11. agw_01

    agw_01
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    Thanks for replying guys.

    The TEAC pumps out 25 w/pch, so I don't know how much ouput I will get from the sub. It'll be interesting to find out tho. Im going to try and get a cheap car amp or something, at least it'll be able to do at least 100 watts, or if not, i might spend a couple of hundred on a loudmouth paradigm sub or something along the lines of "BOOMING BASS" :eek: :D :eek:

    Oh, Nobber22, you mean clipping. Oh yeah, I know about that. Thanks. :)

    Im getting the Yamaha amp for christmas, and picking up a new pair of speakers on Satuday... I think im gonna get some Mission 702e's... hopefully they will compliment my current 700's.

    edit... The DSP-AX620 does 90w RMS (5 channels)
     

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