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Receiver/Amplifier Advice Please...

Discussion in 'AV Receivers & Amplifiers' started by Les E, Aug 31, 2005.

  1. Les E

    Les E
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    Need some advice, just to clarify matters on amps/receivers.

    If I have 6.1 receiver, and I add 2 mid-rear centres for EX/ES does the receiver seperate the audio coming from both speakers or would I need a 7.1 receiver for this scenario?

    Also what is bi-wiring and how does it work? I keep getting conflicting advice on this and would I need it for the above set-up?

    And when do I add a power amp into my system? At what stage would I think I need to buy one of these and what advantages would it have over my current amplifier/receiver?

    I know a few of these questions are probably very basic knowledge, but when I keep getting conflicting answers it doesn't end up so basic!! :confused:
     
  2. KoThreads

    KoThreads
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    i've got a 6.1 and thanks to Eviljohn2 got a 7.2 out of it.

    I believe that true 7.1 amps have 2 rear outputs but they send out the same mono signal (like pro-logic) so after ending up with 7 Cantons decided to try it, and the rear, when used, is much less localised than before.

    I wired the rear channel in series to get 2 speakers at the rear about 1m apart (had to increase the rear channel output by +3 db) and stuck in another sub.

    It works a treat although the 2 subs can get out of control at times.

    Bi-wiring is probably the most talked about subject. Does it/doesn't it. I took out the jumpers and replaced it with the same speaker cable as on the speakers as 'appaently' this gets you most of the benefits without two runs of cable.

    I've had them 1. single wired, 2. bi-wired, and 3. this way.

    If it makes any difference on my setup i can't hear it. I've just stuck to 3, and left it.
     
  3. narcoticsuite

    narcoticsuite
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    To answer your points in order:-

    The centre back channel is really only one channel as the signal is mono, but you can run it into two speakers for "7.1", and this does improve the performance slighly IMO. There are several ways of doing this - get a 7.1 amp which has 7 power amps and 7 speaker outputs, use your current amp and run a pair of speakers off one set of outputs (be careful - best to use a speaker switch for this), get a power amp and hook it up to the centre back pre-out of your 6.1 amp and use the power amp to drive a pair of speakers. The first and third options would give you better performance than the second but as long as your speakers don't present too difficult a load for your amp and your amp is reasonably highly powered then it should be okay. Do be careful though as wiring speakers up wrong can lead to damage, best to use a speaker switch which you can get from RS and other places for about £15.


    Biwiring - you simply remove the bridge between the two sets of inputs on a biwirable pair of speakers and then run seperate lengths of cable from the amp's outputs to the two sets of inputs. Highly debatable as to whether or not it makes any difference, I personally don't think it does and can't see how it can, but maybe more esoteric kit is more revealing of the benefit of such a tweak. Is is not essential to biwire biwirable speakers, they will work just as well IMO if you leave the factory fitted bridge in place or maybe replace it with a short length of speaker cable.

    You don't need to add a power amp but budget all in one amps can have cheap and cheerful power amplifiers in them and so over time you can add better quality power amps to improve the performance. You hook the power amps up to the pre-outs on your receiver and use them to drive the speakers, your AV amp then effectively becoming a controller or pre-amp. You can do this one pair of channels at a time or all at once. May be disproportionately expensive to do this though. As mentioned above, you could use one to get a 7.1 performance out of your 6.1 amp.

    Hope this helps.
     
  4. Les E

    Les E
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    That all sounds good stuff...thanks for all the info.

    Couple of questions though. If a mono signal is sent to the 2 mid-rears, what would be the advantage of having two speakers (7.1) compared to the one speaker (6.1)?

    Is it essentially a 'how much room I have' issue, that could warrant a set of 2 speakers?

    Cheers!
     
  5. KoThreads

    KoThreads
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    Because with a single speaker I had a localised sound from one point. Now i have two speakers a metre apart, and as i said above, when in use the whole rear sound field is better.

    Be careful, if you wire them in parallel you could put too much load on your amp and damage it.
     
  6. Les E

    Les E
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    When you say wire them in parallel, does that suggest the 2 speakers are connected to each other as well as inputs from the amp?
     
  7. KoThreads

    KoThreads
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    WIRE IN SERIES ONLY

    Connect for a single speaker and split the cable at the speaker end. Take only the + and connect TO spk1+ then use a seperate single run of cable from spk1- TO spk2+ then connect the original amp- TO spk2-

    AMP+ TO (+ SPK1 -) TO (+ SPK2 -) TO AMP-

    Eviljohn2 and JJ to thank.

    The way i was going to do it would have ended in disaster.

    PLEASE REALISE YOU DO THIS AT YOUR OWN RISK.
     
  8. Les E

    Les E
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    And does this apply to any 'type' of speakers used for the rears? I currently have 'KEF eggs'

    The Sparky is going to kill me when I ask him to do this in my new build!!!!
     
  9. KoThreads

    KoThreads
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    I can't see why not so long as their not active, the eggs should be fine, similar to the Cantons.
     
  10. Glenzo

    Glenzo
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    :confused: Why not just stick to your 6.1 as we only have really True discrete dts-es as well as a matrixed version and the matrixed Dolby 5.1 ex (which IMO is no real difference different than Dolby 5.1) ??

    If IMO you try to force sound from a DVD that it wasn't designed for, you are flawing the work of the Sound Department.

    I think back to Pro-Logic and how we were duped with it as it was never 'True' Surround sound as was being shown in the Cinema in the 90's, yet I'd got it and was always so disappointed with having to put my ear to the rears to really hear anything. This was a Technics system that was advertised as 'Letting you hear the sounds in the Director's head'. Some naff was in someone's head (imaginary).

    Then I was blown away with DD/DTS 5.1 :smashin:

    That's how I feel so unless soundtracks start arriving in 7.1 (which will be getting a little excessive and silly really) Don't worry about it till then. :thumbsdow
     
  11. KoThreads

    KoThreads
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    Glenzo

    The rear (6 or 7) are only mono.

    I don't use any of the 'rear mix' efects, so my rear channels only power up on 'true' 6.1 mixes.

    I agree, DD EX sounds no better to me than DD. But DTS ES discrete and even matrix to my ears on my setup is miles better.
     
  12. Glenzo

    Glenzo
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    Exactly
     

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