yamaha 750- questions from the thick!

Discussion in 'AV Receivers & Amplifiers' started by shuggy, Mar 9, 2005.

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  1. shuggy

    shuggy
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    I am having some special cables made so my loewe spheros can act as my centre in my 7.1 set up. Wife will not have a certos. I have been cautioned to ensure that the Yamaha drives 8 ohm speakers. Can anyone set me straight on this?
    What does a presence speaker do?
    Many thanks
     
  2. phillfyspoon

    phillfyspoon
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    4 ohm speakers are more power hungrey then 8 ohm speakers. 4 ohm speakers would require a decent power amp to get the most out of them.
     
  3. Andy_Lee

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    The Yamaha does drive 8 ohm speakers no problem The idea for the Presence speakers is to site them behind and above your main fronts and screen to add "depth" to the front sound presumably in a similar way to the surround backs in a 7.1/6.1 system I've just added these(Surround backs) to my 750 and they do make a difference to the sound.

    I'm tempted to do the presence speakers but need to find something suitable maybe something like the NXT panels would do as having any more largish speakers in the room is a bit of a non starter.
     
  4. probedb

    probedb
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    You can't use the surround backs if you use the front presence speakers from what I've read. It's one or the other.
     
  5. Andy_Lee

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    Hmm shall have to get the manual out to check that well actually I can't see tha point baring in mind I've just brought the Denon 3805 to replace it shall get that set up first.
     
  6. shuggy

    shuggy
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    did your yamaha give problems or were new toys needed :devil:
     
  7. dmurfet

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    I can confirm that mt yamaha will drive my set up. I don't have a centre, but my SFs are 6 ohm. I have got it to clip already though, but I do listen louder than any demo I have ever had........ :eek:

    If you are not a noise monster, you should be just fine!
     
  8. Blu Ray

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    That would appear to be correct.
     
  9. pragmatic

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    The Z1 and Z9 can control 9.1 i.e. both extra rears and fronts, i'm guessing the processing required to do both dd/dts - ex and yamaha pressance DSP was too expensive to include in anything less than a flagship model.

    Maybe the 3600 when it comes out will remedy this, as it's abit disapointing that the 2500 can't do 9.1 even with pre-outs and external amp(s).
     
  10. Zacabeb

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    When not using separate presence speakers, the front presence sound field is still there, even with 7.1 output, and simply downmixed into the left and right front channels. So, the DSPs are powerful enough to do everything at once (as required by Yamaha's Quad-Field Cinema DSP), the presence channels simply just don't have their own pre- and power amp stages, but have to "borrow" the back surround amps if you decide to hook up separate presence speakers.

    In the RX-V1500 and 2500, all channels (including the front presence soundfield) are actually treated independently, with their own respective DAC stages and volume control paths, all the way until the analog mixdown stage. Immediately following the volume control, the channels are mixed down into 7.1. If you hook up separate presence speakers, the same DACs and volume controls used for the back surround channels will be used for either them or the presence channels, depending on which you gave priority in the settings.

    I don't know how exactly how the 750 is configured, but it is probably not too different. Like on the bigger models, the presence sound field is simply mixed down into the left and right front channels, unless you choose to use separate presence speakers.
     
  11. shaithis

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    From the manual:

     
  12. pragmatic

    pragmatic
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    It is abit silly that the rears and pressence share the same pre-outs if the processing can be done, maybe the though the option of 9.1 would put people off as it should be integrated anway, also the pressence speakers have only 40w/ch where as all other are at 130w/ch. This does not seem to correspont to them sharing the same amp, although it mighgt suggest the internal power supply is no good enough to run all 9 speakers/amps within acceptable tolerances.
     
  13. Zacabeb

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    The dedicated power amps for the presence speakers in the DSP-Z9 and other flagship models don't need to have much power, as the sound from the presence channels is relatively undemanding.

    When using the presence speaker outputs on the lower models, of course it is overkill to use the same beefy power stages as the back surround channels, but it does save the extra space and money needed even for a modest dedicated presence power amp. I guess Yamaha decided against putting it in as most people would not bother with presence speakers, especially given it's a Yamaha quirk that's used only in their proprietary DSP programs.
     
  14. shuggy

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    I am trying to attach my yamaha 750 to my TVs speakers as my centre. These are the TV speaker ratings
    Rated audio power 2 x 15 Watt / 6 Ohm
    Audio music output 2 x 40 Watt / 6 Ohm
    Speakers 2 closed boxes
    Tweeter 2 x 20 mm
    Bass 2 x 75 mm

    Does that sound incompatible with a 100w output yamaha 750 or would the mushroom cloud be visible for miles :rolleyes:
     
  15. pragmatic

    pragmatic
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    I'm not sure, on this one, generaly having more power is a good thing, but as you speakers are rated at 15 watts that is alot lower than 100 (obviously) so if you play loud and you'll want to there is a chance of braking the tv speakers.
     
  16. shuggy

    shuggy
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    Thanks gazbarber for the advice. I wont play it too loud! I do have to say the speakers on the tv are unbearable when I crank them up wiyh the volume. Plenty of room for audio manouevre!
     

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