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Power Amp with Pre amp or not?

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by BLACK_MAGIC, Mar 15, 2003.

  1. BLACK_MAGIC

    BLACK_MAGIC
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    Ok this is probably an easy question for you guys to answer so here goes.

    In adding an additional amp to my dsp amp for better music am i better off by just buying a Power amp and plugging it directley into the main out of my dsp amp and using that as the pre amp for stereo or buying a pre amp for the power amp and plugging my dsp into the aux of the pre amp and also my cd player into the pre amp, and only switching the dsp amp on for movies?
    Which method would give the better sound and performance?
    Thanks to those who can help.
     
  2. Yummy Fur

    Yummy Fur
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    To be honest, unless you've got a 'high end' (ie Theta, Tag, Lex, Meridian etc) processor, I wouldn't even consider feeding stereo into your AV amp. Your idea of having a seperate pre amp and power amp is much better. Your music is only going to get mangled within an AV amp. I run the L & R outputs of my AV amp into the aux inputs of my pre power. I then run all my stereo sources directly into the pre amp and completely avoid the AV amp.

    Yummy Fur
     
  3. sounddog

    sounddog
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    As you can see in sig and probably read ... I've got a Rotel RSP1066 processor (£1000). I find that stereo sources with this sound very close to when using a £550 Rotel RA1060 (using same amplification) - so this should give some relative indication of AV processors (and amps) compared with pure stereo sources.

    If you've got AV amp, pre-amp and power amp the best way would be a simple 2-way input switch with the AV and Pre amps as the input and the Power amp as the output. Otherwise if you've got an integrated stereo amp, connect the AV amp to a spare line in.

    (Using a Marantz SR5200) there was very little difference in quality of music using the SR5200 alone, and using it with a power amp for the front 2 channels. With lower end kit it's not the power amps that are lacking for stereo, but the pre-amp section (IME).

    Vikki
     
  4. Yummy Fur

    Yummy Fur
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    Vikki said-

    I agree, I would think I would say that the pre amp section is more compromised than the power amp section....

    I'm probably being a bit thick here :blush: but why the input switch Vikki? Why not connect to a spare line in on the pre amp?

    Yummy Fur
     
  5. sounddog

    sounddog
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    The idea of using the input was that it eliminates the need to adjuct the volume when changing between the two. Will aslso give you a (theoretically) cleaner signal. A switch box like the QED MA20 should cost less than £30.

    The other option - if you use use one source for music (i.e. a CD player) is to get a passive pre-amp - either the QED or the Creek are good value for money.

    Or as you say ... just plumb the AV amp in via the pre-amp.

    Vikki
     
  6. Yummy Fur

    Yummy Fur
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    Well, I'm being really thick now....... :D I can see how you can volume match more easily. Although, I really don't think that it's much of a problem -- one can easily put a sticker/or mark the volume controls (or just make a note of the settings) for the correct relative levels. My preferred solution is just to adjust pre-amp volume cntrol until the sound comes into 'focus' --very easy to tell when it's right and only takes a few seconds...... However what I cannot see is how the addition of an input switch can result in a (theoretically or not) cleaner signal..... As you you say, a passive pre is one possible solution--- providing it has sufficent 'gain' in the first place....

    Yummy Fur
     
  7. sounddog

    sounddog
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    I may be talking rubish here ... and forgive me if I am but ...

    If you add a pre-amp between the AV amp and the Power amp, then there is more analogue electronics in the way, possibly colouring and distorting the signal,

    If you use a switch, then you are eliminating the electronics - though you are adding a switch between the pre and poweramp which MAY add problems.

    If you're happy with setting the volume each time, then thats fine and the switch serves no purpose really ... but some people find it a pain so the switch will eliminate this. It's just an option for those who don't like having to keep adjust volumes and have pre-amp and power-amps separate.

    Vikki

    (I'm thinking of buying one of them QED passive pre-amps and trying it out with our RB985 so will let you know the results if I do so)
     
  8. Yummy Fur

    Yummy Fur
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    I may be talking rubish here ... and forgive me if I am but ...

    No you're not !:D I can see what you are saying... I must admit that I have found (as I have tried what you suggested) that my Pre-amp is more transparent (despite the more complex signal path) than the cheapish (presumeably noisier?) switcher that I used..... I may have erroneously tarred all input switchers with the same brush, hence my uncertainty about your suggestion :blush:. I'd be most interested to hear how you get on with your passive pre-amp experiments....

    Yummy Fur
     
  9. BLACK_MAGIC

    BLACK_MAGIC
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    Ok thanks for the help so far guys. Ive been looking at the amps and pre amps and nearly cryed when i saw the price so i was thinking of using an intergrated amp. Im looking at the Rotel RA1060. Now in theory i could just plug my dsp amp into the aux of this rotel amp when the home cinema was needed.
    Would this be a bette option then going the power amp and pre amp route. I guess it would mean less cabling and less loss in quality or am i getting the wrong end of the stick here?
    BTW im using ageis evo 3,s as the mains is ths rotel amp more then ample for driving these speakers cause eventually im gonna up the mains and dont want to have to buy another amp again.
    Thanks
     
  10. sounddog

    sounddog
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    Without actually having tried it ... I would think the Rotel RA1060 would easily power speakers upto and possibly beyond the level of B&W CDM 7NT series (and similar). If you do find you go for more escotic speakers later can always add a RB1050 (70w x2) power amp to bi amp your speakers.

    And yes you can just plug your AV Amp's pre-out into a spare aux input on the RA1060 ... thats what we were doing until we upgraded to a Rotel Processor for AV duties. Just select the correct input, then set the level to a pre-marked point (usually around 10-12 o'clock on the dial) that you've previously calibrated using the test tones on the AV Amp.

    Yummy Fur ... I admit I've never tried the QED switch I was advocating but have never found their Speaker Switches to be noisy so was assuming a similar quality in their input switches. BTW ... what is your pre-amp?

    Vikki
     
  11. BLACK_MAGIC

    BLACK_MAGIC
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    You've been amazingly helpful. Thanks very much:)
     
  12. Yummy Fur

    Yummy Fur
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    Vikki, it's a Musical Fidelity Nu-Vista Pre-amp.

    Yummy Fur
     
  13. sounddog

    sounddog
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    Ahhhh ... well in that case I not sure comments about transparency of pre-amps apply.

    I was assumeing the original poster was looking at more budget pre-amps :) with the nu-vista I think a switch would deffinately do more harm than good.

    Vikki
     

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