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Bi-Amping Confusion!

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by Vodder, Sep 24, 2004.

  1. Vodder

    Vodder
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    :confused:

    After bi-wiring my front speakers and being well impressed I am now thinking about adding a DAC and bi-amping them for improved stereo performance but I'm getting a tad confused. Think this is due to not fully understanding the difference between pre, power and processors

    I've currently got a Yamaha 1400 - is this a pre, power and a processor all in one? If you bought separates do you have to have all 3?

    If I bi-amp it should I be looking at power amps that match my 1400 in output?
     
  2. mjn

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    yes you are confused :)

    You can't bi-amp a DAC for starters. A DAC (stereo only) will sit between your CD/DVD and convert the digital signal to an analogue signal, which you would then input into your Yamaha, which in turn would use the pre-power parts of the amp.

    A pre-amp is the control section, ie selecting the inputs and volume.

    A power-amp has no controls, and only has one set of inputs from the pre-amp.

    To bi-amp, you need 4 channels of amp for a stereo pair, either 2 stereo power amps, or a 5 channel amp will do.
     
  3. MarkE19

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    Yes, any receiver will be all 3.
    As mjn said: pre - volume & input selector; Power - the amp that takes a very quiet sound and boosts it loud enough to drive your speakers; processor - decodes the digital signals from a DVD and outputs them as 5.1 analogue signals.
    So in a typical system the signal path would be:
    CDP/DVDP(1) > DAC/Processor(2) > preamp(3) > Power amp(4) > speakers(5)
    1 & 2 are often combined in the same box - integrated CDP/DVDP
    2, 3 & 4 are often combined in the same box - receiver
    4 & 5 can be combined in the same box - active speakers

    To biamp the preamp needs 2 have 2 outputs per channel (good) or a cable that splits the signal (not so good) and then 2 amps per output to go to the individual inputs on the speakers. As you can see this is done well after the DAC, so as mjn also said you don't biamp with a DAC.

    So in effect a processor is just a multichannel DAC, but can decode many different signals ie DD, DTS, DPL etc
    In most cases the pre & pro are all in one so you will more than likely only need 2 boxes - processor (with built in preamp) and the power amplifiers.

    I hope I have cleared a few things up without teaching your granny to suck eggs :blush:

    Mark.
     
  4. Knightshade

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    Hi Vodder,
    You can use your Yamaha as a the Pre-amp stage and add a power amp to it. I would suggest using the Yamaha to drive the mid/high and the power amp for the bass. You don't need to go down the totally seperates route to bi amp. You will get better results but the stereo channels on the Yamaha (By all accounts) are pretty good. Use the pre-out/analogue out connectors on your Yamaha to connect a power amp.
    As for what to buy? I have no idea. Something with the same or similar musical signature of the Yamaha I would say, but what? I don't know.
    If your Yamaha will take it you could bi amp fronts, rears and centres if you wanted to be really outrageous!
    HTH
     
  5. Vodder

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    Cheers all - that has tidied things up and no eggs sucked at all :thumbsup:
    BTW - I realise you don't bi-amp with the DAC, I just can't write properly :blush: Been going on about DACs in another thread and probably confused my head in the process.

    Power amp wise, I've been recommended anything by Rotel should be good, in particular the 981 - my idea is that the 1400 is pretty mint for AV, so addiing the DAC and power amp and I pretty much a setup I can't complain about (till the nextupgrade :rolleyes: )

    So I'm sticking to getting a DAC and bi-amping the fronts for now - I'd like to bi-amp everything not so sure the bank manager would enjoy it so much!
     
  6. mjn

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    if you're going to add a DAC to improve stereo performance, make sure your amp has a "pure" stereo input mode, otherwise all the good work done by the external DAC will be un-done by the processing in your amp.
     
  7. Vodder

    Vodder
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    Thanks mjn - it has a "straight" mode, which I actually use quite a bit. Its strange - some CDs sound better through that mode and others with the amp messing with it!
     
  8. Vodder

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    LOL!!

    If only I had :rtfm: !!! Just found a whole load of new features, straight isn't direct stereo - jst foudn out how to switch that on and it is mint!! Even found 7 channel stereo now - some upset neighbours tonight!! :devil:
     
  9. Dfour

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    Its amazing what you pick up when you :rtfm: :eek:

    All you need is to run the HFE on your speakers from the B channel on the 1400 and connect your power amp to the pre outs on the 1400 and run the LFE channel with the power amp. Remember to turn the A channel off on the 1400. :lesson:
     
  10. wookie

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    FWIW IMHO, Its not worth Bi-Amping "two way" loudspeakers as a tweeter does not really require its own amp channel.

    A three way design with a mid tweeter / bass driver input terminals split, would benefit with bi-amping as the power is doubled for each half of the 20Hz-20kHz spectrum (assuming a "passive" crossover of 250 - 500Hz is used) as this represents about a 50% (accoustic) load on the amp and the combined HF & MF load can use the extra power to better effect.

    Bi Amping can and does make a system sound more dynamic, but you are also doubling the power input to the speaker whilst halving its power handling!

    Your B&W tweeter is likely to have a power handling of about 30wrms before it burns up.
    The unit used for mid/bass may have a 50w rating.

    I would use a power amp on the Yams Main pre outs and let the yam save some headroom from not having the front amps loaded.

    I had a DSP-AX620 then added a NAD C370, the movie results were quite superb as the centre speaker suddenly started sounding like it should.
    Music sounded much better too, esp bass at low listening levels due to the extra current on tap!

    I can only attribute this being due to the PSU in the Yamaha not been bogged down by 5 channels of 4ohm speakers (your B&W's may dip below 4ohms in places)!!

    Adding the Power Amp should work well.
    The Yamaha already has a pretty good DAC? Hasn't it got a 32bit floating point jobbie already installed?

    It may be worth a listen from a good transport straight into the yam via coax/toslink before trying a DAC. (Chord are very good) :D
     
  11. mjn

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    the "straight direct" bypasses all the DSP circuitry in your amp, so the signal should be untouched apart from volume. And if you've a good CDP /DAC you'll notice the difference, as you have.
     
  12. Vodder

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    I've now upgraded my fronts to 603s3 and moved the 602s to the rear (£425 brand new from Superfi Sheffield cos it's closing down!!)

    Wookie - in your opinion do you think the 603s would be worth bi-amping? B&W call them 2.5 way speakers?

    I've kinda decided that my stereo performance is good enough for me, so for now I'm not looking to get a DAC (unless one turns up cheap :))

    As my front room though isn't big enough though for full 7.1, I am going to move the smaller 601s upstairs. Does anyone know if there could be any problems if I connect them direct to the TV in my bedroom? Its a 28" sony, but the speakers it has have strange pin connectors.

    My other thought was to buy a cd player and have that in the bedroom with the 601s - but I would need an intergrated amp for that like the RA01?

    Dfour - Just getting a power amp like the 1070 would be no good right? I don't want to buy anymore kit than I need too!
     
  13. Dfour

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    On the contrary, getting a Lovely new 1070 would be an excellent idea and bi amping the LFE on your shiney new speakers. Just run them in first so you know what the sound like and then put the 1070 on the LFE channel and listen to it go :D
     
  14. Vodder

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    Aye, the 1070 is mint piece of kit. What I meant was for the time being as I am moving the 601s upstairs with a cd player, just adding a power amp wouldn't work? Am right in thinking I would need an integrated one?

    If I could use a power amp then I'd get one so that at a later date when I move the speakers back downstairs for 7.1 (when I get a bigger front room!) I would be able to bi-amp. I don't want to be buying an integrated stereo amp just for upstairs if I don't need too.

    I have another thread running asking if I could just connect the cd player to the line-in on the TV and listen to CDs via the TV, I do the same with my PC currently. I know that's not ideal if it can be done? but I'm over budget now! :devil:
     
  15. Dfour

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    The best option (read not cheapest:devil: ) Would be to get a pre and power setup for upstairs then when you amalgamate it all you can seel the pre amp and make some money back and use the power amp to bi-amp the front speakers:D

    Yes you could connect the CDP to the line in on the tv and use the tv speakers to play music.:eek:
     
  16. Vodder

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    I'd love too, but I'm not sure I can afford it - meant to be going on holiday on Sunday and spent the money in Superfi!! :blush:

    Reckon what I'll do is connect the cd player to a (v) cheap stereo amp off ebay, "nothing special" ones are £20-£30! Nice! Rotel RA931 - any good do you know?
     
  17. Dfour

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    Dont know them. I have heard arcam alphas and they are good cheap amps. Look on ebay most people ignore the early alphas.:D
     
  18. Vodder

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    sound - did a quick google and the RA931 didn't review too well - can't really complain though for £20!! :D

    Will keep a look out...cheers...collecting the 603s shortly, lovely jubbly :smoke:
     
  19. wookie

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    A 2 and a .5 way speaker still has a single (electrical) crossover split. (the mid bass is usually rolled off at 150Hz 12db/oct due to its enclosure volume/design and driver properties and connected in parallel with the bass unit (that has its own reflex enclosure).
    So,You would still be giving that tweeter a dedicated amp for everything above 4kHz!, IHMO its not worth the expense.

    A three way speaker with a 300 ish Hz crossover to the mid would benefit from BI-AMPING as the power split would be aproaching 50/50 (MID HF & BASS), IN ACCOUSTIC POWER TERMS as well as amplifer load terms.

    HTH's.
     

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