Receivers as pre-amp

Discussion in 'Archived Threads 2001-2004' started by StevenK, Mar 11, 2002.

  1. StevenK

    StevenK Second Unit

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    Some advice/opinion on this matter please.

    I would like to buy either a HK 320 (or perhaps some other sub $500 6.1 receiver with pre-outs) to use as a pre-amp since I can't wait for the 950 and I don't actually have enough dough for the 950.

    The BIG thing here is...I won't be listening to music. I mean, I will, but not in a critical sense. I'll be using an HTPC to play MP3s, with an occasional CD here and there, and even some -gasp- tapes or recorded shows. My main concern is performance in DD-EX, and DTS-ES movie soundtracks. Seeing as how movie soundtracks are so busy and the main focus will be the visuals, how much will I lose if I go with a receiver instead of a pre-amp?

    PS...the equipment that will be going with the pre-amp:

    NHT 2.5i Fronts

    NHT AC-1 Center

    HTD Level 3 Rears

    Sherwood 9080 Amplifier

    HTPC source
     
  2. Elbert Lee

    Elbert Lee Supporting Actor

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    Steven - you should be fine. Most people are less critical of HT soundtracks than for music so I don't think the difference will be that dramatic. However, I would consider using your receiver's internal amps for the rears so as to discharge some of the heat that it might generate. But, if the receiver doesn't give off that much heat, it might not be an issue.

    Elbert
     
  3. StevenK

    StevenK Second Unit

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    dumb question...

    why would the receiver give off any heat if the amps are being by-passed? I thought the pre-pro section gave off minimal heat by itself, but not too much to be concerned with. wouldn't driving the rears actually up the amperage running through the amps in the receiver so more heat is generated?
     
  4. Aslam Imran

    Aslam Imran Second Unit

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    A receiver would give out idle heat if its channels were baised into Class A operation, but then again there are no receivers built with Class A amplification, heck even most of the high-proced stuff isnt Class A. So your questions answer is that bypassing receivers internal amps would not generate heat.
     
  5. Mal P

    Mal P Stunt Coordinator

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    Hi Aslam - The two channel amp I've ordered is Class A to 8 watts. A higher up model has Class A to 16 watts, so there are amps out there which do produce that kind of power. However, most receivers wouldn't be Class A at all, maybe to 0.05 watts or so.

    Cheers,

    Mal
     
  6. StevenK

    StevenK Second Unit

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    Regardless of whether or not the receiver produces IDLE heat...wouldn't more heat be generated if the receiver were driving a pair of speakers versus sitting idle.

    I don't quite understand the concept of driving speakers to discharge heat since it seems counter-intuitive.
     
  7. Jedd

    Jedd Second Unit

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    Steven,

    I'm trying to solve the same problem ..(gotta build HTPC source too), so far I'm leaning to the H/K AVR 520, because of the amplification reroute ability. If you already have a stereo apm you probably should look into this too.

    But I'm still considering Denon 2802 or Marantz SR7200..
     
  8. Aslam Imran

    Aslam Imran Second Unit

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  9. StevenK

    StevenK Second Unit

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    So amps that are biased in to Class A (not that I know what that means) draw in more current when they are idling? Why would they need to draw in any current if they are not driving anything.
     
  10. Aslam Imran

    Aslam Imran Second Unit

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    Actually Class A amps have a current flowing through the output devices all the time unlike other class amps that have current flowing through the output devices only when a signal is applied. The advantage of this is that there is current that is immediately available for use by the load as soon as the signal is applied. This leads to a very high slew rate and very low distortion. The disadvantage is that all the current flowing through the output devices during idle has to be dissipated (as heat) and hence the very low efficiency of these amplifiers. They are about 25% efficient meaning they are dissipating four times as much heat with no signal applied to them as when a signal is playing through them.

    Only the very high end amplifiers (like the Mark Levinsons, Krell FPBs and ofcourse the high-end SET tube amps) employ this mode to full output with fabulous results. The other mid-fi gear makers are Class A up to a few watts of their rated output switching to Class AB for the remaining output.
     

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