So what are the basics to amps and preamps?

Discussion in 'Archived Threads 2001-2004' started by Adam Bluhm, Feb 12, 2002.

  1. Adam Bluhm

    Adam Bluhm Supporting Actor

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    Okay. I'm pretty new at this. [​IMG] I've read about advantages to bi-wiring/amping and what not. Anyway, I think I'm not getting it because I'm missing some of the obvious material. Can someone take a second or give a link (or two) to some info reguarding the very basics to amps/preamps and what not?
    Very basics you ask? [​IMG] That may even include the purpose of the amps/preamps and where and what they hook up to. I'd like to learn about this end of HT.
     
  2. Bob McElfresh

    Bob McElfresh Producer

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    A modern AV receiver combines the Preamp & Amp steps into a single box. Unlike in the 70's where you had to have preamp/amp systems to get good sound, the modern units are very, very good.

    You can even hedge your bets by looking for a receiver that has "line-level" outputs. This allows you to later add a external amplifier and your receiver still does the pre-processor functions.

    In a nutshell:

    Your DVD player feeds video to the TV, and a Dolby-Digital bitstream to your receiver. The Dolby-Digital only needs 1 cable to carry 6 channels of sound. (Each channel carries the sound for 1 speaker).

    The receiver decodes the digital into 6 analog signals. These signals are then sent to an amplifier which powers them up to drive speakers. You run speaker wire from "binding posts" to each speaker.

    Sounds simple? It is.

    It gets complex because not everybody has 5 speakers and a external sub woofer.

    It gets complex because some speakers are large, others are bookshelf/monitor style.

    It gets complex because not everybody sits in the exact center of a circle of speakers.

    It gets complex because some people have CD players, VCR's, DVD players, DSS/satelite systems, & game systems

    The "PreProcessor" handles all this complexity. The amplifier does 1 job: amplify.

    Hope this helps.
     
  3. Adam Bluhm

    Adam Bluhm Supporting Actor

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    Thanks, Bob. Tell me if I understand this...

    IE: When someone talks about adding a seperate amp for the 'front channels,' they're just adding more pop for the speakers. Is that all? I'm sure there are power issues and possibly compatibility issues, but am I on the right track?

    I appreciate the response.
     
  4. Greg_R

    Greg_R Screenwriter

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    The advantages of a dedicated amplifier are lower noise floor (quiet sections are more quiet) and usually more watts/ch. Watts is a measure of electrical power (volts*amps). When your speaker reproduces sound, it draws current from your amplifier. The harder the speaker needs to work (loud passages) the larger the current drawn. Your amp has a reservoir of extra energy which is filled by it's power supply and depleted by your speakers. If the reservoir empties, then your amp could clip (making a loud sound which may damage your speakers). A dedicated amp typically has a larger power supply (transformer) as well as a larger reservoir of energy. The question is do you need an external amp? Check your speaker's efficiency ratings (published by manufacturer). Anything below 90dB/W is considered harder to drive (needs a larger amp). Also, 4ohm speakers require 2x the power of 8ohm speakers (most HT speakers are 8ohm). Also, a 3dB increase in SPL (sound pressure level) requires a doubling of amp power.
     
  5. Bob McElfresh

    Bob McElfresh Producer

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  6. Ted Lee

    Ted Lee Lead Actor

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    another benefit to a pre-pro/amp combo is flexibility. usually amp designs (for the most part) don't change much...an amp you buy today should work the "same" as a amp made five or even ten years from now.
    sound formats (as we all know) is a whole different game...just take a look at all the different formats out there right now...i still can't get them straight! [​IMG]
    i'm pretty sure my next setup is going to be a combo
    ...cough...cough...outlaw 950/770....cough...cough...
     
  7. Adam Bluhm

    Adam Bluhm Supporting Actor

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    Thanks for the info, fellas. I'm gettin' the hang of this! This preamp/amp stuff is kinda new to me. I'm always learning.

    Thanks again.
     
  8. rick_perez

    rick_perez Auditioning

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    i'm also new at this and this is my first post!

    i've read the buzz surrounding the new outlaw 950 preamp, will this enhance an existing entry level reciever? or will it be used for some other purpose?

    any post will be appreciated.
     
  9. Ted Lee

    Ted Lee Lead Actor

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