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Preamps what dey do?

Discussion in 'Home Cinema & Hi-Fi' started by Sparky191, 13 Nov 2006.

  1. Sparky191


    Joined: 6 Dec 2005

    Posts: 790

    I'm a bit clueless when it comes to HiFi. What does a preamp do. I see talk of phono preamps which I assume boost the signal level from a phono input into a regular amp. But then I see regular amps used as preamps for other amps. Whats that all about then?
  2. Sparky191


    Joined: 6 Dec 2005

    Posts: 790

  3. squiffy


    Joined: 17 Mar 2006

    Posts: 9,155

    They control the volume. The output from a CD player is 100%, you can't plug that into a poweramp as it'll blow up your speaker cones. The pre-amp reduces the gain to a acceptable level, the output is variable so the poweramp recieves this lower signal. A pre-amp is also a input/output switcher.

    Phono stage is used to increase the gain from the very low level from the pickup, it also adds RIAA EQ.
  4. clockworks


    Joined: 4 Jan 2005

    Posts: 407

    As Squiffy said, a pre-amp controls the inputs (selection and volume, maybe tone, balance, digital to analogue conversion, digital processing, etc.), and a power amp boosts the signal to drive the speakers.

    Most amplifiers and receivers are integrated, which means that they combine pre- and power amps inside one case, with a common power supply. Some integrated amps have pre-outs, so that you can add a separate power amp.

    As you spend more money, you get separate pre- and power amps. The idea is that sound quality is improved by separating the low-level signals in the pre-amp from the high-level signals in the power amp. This works because the components are isolated inside separate metal boxes, and they each have their own power supplies.

    Some source components, such as CD players, effectively have pre-amps built-in - they have volume controls, so can be connected directly to a power amp.
  5. Sparky191


    Joined: 6 Dec 2005

    Posts: 790

    ah....thanks for the explation that makes it clearer. I often see set ups with multiple amps whats that all about then?
  6. Daniel


    Joined: 3 Jun 2004

    Posts: 562

    Location: Bristol

    Multiple amps could be bi-amping where you use one amp to power the lows and the other for the mid/high on bi-wirable speakers.