Preamp mixer vs. HiFi preamp - what parameters determine sound quality:

Discussion in 'rec.audio.pro' started by Martin Fuchs, Sep 2, 2003.

  1. Martin Fuchs

    Martin Fuchs Guest

    Hi, this is a follow-up to my question about a comparison between HiFi
    preamps and mixers; I consider buying a mixer/poweramp combo for my HiFi
    system at home instead of a full HiFi amp:

    I've gone through some technical specs of mixers that were recommended
    and looked for parameters that I sort of understand, such as Signal to
    noise (S/N) and crosstalk between channels.

    Allen&Heath, Rane and Numark mixers looked pretty good there, for
    example (S/N -90 dB or better). Denon, OTOH, had S/N specified as better
    -80 dB only.

    So is this as important as I think it is?

    What other parms determine "sound quality" on paper? I know that numbers
    on paper are not everything but they certainly help to rule out some
    mixers for what I want to use them. Are the THD (total harmonic
    distortions) important there?

    In the end I will listen to a few models, but I'd like to know how far
    off (if at all) mixers are from HiFi preamps.

    Price range should be 500-1000$.

    Thanks for all input, cheers, Martin
  2. P Stamler

    P Stamler Guest

    Unfortunately, the published specs on mixers typically correlate not at all
    with perceived sound quality. Most mixers have specs that are adequate, as
    quoted, but some sound decent (= sound like they're not there) and some don't
    (= add stuff). As a general rule, in mixers, the more you spend, the less
    impact it will have, which is good.

    BUT -- most hi-fi preamps have much less circuitry in them than a typical
    mixer. A line-level preamp (really a misnomer, but let it pass) usually has
    only one amplifier in it, following the level control, with perhaps a buffer
    for the REC OUT jack. If there are tone controls (increasingly rare in hi-fi
    preamps) there'll be an amplifier for that.

    In a typical mixer, however, the signal will pass through a minimum of about
    half a dozen amplifier stages. Now, an amplifier stage, unless it's perfect
    (and there aren't any) must add some degradation to the signal. So you're
    guaranteed that, all other things being equal, half-a-dozen amplifiers will
    usually sound worse than one. Obviously there are exceptions (compare and
    contrast a high-quality professional console with a Radio Shack hi-fi preamp,
    for example), but as a general rule less stuff means better sound.

    This also applies to consoles, of course, which is one reason a lot of people
    track through stand-alone preamps instead of consoles, or at least take a
    direct out from the channel strip rather than go through all the mixing
    circuitry unnecessarily.

    Peace,
    Paul
  3. Mike Rivers

    Mike Rivers Guest

    In article <bj2c7n$ep2ap$1@uni-berlin.de> REMOVEMEmartinDOTfuchs@physik.fu-berlin.de writes:

    > Hi, this is a follow-up to my question about a comparison between HiFi
    > preamps and mixers; I consider buying a mixer/poweramp combo for my HiFi
    > system at home instead of a full HiFi amp:


    They're two very different things. A HiFi preamp has two functions.
    First (and why it's called a preamp) is to amplifiy and equalize the
    low level signal from a phono pickup. Second, it's to provide a
    control center for selecting one of various sources to be amplified
    and fed to speakers or headphones. There are often tone controls and
    sometimes other routing, for instance to and from a recorder.

    A mixer is designed to combine several sound sources so that, rather
    than listening to one or another, you hear a mix of them. Nothing's to
    say that you can't make a mix consisting of just one source, but
    that's really not what it's for.

    > Allen&Heath, Rane and Numark mixers looked pretty good there, for
    > example (S/N -90 dB or better). Denon, OTOH, had S/N specified as better
    > -80 dB only.
    >
    > So is this as important as I think it is?


    Sounds like you're talking about DJ mixers here, not general purpose
    mixers. They're designed mostly to switch between two sources
    (turntables), but they're mixers in the sense that instead of using a
    selector switch, they crossfade between sources. Using this
    cross-fader effectively is part of the DJ's craft.

    As far as the difference between 80 and 90 dB s/n ratio, whether it
    makes a difference depends on how you're using it and how the
    manufactuer has measured it.

    > What other parms determine "sound quality" on paper? I know that numbers
    > on paper are not everything but they certainly help to rule out some
    > mixers for what I want to use them. Are the THD (total harmonic
    > distortions) important there?


    Sure, THD is important. But the best way to determine sound quality
    for your personal application is to listen for yourself. When it
    comes to DJ mixers, quality of mechanical components (like the all
    important cross-fader) and construction are often more important than
    some tweak parameters on paper, particularly since often measurements
    of the same parameter can't be directly compared unless you measure
    them yourself.



    --
    I'm really Mike Rivers - (mrivers@d-and-d.com)

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