Connect with us

phono vs line inputs on stereo

Discussion in 'Misc Electronics' started by Steve-o Stonebraker, Jun 11, 2004.

Scroll to continue with content
  1. My apologies if this isn't the proper sci.electronics group for this
    question --

    I have an old one-piece stereo, the kind that's designed to look like a
    rack system but isn't. It has just one set of RCA inputs, which are
    intended for a phonograph. It's my understanding that the phono inputs
    expect a much lower-amplitude signal than a regular set of inputs would.
    I'd like to use this stereo, though, for my VCR, DVD, Nintendo, etc..
    I've done a little searching, and seen a suggestion to go inside and short
    out the phono pre-amp, as well as a couple simple circuit designs[1] to
    un-amp the line to get it ready for the phono's pre-amp.

    Now, I'm a physicist, so I should probably be able to do either of those,
    but my only electronics class was way back in 1996, and I didn't enjoy it
    very much. If there's a cheap little device I can buy that will fix this
    up for me, I'd prefer that. I see that there are separate phono pre-amps
    available to allow a phono to go into a line input, but I don't know if
    the reverse is possible. Or even if I can just hook up a device like that
    backwards and have it work. A non-powered device would be highly
    preferred, naturally.

    Anybody have a suggestion?


  2. Sounds like two resistors should take care of it (called a voltage divider
    or a pad).
  3. John Miller

    John Miller Guest

    Because phono inputs are RIAA-equalized, they also need to be bypassed, so
    in addition to resistors (and probably coupling/DC blocking capacitors) we
    need to bridge around the RIAA EQ.
  4. Captain Rick

    Captain Rick Guest

    I am not certain about this, but I think that phono inputs generally
    have a tailored frequency response, not a flat one as a standard input
    would, so your sound might be a little weird even with level

    RIAA equalization rings a bell, try searching Google for more info.

    I have found a reverser for RIAA, try this - it seems to be what you

  5. Is it matched for magnetic or ceramic cartridges? How old is it?

  6. Yeah, that bears some similarity to the design I found. I can try to
    build something myself, I guess. Maybe I can bug the guys in the
    department electronics shop to make a nice little boxed device for me. :)

    Thanks for the suggestions, everyone.

  7. If you look at the URL he gave above, you will see that there needs to
    be equalization. If you use just "two resistors", then you will get
    terrible sounding audio.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day