Line Out to Headphone adapter

Archived from groups: rec.audio.pro (More info?)

I'd like to add a gadget to my emergency kit to let me plug a pair of
headphones into a -10 stereo line out. I just want to make sure that the
device is putting out without having to connect it to another device with
a headphone amp.

a) Portability is paramount--ideally no larger than the connectors and an
inline bump.

b) Quality is secondary. It doesn't have to be loud or especially
accurate. This is a test for output, not a critical listening
experience.

c) It must be passive. I don't want to depend on (or wait on connecting
to) a power supply, be it batteries or house current.

Can I make do with just a pair of transformers? Showing a load of 10K
for 8-ohm headphones, that means a 1000 to 1 transformer? Any particular
suggestions?

Or does someone have an entirely different solution I should be
considering?

This came up last week when I was trying to record a keyboard. I plugged
into the line out and got no signal. I spent several minutes trying to
discover my error (bad connection? incorrectly plugged? some switch set
wrong?) before I realized that the keyboard line out was defective.
10 answers Last reply
More about line headphone adapter
  1. Archived from groups: rec.audio.pro (More info?)

    Carey Carlan <gulfjoe@hotmail.com> wrote:
    >I'd like to add a gadget to my emergency kit to let me plug a pair of
    >headphones into a -10 stereo line out. I just want to make sure that the
    >device is putting out without having to connect it to another device with
    >a headphone amp.

    So, make a cable with a female 1/4" on one end and two RCA connectors on
    the other end. It won't be loud and the response won't be as flat as possible,
    but it'll work fine with an efficient pair of phones like the Sony MDR-V6.

    >This came up last week when I was trying to record a keyboard. I plugged
    >into the line out and got no signal. I spent several minutes trying to
    >discover my error (bad connection? incorrectly plugged? some switch set
    >wrong?) before I realized that the keyboard line out was defective.

    Keyboard line out should have been a 1/4" jack. You can just plug a pair
    of headphones in there. If it's a mono TS output, you'll hear sound in
    one ear. If it's a balanced TRS output, you'll hear it out of phase in
    both ears.
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  2. Archived from groups: rec.audio.pro (More info?)

    In article <Xns9618636F2FDCgulfjoehotmailcom@207.69.189.191> gulfjoe@hotmail.com writes:

    > I'd like to add a gadget to my emergency kit to let me plug a pair of
    > headphones into a -10 stereo line out. I just want to make sure that the
    > device is putting out without having to connect it to another device with
    > a headphone amp.

    Whirlwind used to make a gadget like that, and maybe they still do. I
    think it was called the Q-Box. Here it is:
    http://www.whirlwindusa.com/test.html

    > c) It must be passive. I don't want to depend on (or wait on connecting
    > to) a power supply, be it batteries or house current.

    Sorry 'bout that. Batteries required.

    > Can I make do with just a pair of transformers? Showing a load of 10K
    > for 8-ohm headphones, that means a 1000 to 1 transformer?

    That might work. Actually the impedance ratio is the square of the
    turns ratio, so you'd want a 35:1 transformer which is a little more
    practical but you can probably do with less. Or you might just hunt up
    a high impedance set of headphones and try hooking them across a line
    output. I frequently plug headphones into an output jack to see if
    anything's coming out. Since you just want to know if there's a signal
    present (and what signal) it doesn't need to be ear-bleeding loud.


    --
    I'm really Mike Rivers (mrivers@d-and-d.com)
    However, until the spam goes away or Hell freezes over,
    lots of IP addresses are blocked from this system. If
    you e-mail me and it bounces, use your secret decoder ring
    and reach me here: double-m-eleven-double-zero at yahoo
  3. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:d11l2b$2v8$1@panix2.panix.com
    > Carey Carlan <gulfjoe@hotmail.com> wrote:

    >> I'd like to add a gadget to my emergency kit to let me plug a pair of
    >> headphones into a -10 stereo line out. I just want to make sure
    >> that the device is putting out without having to connect it to
    >> another device with a headphone amp.
    >
    > So, make a cable with a female 1/4" on one end and two RCA connectors
    > on the other end. It won't be loud and the response won't be as flat as
    > possible, but it'll work fine with an efficient pair of phones like
    > the Sony MDR-V6.

    Sounds like something I've done and had work well.

    MDR-V6s have pretty low impedance - what 32 ohms? The Sennheiser HD 580s
    have similar voltage sensitivity, but with more like 450 ohm impedance. They
    seem like the better choice.
  4. Archived from groups: rec.audio.pro (More info?)

    On Sun, 13 Mar 2005 14:46:18 GMT, Carey Carlan <gulfjoe@hotmail.com>
    wrote:

    >I'd like to add a gadget to my emergency kit to let me plug a pair of
    >headphones into a -10 stereo line out. I just want to make sure that the
    >device is putting out without having to connect it to another device with
    >a headphone amp.
    >
    >a) Portability is paramount--ideally no larger than the connectors and an
    >inline bump.
    >
    >b) Quality is secondary. It doesn't have to be loud or especially
    >accurate. This is a test for output, not a critical listening
    >experience.
    >
    >c) It must be passive. I don't want to depend on (or wait on connecting
    >to) a power supply, be it batteries or house current.
    >
    >Can I make do with just a pair of transformers? Showing a load of 10K
    >for 8-ohm headphones, that means a 1000 to 1 transformer? Any particular
    >suggestions?

    As Scott says, most "line outs" directly to headphones should drive
    them audibly (unless there's an electric guitarist or drummer in the
    room), but transformers will give the device's output a "reasonable"
    load and possibly be substantially louder (if the line-out's impedance
    is too high or doesn't have the current capability to drive 8 ohms
    directly).
    Also, keep in mind that the impedance ratio of a transformer is
    equal to square of the voltage ratio. So if you have an old unused
    wallwart with 120VAC input and 8VAC output (hmm, Alesis...), the
    impedance ratio is (120/8)^2 or 225, which (with 120V primary to line
    out and secondary to phones) turns 8-ohm phones into 1800 ohm phones.
    That may not be the perfect load, but it's a lot closer to 10k than it
    is to 8 ohms.

    >Or does someone have an entirely different solution I should be
    >considering?
    >
    >This came up last week when I was trying to record a keyboard. I plugged
    >into the line out and got no signal. I spent several minutes trying to
    >discover my error (bad connection? incorrectly plugged? some switch set
    >wrong?) before I realized that the keyboard line out was defective.

    -----
    http://mindspring.com/~benbradley
  5. Archived from groups: rec.audio.pro (More info?)

    On Sun, 13 Mar 2005 14:46:18 GMT, Carey Carlan <gulfjoe@hotmail.com>
    wrote:

    >Or does someone have an entirely different solution I should be
    >considering?

    No, I think you have a really good solution. Nothing is as fast
    and as convincing as actually hearing the signal.

    I keep an old pair of Sennheiser 414's (2000 ohms) and a variety
    of adapters just for that purpose. There are also several 600
    ohm phones that are modern and otherwise useful.

    If I were really smart (fat chance), I'd also have a portable
    signal source and adapters. Maybe a portable CD player. Always
    wanted one anyway.

    Good fortune,

    Chris Hornbeck
  6. Archived from groups: rec.audio.pro (More info?)

    "Mike Rivers" <mrivers@d-and-d.com> wrote in message
    news:znr1110735271k@trad...
    >
    > In article <Xns9618636F2FDCgulfjoehotmailcom@207.69.189.191>
    > gulfjoe@hotmail.com writes:
    >
    >> I'd like to add a gadget to my emergency kit to let me plug a pair of
    >> headphones into a -10 stereo line out. I just want to make sure that the
    >> device is putting out without having to connect it to another device with
    >> a headphone amp.
    >
    > Whirlwind used to make a gadget like that, and maybe they still do. I
    > think it was called the Q-Box. Here it is:
    > http://www.whirlwindusa.com/test.html
    >
    >> c) It must be passive. I don't want to depend on (or wait on connecting
    >> to) a power supply, be it batteries or house current.
    >
    > Sorry 'bout that. Batteries required.

    When I was a youngster 60 years ago, I connected an LP player to a pair of
    Brush crystal headphones, with no amplification. It worked quite well.

    Norm Strong
  7. Archived from groups: rec.audio.pro (More info?)

    In article <aIWdnUdG4djtfKjfRVn-1A@comcast.com> normanstrong@comcast.net writes:

    > When I was a youngster 60 years ago, I connected an LP player to a pair of
    > Brush crystal headphones, with no amplification. It worked quite well.

    I connected a set of crystal headphones to a galena crystal detector
    and listened to the radio. No batteries required.

    Fidelity? What's that?

    --
    I'm really Mike Rivers (mrivers@d-and-d.com)
    However, until the spam goes away or Hell freezes over,
    lots of IP addresses are blocked from this system. If
    you e-mail me and it bounces, use your secret decoder ring
    and reach me here: double-m-eleven-double-zero at yahoo
  8. Archived from groups: rec.audio.pro (More info?)

    In article <znr1110844387k@trad>, Mike Rivers <mrivers@d-and-d.com> wrote:
    >In article <aIWdnUdG4djtfKjfRVn-1A@comcast.com> normanstrong@comcast.net writes:
    >
    >> When I was a youngster 60 years ago, I connected an LP player to a pair of
    >> Brush crystal headphones, with no amplification. It worked quite well.
    >
    >I connected a set of crystal headphones to a galena crystal detector
    >and listened to the radio. No batteries required.
    >
    >Fidelity? What's that?

    I bet a nickel that the frequency response of that combination was flatter
    across the band than a typical AM table radio today. Not much selectivity,
    though.
    --scott

    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  9. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:d15g00$al3$1@panix2.panix.com...
    > In article <znr1110844387k@trad>, Mike Rivers <mrivers@d-and-d.com> wrote:
    >>
    >>I connected a set of crystal headphones to a galena crystal detector
    >>and listened to the radio. No batteries required.
    >>
    > I bet a nickel that the frequency response of that combination was flatter
    > across the band than a typical AM table radio today. Not much
    > selectivity,
    > though.

    You're not kidding about the selectivity. When I built my first crystal
    radio, there was an AM station's antenna across the valley from me. It
    didn't matter how I adjusted the variable condenser, I could only get that
    one station.

    Hal Laurent
    Baltimore
  10. Archived from groups: rec.audio.pro (More info?)

    In article <Q2tZd.16$sa6.3672@news.abs.net> laurent@charm.net writes:

    > You're not kidding about the selectivity. When I built my first crystal
    > radio, there was an AM station's antenna across the valley from me. It
    > didn't matter how I adjusted the variable condenser, I could only get that
    > one station.

    You had a variable condenser in your crystal radio? You must have
    built the advanced version. Mine all had a fixed capacitor (mica, of
    course) and a coil of enameled wire wound around an oatmeal box. I
    don't remember the slider arrangement, but it must have involved a
    strip of metal mounted on a board sliding across a sanded-off strip
    along the length of the coil.


    --
    I'm really Mike Rivers (mrivers@d-and-d.com)
    However, until the spam goes away or Hell freezes over,
    lots of IP addresses are blocked from this system. If
    you e-mail me and it bounces, use your secret decoder ring
    and reach me here: double-m-eleven-double-zero at yahoo
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