Stereo headphone jack: how can I make it mono?

Discussion in 'General Electronics Chat' started by cazksboy, Sep 19, 2015.

  1. cazksboy

    Thread Starter Active Member

    Nov 9, 2009
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    This question may be so simple even a caveman could answer it - but I'm stumped! I did my due diligence with a search; I couldn't find anything related to my question.
    I am a musician (I play electric bass) and I am trying to follow along with my instructor's lessons, in mp3 format. I have them loaded into my mp3 player, listening with a nice set of headphones. I realized that the lessons were mixed in the studio with the spoken vocal lesson in the left channel and the instructor's electric bass in the right channel.
    My problem is that I am deaf in my left ear (born that way) so I can't hear anything coming out of the left headphone cup.
    MY QUESTION: Is there a way I can rig some kind of adapter that will sum the left and right channels into a single monaural channel? That way I could hear all the material out of my good ear.
    Before you ask, I know I could just use a boom box, but I prefer to use headphones - it just works better for me that way.
    Thanks in advance,
    ...Doug
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    Google "Audio Mixer". Your choice -- build or buy.
     
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  3. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    The other option is to use audio editing software to produce a mono version of the file or find an MP3 player that has a mono setting; I believe mono is an option within the Rockbox firmware but you would need to buy a Rockbox compatible player.

    http://www.rockbox.org/
     
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  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    @cazksboy

    The software solution will be the best in general. There is one trick - If there is absolutely nothing in common on the two channels, and you claim there is not so this MIGHT work. Put a piece of scotch tape around the sleeve of the plug (closest to the cord, leaving the tip and center conductor as is). you may have to turn up the volume 2x of what you normally do. A quick and easy solution (hopefully). I haven't thought it out completely but, the risk of failure is limited.
     
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  5. cazksboy

    Thread Starter Active Member

    Nov 9, 2009
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    Thanks guys. I was hoping to steer clear of software, so GopherT's suggestion sounds like something to try.
     
  6. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    It's a gutsy move. Lifting the ground causes the headphones to produce only the differences between the left and right audio signals, an for a normal stereo signal pair it can sound pretty weird. But for artificially separated audio it probably will work.

    Another option is to wire the two signals together with a home made adapter. More on htat if you want it.

    ak
     
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  7. #12

    Expert

    Nov 30, 2010
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    I double checked it. I believe Gopher is correct. No modifications to the wiring in the headphones are necessary. If you can open the plug and disconnect the ground wire, that would accomplish the same thing and it wouldn't depend on the tape not falling off or getting crumpled. It would also make your headphones miserable for normal music.

    Your choice. If you can get the tape to hold still, this method should work.
     
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  8. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    A 2-channel mixer might work. This http://www.zzounds.com/item--GEMMM1?siid=170354&-_6AhcgCFcQUHwodUksNvg= has absolutely no specs. Not even what the power source is.

    A lot depends on your MP3 player and your Phones. Basically the output voltage and the impedance of the headphones. https://en.wikipedia.org/wiki/Headphones

    it's easy to divide the voltage down with a potentiometer, dual gang even. Maybe something like 1K to 10K, You might need a buffer amplifier stage.

    That $49.00 unit has a headphone amp etc. If the MP3 player can drive the inputs directly your pretty much home free.

    Battery power may be another story.

    Probably not too hard to build from scratch, but I would start with a headphone amp with a known schematic and modify the input stage. It could take a couple of OP amps.

    Although, what I was thinking is to get a kit. e.g. http://www.ramseyelectronics.com/Ra...archPage=1&searchRank=salesrank&searchSize=12

    Usually you get a schematic and modify the input with a 2 channel summer.

    Battery power would complicate things.

    In reality, your looking for a 2 channel mixer/headphone amplifier that;s used in a non-standard way.
     
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  9. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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  10. KeepItSimpleStupid

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  11. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Last edited: Sep 20, 2015
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  12. RichardO

    Well-Known Member

    May 4, 2013
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    I like the general idea. If you are worried about the tape and you have some soldering skills then you can make an adapter using a plug and jack. Only 2 wires are needed -- connect tip to tip and ring to ring.
     
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  13. cazksboy

    Thread Starter Active Member

    Nov 9, 2009
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    I like this idea a lot. Mostly because of its simplicity and cost-free approach. Yes, the stereo mix on the tracks are vocals panned hard-left and electric bass panned hard-right. So, the two channels seem to have nothing in common.

    I'm going to make a passive summing adapter like the schematic you just showed me. THANK YOU for that! So far, this is EXACTLY what I was looking for.

    Isn't that just like the idea of taping the sleeve of my headphone jack? At least electrically....
     
  14. peter taylor

    Member

    Apr 1, 2013
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    Put it on one ear
     
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  15. RichardO

    Well-Known Member

    May 4, 2013
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    Yes. Just more permanent. :)
     
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  16. #12

    Expert

    Nov 30, 2010
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    As Columbo said, "One more thing"...
    In some circuits, the resistors are important to stop the amplifiers from interacting (much).
     
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  17. cazksboy

    Thread Starter Active Member

    Nov 9, 2009
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    Uhh... I'm deaf in one ear (see my original post) and I need to hear both channels summed into my good ear.

    Ahh...OK, I see! Thank you very much RichardO!

    OK, I was wondering what the resistors were for. My headphones are Sony MDR-7506, but I don't know what their impedance is, or if that would influence the choice of resistors. But I'm going to head for Radio Shack and put together a couple of versions of this idea. COOL!
     
  18. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I hope you find one. Most have been closed since April. Only a few corporate owned stores remain open as phone stores and the franchise stores are looking for a new business model after radio shack declared bankruptcy.
     
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  19. cazksboy

    Thread Starter Active Member

    Nov 9, 2009
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    Hey KJ6EAD, I just clicked on the link from Far End Gear - that looks like EXACTLY what I want, but I don't even have to build it! Now - do I want to build my own, or order the single earbud? If I build my own, I'll keep the sound quality of my high-quality Sony headphones. I know - I think I'll do both just for fun!
    You guys are so great, I really appreciate your help.
     
  20. cazksboy

    Thread Starter Active Member

    Nov 9, 2009
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    Yes, I know that, and it's sad because it's due to corporate mismanagement (or so I'm told). But there's a Radio Shack open only two miles from my house - at least it was open last week! I haven't checked in a few days...sigh...
     
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