Friday, 4 January 2013

MXR Headphone Amp

Not a lot of info around, but this one is apparently simple little box that allows you to play at nighttime - without disturbing the missus. Seemed like a quick and painless schematic, but took me a few hours to finish...

Sort-of-requested by PaulR. :) I think i won't be posting anything more today. :D




53 comments:

  1. You guys are on a roll :) Thanks for the amazing layouts...I had a request for a layout,but have no idea where to post it,so here goes...

    http://www.musicfromouterspace.com/analogsynth_new/GUITARSYNTHAUG2007/GUITARSYNTHAUG2007.html

    If you can make a vero out of that, it'd make DIY history :)

    Thanks and regards,
    J.

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    1. Not a chance :) You would be much much much better off with PCBs on that one.
      +m

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  2. Awesome! Will this work well with pedals? I've tried a Ruby with headphones and pedals in front but it doesn't work out very well.

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    1. I do believe so. (but not 100% sure)
      +m

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    2. It will sound better with a cab sim, or eq tossed in between the pedals and the headphone amp, can sound kind of fizzy without one.

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  3. Verified! Works well. Used 2N3904 / 3906 no problem. Also used a 47 pf cap instead of the 50 pf as it was available. The volume is always "on". Just gets louder. Possibly Vol 1+ 3 are reversed, but it all depends on where you reference the pot lugs. In the end, just flip them around if it's a backwards vol response. Nice clean sound, and plays well with other pedals in front of it. Just what I needed for the night time baby hours. Thanks.

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    1. Thanks for verifying!

      I do believe it should be Volume 1&2.. My mistake. I'll fix it tonight.
      +m

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  4. Hey guys, I did verify this a few days ago? Just a friendly remimder to list as so for the others :)

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    1. Sorry mate I thought Miro changed the tag, I will now. Thanks for verifying!

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    2. I thought so too. Thanks for both of you :)
      +m

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  5. Evening,

    Just a little (stupid) question. How this little amp should sound? My build sounds very clear and just a bit saturated (but not even overdriven) with the por fully clock wise. Is the way is intended to work or I have made something wrong?

    BR

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  6. Hello!

    Is the cap value 150pF or 50pF? Sorry I just can't read it...

    Thanks a lot!

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  7. Can I assume that you use a stereo jack for the output?

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  8. Can I assume that you use a stereo jack for the output?

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  9. What is input impedance of headphone amp? Is it suitable to plug in guitar directly? I want to plug here output of my piezo buffer which have about 10k ohm ouput impedance.(this buffer convert 10M ohm output impedance of my cello piezo transductor http://www.realistacoustic.com/installation.php?type=cello)
    Thanks for answer

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  10. Hello

    I want to be able to offer an headphone jack and the output to the daisy chain of effect, staight to the real amp (I think it will add versability to the effect, or am i dumb?)
    Can i use Left Output to feed a mini mono jack socket, and the Right Out to feed mono guitar jack socket, or should i use stereo jack of correct diameter, perhaps in parrallel?

    Ben

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  11. So - how would I add an auxiliary input to this? So you could say, jam along to a ipod track?

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    1. Put this in front of it. http://tagboardeffects.blogspot.fi/2013/01/4-channel-mixer.html
      Use two channels for stereo aux input with dual pot and one channel for guitar. That will kill the stereo, but you'll get the functionality pretty easy.

      Or.

      Put it after this...
      +m

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    2. Just another me too to say it works really well. Thank you.
      -Jimi Lee

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    3. This comment has been removed by the author.

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    4. Ok, I get it, but what do you mean that it will kill the stereo? on input or output? how will it sound then? also do I need to put RCA jack inputs for stereo to plug in ipad or can I plug it in to just one of the channels? I will build this and mixer because I wonna to jam along mp3 trough my headphones at night. Also can I use both 2n3904's on q1 and q2 and does IC have alternative (I'm asking for mxr headphone amp)?

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    5. 1. Build the four channel mixer. Take channels 1&2 and use dual gang pot for them, as the output of the ipad is stereo. Use 3.5mm stereo jack for input, hooking it up with your ipad. Use 6.35mm mono jack for channel 3. That's for the guitar.
      2. Build the headphone amp and take the output from the mixer to the input of the headphone amp.

      That will omit the real stereo from the headphone amplifier output, but both channels will be in mono mix coming out.
      +m

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    6. The headphone amp has only one channel, which is splitted at the output. So the two channel stereo signal coming from the ipad will be mixed into single signal. If you use only other channel, then the other will be dropped out altogether. So you'll want to have both channels into the mixer.
      +m

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    7. Thanks. Ok, but what is dual gang pot? sorry if I sound noob...:-) ok but how will it sound without stereo in headphones? can I make it stereo output because of stereo, can mxr amp be stereo output?

      Delete
    8. The method above will merge the stereo channels. The "stereo" (mono in reality) output of the headphone amp is just splitted for two channels. If you wanted true stereo, you'd need to build two headphone amps, two mixers and one additional circuit to split the guitar signal for both headphone amps.

      Now. If you take only one channel from the ipad, may it be left or right, you'll miss the second channel completely. That will make jamming to Strawberry Fields pretty weird.

      http://www.taydaelectronics.com/potentiometer-variable-resistors/rotary-potentiometer/logarithmic/10k-ohm-logarithmic-dual-taper-potentiometer.html
      With dual gang pot you'll be able to turn just one pot to control both stereo channels volume.
      +m

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    9. Can I just solder wires from both channels to a one standard pot? Or can I just leave two pots for one input? Also can you tell me how to wire stereo on input with left and right wires? where does they go on standard 3 lug stereo jack? and can I build this amp with 2 of 2n3904s? and also how to wire input jack where ipad goes - is it to take two input wires and connect them to a single input jack? sorry for many questions I really need to build this so I need all info before...:-)

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    10. >Can I just solder wires from both channels to a one standard pot?
      No. You'll be shorting them both out with each other.

      >Or can I just leave two pots for one input?
      Yes. Bot then you have level control for each channel separate. Not too convenient.

      >Also can you tell me how to wire stereo on input with left and right wires?
      Use one channel for left and one channel for right. Ground is a ground is a ground.

      >where does they go on standard 3 lug stereo jack?
      Outer sleeve is the ground inner sleeve is right channel and tip is the left channel.

      >and can I build this amp with 2 of 2n3904s?
      No. You can't. 2N3906 is PNP transistor. You'll need 2N3904 and 2N3906 or 2N5088 and 2N5087.

      >and also how to wire input jack where ipad goes - is it to take two input wires and connect them to a single input jack?
      If you use a cable with 3.5mm stereo plugs at each end, then you need 3.5mm stereo jack (check above what goes where). Or if you have a cable with 3.5mm stereo plug and two RCAs on the other end, then you need two RCA jacks. With those, the tip of the red lead is left and tip of the black lead is right. Both sleeves go to ground.

      I really don't mind the questions, but whenever anyone "needs" anything i may suddenly become reluctant to answer..
      +m

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    11. Ok, get it. Just one more question. I wanna build this in one box (mxr + mixer) but with a switch to select between mxr amp and 4 channel mixer. How to wire this on either dpdt switch or 3pdt switch? So when I plug in headphones that I select on switch "headphone" and when I wanna just to use 4 channel mixer I select "mixer". Of course they both to have separate output jacks.

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    12. If you plan to have the mixer always on, then that would work. Output of the mixer to SPDT switch's lug 2. Lug 1 to headphone amp's input. Lug 3 to "mixer only" output jack's tip. That's it at the simplest.

      If you want two LEDs (let's say red for headphones and green for mixer only), you'd use DPDT switch with first three lugs like above. Lug 5 to ground. Red LED's cathode to lug 4 and green LED's cathode to lug 5. Needless to say that you take two resistor like 1K from the supply to each LEDs anode...
      +m

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    13. Thank You, this is all the info I need. :-)

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    14. Hi Larry and mirosol
      Larry, have you done this project successfully ? (amp + mixer)
      Is it ok ? does it works ?
      I had the same idea, and found lots of answers to my questions here, with the posts of mirosol (thanks !!)
      But, first, I thought put the amp before the mixer and not after ... like this :

      guitar ===> mxr headphone ===>
      ===> mixer ====> headphone (my ear :-) )
      ipod (or mp3 or CD or PC) ===>

      (or the guitar could be plug directly in one of the mixer input ?)

      In this case, Is it possible to use the 2 channel mixer, but by joining the 2 channels of the mp3 BEFORE the mixer ? (stereo => mono => mixer input 2)

      like this ?
      https://www.gearslutz.com/board/attachments/geekslutz-forum/246857d1311841872-mono-stereo-passively-help-sought-stereo-mono-passive.jpg

      values of resistors are ok ?

      Thanks a lot ! (sorry for my English ...)

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    16. sorry ... schematic was bad ...

      guitar ==> mxr headphone ==>.........input 1
      .......................................................mixer ==> headphone (my ear :-) )
      ipod (or mp3 or CD or PC) ==>..........input2

      Delete
  12. For those who have built the layout, i can´t get a lot of output from it and if i put a booster in front of the amp to push the level i get not very nice overdrive tones. I used a mono socket, would a stereo socket increase the volume or should i search the problem elsewhere?

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    1. Wouldn't really make it louder no. I'd put a couple of boosters to the output, or check your soldering and trace the signal backwards from the out puts.

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  13. Are there more powerful ic´s or transistors i could use ?

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  14. Where can I find a layout similiar to this (mono headphone amp), but with line-level input? Or can this one be modded to such?

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  15. I built another one but this time I put a 2 channel mixer in from of it with 1/8" jack on channel 1 for an iPod and 1/4" on channel 2 for guitar and then the out put of the headphone amp is 1/4" slaved to 1/8" so I can go headphones or amp. Works great for learning songs or playing along with tracks.

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  16. Since LM741 has the same pinout, is there any reason it can't replace the TL071?

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  17. The TL071 is low noise and low distortion and has a high input impedance, which works well for a direct guitar input. The LM741 will drop in and "work", as long as you don't mind the increased noise and decreased fidelity.

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  18. Thanks for the response. I will get my hands on some 071s.

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  19. Watching TV with headphones!!! Is it possible? Yes it is with Wireless Headphones for TV. Today we are going to list the best wireless headphones for tv

    best earbuds under 100

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  20. do you can post the schematics?

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    1. schematics can not be posted. search it on google and you'll find it.

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  22. hi, is the 4.7uf electrolytic on rows 4 and 6?

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  23. Seeing Television with earphones!!! How is it possible? Indeed it's having Wireless Earphones for telly. Nowadays we're likely to number the best wireless headsets for tv
    best headphones for mixing

    ReplyDelete