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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




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69 comments:

  1. Jishnu Dasgupta4 January 2013 at 19:04

    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.

    ReplyDelete
    Replies
    1. mirosol4 January 2013 at 19:52

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

      Delete
  2. IfIOwnedAMidget4 January 2013 at 21:47

    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.

    ReplyDelete
    Replies
    1. mirosol4 January 2013 at 22:13

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

      Delete
    2. Unknown4 January 2013 at 23:28

      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.

      Delete
  3. LettucePrey4 January 2013 at 21:54

    THANKS!

    ReplyDelete
  4. bigrigg6 January 2013 at 16:25

    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.

    ReplyDelete
    Replies
    1. mirosol6 January 2013 at 17:18

      Thanks for verifying!

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

      Delete
  5. bigrigg10 January 2013 at 02:14

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

    ReplyDelete
    Replies
    1. IvIark10 January 2013 at 02:54

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

      Delete
    2. mirosol10 January 2013 at 05:44

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

      Delete
  6. JaviCAP16 January 2013 at 02:11

    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

    ReplyDelete
  7. Marcos20 January 2013 at 02:14

    Hello!

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

    Thanks a lot!

    ReplyDelete
  8. Piltdown Man14 February 2013 at 17:56

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

    ReplyDelete
  9. Piltdown Man14 February 2013 at 17:59

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

    ReplyDelete
  10. Robo10 March 2013 at 17:00

    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

    ReplyDelete
  11. Ben22 March 2013 at 15:42

    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

    ReplyDelete
  12. toddvirgil7 July 2013 at 15:47

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

    ReplyDelete
    Replies
    1. mirosol7 July 2013 at 17:36

      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

      Delete
    2. Jimilee6 October 2013 at 04:39

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

      Delete
    3. Unknown2 January 2014 at 08:58

      This comment has been removed by the author.

      Delete
    4. Unknown2 January 2014 at 09:19

      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)?

      Delete
    5. mirosol2 January 2014 at 09:28

      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

      Delete
    6. mirosol2 January 2014 at 11:08

      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

      Delete
    7. Unknown2 January 2014 at 12:36

      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. mirosol2 January 2014 at 15:09

      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

      Delete
    9. Unknown2 January 2014 at 17:45

      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...:-)

      Delete
    10. mirosol2 January 2014 at 18:48

      >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

      Delete
    11. Unknown3 January 2014 at 18:54

      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.

      Delete
    12. mirosol3 January 2014 at 19:17

      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

      Delete
    13. Unknown4 January 2014 at 15:19

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

      Delete
    14. sylvain31 July 2015 at 01:05

      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 ...)

      Delete
    15. sylvain31 July 2015 at 01:10

      This comment has been removed by the author.

      Delete
    16. sylvain31 July 2015 at 01:13

      sorry ... schematic was bad ...

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

      Delete
  13. Njokki27 November 2013 at 11:09

    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?

    ReplyDelete
    Replies
    1. Jimilee23 August 2014 at 06:29

      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.

      Delete
  14. Njokki13 December 2013 at 17:14

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

    ReplyDelete
  15. horseman4 May 2014 at 11:38

    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?

    ReplyDelete
  16. Jimilee23 August 2014 at 06:26

    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.

    ReplyDelete
    Replies
    1. Unknown8 April 2018 at 09:52

      Hi,
      I like to do the same thing. But I am new at this, read the older post on this subject, there is a lot of talk about mixers. But I was thinking to completely bypass the Amp, so keep the input music player stereo, and add the output from Amp, mono, to the output. I don't know if this will work or a stupid idea. Do I need to ad any resistors or diodes in between the mono to stereo output?
      Thanks

      Delete
  17. Mr. Geisen28 March 2015 at 19:52

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

    ReplyDelete
  18. EddieB29 March 2015 at 16:26

    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.

    ReplyDelete
  19. Mr. Geisen31 March 2015 at 15:39

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

    ReplyDelete
  20. leela8 March 2016 at 14:28

    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

    ReplyDelete
  21. somsalomao9 March 2016 at 21:47

    do you can post the schematics?

    ReplyDelete
    Replies
    1. Zach10 March 2016 at 00:13

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

      Delete
  22. Unknown24 March 2016 at 00:03

    This comment has been removed by the author.

    ReplyDelete
  23. Unknown24 March 2016 at 00:05

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

    ReplyDelete
  24. umair6 April 2016 at 15:53

    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
  25. T12 March 2017 at 18:25

    Built today and it fired right up, but the gain control is wonky. I used a 500K linear because that's what I had, but the sweep goes from on (and pretty loud, about where most people like headphones), to suddenly massively loud. I know to expect a sudden transition with a linear vs. rev log pot, but this sounds like an on-off behavior. Just for kicks I replaced the pot with a 5M resistor and then took it out entirely, and got the same volume as with it all the way off. I did use 3904/06 for Q1/Q2, but I expect pretty much everyone who has built this will have done the same.

    I'll go through the normal debugging steps, but was hoping someone could shed light on the gain control issue. It's still very usable, just a heck of a lot louder than I want it. It's an exceptionally clean circuit with a very "Hi-Fi" sound, doesn't sound much like a guitar amp but that's not the point. If your headphones are any good you'll probably want to roll off some of the lowest bass and highest highs.

    ReplyDelete
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    1. Unknown28 June 2019 at 22:20

      I seem to be having the same issue with the pot. Level is constant from 1-8 and then sweeps to huge volumes from 9-10. Like you described, it's an on-off feel. I'm thinking I should change the pot as I would like some more control over the level.
      Also it might be worth messing around with resistors and omitting the pot entirely.

      Does anyone else have this issue?

      Delete
    2. Paul_53 September 2021 at 15:15

      Did you ever find the cause? Mine does this too. I used a 3904 and 3906 for the transistors and a TL071 for the IC. Even with the correct 500k reverse log pot it’s still a constant volume until the last 1/4 turn, and then it gets LOUD!!

      Delete
  26. andrea839 October 2017 at 14:05

    This comment has been removed by the author.

    ReplyDelete
  27. Anonymous14 January 2018 at 20:06

    Hi, my MXR headphone amplifier is shot and since this is a pretty rare pedal, can I use the micro amp instead for a similar effect (line driver), or is it a completely different design? Txs!

    ReplyDelete
  28. Unknown9 February 2018 at 13:08

    This comment has been removed by the author.

    ReplyDelete
  29. akplm9 February 2018 at 13:12

    Hi to everyone; How is it possible modify the lyout putting up two outputs (mono) more)

    ReplyDelete
  30. mamah chyntia6 March 2018 at 09:03

    I will try this night.. I think this awasome.. Thank you

    ReplyDelete
  31. mamah chyntia7 March 2018 at 14:49

    Excuse me sir .. Can tL071 be replaced with tl081?
    thanks.

    ReplyDelete
  32. Unknown23 September 2020 at 00:26

    Works great. Perfect for self-practise without disturbing anyone.

    ReplyDelete
  33. Anonymous1 December 2020 at 03:05

    This headphone amp is awesome. I finished building mine over a month ago but wanted to get some real practice time in before I left a review. Honestly I use it more than my regular amp these days because I have housemates on opposite sleep schedules. It sounds really good with my guitar going straight in, but much better if I cut some of the lows with an EQ right in front of it. It doesn't take most dirt pedals well (perhaps this would change with a cab sim in front), but chorus, octave, delay, etc. sound great. I was ready to be disappointed by this headphone amp, but I now consider it an essential piece of my gear collection.

    ReplyDelete
  34. Hugo26 September 2023 at 03:39

    Does anyone know the current draw on this circuit? Thank you

    ReplyDelete
  35. EMedlin27 November 2023 at 19:51

    This sounds really good but is always full volume? i cant find the culprit.

    ReplyDelete
  36. Juanma12 July 2024 at 09:36

    Hi team,
    Is there a possibility of putting a 6.5 mono output to connect to the amplifier but not pass through the board?
    Let me explain, I want to have my pedal permanently connected to my pedal board, and when I connect headphones it does its job, but if everything is with the amp, this pedal will be disabled.
    Thank you very much for your answers and thank you also for sharing all these works.

    ReplyDelete
  37. Juanma12 July 2024 at 09:38

    This comment has been removed by the author.

    ReplyDelete