X-Altra Mini One Line Preamplifier

The X-Altra Mini One is a simple line preamplifer based on the National Semiconductor LM4562 (also known as the LME49720) that I built around 2008 and which served me well until about 2014 when it was replaced with newer more sophisticated designs. Nevertheless, this simple preamp sounded very good, and thanks to the LM4562 (which was quite new back then), the distortion is very low. I would characterize the sound as warm, open and pleasingly rounded.

Download and read the article here:-

X-Altra Mini One.pdf

(Please note, there are no PCB’s or  Gerbers available for this project.)


11 responses to “X-Altra Mini One Line Preamplifier”

  1. Tudor Cristian says:

    Thank you for this pdf is the best I solution for me and many others!
    I was looking for this kind of pream from a long time…so thanks again for it

  2. Tudor Cristian says:

    Helle again! Do you have the pcb design and schematic because from pdf I can’t build the preamp.

  3. Cristian Tudor says:

    I appreciate all your very good work and I really want to build this beautiful preamp but, I don’t understand where the joints are in the schematic, so I can’t make the circuit/pcb ….it is not so clear for me …sorry can you help me please?

    Best regards!

    • Bonsai says:

      Christian, thanks for you kind comments.

      I will layout a new preamp board in the next month or two – I do not recommend you build the X-Altra Mini.

      Please wait a month or two.



  4. Cristian Tudor says:

    Thank you so much, I will wait for the new project …thank’s for reply.
    Best regards!

  5. jcdrisc says:

    Hi AR enjoying the dialogue on diyaudio.
    I want to build the X-ALTRA MINI ONE
    Ideally I want to buy a board from you.
    If not possible where are the gerber files so I can have a pcb made ?


    Julian C Driscoll

    • Bonsai says:

      Hi Julian,

      Unfortunately I ditched the gerbers about 3 years ago – sorry about that.

      I may return to look at a basic line preamp again after I go back to the UK (I am based in China right now).

      Thanks for your interest – appreciate it.

      (I hear the Self preamp is good – might be one to take a look at as well)



      Sent from my iPad

  6. Hi,

    Have you ever used a passive ldr preamp? If so, did yo compare it to any of your active designs?



    • Bonsai says:


      Unfortunately not. I have heard passive LDR pre’s are very transparent if matched to the load carefully. Something for me to look at in the future I guess!

  7. alain98 says:

    Do you have PDF for the pcb layouts?
    Best regards

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