The B1 Buffer – Redux

I have built a couple of versions of the Pass B1 Single JFET buffer (one is shown here), but I really wanted a more compact and “elegant” version of the board layout. I like the B1 for a number of reasons, mainly 1) simplicity, 2) great sound and 3) the fact that it has no gain and it is a versatile design that has many uses.

My PCB layout tries to be compact as possible, mainly by tailoring the footprints to the components I had available. Most of the board space is consumed by a pair of large 10uF Wima MKPs for the output caps. Input caps are fairly compact Wima MKPs as well and the space for the power supply capacitors have been shrunk a little. There is no space for an onboard volume control, but instead a couple of three-pin headers that can be used to connect on (or jumpered on the board if a volume control isn’t needed).

Silkscreen rendering made with

Eagle layout screenshot

The first prototype board shown above is playing music but it isn’t cased yet. However, I have the case more or less ready and only have to cable it up, so that should not be too long until that is done (by my standards of course…)

Oh and again, plans for a balanced version are being drawn up as I got 10 boards to play with 😉


9 Responses to The B1 Buffer – Redux

  1. Mike says:

    Are these PCBs available for purchase?
    Thanks Mike

    • theslowdiyer says:

      Hi Mike,

      Not as such (i.e. I am not planning on getting any more made), but I do have a couple of spares left over from my test run. Contact me through the contact form on the “about me” page if you are interested 🙂


  2. Pingback: Project files: B1 buffer/preamp | theslowdiyer

  3. Bogdan says:

    Any news of your plans for a balanced version?

  4. Bogdan says:

    Why C1 and C2 are different? What values did you used?
    Thank you!

    • theslowdiyer says:

      They are different to make them fit on the board 🙂 I wanted to make this smaller than the original Pass board and therefore I choose smaller capacitors. if you feed it from a regulated DC supply it makes no difference as the B1 draws very little power. I think my smallest version uses 4700uF for C1 and 3300uF for C2, but that was with a max. cap. height of 30mm to fit a 1U enclosure.

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