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For want of a better name: the HackerNAP board

Discussion in 'd.i.y.' started by hacker, Mar 12, 2010.

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  1. hacker

    hacker Delicious and nutritious

    One of the prototypes.

    Group Buy is underway!

    Working from home all day today has given me the chance to really crank this amp up for extended periods of time. I love it. I think you'll love it. No more messing around, let's start this GB properly!

    As usual, it's payment in advance for the PCBs plus postage. Each board is $5 plus P&P at the following cost:

    USA: $5
    World: $9

    That'll cover materials and actual postage costs. Any leftover cents will go to the pfm coffers.

    To figure out how much to pay:

    • Take the number of boards you'd like and multiply by $5. Eg. 4 PCBs = $20
    • Add postage for your order. Eg. $9 to the UK + $20 = $29 for 4 boards posted to the UK.
    • Send payment via PayPal.
    • If you can't do a gift, please calculate the PayPal fees yourself (i'm too old and lazy for that!!)
    • Please please please put your REAL NAME and PFM alias somewhere in the payment subject or message. If you don't tell me your name and alias, you'll hold things up.
    • Make sure you provide a postal address!
    • As each pfm member pays, I'll put a check next to your name (not your real name, your pfm alias) on the first page of this thread.
    • Once either (a) everyone has paid, or (b) we get to Friday 30th of April, I'll close the group buy and place the order.
    I'll place the order on Monday May 3rd unless everyone pays early, in which case I'll place the order early.


    The latest schematic can be downloaded here. Like I said earlier it's a mix of NCC, Acoustica, and PD.


    The latest BOM can be downloaded here.

    Connection diagram

    A diagram of how to wire this thing up to two separate power supplies can be found here. Note: the diagram assumes you're using HackerCAP PSU boards. If you're using anything else, I assume you know enough about what you're doing to not need a diagram.

    Some background

    My current power amp is made up of a dual-mono configuration consisting of heavily modified NCC clones off eBay, separate front-end and output stage transformers, separate VBEs for the front end, etc etc.

    It was a pain in the arse to build and wire up. It also takes up too much space in the case.

    I wanted to simplify things and, to that end, came up with a new layout for NAP-style power amp PCBs. They're the same size as Naim NAP boards (5" x 3.5") and borrow from the NCC circuit, the eBay clone circuit, Acoustica mods, and PD's FET-based VBE.

    The PCB incorporates:

    1. Pretty much the same audio circuit as the NCC200/eBay clones
    2. TO-247 output transistors
    3. Acoustica-style output transistor decoupling with on-board 470uF caps
    3. Magic pixie dust
    4. Well-sorted grounding
    5. Big spaces for feedback caps (will accommodate MMKs and even 68uF Wima MKS4)
    6. Big spaces for input coupling caps
    7. Separate power inputs for front-end and output stage supplies
    8. On-board FET-based VBE front-end power circuitry ala PigletsDad
    9. Each of these amp boards is designed to be used with two of my poweramp rectifier PCBs, one for the front-end one for the output stage. The front-end requires 5 dedicated 0V returns, the output stage requires 4.

    Grounding is carefully arranged so that the on-board 0V star is where all of the different 0V points meet, and is therefore the only common point for:

    1. Audio 0V
    2. Front-end supply 0V
    3. Output stage supply 0V

    The rest of the 0V points are labelled FE (front-end) or OP (output stage) to make it clear where each 0V return should be wired to.

    Here's the board layout as it stands just now. It's pretty much done (although I'm considering a dedicated 0V return for the feedback cap to return to the front-end PSU board's 0V star), I'm just tidying up the BOM:


    I was just going to have a handful made for my own personal use but figured I'd throw it out there: anyone else interested in some of these? Clearly they're only really of use to people building NAP-style amps with separate front-end regulation so I imagine there's a limited audience, but we'll see how much interest there is.



    They're $5 per PCB plus postage and packing.


    HackerCAP (haha, couldn't resist!) interest so far

    You need 2 PSU boards per amplifier board. In other words, 4 PSU boards and 2 amplifier boards for a stereo power amp. See this thread for the power amp PSU PCB group buy.
  2. stackowax

    stackowax pfm Member

    I'm game.
  3. flashgo

    flashgo DIY Practitioner

    Thanks, Carl, I'll take 6 – no, maybe 12! :D
  4. flashgo

    flashgo DIY Practitioner

    Carl, I'm playing around with the 0.47uF Soviet polystyrenes that you pointed me to, and they make for very nice input couplers (with suitable choice of R). Would it be possible to shift the holes for C1 around a bit so that a big round radial cap could be fit?

    Also, I'll likely regret this, but I might be willing to organize a GB for components. Of course, if you've got a Mouser shopping list set up, it's probably simpler for folks to just click the "buy this list" button and have Mouser do the work.
  5. benzp

    benzp pfm Member

    Carl, Count me in.
  6. olpplo

    olpplo pfm Member

    Please, I'll take 4 board and related smoothing PCB.

  7. cromodora

    cromodora foshfishfie

    It will be a first for a NAP type board if you can put the bias transistor on the same heatsink with the output trannies
  8. Bemused

    Bemused What's this all about then?

    Hi Carl, absolulty great work, looks mighty impressive.
    I would be pleased to take four.
  9. Pete MB&D

    Pete MB&D Pete Maddex, the one and only!


    I will take a couple or 4 depending on the price, its about time I re-built my 135 clones.

  10. sq225917

    sq225917 Bit of this, bit of that

    Jesus I haven't finished my NCC's from Les yet.
  11. James Evans

    James Evans Bedroom Bodger

    Only just sodding bought my NCC boards as well.
  12. Uzinusa

    Uzinusa Happy Chappy

    Only just built my NCC200 as well...arse! I'm up for 4 though :-0
  13. Uzinusa

    Uzinusa Happy Chappy

    I feel a group-buy coming on
  14. Yank

    Yank Bulbous Also Tapered

    If we're doing a group buy, sign me up for a pair please.
  15. sam_cat

    sam_cat C'est Crounchifique!

    Depending on cost I am interested in a pair of boards (maybe even 4).

  16. John Luckins

    John Luckins Well-Known Member

    Hi Carl,

    I've just sold my 135's so this is fantastic timing. I'd be interested in 4. Might even bridge them to keep the earth rail clean and quiet.

    Good interest so far. I never realised how many (other) people read this forum over breakfast!

  17. chiily

    chiily PFM Special Builder

    OH NO! Not another group buy...I'm going to have to leave this forum...

    On the other hand...fantastic Carl! Mark me down for 2, 4 at a push with the right price...
  18. Uzinusa

    Uzinusa Happy Chappy

    Yes - it's a jolly expensive place in the DIY room :)
  19. paulski

    paulski pfm Member

    I'm up for 2 (maybe 4 dependent on cost) and associated psu board(s) if available.
  20. TonyK

    TonyK pfm Member

    Hi Carl
    can you put me down for 4 boards please.

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