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Building a HackerNAP

Discussion in 'reference' started by hacker, Aug 25, 2012.

  1. hacker

    hacker Delicious and nutritious

    Hi all,

    Here's a rough guide to HackerNAP building. It's incomplete, inaccurate, and omits stuff. Enjoy!


    Latest BOM (v1.8): http://hackernap.com/docs/HackerNAP BOM v1.8.xls

    Latest build manual (v1.4): http://hackernap.com/docs/Build Manual v1.4.pdf

    HackerNAP Gerber files: https://www.dropbox.com/s/dw2rh9ik1tlsln6/HackerNAP Gerber Files.zip?dl=0

    HackerCAP Gerber files: https://www.dropbox.com/s/256qweqeluxon81/HackerCAP Gerber Files.zip?dl=0

    I started with boards that were mostly built except for the input cap, driver transistors, output caps, output inductor, and output transistors, and 5mm spade connectors.s the wrong way round!! Don't do that at home...

    The big grey feedback cap is a 68uF AVX:

    [​IMG]

    Here's the raw parts for the output inductor. I used 16 inches of 16AWG solid core enameled copper per inductor. Each was wound around a 1/4" drill bit and the ends are scraped free of enamel using my pocket knife:

    [​IMG]

    Pop the resistors inside the inductors, like so:

    [​IMG]

    Then solder them into the hackernap and make sure that in a continuity test they measure 0 Ohms - no resistance whatsoever. If you measure anything else, go back and check your soldering:

    [​IMG]

    Voila! Inductor:

    [​IMG]

    Add in the input coupling cap (a lovely 10uF Evox SMR in this case), the driver trannies, the output trannies, and the output caps:

    [​IMG]

    Build up your front end HackerCAPs (this is 1000uF/4R7 with Qspeed 3A diodes):

    [​IMG]

    And your output stage HackerCAPs (6800uF Kendeils with Dale 10mH/8A inductors and 30A Qspeeds). Take note! Fit the 5mm spade connectors first or you're going to have a bollocks of a job fitting them after the caps:

    [​IMG]

    The output trannies will be mounted on this chunk of aluminium, which has been drilled to accommodate the transistors:

    [​IMG]

    The bottom of the heatsink has been drilled and tapped with 1/4" threads so that I can bolt up into it from the underside of the amp, pulling it tight against the floor of the amp. This picture doesn't show it well, but those are 1/4" taps:

    [​IMG]

    The heatsink bracket will be bolted to a 1/4" thick piece of aluminium that's bolted to the floor of the amp:

    [​IMG]

    The plan was to lay it all out like this. It's 4 trafos, 2 Vellemans, 4 HackerCAPs and 2 HackerNAPs squeezed into a Modushop 2U Pesante case, which had previously been doing duty as a power supply (hence the big-ass hole in the rear panel):

    [​IMG]

    These are the transformers. Two 40-0-40 50VA for the front ends, and two 35-0-35 500VA for the output stages:

    [​IMG]

    Test your AC before attaching it to stuff you care about!!

    [​IMG]

    I'm using thick aluminium oxide heatsink pads. The underside gets a nice tiny blob of heatsink paste like this, which is then smeared evenly across the pad. It's then up-ended and smooshed onto the aluminium heatsink. Another blob the same size is then applied and the output transistor is laid atop it, like so:

    [​IMG]

    I'm using rubber insulated washers. Not because I want insulation, but because I think it's less likely to damage the transistors than a metal washer:

    [​IMG]

    On the other end of the HackerNAP boards I'm using thin rubber hose to make stand-offs:

    [​IMG]

    And here they are all mounted nice and snug:

    [​IMG]

    The HackerCAPs are mounted on top each other, with the low-power caps on the bottom of the stack. The bolts are 2 1/2 inches long and I've used more of the rubber hose to make very small stand-offs for the bottom HackerNAPs:

    [​IMG]

    The output stage HackerCAPs go on top:

    [​IMG]

    When wiring the lower HackerCAP there's very little room for connectors. If you've got 90-degree push-on spades, that's great. I didn't have any, so I used regular spades, hacked off the top part of the plastic, added heatshrink, and bent the wire at 90 degrees like so:

    [​IMG]

    All wired up, it looks like this:

    [​IMG]

    Input signal is via XLR connections:

    [​IMG]

    And wired to the HackerNAP using really short twisted wires:

    [​IMG]

    The speakers are protected by Velleman circuits. I was unimpressed by the standard pin connectors supplied with the Vellemans, so I bodged my own out of 16AWG solid copper:

    [​IMG]
    [​IMG]

    First tests involve bias adjustment and running square waves through it to make sure there's no overshoot, undershoot, or distortion. Here's a 2.5kHz square wave being scoped at the HackerNAP's speaker output:

    [​IMG]

    It looked good, so I hooked up my iPhone to play music through a shitty old speaker:

    [​IMG]

    Finally the second channel was made in the same way:

    [​IMG]

    Notice that I've stacked the Vellemans on top of each other:

    [​IMG]

    And with the lid on, it's ready for action in the main rig!

    [​IMG]

    And there you have it - one HackerNAP. It sounds bloody brilliant :)
     
  2. 337alant

    337alant Negatively Biased

    Nice job Carl looks like one for the reference section me thinks:D

    Alan
     
  3. 337alant

    337alant Negatively Biased

    If anyone has a pair of those 68UF AVX caps for sale I want a pair so PM me if you want to sell them

    Alan
     
  4. hacker

    hacker Delicious and nutritious

    Please note: In the first few pictures D5 is mounted the wrong way round!!

    You might notice a lot of the wiring is different colours. That's because I just used what I had in the bits box. It's all 14AWG for the power/ground cables, except the speaker returns, which are, I think, 10AWG. Just because :) All wire (except input wires, which are silver/PTFE bought from pfm years ago) was bought for about 30c/foot from Home Depot (B&Q).

    Odds n sods:
    • The power switching is done with an e24: http://www.amb.org/audio/epsilon24/
    • Speaker connectors off eBay.
    • Case: re-used Modushop Pesante 2U
    • Alu floor: re-used aluminium sheet
    • Input connectors: re-used gold-plated Neutrik XLRs
    • Most HackerNAP parts: from the bits box. I used parallel resistors to make up values I didn't have.
    • I avoided polyester caps where possible. Only the feedback cap (68uF), the -ve CCS filtering cap (1uF from bits box), and the 10uF front-end VBE caps are polyester. The rest are polypropylene (all the 100nF) or polystyrene. The big PSU rail caps are a mixture of 470uF Panasonic FC, 100uF FC, and 68uF FC.
    • Before mounting the aluminium U-channel to the case, and before mounting the output trannies to it, both contact surfaces where sanded with 400grit paper, then 600grit wet-n-dry, then 0000 steel wool to get a mirror smooth finish. I applied Radioshack heatsink paste to all contact surfaces, but sparingly - do not squidge a ton of that crap onto your amp!!
    • You'll notice a hodge-podge of resistors. That's because they're from the bits box, except for the feedback resistors that I bought a few years go. Those are 1k02 and 26k7 Welwyn RC55Y.
    • My 3rd and final HackerNAP will use 68uF Wima polyester caps for feedback.

    You don't need wanky components to make this amp sound good! The power supplies and grounding are what give most of the performance. To that end I'd really like to try some low-power 55VDC shunt-regulated supplies for the front-ends... I'd keep the FET VBE and insert the shunts between those and the front-end circuitry. But at that stage it really is just gilding lillies!
     
  5. 337alant

    337alant Negatively Biased

    Carl
    I see you still have all of the decoupling caps in their?, I thought that general consensus is that most of them are no longer required with the front end reg being on board anyway, did you experiment?

    BTW here’s my humble Hackernap effort :)
    http://www.flickr.com/photos/69508926@N05/6969569707/in/photostream
    http://www.flickr.com/photos/69508926@N05/6823446302/in/photostream
    http://www.flickr.com/photos/69508926@N05/6824034044/in/photostream
    http://www.flickr.com/photos/69508926@N05/7831547648/in/photostream
    Alan
     
  6. captain

    captain pfm Member

    thats great alan, i hope others who have built hackernaps will contribute some tips and pictures especially, i actually getting quite excited about the build
     
  7. stackowax

    stackowax pfm Member

    What pre are you using Alan?

    oops. Just looking at your other photos. Looks like a B4.
     
  8. bivalve

    bivalve pfm Member

    Mr Phil had a nice alternative. Any chance of a pic.
     
  9. sam_cat

    sam_cat ʇɐɔ_ɯɐs

    Couple of pics of mine:

    [​IMG]
    (Click for details of whats what)

    [​IMG]

    And #2:
    [​IMG]

    If you compare the 2, #2 had a lot of electrolytics replaced with film caps, some resistor values changed etc as per the suggested upgrades.

    Smaller case due to the massive heatsinked side panels.. The one used (on the right in these pics) barely gets above room temperature.

    Sam
     
  10. sam_cat

    sam_cat ʇɐɔ_ɯɐs

  11. GWM

    GWM Lost in the 70's

    Have to agree with Alan replace 4.7R on front cap board with 47 or more, film cap after Vbe I used some 5.6uF in my parts bin obvious improvements.I had some spare 1000uF Panasonic HG 100v so put them in place of the 100uF on the inlet of the Vbe and pulled the last caps on the cap board another obvious improvement.I would go for more voltage on the front end tried both it makes the amp sound more powerful.there's lots of stuff on input/feedback caps fit flying leads and tune to your system.
    Perhaps we should start a porn thread just for all the different builds.
    Geoff
     
  12. hacker

    hacker Delicious and nutritious


    Sounds like a good plan. I built mine from the parts bin without making a single order from Mouser, Digikey, or anywhere else! Perhaps one little order wouldn't hurt....

    I'll need to get some 63V parts - mine are all 50V rated.

    That's actually surprising. I'd have thought with the constant low current and upstream CRCRC I'd have thought it'd make little difference. Good to know :)

    All of the caps, even the film one? I wouldn't want to do that. I'd want at least a small film cap in C9 and C11, where the front-end PSU rails are starred.

    Yup, highly recommended.


    I think the most popular are 68uF film caps or wet tants. Any other favourites?

    Yes!
     
  13. GWM

    GWM Lost in the 70's

    Hi Carl think most of the things I listed were your ideas anyway so congrats to you, the 1000uf on the inlet to Vbe just replaced the outlet cap on the cap board so still have a CRCRC arrangement I did not do it to get an improvement but just to try out John Luckins idea on a choke input.It did sound beter though, feedback caps are a mater of taste and system tried all types and had wet tants in for a long time have 47uF MMk's in at the moment sounds outstanding.This amp really is good my Gales just love them so cheers to you.
     
  14. 337alant

    337alant Negatively Biased

    A month ago I did a mod on my Hacker caps for the output stage were I changed the last cap on each module to a 10,000uf Elna cap this did give a nice extra bump in the bass and a bit better bass line definition.
    Only down side is its not easy to desolder snap in caps and I lifted 2 pads in the process but I managed to repair them with wire links
    http://www.ebay.com/itm/190648119872?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

    Alan
     
  15. 337alant

    337alant Negatively Biased

    Did anyone try removing the following caps,
    C6, C7, C9, C10, C11, C12?, Just for discussion are they still necessary?, I dont see what they are doing and the FE 0V at the front left and right of the boards dont go to anything so thats a couple of ground leads we could do away with ?

    Keep C5 and C8 and just stick a 100N wima accross it on the back of the board or keep C10 & C12?

    Alan
     
  16. Sparts155

    Sparts155 pfm Member

    I don't know if anyone has actually tested what decoupling is necessary for the amp to work properly, but I'd want a small film cap after the "Vbe" to keep impedance reasonably low at high frequencies. Having extra electrolytic caps here isn't necessary, but may change the sound of the amp to taste.
     
  17. GWM

    GWM Lost in the 70's

    Yea replaced C6 through 12 with a pair of 5.6uF MUNDORF polyprops I had spare cleaner smoother sound.
    Someone else mentioned replacing the last cap on the outlet of the main CAP board with a 10,000uF as well think it was a Mundorf does it ever end.
     
  18. mr_phil

    mr_phil If it isn't broken, try harder

    Anybody got a link / part number to the 68uf Wima films? There are so many of the b****y things I want to get the right ones!
     
  19. hacker

    hacker Delicious and nutritious

  20. DJM

    DJM pfm Member

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