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Avondale m130 build

Discussion in 'd.i.y.' started by longmanjon, Jun 6, 2021.

  1. longmanjon

    longmanjon pfm Member

    Hi guys​

    I would like to build a pair of Avondale m130 monoblock amps like the image below


    I have a pair of ncc200 from Eddie on here and have ordered a pair of cap6 boards from les and some cases.

    on advice from the transformer purchase post I have a quote from tiger toroids for the below
    Primary of:-
    Primary- 0-240VAC

    Primary: 0-230/240/250VAC
    Electrostatic screen
    Secondary 1: 35-0-35V @ 5A rms - 350VA
    GOSS band
    Mounting: M8x30mm bush In a potted centre,
    Heavy gauge lead outs 300mm long

    my intention is to also use switched/fused iec connector in the case.

    what else should I be doing or get, not sure if anyone has a wiring diagram etc??

    many help/advice would be great, types of wire to use grounding etc

  2. Vinny

    Vinny pfm Member

    Speaker protection boards. They'll be a tight fit in a half width case and would normally be run from a seperate transformer (albeit a tiny one).
  3. Mike Hanson

    Mike Hanson Lovely!

    If you're ordering custom transformers, then ask them to include a 0-12VAC secondary for a UPC1237 speaker protection module.

    You'll also need RCA input connectors and speaker output binding posts (and/or Neutron SpeakON connectors, if you like those).

    Plus standoffs, wire, spade connectors, etc.

    And a switch.
    Mynamemynaim likes this.
  4. chiily

    chiily PFM Special Builder

    And a DMM to set the bias and check the output offset.
  5. Mike Hanson

    Mike Hanson Lovely!

    And a crimping tool for the spades, and some hardware (screws and perhaps a few nuts) to mount stuff to the chassis. M3 is good for most things. The Avondale heatsinks take M4 (although they're usually provided with screws).

    You'll also have to drill or punch holes in your chassis.

    And of course you need some type of case, if you haven't got one already. Note that it should be aluminum for proper heatsinking.
    Last edited: Jun 7, 2021
  6. longmanjon

    longmanjon pfm Member

    Last edited: Jun 7, 2021
  7. Mike Hanson

    Mike Hanson Lovely!

    There isn't a speaker protection module on the amps you've highlighted so far. Earlier Naim amps didn't have one, and I've no idea what's in their current amps.

    SPM modules are like insurance. You don't need it until you need it. ;) Due to the design of the Naim and Avondale boards, if a power transistor fails, then the amp can go DC, which will quickly blow your speakers. If you can fit an SPM into your design, then that's a good thing. If not, then at least you realize the risk involved.

    At this point the only "good" amp in my house without a speaker protection module is the Avondale'd NAP110, which is definitely too tight to fit one.
    Mynamemynaim likes this.
  8. Vinny

    Vinny pfm Member

    Not ideal, though easy enough to add on - speaker protection in a seperate box, which could handle both channels in one box with one SPM, whch almost invariably have 2 channels on one board.

    I have had an Avondale board fail and it fried an irreplacable, except from salvage, woofer.
    Mike Hanson likes this.
  9. Mike Hanson

    Mike Hanson Lovely!

    That's an interesting idea, and would be easy to build into a separate box. Of course, it does mean you have a few more connections in the signal path, but not the end of the world.

    In that situation, connect the ground lines directly from in to out. The signal wires would go through the SPM (via independent internal paths). Then connect each incoming ground via a 10K resistor to the shared ground on the SPM.
    Vinny likes this.
  10. 337alant

    337alant Negatively Biased

    There are some UPC1237 modules that can be bolted vertically to the back panel and the speaker binding posts bolt directly to these boards so I think you could fit them in at a push
    Cant seem to find a mono version ATM but nothing to stop you just using 1 channel of a stereo version
    UPC1237 Speaker Protection Board Directly Mounted Hifi Amplifier DIY AC12- AKA | eBay
    Just make sure you get that 0-12V secondary on your transformer to power it

    Last edited: Jun 7, 2021
    Mynamemynaim and Mike Hanson like this.
  11. S-Man

    S-Man Kinkless Tetrode Admirer

    Interesting that Naim choose not to fit an SPM. They do include SOA protection though, so obviously think that output devices rarely fail short if they are kept within the SOA.

    Or perhaps they just don't care about your speakers :D
  12. ramona

    ramona Music lover

    Or they think that relays and such degrade the sound. Quality over Safety says me, the Devil's advocate.
    Decisions, decisions.
  13. 337alant

    337alant Negatively Biased

    I did that for years until I blew a Tweeter and damaged a woofer £140 + £190, its not funny :eek:
    The trick is to get good quality genuine good quality relays like Omron & Songle
  14. ramona

    ramona Music lover

    I must admit that I'm not good for devil's advocate, personally I opted for the most advanced DIY protection circuit I could find from VZ Audio which include a lot of protections. DC protection is the minimum I personally suggest. My vote goes for the most tried solution, Velleman DC protection, dirty cheap too.
    If you are not a relay guy, there are SSR solutions out there nowadays and they are cheap enough.

    Standard NCC200 don't need big fancy transformer and choosing a smaller one (<500VA) you get away using inrush circuit of some kind and the risk of possible buz.If you go on and order a custom one, you might better have an additional secondary winding in case later on you want to add front-end regulation.
  15. longmanjon

    longmanjon pfm Member

  16. 337alant

    337alant Negatively Biased

    The piece of paper next to the toroid has the answer
    the transformer has 2 secondarys like 35-0 / 35-0, so if you join the orange and red wire together you have 35 - 0 - 35, where the black and yellow are your 35s the red/org becomes like a centre tap 0
    Mike Hanson, bugbear and Mynamemynaim like this.
  17. longmanjon

    longmanjon pfm Member

    Some help needed, everything installed and mains plugged in voltages ok. As soon as I plug in the rca and speaker cables I get smoke in the middle of both the ncc200.
    Something wrong in both setups
  18. 337alant

    337alant Negatively Biased

    Do you have insulating kits on bolts to the output and driver transistors
    Have you observed the polarity on the two BC128 caps
    Where about is the smoke coming from ?
  19. eddie pugh

    eddie pugh pfm Member

    What DC voltages are you getting at the output of the rectifier boards
    My boards were running on 50 volts I would advise you to not exceed 50v a bit lower would be better

  20. eddie pugh

    eddie pugh pfm Member


    Check your speaker output sockets Make sure they are totally isolated from the metal casework and make sure there is no solder bridge between terminals

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