• Hi guys.
    Got myself an A15MK2 kit for Christmas. The wife knows it will keep me quiet.

    Not my first venture into amp building. I've made an 18watt lite and a couple of TMB's in the past. As well as making various modifications to many amps. Making pedals, pickups, switching systems.

    I over estimated myself and mistakenly ordered the A15 kit rather than the A15 Deluxe kit. But Klaus managed to sort that out for me and sell me a Deluxe chassis. So I've been able to take up the build again after a two week break.

    Here are some pictures. If anyone sees anything glaringly wrong, please feel free to call me silly.

    Nick

  • Hi and welcome to the forum!

    I suggest you simply take your time and check everything over and over. You don't want us to look for anything in particular. Do you?

    Simon

  • No, just showing what I've done so far and wanted to encourage anyone who may have spotted something that I've overlooked to voice their concern.
    I know my component placement is right. And every component aside from the rectifier has been checked once coming out of the bag, and again before placement

  • Have you added isolation to one of the legs of the rectifier? I think for this way of mounting this is a must have.

  • What does "glooping" mean?

    You should really, really isolate the one leg that reaches diagonally across the base. IMHO this isn't just "an option".

  • This isolation is only for safety because the air gap is tiny and it wouldn't be unlikely to accidentally get a short circuit for example by measuring and moving a leg with probe.

    Edit after rethinking: I don't know the layout and which leg goes were. If the legs are not crossing underneath, there is no need for extra isolation.

  • They are crossing. I looked, I took the board out and looked and saw that the wires were crossing too close for comfort. A slight press on the rectifier and it would have shorted.

    I think some things are lost in translation into English in the instruction manual. Not a massive issue for someone who has built a few circuits and has an idea that pitfalls happen in the most unlikely places. But to someone new, who only speaks English, it could have been explained in writing on the section about populating the power board.
    Not a massive problem. It doesn't matter who you are, you have to check and check again.
    Thank you for spotting it Simon. I wouldn't have seen it without you.

  • Well, in section 2.2 of the manual, it says: „The PLUS connecting wire of the bridge rectifier needs to be isolated to prevent contact with other connection wires of this device. You can use some of the isolation of the yellow wire for this purpose“. I‘m not a native speaker, but for me it‘s clear enough and the requested isolation is shown on the photo in the same section…

  • Ok I'm only seeing 17.6v across the bias pot.

    Also does anyone have a good way to house this pot inside the chassis. Having the adjustment exposed to the outside of the chassis isn't great.

  • The documentation of the amp is not freely available. Without any schematics and layouts it's impossible for us to help you out. MAD can help you I guess.

    "Perfektion ist nicht dann erreicht, wenn es nichts mehr hinzuzufügen gibt, sondern wenn man nichts mehr weglassen kann."
    - Antoine de Saint-Exupéry

  • NickF, the more imprecise your question is, the worse our answers will be ;)

    As set out on page 18 you should measure at pins 2/3 of the variable resistor. ALL measurements if not stated otherwise are against star ground. The measurement should be abour -21V at min and -27V at max setting of the bias control.

    Are your measured values in that area or way off?

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