Paul’s 3 Channel Bienne Mixer

(PICTURE DELETED) I can see three balanced mike transformers and a heap of hard-wired Veroboard! That’s how stuff used to be made a lot, although I usually designed my own boards to match the circuit diagram. It’s got Nicad batteries, charged up from the front panel by a couple of sockets. I also noticed in the Ebay ad that it’s got a two frequency test oscillator. You’d use this for various purposes; you could send the signal through your chains to check for distortion; you could set up your meter (the one on top of the case) so that it read 0Db for whatever level you’d choose. Quite handy really, and all in a bullet-proof box!

Have you bought it yet? It should have more than enough analogue sound to satisfy any man!


  1. Strangely( author ) :

    Sep 11, 2007 2:01 am |

    I thought you’d like the last bit…

    It seems to do all the things you want – only thing is that it’s just 3 channels into 1. If it works then you are laughing. The batteries pack in after a while but you can easily get some new ones from Halfords etc. And yes – it WILL have the analogue transistory sound!

    I did it by laying out the bits on a board in much the same layout as the circuit diagram. Usually, to minimise positive feedback, you keep the output away from the input, just like the circuit digram, where the signal flow goes across the circuit. Try and get everything nice and compact. I actually did it on tracing paper, then traced through onto the copper where I needed the tracks. Sometimes it’s a bit topological but quite often, the components are about the same size as the circuit representations (except for transformers and big fat electrolytics)

    I’d also make sure that a nice fat ground airplane could be left right around the edge of the board as well as decent areas for the power feeds.

    Components come in standard sizes – I’ve forgotten now but something like 10mm for resistor, 6mm for tantalum bead capacitors etc. You can buy bits to stick on a board, use a resist pen or cover the whole board in plastic then slice off the unwanted bits. What is needed is to etch away the copper from a board THAT IS NOT NEEDED. So you are left with the tracks. You do this with foul smelling ferric chloride.

    Clean the copper with VIM
    Make the tracks on the board
    Remove the bits to just leave the copper bit you need covered
    Float the board in the FeCl3 for half an hour
    Remove the protective film/etch resist stuff with alcohol or scrubbing stuff (VIM)
    Drill out your component holes with a 0.8mm drill
    Insert some solder pins for power take-offs, signal feeds etc
    Insert some dinky sockets for ICs (A lot safer than direct soldering)
    Solder in all the components
    Wire up and test!!

    Don’t leave ferric chloride on your hands, get it in your eyes or swallow it. It’s pretty dodgy stuff!

    I look forward to seeing this tank at some point. Hope all this helps. I’ve stuck a chat box on this site and little page preview icons on the Crawling Chaos site. What do you reckon? I’ve got a bit of edditting to do with the previews and slim down the numbers.


  2. paul( contributor ) :

    Sep 11, 2007 12:49 am |

    I am definetely interested, but wanted to run it passed you and your thoughts of the guts(components). I wanted to make sure it was worth buying and could be repaired/modded at any point in the future.

    Talking of designing your own boards to match circuit diagram. How does one go about that?

    Have you bought it yet? It should have more than enough analogue sound to satisfy any man!(Are you mocking me dear fellow?) lol