Other ADA Gear > ADA Cabinet Simulaters

Ampulator

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Yazoo55:
Thanks for posting this. The transistors are the 2SK364s used to mute the outputs.

I tried reproducing this section of the circuit which sends the power to the transistors using a spare bipolar supply. I connected GND2 to the existing ground, as you said, the yellow centre-tapped wire from the transformer. This all worked fine.

I've gone ahead and built the Ampulator. I used Kicad and got the boards manufactured by a Chinese fabricator to keep the cost down. I made a couple of mistakes on the power board and ended up having to solder on a couple of jumper wires and very carefully enlarging the holes for the power connectors, but it is all up and running now. I've posted a picture of it minus the lid.

MarshallJMP:
Very nice !!

May I ask where you got those large push switches?

Yazoo55:
Thanks!

I got lucky with the 8PDT switches and found them on eBay. The supplier is called acwsoft and they are listed as "Pushbutton Switch Schalter for Marantz 8PDT switch 8xUM Druckschalter". He has other sizes as well.

MarshallJMP:
Ok found him, thanks ! :thumb-up:

Yazoo55:
There was just one thing I was never sure about when I built the Ampulator. In the schematics the chassis ground symbol appears twice, the symbol which looks like the bottom of a rake. It appears on the power supply schematic and connects to R316 and C310 which are connected in parallel to the yellow centre-tap transformer wire. The only other time the chassis ground symbol is used is for the large cable which connects the two boards carrying the audio signal from U200 to end up at the balanced and unbalanced outputs. I think this is to shield the signal using the third ground core in the cable, connected at only one end of the cable in K204.

What I could not work out though was whether the chassis ground is actually connected to the metal chassis of the box itself. I went through the documentation several times and couldn't find anything. I did connect the bus wire to the tops of the potentiometers and wired this to the main chassis/box, but the signal ground does not seem to be connected anywhere to the main chassis/box.

Have I missed something here?

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