Saturday, 22 March 2014

Quart Into A Pint Pot

The other day I completed wring up the mic and line inputs and the pre-fader unbalanced insert points including the wiring to the four channel faders themselves. The next job was to wire up the direct outs. These are fed from OUT2 of the channel amp, via a VTB2291 transformer to the direct output XLR connectors at the rear. As there are four channels there are four transformers. There are also the two AUX send outputs and the two main bus outputs that need output transformers for a total of eight. Initially, I intended to mount these eight transformers on the bottom of the Rackz enclosure towards the back. The main sub-rack is plenty high enough to fit the transformers in and there are some convenient ventilation slots in the bottom of the enclosure that could double up as fixing holes for the transformers. However, I had not allowed for the mass of wiring I had just put in. Here is a picture of the bottom of the enclosure looking through from the back:

You can clearly see there is no room to fit the transformers on the right hand side because of all the wiring and when the AUX send and returns and the main outs and the 2 track playback all get wired in there will be no room on the left either. Clearly the transformers can no longer fit there. So where to fit them?
Above is a view of the partially completed rear panel. The mic, line and insert connectors are annotated. Above the connector panels is a good sized black panel marked 'X'. This panel can be removed and behind it you can see the top of the rear of the sub-frame:

The bottom of the panel is 80mm from the sub-rack and the top of the panel is 130mm from the sub-rack. This should leave plenty of room to fit the transformers to the rear of this panel. The only downside is that the channel output transformers are now quite near the channel input transformers.Fortunately they are at 90 degrees to each other so hopefully there will be no magnetic feedback! Here is how the transformers will fit onto the panel.

Now all I have to do is drill 16 holes on the steel panel, bolt on the transformers and wire them up. Did I mention I hate mechanics?

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