Improving Daisy (Part 3)
The third of Stephen Delft's series on building a guitar routing box.
All that remains is a diagram of the pre-amp board and details of the output transformers.
These are a special item, made by Sowter Transformers, (Contact Details). The part number is 3642, and at present, two will cost £12.36 incl post + VAT in the U. K. These transformers will remove any possibility of hum loops via the two output sockets and the switch box's own earth, and also give a small voltage gain (1.2 times) to compensate for losses in the buffer stage. They will also isolate you from any electrically doubtful equipment connected to the output jacks.
The transformers are mounted in any convenient place away from the power supply, by pairs of 6 B.A. screws. Remove all connections from both output sockets, trace two of the wires to the link switch and disconnect them there also. Re-arrange a standard three-way tag strip to give two down and one up as shown in the photograph last month, and solder to the tags of the link switch from which you just disconnected two wires. You must now identify the leads from the transformers. The secondary leads each have two inner wires. Blue and the braid connect to the sleeve tag of their output socket, and Red connects to the tip tag.
The transformer input leads have only one inner. You should still have one wire hanging around loose which comes from the sleeve tags of the input jacks and formerly connected to the sleeve tags of the output jacks, until you removed it. This wire, and the braids of both transformer input leads, connect to the turned-up tag on the three-way strip, and to nothing else. The inner wires to the transformers go to the other two tags on the three-way strip which are soldered to the link switch.
Feature by Stephen Delft
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