A single PCB laid out for two line drive amplifiers. PCB is laid out to take a Lundahl 5402 Line Output transformer thus providing a balanced floating output if required. A 75 ohm output is available before the transformer. The nominal gain of the amplifier is 10dB to provide unity gain when the transformer is fitted and the output terminated. The gain may be adjusted, if required, by altering the feedback resistor (R3). Typically 56k for 20dB gain. (27k fitted as supplied)
Mixing resistors (R2a,b,c &d) may be fitted enabling up to 4 inputs to be mixed into the amplifier. We would, however, recommend the use of the 4078 Mix amp if very low noise mixing is required. The output of the 4078 could then be fed into the 4173. The 4173 Dual Line Drive amp can also be used as a distribution amp by the addition of a suitable multiple output transformer. The audio signal is applied to the normal input of one amplifier, the direct output of this amp is then fed into one leg of the transformer primary. This same output is fed into one MIX input of the other amplifier, the output of which is fed to the opposite leg of the primary.