Golden Age Audio PRE-73 Deluxe Mic Preamp & DI

The PRE-73 is the first one-channel low-cost preamp on the market that is using a fully discrete signal path with three separate transformers for the balanced mic input, the line input and the output.

The circuit is very similar to the classical preamp section of the Neve 1073 pre/eq module with a corresponding sound character that is warm, punchy, sweet and musical.

This classical sound has been heard on countless recordings through the years and it is a versatile sound that works very well on most sound sources and in most genres.

The PRE-73 has a maximum gain of 80 dB on the mic input and the gain range on the Line input is -20 to + 10 dB. There is also a high-impedance instrument input.

The PRE-73 is perfect for almost any signal source, no matter if it’s a microphone with a high or low sensitivity (like a passive ribbon mic), a syntheziser or sound module or an electric guitar or bass.

The input impedance of the microphone input can be switched between 300 and 1200 ohms, which makes it possible to affect the tone of most microphones. There is also phase switch and an simple 4-step LED signal level meter.

The output level control makes it possible to make fine gain adjustments and also to overload the main gain stage for more character and then lower the signal to a suitable level before the output stage.

The Deluxe Version Pre-73 contains the following improvements and additional features: 

• Tantalum capacitors in the signal path. 
• Selectable 1073-style high pass filter, 50Hz, 80Hz, 160Hz and 300Hz.
• Output Attenuator -7, -14, -21 and -28 dB (located after the output transformer) allows overdriving the output stage and the output transformer for added character by lowering the output signal to a suitable level.
• The circuit board is prepared for Carnhill Mic and Line transformer and high pass inductor.
• The Insert jack that can be switched in/out from the front panel. An internal jumper can select that the Insert jack always has an output signal.
• Selectable Active or passive DI input and selectable input impedance in active mode, Hi Z or 100 kohm, by internal jumpers.
• The DI can signal can be selected to pass or bypass the mic input transformer by internal jumpers.
• Relays are used to control internal switching for DI input, Phantom power, Mic Low Z, Insert and Phase for shorter circuit board signal paths. The relays are controlled by front panel switches.
• Revised gain switch for added headroom. 
• Circuit board star grounding scheme. 
• Revised power supply with separate regulators for the audio circuits and relay and LED circuits.
• An unbalanced insert jack (nominal level about 18 dBu) added on the back panel for inserting units like the coming GAP EQ-73, a three band eq.
• LED meter levels adjusted.
• 600 Ohm termination resistor and jumper added to power supply board (accessible from the inside of the unit).
• Revised Gain switch, turning the know clockwise now increase the gain.
• Reduced noise at high gains by a change to the power supply grounding scheme.