The PRE-573 MKIII is a one-channel vintage style microphone, line and instrument preamplifier. The signal path uses only discrete components like resistors, capacitors and transistors. The microphone and line input and the line output are transformer balanced, using two different transformers, each one optimized for its purpose.
This is the way audio components were built before integrated circuits became available. The subjective sound quality delivered by vintage equipment is often preferred to the one delivered by modern units, a situation that is even more obvious now when music is recorded with clean sounding digital audio equipment.
The circuit used in the PRE-573 MKIII is similar to the preamp section in the classical 1073 module with a corresponding sound character that is warm, punchy, sweet and musical. These classic characteristics have 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 essence of this sound is now available at a surprisingly low cost, making it available to almost everyone.
- Vintage Style electronics. No integrated circuits in the signal path.
- The output is transformer balanced and fully floating and can drive a 600 ohm load up to a level of about 28 dBu.
- Maximum gain in MIC mode is 80 dB, enough to handle passive ribbon mics with quiet sound sources.
- The total gain range goes from -10 to +80 dB. The 20 to 70 dB range (in MIC mode) is handled by a turn switch and a toggle switch selects an additional 5 or 10 dB gain.
- Switchable impedance on the mic input, 1200 or 300 ohms, will change the tone of many mics.
- The input can be configured to accept line level signals by another switch, the level is then lowered by about 30 dB and the input impedance increased to about 10 kohm.
- A selectable two-position 6 dB / octave highpass filter with frequencies of about 45 or 180 Hz.
- A flexible front panel instrument input for electric guitar or bass that can be switched between a high impedance active or a mid-Z passive mode. These two DI options make it possible to get different tones from instruments. Mains connected sound modules or other signal sources should be connected to the MIC/LINE input of the 500-rack, unless they have a fully floating, transformer balanced output stage.
- The output level control makes it possible to make fine gain adjustments and also to overload the main gain stage(s) for more character and then lower the signal to a suitable level before the output stage.
- Insert jack for inserting Golden Age Project and Premier 500 Series eq and effect units. The insert is activated by removing a jumper at the back of the module.
- A soft start circuit that ramps up the supply voltage slowly (~10 sec.) to avoid a power-on current surge.
- Phase switch and switchable phantom power with an LED indicator.
- Selectable AIR equalizer adds a boost of about 6 dB centered at 30 kHz.
- A simple but effective signal and overload indicator is offered by a single LED that starts glowing red at about +4 dBu and then increases its intensity up to the maximum output level.
- Tantalum capacitors in the signal path.
- The 6.8 kohm phantom power resistors are matched to within 0.1% to maintain good common-mode rejection in the circuit.
- Selectable 600 ohm output termination at the back of the module.
- Circuit board star grounding scheme.
- A solid build quality that will last many years of normal use.
