Retro Instruments OP-6 recreates the RCA OP-6 portable amplifier, keeping the original circuitry and the look of its faceplate while adding what a modern studio expects. Available gain exceeds 80 dB, and a stepped gain control means a setting can be written down and returned to. The case carries a durable hammer tone finish, input and output are on XLR connectors, and mains voltage switches between 115 and 230 volts.
Over 80 dB of clean gain for low-output microphones
Ribbon microphones and some dynamics deliver so little signal that a typical preamp has to be run wide open, and its own noise rises along with the source. The OP-6 has more than 80 dB in reserve, so a quiet ribbon placed well back still produces a usable level. In the opposite case, a loud source or a condenser in front of a guitar cabinet, a 25 dB pad keeps the input stage out of overload. A built-in VU meter and an output attenuator let you separate the choice of tone from the level fed to a converter.
Impedance matching as a tone control
The input impedance switch, with 37, 150 and 600 Ohm positions, is not there purely for technical correctness. On ribbon and dynamic microphones the load across the coil shifts the transducer's resonance, which audibly moves the bottom end and the fill through the midrange, so those three positions give three different voices from the same microphone. Added to that are an instrument input, a phase switch and 48 volt phantom power, covering whatever source arrives. Integral tube test functions let you check the unit's condition without opening the case or reaching for test gear.
KEY FEATURES
- Recreation of the RCA OP-6 portable amplifier with the original circuitry
- Over 80 dB of available gain
- Stepped gain control for repeatable settings
- Switchable microphone input impedance: 37, 150 and 600 Ohms
- 25 dB input pad
- 48 volt phantom power and phase switch
- Instrument input
- High-quality VU meter and output attenuator
- Integral tube test functions
- Faceplate true to the original OP-6 design
TECHNICAL SPECIFICATIONS
- Type: tube microphone preamplifier on the RCA OP-6 circuit
- Gain: over 80 dB
- Gain control: stepped
- Microphone input impedance: switchable 37, 150 and 600 Ohms
- Pad: 25 dB
- Phantom power: 48 volts
- Phase switch: yes
- Instrument input: yes
- Meter: VU, with output attenuator
- Connectors: XLR input and output
- Power: 115/230 V, 50/60 Hz
- Case finish: hammer tone
