New Gear Review: Retro Instruments OP-6 Portable Amplifier

retroinstrumentsOP-6Retro Instruments’ OP-6 Portable Microphone Amplifier is a proper rendition of the classic portable RCA OP-6 tube microphone pre-amp that came out in the 1930s and was used mostly for remote on-location, live radio broadcasts—some of the greatest recordings of the past century.

Retro’s OP-6 sports five, 6J7 pentode tubes in a kind of “redundant” all Class-A circuit design. It has the same size, look and 20-lb heft of the original yet is fully modernized with XLR connectors, a 1/4-inch (DI) instrument input, 48-volt phantom powering, polarity flip, 25dB pad, output level control and a VU meter ranging switch that doubles as a “tube checker” for the three amplifier stages.

The Retro offers three choices of input impedance to match any microphone from vintage low impedance ribbons to modern condensers and dynamics. Purposely mismatching impedances also offers a range of tonality changes for any dynamic or velocity (ribbon) mics.

I first tried my Fender Strat plugged into the DI making it sound very fat. My AKG D12 VR dynamic on a voice and kick drum with the Retro OP-6’s three different impedance choices was like having several different mic choices.

Next I tried recording vocals using both ribbon and condenser mics. There is plenty of gain here if you are recording quiet singers with a low output microphone—compared to my transistorized pre-amp, the sound is thick and warm but not “dark”—more of a glow!

The Retro Instruments OP-6 Portable Amplifier sells for $3,500 MSRP.


Barry Rudolph is a recording engineer/mixer who has worked on over 30 gold and platinum records. He has recorded and/or mixed Lynyrd Skynyrd, Hall & Oates, Pat Benatar, Rod Stewart, the Corrs, and more. Barry has his own futuristic music mixing facility and loves teaching audio engineering at Musician’s Institute, Hollywood, CA. He is a lifetime Grammy-voting member of NARAS and a contributing editor for Mix Magazine. http://barryrudolph.com