Great River MP-500NV — 500-Series Single-Chanel Compressor

500-series microphone preamplifier designed to re-create the big-iron sound of the early 1970s large-format consoles

If you’re not sure which large-format console sound from the seventies the Great River MP-500NV recreates, the letters, “NV” should provide a clue (try throwing a couple of “ees” in there). While the 500-series format MP-500NV takes its cues from the vintage preamps of yore, its modern components give the MP-500NV more clarity, punch, and stable performance. In addition, features like metering before and after the major gain stages let you drive the MP-500NV hard to greatly expand your sonic options. In order to accommodate the same audio and metering circuit board found in the rackmount Great River NV series preamplifiers, the MP-500NV is designed to fit into a 500-series rack using two available slots. Plus, all specifications and performance details are identical to the NV series preamplifiers. Like all Great River products, the MP-500NV is designed and built in the USA.

Great River MP-500NV unique features:

• Hi-Z input is ideal for bass, guitar, and sound modules (FET-buffered and routed into the input transformer, a Great River exclusive)
• Gain stage monitoring via dual meters (also a Great River exclusive)

Great River MP-500NV key features:

• “Big-iron” vintage sound from custom-wound transformers
• Ultra quiet noise floor for outstanding performance at any gain setting
• Powered by 500-series rack's internal power supply
• I/O connections: XLR balanced; Hi-Z input on front panel (disconnects mic input)
• Adjustable gain stages: input in 5dB steps to 60dB; output from -25 to +10dB; maximum overall gain 70dB; 2 to 3 stages of single-ended, solid-state amplifier gain blocks, depending on gain structure; high-current 70ma Class A bias on output stage
• Input and output meters (dual-stage metering is a Great River exclusive)
• Front panel switches: polarity; phantom power; input impedance (1200 / 300 ohm); output loading (600 ohm resistor across output transformer)
• High quality, custom wound Sowter transformers
• Gold-plated switching contacts
• 3-year warranty with registration
• Mounts in two spaces in a 500 rack

Don’t forget to check out RSPE’s Rack Revolution, a virtual 500-series rack builder that lets you custom-configure the perfect 500-series lunchbox for your studio, DAW, or mobile recording rig. RSPE carries every 500-series module imaginable, including mic preamps, compressor-limiters, equalizers, and 500 power racks.

INSIDE THE BOX — Great River MP-500NV

Front-panel DI While the idea of a front-panel DI is not exactly unique, Great River’s implementation is. The MP-500NV is equipped with a HI-Z instrument jack that has its own input amplifier specifically designed for “DI” applications. The Hi-Z or Direct Injection (DI) jack presents approximately 1.2M-ohm impedance and utilizes a unique FET/Bipolar buffer amplifier to drive the input transformer. This presents the proper input load to an instrument, yet allows tonal shaping by changing the load on the input buffer with the impedance switch.

Many instruments will benefit from the added coloration of this input. More coloration will happen sooner with the impedance button in. This is an “instrument” level input, not “line” level, so putting a full “+4dBu” signal into it is likely to distort on peaks.

Dual gain staging The NV Series preamplifiers offer comprehensive gain staging capabilities controlled by two knobs on the front panel. The large gain knob adds an increment of 5dB gain with each step, while the small output knob delivers continuous adjustment of the output level. The input range of the large knob is 0dB to 60dB and the output range of the small knob is approximately -22dB to +10dB relative to the "CAL" marking on the front panel. The overall maximum gain of the MP-500NV is 70dB in the 1200-ohm input impedance mode.

Generally, the signal will be affected the least by keeping the large knob turned down and the small one up. More coloration occurs when the input stage does most of the work, so cranking the large knob and trimming back the output control will tend towards a thicker sound. When the input stage clips, it gets ugly, so keep an eye on it.

Output Transformer Loading: This button controls the output termination relay. When in the out position, the output transformer is unloaded. When pushed in, a 600-ohm resistor is connected across the secondary. The output transformer has an inherent resonant peak that affects the frequency response at high frequencies. This peak is at approximately 50kHz, is about 6db up from flat, and is cable and load dependent. For optimal flatness in both frequency and phase response, the amplifier is designed to take a 600-ohm load, but some interesting effects happen when un-terminated. A gentle high-frequency lift, like an “air band” EQ and a bit grittier midrange are the effects you should hear when the Loading button is out.

OUTSIDE THE BOX — Great River MP-500NV

The MP-500NV front panel controls include:

• Input Gain: 12-position gold-plated switch, +5dB to +60dB (5dB steps)
• Output Level: Continuous control, -25dB to +10dB
• Loading In/Out: Output transformer loading gold-plated relay
• Input Impedance Selector: 300/1200 ohm: gold-plated relay w/LED
• Phantom power: +48 Volts DC w/LED
• Output signal polarity: gold-plated relay w/LED Metering:
• Input meter: 6-LED ladder
• Output meter: 6-LED ladder

Who’s using Great River

I am, and have been the drummer for the band Cinderella for 22 years and am now also a composer for TV and Film. I just wanted to let you know that I just picked up a 500NV and it is without a doubt, incredible. I called Troy at RSPE (where I bought it) and told him 10 thumbs up!!!! I started by plugging into the DI and just turned it up. Holy cow, that was all I needed to convince me. I A/B'ed with a couple of other top shelf pres in my lunchbox and there was no comparison. Vocals through it are ridiculous! I can't wait to track my 26" kick through it. Absolutely awesome piece of gear!

– Fred Coury

When shooting out various mic pre's to match with a pair of vintage U67's to record Jerry Douglas' dobro on the album, Glide, it was Great River mic pre's that WON!

– Bil VornDick (Alison Krauss, Ralph Stanley, Marty Robbins, Bela Fleck, Jerry Douglas, Mark O'Connor, Charlie Hade, Jesse Winchester)

Even though the combination of an MP-2NV with an EQ-2NV provides you with almost unlimited choices for sound shaping, each one is an amazing sound tool in itself. The MP-2NV is my go-to mic pre when I'm not sure which direction I want to go with a certain mic. It provides such a wide spectrum, that I can always count on it to get the best out of any mic. The EQ-2NV is simply one of THE most musical EQ's I have heard and is used on every session at my studio.

– Michael Wagener (Mötley Crüe, Overkill, Accept, Great White, Poison, Alice Cooper, Extreme, Megadeth, Janet Jackson, Ozzy Osbourne, Dokken, Metallica, White Lion, Skid Row)

About Great River Electronics

Located on the banks of the Upper Mississippi River, Great River Electronics designs and builds handcrafted quality audio recording tools. All products undergo extensive research, development, and fine-tuning to meet and exceed the needs of audio professionals. Years of concurrent experience as an OEM manufacturer of industrial measurement and control systems for industries where safety, reliability, and quality control are critical are what give the Great River design-build team an edge. Carefully designed analog signal paths, many with digital controls, are the foundation of Great River audio recording designs.

Using a wide range of classically proven circuit styles, Great River continues to create a product line of audio recording tools that deliver a diverse tonal spectrum and solid sonic performance. From tracking to mastering, dual transformer-based preamps, sweet sounding EQs, and a hybrid-style summing system, all make consistent, concrete contributions to any recording studio.

The Great River NV-series big-iron sound of the seventies comes to the 500 format in the MP-500NV. For more information, call or chat with an RSPE representative today.

This product is also available as part of the RSPE Demo 4 Free & Rental Program, click here to see the rental product page.