Color My World
Page 1, 2, 3, 4

THE MERCENARY
Inspired by the ever-colorful Fletcher of Boston-based Mercenary Audio, the Great River MP-2NV is a stereo mic preamp based on the Neve 1073 module. Like a real Neve mic preamp, the MP-2NV has a rotary switch for coarse gain and the equivalent of a fader to trim the gain. (The gain switch actually dials in various combinations of amplifier stages, gain and input transformer attenuation.)

Figure-2a: From left to right, a "clean" sine wave with distortion below .01%. Next, 1% distortion of the Direct Input FET is barely visible on the bottom of the wave. At 2%, the bottom edge of the Preamp Stage is clearly flattened, while the top is just beginning to get leveled. Finally, the output amp is taken to 5% distortion and still doesn't show any signs of clipping the positive excursion of the wave (click image).

Input Gain for the MP-2NV is in 5-dB steps, Output Gain is continuously variable from -20-dB through unity to +10-dB plus metering for both stages. As such, it is possible to purposely run the preamp hotter than the output amp, or vice versa. I found this extremely helpful when recording drums using a single pair of Marshall MXL-2003 large-diaphragm condenser mics (in X-Y about 3-feet off the ground and about 3-feet in front of the kit). With the "Fader" set to unity gain I allowed 4~6dB of headroom, easily readable via HEDD's metering, which is in 1dB steps all the way down to -10dB FS.

THE ANIMAL RUMBLES
Drummers being the animals they can be, repeated "overs" during moments of excitement can be tamed by turning down the output gain and cranking up the input gain. Again allowing 4~6dB of headroom at the converter, the new settings eliminated all "overs" and, with drums at least, there was no sign of undesirable distortion. How cool is that? Of course you also can be "nice" to the MP-2NV. On vocals and cello I found it full-bodied - round on the bottom and crystal clear on top.

It is common to see Neve gear being abused - I always felt sorry for the mechanical VU meters because people "buried" the needles. Maximum output level is +27dBm, easliy 10-dB more headroom than any mass-produced IC opamp-based preamp or mixer. At the other end of the spectrum, the Great River MP-2NV has 15- to 20-dB less noise than its vintage ancestor. By consolidating all the plug-in cards onto one circuit board, and using low-noise components throughout and a very quiet power supply, the signal-to-noise ratio is in excess of 105dB at the 30-dB gain setting and 96-dB at 60-dB gain, unweighted.

Figure-2b: A 3rd octave analyzer shows the spectral content of the MP-2NV output amp driven to 2% distortion. This is not an easy thing to do as the maximum output level is +27dBm! (Click image for larger view.)

When driven hard, Class-A Neve circuits - and the transformers that interface them - react to transients like peak limiters. There is even a dynamic recovery time, although that's not easy to show in print. You can see what happens to "static" sine waves in Figure-2a. Note that each stage behaves similarly, clipping only half the wave first. Assuming your signal "goes there" only momentarily, the effect is must less obvious than with any IC opamp, where symmetrical clipping is "instant nasty." In reality, the color starts before any obvious clipping occurs. In Figure-2b, the third octave display of the NTI MiniLyzer indicates not only the second harmonic, but a cluster of harmonics starting with the third.

PAINLESS ASSESTS
Three other features make the MP-2NV an asset starting with the Direct Input. A traditional mic pre / active DI connects the instrument directly to the first amplifier, bypassing the input transformer. Fletcher insisted on using the input transformer for additional color and, as unconventional as that might be, Dan Kennedy's clever and effective solution was to put a FET impedance converter in front of it for Hi-Z happiness - the perfect match for passive bass and guitar.

My Univox P-Bass copy sounded surprisingly round through the direct input. It was neither clangy nor unnecessarily subsonic. While there is no metering to indicate FET overload, doing so is pretty obvious. I simply turned the level control down on the bass. Again, manipulating the input and output gain controls can massage the tone range, which is enhanced by good technique and a consistent touch. (I'm still working on that.)

[an error occurred while processing this directive]