With the widespread acceptance and use of digital editing systems in radio production, the need for new stand-alone microphone preamps has grown. Most digital editing systems have a built-in mixing capability. In addition, many broadcast facilities are installing signal routing systems that can mix. Without a conventional broadcast console to provide one, the need for a stand-alone microphone preamplifier has grown.
Great River Electronics has been making high-quality preamps for a long time, to much acclaim in many recording studios and production houses. In addition, the company has designed custom analog electronics, and among its customers are the CBS Radio Network and Minnesota Public Radio. The MEQ-1NV is a stand-alone preamp and a separate equalizer in a 1RU package.
|Performance at a glance|
|Four-band parametric EQ
1/4” TRS send and receive jacks
XLR inputs and outputs
Rackmount ears and rubber feet supplied
Continuously adjustable gain from 70dB to 0dB
Zero to 20dB attenuation
18dB per octave low frequency roll-off
Built-in power supply
Discrete semiconductor circuit design
The MEQ-1NV comes in basic black. Right away the bright blue power-on LED on the mic preamp is a sign that this is no ordinary black box. The preamp features a large gain selector knob, calibrated in 10dB steps from -70 to +20 with a smaller gain pot next to it that sets the gain within that 10dB range. On the bench we set the range to 40, as the instructions indicated, and all tests were conducted here. There are switches on the front panel to select phantom power, input impedance and output termination.
Because the microphone preamp plays a critical role as the first step in any recording or broadcasting system, it follows that its specs should be as close to ideal as possible with regard to noise and frequency response. Most amplifiers are not ideal and much has been written about how different amplifiers have a different sound. For this article we tested the MEQ-1NV on the bench, and then made some qualitative tests using speech with a few varied microphones. These tests were recorded on a DAT tape and later played through a few different sets of monitors.
Figure 1. The response with all the bands disabled and the low frequency roll-off filter set to 150Hz.
The frequency response was as expected. With the termination turned on, we measured less than 0.2dB change in the output from 20Hz to 20kHz. It was only off 1.25dB at 40kHz. The distortion measured was 0.014 percent at 1kHz. With the termination turned off, the response changed slightly, with almost 1dB lost below 100Hz and 2.05dB gained at 45kHz. The weighted noise floor at 120Hz measured at -104dB terminated. The published noise spec is equivalent input noise of -128dB or better. This figure includes the amplifier's gain as well as the measured noise floor level. Our test results are considerably better than that.
Next we fed it with a 1kHz square wave and turned on the termination. Some tilt was observed at 100Hz and there was some rounding at 20kHz, but the results are good for a transformer-balanced circuit. The square wave performance without the termination on was not pretty.
Figure 2. The response with only the midrange band in use with the broad bandwidth selected and a slight 4dB increase.
The four-band equalizer is every bit as good as other legendary units. One advantage the MEQ has is that each band can be disabled individually. Our frequency sweeps were made using a Sound Technology 1510A analyzer. With all other bands disabled, the low frequency roll-off filter was set to 150Hz, and the results are in Figure 1. This setting would tame the wildest morning zoo jock. Figure 2 shows just the midrange band in use with the broad bandwidth selected and a slight 4dB increase. Figure 3 shows just the high equalizer in use, with the shelving mode on and the gain set for a 12dB cut.
In the end we recorded speech with three microphones: an EV RE-20, an AKG C-1000 and an AKG Solitube to check the preamp's sound coloration. With the big gain knob set for 40dB, the results with all three mics showed little coloration. The instructions pointed out that the sound would be different depending on the settings of the two gain knobs, so we played. Indeed, the coloration as we heard it was noticeably different when using the low gain as it was for higher gain. And likewise, removing the termination produced a totally different sound, which was especially pronounced in the recordings done with the RE-20. We did not have a guitar handy to check the instrument input, but this amplifier would make an excellent direct box for recording.
Figure 3. The response with only the high equalizer.
Great River has a great product in the MEQ-1NV. The internal circuitry is discrete, using top-notch transistors such as MPS A10/A18, BC5508 and TIP41. Interstage coupling capacitors are high quality Panasonic HFS electrolytics. There is only one op-amp in the mic preamp, and it drives the unbalanced output. The equalizer uses tuned RC circuits and similar quality semiconductors, and has no op-amps. It is a must for critical recording, and would be excellent in the air studio for that major-market sound. Such quality comes at a price ($3,300), but it is worth every penny if you want an outstanding sound.
Landry is a maintenance technician at CBS Radio/Westwood One Technical Services, New York.
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