Tests and adjustments

We suggest that you either use test complexes (like Audio Precision) or download a good measuring software (for example, trial version of SpectraPLUS-SC). You will need to make precise measurements of THD and frequency curves and these tools will be very useful.

Here is our suggested procedure for testing the unit:

  • Make sure all the switches are disengaged (levers down).
  • Set the Gain switch to the 5th position (Line, 0).
  • Inject 1 kHz 0 dBu test tone to the line input of the unit. Make sure the unit is passing clean and not distorted audio.
  • Measure voltages between pins 2 and 3 of input XLR and output XLR. Voltages should be close in value.
  • Measure THD and adjust RV1b for minimum distortion.
  • Turn the Gain switch counter-clockwise and check that each step increases output by 5 dB.
  • Now inject the 1 kHz test tone through the resistor pad to the microphone input. Turn the Gain switch clockwise and check that each step increases output by 5 dB.
  • Inject white noise 0 dBu test tone to the line input. Put spectrum analyzer at the output and make sure that it shows flat line from 20 Hz to 20 kHz.
  • Engage the EQ switch and check equaliser controls. It is convenient to observe resulting frequency curve on the analyzer. Check that all frequencies marked on the front panel coincide with center frequencies on the analyzer. Check that equalizer boost and cut ranges are up to specs (+/-16 dB for shelf filters and +/- 18 dB for bell filter).
  • Check that high-pass filter is working up to specs.
  • Connect the condenser microphone and turn on the phantom power. Make sure the microphone is working.
  • To check the Phase switch you will need to record a short piece of audio and observe the waveform at full zoom in your DAW. Make sure your unit ouputs signal in phase when the switch lever is down, and out of phase when the switch lever is up.
  • Bring the unit to the studio and make some real-life recordings to enjoy the "Neve sound"!

Before putting the lid on the unit you may want to adjust the power transformer angle for minimum interference. In order to do that listen in the headphones to the output (you need to apply a lot of gain afther the preamp output. It may be convenient to use universal input on the soundcard that can serve both as line and mic input, and turn up the gain 40-50 dB). Carefully turn the power transformer and listen to the hum in the headphones. After you find the position with minimum hum, fix the transformer firmly with cable ties. Be extra cautious while moving the transformer!

It is also advised to put a piece of paper over two top cards to make sure there is no possible contact between the top lid and the cards.

That's it! Enjoy your Neve 1073 clone!

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