User Manual
7
Aligning Levels — VU and Peak Metering
The VU meter is a liar—the equipment must have headroom to allow for peaks which the meter does not show.
Traditional analog consoles and peripherals (such as compressors) equipped with VU meters are usually aligned
to +4 dBu, so we recommend adjusting the digital system so +4 dBu or lower equals -20 dBFS with a sine wave
alignment tone and an external analog voltmeter. Then in operation, watch your digital peak meters on your digital
DAW and apparently as long as they do not go over 0 dBFS then the digital will not clip and neither will the
EQ232P. I said “apparently” because there is the hidden factor of the true peak overload, described below. Also,
during normal operation, glance at the clip indicators on the equalizer as further conrmation that everything is
safe, especially if you are doing heavy EQ boosting.
Here’s a tip: Even if you do not have an analog voltmeter, with a little care and time you can still calibrate
your system, achieve exactly the same analog headroom and matched levels, using the clip lights of the EQ232P
as an analog measuring tool and also reading the digital levels returning from the ADC. Feed your DAC into the
EQ232P (set to at and engaged*) and adjust the DAC output to ensure that the clip lights do not light with a
full scale (0 dBFS) sine wave from the DAC. (You can use the incoming meters from the ADC to determine how
far your DAC is below Equalizer clipping. You can even add a safety zone of 1 or 2 dB to keep your DAC well
below DAC clipping). Then align the ADC input for unity gain when inserting the D/A/D insert into the chain and
you’re done!
If you nd the Equalizer clipping during normal operation with a lot of EQ boost, just turn down the send to
the equalizer until it doesn’t clip. Because you have aligned your DAC and ADC as well, the recording will never
clip.
Eliminate True Peak Distortion
Although you have just aligned your system to unity gain, the fact remains that your DAW’s meters do not
measure the true peak overloads that can occur in DACs. True peaks can actually exceed the DAW’s meter
reading and cause harshness or distortion that typical DAW meters do not see. Adding a true peak meter plugin
to your DAW is a good idea, but under most circumstances you can follow the guideline that true peaks will very
rarely exceed 1 dB over digital full scale. (This would occur only if you are using severe processing in front of
the EQ232P, in which case the sound of clipping probably won’t bother you either). So we suggest that you never
exceed -1 dBFS in normal operation, with music or speech, as read on an ordinary meter reading the return from
the EQ232P. This will result in cleaner, purer sound from your analog equalizer! By the way, true peak overloads
can occur with any analog insert loop, so it’s always advisable never to exceed -1 dBFS “sample peak” whenever
you feed a DAC. Yes, it’s time to get a true peak meter!
*Shortcut to at: Double click on the Preset button of the EQ232P