Quick Start Guide

Last Update: 1/4/21

Applications Manual for Sound Recording with iOS

Meter check and Level Test

This measurement table shows our test generator’s signal levels together with the VRP 7 App’s meter readings and the

headphone analog output level. We set the Input Gain to “0” for these tests. The headphone analog output level is 6dB

below the other iOS Apps we tested. We do not know why this is the case.

The following graphic shows the meter scale for the VRP 7 App. The meter markings shown beneath the scale in normal

type are taken from the App’s display. Our measurements are shown in italics above the scale. There are significant

discrepancies, which explains why we had difficulties setting our recording levels with this App.

-24 -18 -12 -6 -3 -2 0

-20 -15 -10 -6 -3 0 +2 +4

The Input Gain in this App is actually calibrated, and you can set it with the slider or you can key in a number. That’s a

really nice feature, except the gain varies wildly from what you set. For example, setting gain to +3 gave us gain of +10dB.

Reducing the gain to -3 gave us a gain of -10dB. Be careful using this Input Gain control. Small changes result in big

variations that can cause distortion. Here is a table showing our gain measurements.

There’s a lot to like with this App’s especially the User Interface. However, the meters are inaccurate, and we found the

Input Gain setting is very inconsistent. Variations of 6 to 10dB happen for no apparent reason. We also encountered

unexpected shifts in the balance between channels sometimes by as much as 20dB.

Caution: these gain changes and channel imbalances can happen randomly by just stopping and starting the recording.

We found that the best way to cure them is to shut down the App and start it up again.

VR 7 Pro Input Gain = 0

scale grey grey grey grey grey grey grey grey red red

scale marking -10 -6 -3 0 +4

generator mV rms 4 7 10 12 18 50 80 120 190 clip

calculated level in dB -33.5 -28.7 -25.6 -24.0 -20.5 -11.6 -7.5 -4.0 0

PB level dB(analog) -40 -35 -32 -30 -27 -18 -14 -10 -6

reference acoustic level 94dB SPL 114dB SPL

VR 7 Mic Volume

Scale -10 -6 -3 0 +3 +6 +10

Gain dB -26 -20 -10 0 +10 +18 +30