Using AudioTools and one of our calibrated mics or an audio interface you have everything you need to setup, test, and validate a sound system. This document is intended as a guide to take you through the process.
Hardware
You can use a USB audio interface, iAudioInterface2, iPrecisionMic, or iTestMic2. The quickest and most lightweight setup would be either of our test mics, since they are pre-calibrated and required no setup to get started. They also have audio outputs so you can use them for the output signals. If you require Class One performance use uPrecisionMic, for general purpose work iTestMic2 is more than sufficient.
iAudioInterface2 is a great option if you need to connect your own XLR phantom-powered mic, or run long XLR cables. It also includes a balanced audio output with level control.
See our other web pages for details about setting up iAudioInterface2 or a generic USB audio interface.
A note on balanced/unbalanced audio output. AudioTools can be configured to create a normal mono signal, where both the L and R channels have the same polarity, or by selecting Balanced mode, the R channel polarity is inverted, so device such as iTestMic2 and uPrecisionMic can output a balanced signal. Just make sure that your cabling matches the Balanced/Mono setting, which is on the Settings->General->Global Audio page.
Software
Start by installing AudioTools, with at least these functions unlocked. Note that you can use our new subscription option to get all of these tools (and more) for one low monthly fee and you will be ready to go.
Input and Output Setup
Mount the microphone on a stand, typically near FOH or at a central location in the venue. Route the device’s output into the system so that you can assign it to any loudspeaker. If you are using iTestMic2 or uPrecisionMic, you will usually need an 1/8” to XLR or 1/4” cable to get into your system.
Speaker Alignment
The first step is to physically align the loudspeakers for the best coverage. We will use the Signal Generator on the Utilities menu for this. Select Pink Noise, Octave mode, and select the 2000Hz octave. Route this signal to each loudspeaker and check that its coverage matches your needs.
Speaker Polarity
Use the Speaker Polarity module on the Speakers menu, and route the signal to each loudspeaker, one at a time. Make sure only one loudspeaker is playing the signal. You should see the large “+” for all them. If you see all “-“, check that your signal chain is not inverting the polarity of the signal. The polarity tester will work at long distances, just make sure the “pop” signal is at least 20dB above the ambient noise level.
Frequency Response
We will use LARSA for this. On the LARSA setup page, choose the 1.5s sweep, and internal signal mode. The rest of defaults are normally fine. Check your levels to make sure you are not overdriving the system. You can use the Tone button on the main screen to output a single tone before running the sweep.
When you are ready, tap the Measure button to get a reading. From here, you can decide if the system needs EQ changes. Run it again after making changes, and repeat this until you get your desired response. You can control the smoothing of the plot on the LARSA Settings page.
LARSA uses a third-gen reverse-deconvolution algorithm and as such is quite noise immune. You don’t have to be in a super quiet environment to get good results. Extremely loud ambients will be a problem, but most typical venue noise conditions will be fine.
Delay
If you are using delay towers, you will need to add delay to all towers past the mains. We will use the ETC module for this.
In ETC, on the setup page turn off External Signal so that ETC can generate its own pop. Set the screen width to something longer than your distance to the mains. For example, if you are 80’ from the mains, use 100ms. Route the output to the Left Main, and tap the triangle to start the test. You will see a spike and some kind of decay after that. If the plot triggers before the pop plays, or if it never triggers at all, adjust the Trigger Level on the Settings page.
Once you get a stable reading, stop the test and drag your finger across the screen to place the cursor exactly on the initial peak. Note the time in ms at the bottom of the screen. Now route the signal to the first Left delay tower. Restart the test, and you will see the peak to the left of (earlier than) the peak from the mains. Increase the delay time on the delay tower until the peak aligns exactly with the Left mains peak.
Repeat this for all the Left towers, time aligning them as you go. Now move to the Right mains, and start the process over.
It’s a good idea to document the delay times with the event logs.
Level Balance
Using SPL Pro, turn on pink noise (tap the sine wave icon) and using a moderate level (75 dB is a good starting place) measure the level from the Left Main. Match the right main to this, and then repeat the process for all the other towers.
Verify
We will use the STIPA Speech Intelligibility app for this, sending the signal to each speaker one at a time. Run the STIPA test, and confirm that your results are in at least the “very good” area.
