Pocket RTA: Not Just an iPhone RTA

: Pocket RTA, iPhone

Just about every Live Audio Engineer I know carries (or wants to carry) a few tools with them to make their lives easier. Often this would be a Radio Shack dB Meter and some type of RTA (Smaart, handheld or otherwise)…

Who says you have carry several different devices though? Well… Not Me. These days, you can do it all with your iPhone and some Apps (Applications)… Lately I’ve been using one tool for all of my needs, Pocket RTA.

Pocket RTA on iTunes

What Pocket RTA Does

Pocket RTA quite a few different things, all of them useful in that moment where you find yourself thinking “What the…”

RTA (Real Time Analyzer)
SPL Meter (dB Meter)
Spectrogram
Oscilloscope

The RTA Function

Pocket RTA provides a multitude of different types of RTAs… One or more of them are bound to tickle your fancy.

Linear Display (Not Advised) – A linear display of frequencies, showing more detail in the 2k – 20k Range
Log Display – Frequencies are displayed in a Logarithmic fashion. A Better broad view of the full spectrum
Octave Display – Showing SPL changes by Octave, 11 Bands
1/3 Octave Display – (Personal Favorite) Displays SPL Changes by 1/3 Octaves. Matches a 31 band Graphic EQ.

Also, in SPL mode (up next) you also view an Octave Band RTA.

Options Include…

Tracing is user controlled, including hold time and Pausing
Weighting Curve is User Controllable (Flat, A, C, U, Noise)
Tone Generator

See RTA and SPL Shared Features for more Features

The SPL Meter Function

The SPL Meter in Pocket RTA, and has your standard dB Meter/SPL Meter options, as well as a very interesting non-standard option.

Includes current SPL reading
Includes an Octave Band RTA
Shows a display of the Peak Frequency and Level, as well as that frequency’s Musical Note Equivalent
Tracing is user controlled, including hold time and Pausing
Weighting Curve is User Controllable (Flat, A, C, U, Noise)
Tone Generator

Spectrograph

Display is a Linear Frequency Display (2-22 kHz is prominent)
Shows a display of the Peak Frequency and Level, as well as that frequency’s Musical Note Equivalent
Weighting Curve is User Controllable (Flat, A, C, U, Noise)
Tone Generator

Oscilloscope

Display is a Linear Frequency Display (2-22 kHz is prominent)
Weighting Curve is User Controllable (Flat, A, C, U, Noise)
Tone Generator
Includes variable Timebase

Inputs

You have two options for an Input, either your Internal iPhone Microphone, or an External Microphone. Amazingly, you DO NOT need an adapter to use your external mics, as Pocket RTA will pick up Input Signals from an 1/8 Cable on the Outputs, as well as the Inputs.

You can also calibrate internal and external levels seperately, as well as levels for RTAs, Band RTAs, and dB Meters are all saved separately.

Also, Pocket RTA Automatically switches between the displayed input, as well as the saved calibration settings when an External Microphone is Plugged in or unpugged.

Internal Microphone

Pocket RTA is already tuned to your iPhone’s internal Microphone to give as flat of a frequency response as possible.

The only issues that you may run into, is that with a 1st generation iPhone (NOT the 3G) the quality of the microphone and the A/D converters limits you to a sampling rate of 8 kHz (effective frequency spectrum up to 4 kHz)… With the iPhone 3G you can get a sampling rate up to 44.1 kHz, which allows for a full audible frequency range.

External Microphones

The iPhone does NOT have a pre-amp that is capable of gaining up a normal microphone, so without a pre-amp the only external microphone you can use is an iPhone headset microphone.

What you can do, is take an output of any normal microphone pre-amp and put it into the iPhone. This opens up using actual Measure Microphones to the platform!

Microphone Calibration

On the main page of Pocket RTA, you can calibrate whatever input you may be using, to create as flat of a response as possible.

When you bring up the Calibrate menu, Up comes a 31 Band RTA… You simply select what frequency you want to augment, and tap the Adjust at the top of the screen (inbetweenthe frequency selected, and current level). From there you can set +/- Gain to that particular frequency band to create as flat of a response as possible!

Overview

Because of not only the usability and tools provided in Pocket RTA, but also the great calibration and flexibility within Pocket RTA, I have to recommend this over any iPhone RTA I’ve used to date.

And, yes, it costs less than that reliable Radio Shack dB Meter.