Test Signals for Low Frequency Reproduction Evaluation
Published on Friday, 02 December 2011 12:33
Here you can download four MP3
files that help you to evaluate the low frequency reproduction in your audio system. These signals are equally suitable for full-bandwidth monitors and subwoofer systems. The signal that contains only one frequency is called a tone
First of the test signals boink.mp3
is a collection of tones at individual frequencies
. Each of them is 10 cycles long. The frequencies in this signal are 16, 18, 20, 22, 26, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120 and 150Hz. There is a little space between the tones to enable your audio system to build up its forces. As you play this signal pay attention to the purity of the tone. The tone should be clean and all tones should have the same level. If you hear any distortion, noises or rattling check your sound system and your room. The source may be your loudspeakers but also something resonating in your listening room or even the audio equipment feeding the loudspeakers. This signal is particularly useful for testing the output capacity of your system because the signal is not continuous, stressing your audio system similar to actual music and yet the signal is analytical and well defined. Start from a low sound level and work up towards higher levels. Notice any changes.
The second test tone sweep1.mp3
contains a tone that changes linearly in frequency from 10Hz to 150Hz
. The level of the signal remains constant. Use this signal to check at what frequency the sound in your audio system becomes audible, how precisely the sound level remains constant over frequency and to locate any clear dips (antiresonances) and peaks (resonances) in level at your listening location. Also you can locate problematic structures in your room, such as resonating curtain rails or furniture rattling at certain frequencies.
The third signal pink.mp3
. This 'Pink' noise has a particular characteristic (equal power per octave, power density decreases 3dB per octave) that makes all frequencies in the noise equally audible and therefore the pink noise can reveal very small frequency response differences effectively. It is an excellent signal for comparing the effect of any change you introduce in your sound system in the A/B test fashion. It has a spectrum similar to actual musical signal, and stresses your sound system similarly. Also, you can use this signal together with an octave-band or a third-octave-band real time analyzer to calibrate your sound system.
85 Hz Sinewave
The fourth signal 85Hz_sinewave.mp3
contains a tone for adjusting the phase of a Genelec subwoofer. The 7050B, 1092A and 1094A do not have built-in test tone generators so an 85 Hz test tone is useful to help set the phase control correctly. The instructions for its use can be found in the subwoofer operating manuals and Quick Setup Guide. This is full scale signal so turn the volume down before starting the test.