A pink or white noise generator is an essential tool for running many tests on sound systems and their components. Adjustment of equipment drive levels must be made external to the generator. White noise has an equal amount of energy per Hz of bandwidth. For example, there would be equal energy from 20Hz to 21Hz as there would be from 20,000Hz to 20,001Hz. This characteristic is most useful with what are called constant Hz-bandwidth analyzers, which most swept-spectrum analyzers are. White noise is easily shaped or filtered to make pink noise that has equal energy per octave of bandwidth (or in each fraction of an octave). For example, there is equal energy in the octave centered at 125Hz and in the octave at 2kHz, or any other within the limits of the generator. Because of this, pink noise produces a flat response in constant-percentage bandwidth analyzers such as the Gold Line analyzers and other RTAs (real time analyzers). The spectrum of pink noise also approximates that of much music with less power per Hz (-3dB/octave) with increasing frequency. This makes it an excellent test signal for sound systems, where white noise could burn out tweeters. At lower levels, white noise can be used for critical listening checks and some other tests, but pink noise is much more useful, in general. Other Noise Generators available from Gold Line are the PN2 – Pink Noise Only; the PN3A – Pink Noise Only with Burst or Pulse for RT60 or Loudspeaker Timing; The PN3B – Pink Noise Only or 1kHz tone in continuous or gated format; The GLPN – Pink Noise Only plus a Phantom Power detector in a pocket-sized housing; The PWN1 – White Noise Only that is adjustable in output level for sound masking purposes. The PWN1 has a built in speaker.