8121C White Noise & Pink Noise

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Model-8121C uses a logic circuit to generate “Pseudo Random Noise”, it is the newest and the most advanced design to generate audio white noise. It has much flatter frequency response than using diode. Model-8121C has: (1)White noise source.(2)Weighting filters.(3)Built-in power amplifier.(4)” TRUE RMS ” voltage meter circuit. It can generate five different kinds of noise’s spectrum, including White Noise, Pink Noise and three kinds of “Weighted Noise”, conforms to following nation’s standards:(1) JIS C5531, IEEE 219, CNS 4785 (2) EIA 426B(3) DIN 45573
1. White Noise:
-3dB Bandwidth : 20Hz～100kHz,
Roll off:-24dB / Oct. Flatness: ±1dB

2. Pink Noise:
-3dB Bandwidth : 20Hz～20 kHz
Roll-off : -24dB / Oct. Crest factor: 4 ( IEEE 219 )
Noise Type : Voltmeter :
1. White Noise:
-3dB Bandwidth: 20Hz～100kHz,
Roll off:-24dB / Oct.
Flatness: ±1dB True rms response with Hi/Lo two ranges:
2. Pink Noise:
-3dB Bandwidth : 20Hz～20 kHz
Roll-off : -24dB / Oct.
Crest factor: 4 ( IEEE 219 ) Lo Hi
3. Weighted NoiseⅠ:
Complies IEEE 219,CNS 4785,JISC5531. 100 W 0~6V 0~30V
4. Weighted Noise Ⅱ:
Complies EIA 426B Accuracy:＜± (1% rdg.＋ 1% F.S.)
5. Weighted Noise Ⅲ :
Complies DIN 45573. Amplifier:
1.100W output is defined at an unclipped maximum output of sine wave.
2.Frequency response : 20 Hz~20 kHz ±0.2dB 20 kHz~100kHz ±1dB
3. Output: With permanent short circuit protection.
Load Impedance: ≧ 3.2 Ω.
Amplifier:
1.100W output is defined at an unclipped maximum output of sine wave.
2.Frequency response : 20 Hz~20 kHz ±0.2dB; 20 kHz~100kHz ±1dB
3. Output: With permanent short circuit protection.
Load Impedance: ≧ 3.2 Ω.

Since the Noise Generator (Model-8121C) is mainly designed for loudspeaker testing, thus, it is equipped with a 50W or 100W power amplifier, and a “TRUE RMS” voltage measuring circuit, to measure the “TRUE RMS” of output noise. Never use a general VTVM, AC millivoltmeter, or a digital voltage meter to measure noise voltage, unless when these meters have especially noted that their AC testing function is a TRUE RMS mode, otherwise, the testing result of RMS value is only precise for a sinusoidal signal, because these meters are designed for sinusoidal RMS voltage testing. If these meters are used to test nonsinusoidal signals (including noise signals), the results of measured RMS values will be inaccurate, therefore, the 8121C is equipped with a “TRUE RMS” testing circuit, to measure the noise output voltage. Since noise voltage itself is not highly stable, thus, the voltage meter’s indicator needle will have a slight deflection, don’t mistake this as 8121C was faulted.

Model-8121C has also provided a selectable “Filtered Noise Sig. Output” terminal (9), which has the following two usages: (1) It can connect externally with another power amplifier ; (2) It can connect externally with another weighting filter, usage of an external weighting filter is: When users or other national standards required ” weighting filter network with the special specification “; then, users can connect (9) to the external needed filter, for necessary filtering, then, connect the output of an external filter back to the built-in power amplifier input terminal (10) of Model-8121C, for power amplifying, thereby measuring the pre-measure