My digital oscilloscopte has a 3V 1KHz output. I used it to feed into my new phono amp (loading 200 ohms, 0.55mV sensitivity) but the output waveform is distorted. I can see there are at least 3 reasons:
1. The RIAA network distorted the output waveform - I can build an inverse RIAA network to correct this.
2. The phono amp is having distortion - I would like to know this.
3. The output at 3V is too high.
Can anyone teach me how can I calculate/use a resistor to lower the 3V to 0.55mV?
1. The RIAA network distorted the output waveform - I can build an inverse RIAA network to correct this.
2. The phono amp is having distortion - I would like to know this.
3. The output at 3V is too high.
Can anyone teach me how can I calculate/use a resistor to lower the 3V to 0.55mV?
An externally hosted image should be here but it was not working when we last tested it.
It's probably not an "Oscilloscope" that you are using. The "scope" part of the word means - a device for seeing or looking. Your picture represents a oscilloscope display.
The signal is generated by an "Oscillator" circuit.
To design the best voltage reducing pad circuit, one should know the output impedance of the oscillator circuit.
The signal is generated by an "Oscillator" circuit.
To design the best voltage reducing pad circuit, one should know the output impedance of the oscillator circuit.
Hmmmm, maybe. He could be using the probe compensation output from the ocsilloscope. Never say never. 🙂
The probe compensation signal from your 'scope likely has a 1kΩ or so source impedance, and you are feeding a 200Ω load. This will reduce the signal somewhat (3.0V /1200Ω * 200Ω = 0.5V) however the phono input's sensitivity
You are feeding a 3.0V signal into an input with a 0.55mV sensitivity, basically overdriving it by a factor of 10--and hence the distortion.
Try using a 1.2MΩ resistor in series with the compensation signal, that should get the output down to 0.50mV or so
You are feeding a 3.0V signal into an input with a 0.55mV sensitivity, basically overdriving it by a factor of 10--and hence the distortion.
Try using a 1.2MΩ resistor in series with the compensation signal, that should get the output down to 0.50mV or so
If you have a good sound card, use Baudline for testing. Use a voltage divider to reduce the signal voltage.
baudline signal analyzer - FFT spectrogram
baudline signal analyzer - FFT spectrogram
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