Altronics K 5171 Посібник - Сторінка 2
Переглянути онлайн або завантажити pdf Посібник для Підсилювач Altronics K 5171. Altronics K 5171 10 сторінок. Ultra low distortion preamplifier with tone controls
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Fig.1: distortion across the entire range of audible frequencies is
extremely low, whether the tone controls are active or not. There
is a slight rise in distortion above 10kHz, but below that, the
distortion is below the noise floor.
Fig.3: the blue line shows the preamp's frequency response with
the tone controls switched out, and you can see that it's very flat,
varying by only 0.2dB across the entire audible frequency range.
The red and green curves demonstrate the range possible of bass
and treble adjustments.
Fig.5: distortion versus frequency of a simple low-pass filter using
either a 470pF MKT capacitor or a 470pF ceramic (non-NP0/C0G)
capacitor. As you can see, distortion rises dramatically at higher
frequencies with the ceramic capacitor due to its non-linearity and
its lower impedance at higher frequencies, which causes it to shunt
more of the signal and thus have a stronger effect.
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ULTRA LOW DISTORTION PREAMPLIFIER WITH TONE CONTROLS
Fig.2: this shows the effect of noise; as you reduce the volume
and thus the output signal level, the fixed circuit noise becomes
larger in proportion and so total harmonic distortion goes up.
However, even at very low volume levels, it's below 0.01% so it
won't be noticeable.
Fig.4: the crosstalk and separation figures are good. Crosstalk is
how much of the left channel signal feeds into the right channel
or vice versa. Channel separation is how much signal from input
#1 couples into input #2 or vice versa.
Fig.6: if you must use a 20kΩ motorised potentiometer to build
this preamp, fitting the two extra 4.7kW resistors (R1 & R2)
will keep high-frequency distortion low, by lowering the input
impedance seen by the following buffer stage. This allows it to
perform optimally and also lowers thermal noise.