| Electronics > Beginners |
| Trying to find a resistor value for JFET RIAA Phono Preamplifier schematic |
| << < (3/6) > >> |
| Benta:
The RIAA-specified load for MM cartridges is 47 kohm. Period. No additional capacitance is needed, the coax cable between record player and amplifier will provide sufficient capacitance. With moving-coil pickups it's a completely different story... |
| Kleinstein:
47 K load resistance seems to be standard - so ne real need to adjust this. With load capacitance one might want to add some, if the cable capacitance is low. e.g. if the preamp is directly at the source. 470 pF is too much, more like 100-200 pF added. |
| CatalinaWOW:
Since OP wants minimum parts count, does anyone understand the purpose of C3? This is an audio preamp and just about any garden variety capacitor should work fine over the frequency range. Doesn't seem necessary to have C2 and C3 of different capacitor technologies to cover the entire frequency range. |
| Frankentronics:
OK, now I understand. I'll just put a 47k resistor (and perhaps a 470 pf capacitor in parallel) as explained to me. I much appreciate all your quick and informative responses. Thanks... |
| Benta:
--- Quote from: Adinol on December 04, 2017, 07:15:22 pm ---OK, now I understand. I'll just put a 47k resistor (and perhaps a 470 pf capacitor in parallel) as explained to me. I much appreciate all your quick and informative responses. Thanks... --- End quote --- Make space for the cap if you like, but don't mount it to start with. See how the circuit behaves first. |
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