Timeline for Audio line level conversion from consumer to unbalanced (presumably) pro 1/4" jack of unknown sensitivity and impedance. 400W 1980s PA amp
Current License: CC BY-SA 4.0
9 events
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| Jul 28, 2022 at 23:03 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Mar 24, 2022 at 9:09 | comment | added | Justme | You need to know the input impedance. Having a modern preamp may not drive the input if it is 600 ohms for example, as modern inputs have much higher impedance. | |
| Mar 24, 2022 at 8:23 | comment | added | danmcb | I don't find a link for swinging gain stage, don't have time to draw one. Take a 10k pot, put it in an inverting op amp, wiper goes to the - input, put (say) a 4k7 resistor from one end to the output, the input goes to the other end via another 4k&. Now you have a stage with a gain continuously variable from 1/3 to 3. | |
| Mar 24, 2022 at 8:19 | comment | added | danmcb | usual way to do switched gain is make R2 higher (for max gain) and then have jumpers to decrease it with various values, to get gain steps. | |
| Mar 24, 2022 at 8:18 | comment | added | danmcb | yes it is probably +4dBu in balanced. What you have looks good, but you have only 12dB of gain - 6dB on the input buffer and another 6 when you balance at unit gain. Personally I would make the input a "swinging gain stage" with a dual 10k lin pot, or at least have some jumpers to set the gain in steps of say 3dB. By the way R4 and R3 are superfluous but you probably want a DC block cap (10u electrolytic) and a 10k resistor to GND on pin 3 U2A - U1A may have DC offsets. R5 and 8 are a bit bit, I would go with 47R. | |
| Mar 24, 2022 at 8:05 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Mar 9, 2020 at 0:41 | answer | added | labnet | timeline score: 1 | |
| Mar 8, 2020 at 23:05 | review | First posts | |||
| Mar 8, 2020 at 23:50 | |||||
| Mar 8, 2020 at 23:01 | history | asked | Rinderpest | CC BY-SA 4.0 |