| thomgun_lc |
;) Hi, i'm confusing about choose the right potensio's value. Usually people using 50k pot (assumed they don't use a preamp). In a basic theory, max value of the input's pot will give the best result, there is no drop voltage.It's necessary to keep our GC to have HI-Z in.
But, why GC'ers using 50k/20k as an input pot?Why they don't use a higher value like 100k/1M?
Using a lower value will causing drop voltage?is it right?
Need ur opinion please:confused: :smash: |
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| Nordic |
| If I read the datasheet correctly Rin is supposed to be between 10k and 100k..... |
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| slackman |
Usuaslly potis with higher values tend to produce more noise than low-value pots...
Michael |
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| PierreG |
| quote: | Originally posted by Nordic
If I read the datasheet correctly Rin is supposed to be between 10k and 100k..... |
What datasheet are you talking about? |
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| Ropie |
| quote: | Originally posted by PierreG
What datasheet are you talking about? |
I would think the LM3875 datasheet. |
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| Nordic |
Correction it is Rf1 wich is recommended to be between 10 and 100k... lthough it does warn against big values for RIN
...page14
"The desired input impedance is set by RIN. Very high values
can cause board layout problems and DC offsets at the
output. The value for the feedback resistance, Rf1, should be
chosen to be a relatively large value (10 kŮ–100 kŮ), and
the other feedback resistance, Ri, is calculated using standard
op amp configuration gain equations." |
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| thomgun_lc |
| ;) So,do you agree if we using 1M pot?not using 50k pot?As far as i know, high Zin is important to keep the voltage to the chipamp from the source. Ussually after pot, we add a resistor (22k) to ground, why we don't use 1M to keep in High Zin? |
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