2. amps-preamps
  3. 179151-175721

Voltage divider/attenuator

I have a 10V audio source that I want to bring it to line level 1V. That’s pretty easy: I just need to use a voltage attenuator 10:1 like image below. I used resistor values of 1k ohm (R1) and 100 ohm (R2) and it worked great! BUT I have a question: what if I had used 100k and 10k ohm resistors? The ratio is still 10:1 but I think it would not produce a good result (I have no idea why I think so).

 

Would you please tell if I am right? If so... should I use 100 ohm (R1) and 10 ohm (R2) resistors instead of 1k ohm and 100 ohm that I am currently using? Would it be a good idea? I just want to bring this 10V speaker level to line level and so far using 1k/100 ohm worked fine (no noise, no humming...)... but I am wondering if I am doing it right... should I try different resistor values (keeping the same ratio, of course)?

 

batata004

Showing 1 response by erik_squires

erik_squires
16,471 posts
 

It's important to consider the total, final impedance. 

You can use a 9:1 resistor ratio, but the total should be higher than the minimum recommended output impedance of the source.  Consider 9 Ohms and 1 Ohms.  That's a total R of 10 Ohms.

With a 10V source that's 1 Amp that you are going to waste in just the voltage divider.  The final circuit impedance will include whatever is connected across R2. If  your load (not shown) is 10x R2 no problem. :)

 

 

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