Hi!

I would like to know if i have one ordinary audio amplifier and if i change volume (gain) at this amplifier is this influence to input impedance ?

so if i have 10% louder or 80% is impedance change ?

I hope so that you understand me what i mean.

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There are two major products that came out of Berkeley: LSD and BSD. We don't believe this to be a coincidence. —Jeremy S. Anderson

 

Generally the input impedance is fixed and is not affected by the volume control.

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Carl

 

No, because you offer no context - there's no such thing as an "ordinary audio amplifier" - post the circuit you're refering to and we can discuss that.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

On an operational amplifier the input impedance will change with the set gain. A unity gain operational amplifier gives a near infinite input impedance.
Raise the feedback resistor to obtain some gain and input impedance decreases.
On other types of amplifiers, it may not be the case.
Miguel

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Abolish the deciBel !

 

I suggest you try reading your opamp theory again, input impedance is set by the input resistor on both inverting and non-inverting amplifiers - nothing to do with gain.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

OK, look

I'm going on sea and i don't know if i can safety connect my IPOD nano to external computer speakers like this one http://www.maincomp.com/uploads/CB-80401.gif which has amplifier integrated.

__________________
There are two major products that came out of Berkeley: LSD and BSD. We don't believe this to be a coincidence. —Jeremy S. Anderson

 

The output of the ipod will probably drive the computer speakers perfectly.
But the computer speakers are small and will not have any bass nor much power.

There is nothing that is unsafe. The ipod has a low output impedance that has mA of current and the computer speakers have an amplifier with a high input impedance that draws only uA of current.

But check the input sensitivity of the computer speakers to see if the output level from the ipod is high enough.

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Uncle $crooge

 

OK tnx all alot


Audioguru please tell me what does this Input Sensitivity mean ?


I found specification for my hi-fi amplifier:

__________________
There are two major products that came out of Berkeley: LSD and BSD. We don't believe this to be a coincidence. —Jeremy S. Anderson

 

The input sensitivity of your hi-fi amplifier is an input of 150mV RMS for full output when its volume control is maximum. Its input impedance is 47k ohms.

Your ipod probably has an output of at least 250mV RMS so it will drive your amplifier to full output on loud music peaks with the volume control turned down a little.

The computer speakers also probably have the same input sensitivity.

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Uncle $crooge

 

OK, I found another explanation, is it correct?

I don't understand what is bold. If amp have higher sensitivies (input signal can be higher consequently input level can be higher no lower ? )

__________________
There are two major products that came out of Berkeley: LSD and BSD. We don't believe this to be a coincidence. —Jeremy S. Anderson

 

hi,
Its a badly written explanation [ the bold section]

Its trying to say, the amplifier has a higher gain.

Do you follow OK.?

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

OK, understand

__________________
There are two major products that came out of Berkeley: LSD and BSD. We don't believe this to be a coincidence. —Jeremy S. Anderson

 

I think summary of ur says is:
Amplifier input impedance doesn't depend on the source