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Old 8th March 2007, 06:53 PM   #1
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Default Noob Question: What is a volume buffer?

I'm engaged in learning about buffer circuits. I've come across buffers called volume buffers. What are they?

Thank you!
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Old 8th March 2007, 07:18 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

no voltage gain. lots of current gain. high input impedance. low output impedance.

/sreten.
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Old 8th March 2007, 07:59 PM   #3
KISS is offline KISS  United States
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"no gain", being a gain of +1 idealy.
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Old 8th March 2007, 08:05 PM   #4
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Thanks for the help!

-David
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Old 9th March 2007, 12:57 AM   #5
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A volume buffer is usually seen before the volue pot, it provides a fixed high impedence input thus making the load seen by your source output easier to drive by isolation from the volume pots isolation from the outside world in a sense .a sole potentiometer is an ever changing impedence based on where you set it and most standard commercial outputs are pretty wimpy on drive capability but they all will work and distort differently. I have always preferred a gain of2 buffer in all my preamp projects, while the second half after the pot is the gain block.


Colin
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Old 9th March 2007, 06:16 AM   #6
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another volume buffer is shown below. the pot acts as a volume control for the stage by changing the feedback ratio of the op amp. the advantage of this circuit is the high input impedance and low output impedance, and also that if the potentiometer fails, there will still be output (although it's probably not a good thing that the volume will be all the way up when that happens)
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Old 9th March 2007, 07:14 AM   #7
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Quote:
Originally posted by unclejed613
the advantage of this circuit is the high input impedance and low output impedance, and also that if the potentiometer fails, there will still be output

Do you work for a marketing department? What will the output be if the pot fails? Rail DC?
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Old 10th March 2007, 12:25 AM   #8
ReidK is offline ReidK  United States
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Isn't pot failure usually an open wiper? That would indeed result in max volume and not a pinned-up output. That's why the pot is wired the way it is.

BTW, I've passed along a copy of your slur to the Marketers' Anti-Defamation League. You'll be hearing from their flying monk..., I mean, attorneys.

Reid
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Old 10th March 2007, 07:15 AM   #9
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Quote:
Originally posted by ReidK
You'll be hearing from their flying monk...,


I won't. My pots just failed.
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Old 10th March 2007, 08:26 AM   #10
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The circuit in post#6 will not reduce output below unity gain, the circuit in post#1 will !!!
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