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Old 19th May 2010, 09:20 PM   #1
trv is offline trv  Israel
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Default Buffers high freq loss

Hi,

when looking in Operational Amplifier (such as LM833) data sheet , can see that power band width is constant in the audio frequency region.

when passing guitar signal through buffer (consists from LM833 or any similar), high frequency loss is noticed, can any body explain why is that??
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Old 19th May 2010, 09:41 PM   #2
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Schematic needed.
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Old 20th May 2010, 08:51 PM   #3
trv is offline trv  Israel
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I referred to basic buffer circuit (attached jpg)
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File Type: jpg ScreenShot001.jpg (23.8 KB, 78 views)
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Old 20th May 2010, 10:12 PM   #4
freddi is offline freddi  United States
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is the buffer's input Z =>10X that of the guitar source output Z?
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Old 21st May 2010, 06:47 AM   #5
trv is offline trv  Israel
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yep the input impedance is much higher then guitars (about 10k),but why should it infect the high freqs?
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Old 21st May 2010, 06:49 AM   #6
trv is offline trv  Israel
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I had attached the schematic below,very basic schematic without any filter of any kind
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Old 21st May 2010, 08:55 AM   #7
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You are missing gain setting resistors, you are lucky this circuit works at all!
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Old 21st May 2010, 09:58 AM   #8
trv is offline trv  Israel
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What would you suggest?
I had attached another buffer in BJT version, also with the high freq problem
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Old 21st May 2010, 09:59 AM   #9
trv is offline trv  Israel
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Attaching the image..
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File Type: jpg ScreenShot001.jpg (45.9 KB, 58 views)
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Old 21st May 2010, 11:09 AM   #10
Mooly is offline Mooly  United Kingdom
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Like this,
Input inpedance equals RIN. The gain is RF/RIN. Keep Rin sensible>10k note the cap at the input.

No HF roll of (guaranteed)
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File Type: jpg Buffer.JPG (39.3 KB, 57 views)
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