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Old 21st July 2012, 01:18 AM   #12481
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is it that sencitive?
there goes my plan on a 1 turn panel pot.
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Old 21st July 2012, 01:34 AM   #12482
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Quote:
Originally Posted by AudioSan View Post
is it that sencitive?
there goes my plan on a 1 turn panel pot.
yes, it is that sensitive -- and there doesn't seem to be any way around it -- it's only a 200 ohm pot, and 1/16th turn = 1/2 ohm. [Edit] remember it's in parallel with the 10 ohm existing source resistors!

you don't have to make the bias adjustment that "critical" -- and the combined parallel resistances of the thermistor, 2k2 resistors etc also set the gain -- so once you are in the ball park you can adjust P1 and P2 a smidgen (how doe that translate) to effect a bit of a null.
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Old 21st July 2012, 01:41 AM   #12483
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in my case, iwas thinking for the F5 turbo.V3
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Old 21st July 2012, 04:07 AM   #12484
labjr is offline labjr  United States
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Are there any F5 boards with P3 included? Or are there plans to update the boards in the DIY store?
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Old 21st July 2012, 03:07 PM   #12485
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Good mornin'
This is what I did to my board to add a 200 ohm pot for P3 ,most all layouts are the same ,it works ,I don't have a distortion analyzer yet ,but I did notice it tweaks the bias a little bit on those two fets ,I could see it on the output dc with a meter,I have mine set to the middle until I have the necessary equipment to make the adjustment,

NS
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Old 21st July 2012, 03:19 PM   #12486
labjr is offline labjr  United States
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I kind of wanted something that doesn't look like a kludge.
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Old 21st July 2012, 03:25 PM   #12487
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lol,Thanks
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Old 21st July 2012, 03:33 PM   #12488
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a la:

Click the image to open in full size.
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Old 21st July 2012, 07:16 PM   #12489
alazira is offline alazira  United States
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Quote:
Originally Posted by jackinnj View Post
yes, it is that sensitive -- and there doesn't seem to be any way around it -- it's only a 200 ohm pot, and 1/16th turn = 1/2 ohm. [Edit] remember it's in parallel with the 10 ohm existing source resistors!

you don't have to make the bias adjustment that "critical" -- and the combined parallel resistances of the thermistor, 2k2 resistors etc also set the gain -- so once you are in the ball park you can adjust P1 and P2 a smidgen (how doe that translate) to effect a bit of a null.
Why not a 1K (or more) pot instead of a 200 ohm one?
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Old 21st July 2012, 09:14 PM   #12490
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Hi jackiNJ,
You teasing us ,lol
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