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David F  
#1 Posted : Thursday, January 26, 2012 4:56:42 PM(UTC)
David F

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I am attempting to increase the gain by using 332 Ohm resistors for R1-R4 and 1.5K Ohm resistors for R9-R16, but now I cannot zero the DC - still get 8-9 mV with trimpot fully adjusted.

Would a larger trimpot value solve this issue, or is there a better solution?
Russ White  
#2 Posted : Thursday, January 26, 2012 9:14:03 PM(UTC)
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It could help, but it would be better just to match your resistors.
David F  
#3 Posted : Monday, January 30, 2012 1:32:44 AM(UTC)
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They are matched within 1%

Please advise
Russ White  
#4 Posted : Monday, January 30, 2012 5:51:50 AM(UTC)
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Match better. :) or...Use use a larger value pot.
David F  
#5 Posted : Tuesday, January 31, 2012 2:19:05 PM(UTC)
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Whats your recommended tolerance? Is 0.1% OK?
Russ White  
#6 Posted : Wednesday, February 1, 2012 9:54:02 AM(UTC)
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Well the higher value pot may actually be more practical choice for the R values you are using. There are other variables as well.
David F  
#7 Posted : Wednesday, February 1, 2012 2:18:35 PM(UTC)
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The 1.5K resistors vary by about 8 ohms. I can match them within an ohm if necessary. Is there any sonic advantage in tighter matching to this degree vs a larger value trimpot?

I already increased the trimpot to 20 ohms. It will probably need a 50 ohm value to trim the DC.
David F  
#8 Posted : Thursday, February 9, 2012 12:00:30 AM(UTC)
David F

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For anyone else trying to up the gain on a Legato(which I have struck on more than one occasion), 100 ohm trimpots seem to do the job nicely
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