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David F		#1 Posted : Thursday, January 26, 2012 4:56:42 PM(UTC)
Rank: Member Groups: Member Joined: 8/28/2011(UTC) Posts: 17 Location: Australia(+61)		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?
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Russ White		#2 Posted : Thursday, January 26, 2012 9:14:03 PM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 3,979 Location: Nashville, TN Thanks: 25 times Was thanked: 89 time(s) in 83 post(s)		It could help, but it would be better just to match your resistors.
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David F		#3 Posted : Monday, January 30, 2012 1:32:44 AM(UTC)
Rank: Member Groups: Member Joined: 8/28/2011(UTC) Posts: 17 Location: Australia(+61)		They are matched within 1% Please advise
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Russ White		#4 Posted : Monday, January 30, 2012 5:51:50 AM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 3,979 Location: Nashville, TN Thanks: 25 times Was thanked: 89 time(s) in 83 post(s)		Match better. :) or...Use use a larger value pot.
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David F		#5 Posted : Tuesday, January 31, 2012 2:19:05 PM(UTC)
Rank: Member Groups: Member Joined: 8/28/2011(UTC) Posts: 17 Location: Australia(+61)		Whats your recommended tolerance? Is 0.1% OK?
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Russ White		#6 Posted : Wednesday, February 1, 2012 9:54:02 AM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 3,979 Location: Nashville, TN Thanks: 25 times Was thanked: 89 time(s) in 83 post(s)		Well the higher value pot may actually be more practical choice for the R values you are using. There are other variables as well.
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David F		#7 Posted : Wednesday, February 1, 2012 2:18:35 PM(UTC)
Rank: Member Groups: Member Joined: 8/28/2011(UTC) Posts: 17 Location: Australia(+61)		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.
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David F		#8 Posted : Thursday, February 9, 2012 12:00:30 AM(UTC)
Rank: Member Groups: Member Joined: 8/28/2011(UTC) Posts: 17 Location: Australia(+61)		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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