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Indigo		#1 Posted : Tuesday, April 26, 2011 6:28:03 AM(UTC)
Rank: Member Groups: Member Joined: 3/1/2011(UTC) Posts: 23 Location: Italia		I need to reduce output gain on IVI III for both SE and balanced output I've changed R13-14-15-16 from 180 to 90 ohm, but it is not enough. How low can I go with these resistors? Is it better to change R17-18-19-20 ?
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Russ White		#2 Posted : Wednesday, April 27, 2011 8:28:51 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)		First thing to do is to determine what kind of level at output you want. From there I will give you some recommendations.
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Indigo		#3 Posted : Friday, April 29, 2011 4:59:48 AM(UTC)
Rank: Member Groups: Member Joined: 3/1/2011(UTC) Posts: 23 Location: Italia		DearRuss, If standard IVI III have 2v at 0 db, then I believe that something around 0.8 v at 0 db could be fine. Thank you in advance for your precious help
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Russ White		#4 Posted : Monday, May 2, 2011 6:55:46 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)		Ok I would leave R13-16 at 180R and adjust R9-12 up to between 750R and 1K. The higher the value the more attenuation. You could go up to 2K with no problem. But 750 will get you close to what you want.
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Indigo		#5 Posted : Friday, May 27, 2011 1:45:57 PM(UTC)
Rank: Member Groups: Member Joined: 3/1/2011(UTC) Posts: 23 Location: Italia		Hi Russ, I've made some test and I've found 1k for R9-R12 best fit my need. I've a question now Are these resistor (R9-R12) part of the filters ? Is there any drawback in changing the value as I made (beside lowering the gain...)? Should I change at the same time also R5-R8 ?
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Indigo		#6 Posted : Sunday, June 26, 2011 1:46:28 AM(UTC)
Rank: Member Groups: Member Joined: 3/1/2011(UTC) Posts: 23 Location: Italia		Indigo wrote: Hi Russ, I've made some test and I've found 1k for R9-R12 best fit my need. I've a question now Are these resistor (R9-R12) part of the filters ? Is there any drawback in changing the value as I made (beside lowering the gain...)? Should I change at the same time also R5-R8 ? Russ, do you have any comment on this? Thank you
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Russ White		#7 Posted : Monday, June 27, 2011 6:16:32 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)		No they are not, there is no down side to doing it this way. :)
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Indigo		#8 Posted : Tuesday, June 28, 2011 5:20:36 AM(UTC)
Rank: Member Groups: Member Joined: 3/1/2011(UTC) Posts: 23 Location: Italia		Thank you very much.
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acl0056		#9 Posted : Friday, February 24, 2012 7:10:01 AM(UTC)
Rank: Member Groups: Member Joined: 11/16/2010(UTC) Posts: 24 Location: Dallas TX USA Thanks: 2 times		I have a similar but opposite question... Are there any drawbacks to adding gain with the BAL/SE op amp? Would that reduce CMRR? I am looking to drive Pass' F4 amps, which don't have any front end gain. It looks like the OPA1632 can only swing 4.5V, but the LME49720 can give me the voltage I need.
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Brian Donegan		#10 Posted : Friday, February 24, 2012 7:34:44 AM(UTC)
Rank: Administration Groups: Administration, Customer Joined: 10/24/2006(UTC) Posts: 2,868 Location: Massachusetts, USA Thanks: 2 times Was thanked: 141 time(s) in 134 post(s)		There should be no issues adding gain to the SE opamp stage.
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acl0056		#11 Posted : Saturday, February 25, 2012 1:28:03 PM(UTC)
Rank: Member Groups: Member Joined: 11/16/2010(UTC) Posts: 24 Location: Dallas TX USA Thanks: 2 times		Then that's what I will do. Thanks Brian!
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