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Old 6th November 2013, 04:10 PM   #1
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Default Need clarification on TA2024 voltage gain

I want to raise the input gain for my TA2024 amp. From the TA2024 chip manual is says that:
AV = 12(RF/RI)
where RF = feedback resistor, RI = inverting input resistance. And i guess AV = voltage gain?

So if i want higher input gain I have to raise AV, right?

If thats true I can do that be raising the RF resistance.

I am asking because I was told to solder a 4k7 resistor over the RF resistor (22k). This should raise the gain. But when i try to calculate the total resistance from the 4k7 and 22k i get a lower value than the 22k ohm. That makes me confused.

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Last edited by magnus h; 6th November 2013 at 04:12 PM. Reason: formatting
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Old 6th November 2013, 04:29 PM   #2
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Quote:
Originally Posted by magnus h View Post
If thats true I can do that be raising the RF resistance.
Yes. Raise the Rf to increase.

Quote:
Originally Posted by magnus h View Post
I am asking because I was told to solder a 4k7 resistor over the RF resistor (22k). This should raise the gain.
You have been given wrong advice then. That would dramatically decrease gain (by -12dB or so).

Are you sure you read the advice correctly? Could it be that it said to replace the Rf with a 47K resistor for +6dB increased gain instead?
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Old 6th November 2013, 04:36 PM   #3
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This was what i was told
Quote:
Solder a 4k7 ohm parellel over the resistor indicated in this picture: http://oi39.tinypic.com/34yckdv.jpg
But i think you are right about replacing the resistor. I will try that.
Thank you!
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Old 6th November 2013, 04:53 PM   #4
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Seems to me that the person giving the advice does not have the same board version as you perhaps?

The resistor highlighted in that pic seems to be the Rin. Piggybacking a 4K7 resistor on top would indeed increase gain.

Last edited by Saturnus; 6th November 2013 at 04:58 PM.
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Old 6th November 2013, 05:03 PM   #5
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Yes the picture is for another version than the one i have, but i thought it would be the same.
My version is this http://www.sure-electronics.net/down...V300%20SCH.pdf
By looking at the datasheet i guess that i should change R15 and R21. From what you say they should be higher than the 22k ohm that they are now, right?
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Old 6th November 2013, 05:08 PM   #6
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On your version you either replace the Rf (R15+R21) with a higher value or lower the value of Rin (R18+R22) for example by piggybacking a resistor on top. Either would increase gain.
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Old 6th November 2013, 05:16 PM   #7
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Understood. I really appreciate the help.
Thank you!
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Old 6th November 2013, 05:56 PM   #8
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Saturnus, increasing R15 and R21 would increase the resistance right? Then it would be more difficult for a lower power device to drive the amplifier? I thought, and it worked with my version of the amp, decreasing the total resistance to about 4k ohm would increase the max volume with lower power outputs?
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Old 6th November 2013, 07:07 PM   #9
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Quote:
Originally Posted by lutkeveld View Post
Saturnus, increasing R15 and R21 would increase the resistance right?
Yes, as you should.

Higher resistance of Rf = higher gain

Lower resistance of Rin = higher gain

You probably inadvertently decrease Rin, not Rf.
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Old 6th November 2013, 07:19 PM   #10
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Oops that may be the case. Rin=RI on the datasheet right? I thought it was R1, the number of the resistor on the board.

Which of the two is better, or is there no difference?
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