Need clarification on TA2024 voltage gain

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magnus h

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Joined 2013
#1
I want to raise the input gain for my TA2024 amp. From the TA2024 chip manual is says that:
AV = 12(RF/RI)
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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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#2
magnus h said:
If thats true I can do that be raising the RF resistance.
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Yes. Raise the Rf to increase.

magnus h said:
I am asking because I was told to solder a 4k7 resistor over the RF resistor (22k). This should raise the gain.
Click to expand...

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?
 
#4
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.
 
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#8
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?
 
#11
lutkeveld said:
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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Increasing Rf increases the gain of the amp, and decreasing Rin increases the input as the connected source will see a lower impedance. All things being equal and if board is correctly designed for very low noise floor then the former option would be the better one.

You can do both though if it's a very low output source. Then you can start by replacing the Rf to 47K (I normally recommend 82K) and if that's not enough you take the 22K you removed from Rf and piggyback on the Rin to halve the input impedance. Then the input impedance is still in an acceptable range (10K to 50K is the norm) and the gain is still low enough to limit problems with noise.
 
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#17
theAnonymous1 said:
Bridged and parallel are two difference things. It's possible to parallel the outputs if the inputs have identical signals. The output coils act like current sharing resistors because of their DCR. You don't gain anything though unless you use a load with half the impedance.
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Well. You do get something besides better current handling, ie. ability to drive 4 ohm loads. You effectively halve the input impedance and thereby increase the gain. And that was the whole point of the thread.

magnus h, since you're already only using one channel, it's already mono. You just tie the inputs and outputs together, respectively obviously.
 
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