Sony XA2-ES Tweak.

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ctong

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Joined 2005
Keruskerfuerst said:
In my opinion, you should use an adaptor 2xSMD -> DIP8.
Very good audio ops are:
1. BB OPA627
2. AD825

In this case, a OPA2132 may be not the right choice, since it is an JFET input OP. The source impedance has to be <=2kOhm.

And have a closer look at the power regulation.
Click to expand...

JFETs have high input impedence, therefore can tolerate higher source impedence than bipolar transistors.
 
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ctong

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Joined 2005
Keruskerfuerst said:
But a FET has a non-constant input capacity.
Click to expand...

The input capacitance of a typical JFET opams is only a few pf. Therefore, any nonlinear modulation is not likely to result in significant distortion in audio applications. This issue will be important for power FET (e.g., IRF240), which indeed needs a low-impedance source.
 
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ctong

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Joined 2005
Keruskerfuerst said:
The distortion will increase by the factor of 5, if the source impedance is greater than 2kOhm.

You can measure and hear this.
Click to expand...


There are many ways to use opamps incorrectly. I do not know what circuit you use around opamps so I cannot comment on your measurements. However, in general, when the input impedance for both the noninverting and inverting inputs are matched, the nonlinear modulation due to the JFET input capacitance becomes a common-mode signal and is rejected.
 
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