My correction amplifier is a simpler thing, not aiming for the highest quality, but good enough that I cannot hear any
major difference between the corrected XDR and a NAD receiver. As it is for use external to the tuner, it has
unity gain (below the roll-off) to maintain the same output level as the tuner.
Here, the choice of op-amp is not critical, so use your own favourite, or the LM358/LM2904 series
which is something of an 'industry standard' for single-supply low-power applications. This correction amplifier
does not need a low noise or high frequency device.
Component values are not critical as we are not trying for audiophile quality here, so just use the nearest E12 values. If you wish to experiment with the frequency response, start first by changing the values shown as 3n3 and 1n5
The power supply requirements are not critical either, and can be un-regulated, in the range 5 - 15V, supply current is ~0.5mA @ 6V, ~0.6mA @ 12V
If mounting the amplifier internally to the XDR, you can omit the i-p & o-p 1µ cap's & resistors. Cut JW15 (right) & JW14 (left), connect the side adjacent to the tuner module to the amplifier i-p, and the other side of each JW to the amplifier o-p. Take the supply preferably from the regulated +8V line at eg C302; Gnd is at eg JW29
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