At your risk.
At the moment frequency response is affected whether the great Sennheiser HD-580 are connected at the output or not (possibly due to load impedance changing with frequency and the fact that the preamp is a no negative feedback design).
Also the setting of the volume pot affects frequency response. Possibly due to the fact that the load resistors are 100K, 220K and 470K for the potentiometer. Maybe some values will be reduced in redesign of one of the channels. Both channels are still on breadboard but inside an aluminum box.
There is also some 1.5dB peak at say 4KHz.
But the preamp sounds great, effortless, with dynamics, smooth violins.
Possibly due to the fact that all source resistors are un bypassed (no electrolytic capacitor in parallel). Therefore each stage is at low gain. And the passive RIAA network is as close to the input are possible. just after the low gain 1st stage.
So everything sounds smooth, undistorted, violins with no harshness. This is what was told to Thymios, having the pleasure of meeting such a nice engineer for the first time.
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