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barretter · 3rd Sep 2008, 9:06 pm

I doubt that your equalization is very accurate. You can't just stick a CR combination with a time constant of 75 us in the signal path : you have to take into account the output impedance of the EF86 and the input impedance and Miller capacitance of the following triode. And using negative feedback for the other two poles is even more complicated. You can find all the grisly details in Morgan Jones' books.

3rd Sep 2008, 9:06 pm	#25
barretter Heptode Join Date: Jan 2006 Location: Todmorden, West Yorkshire, UK. Posts: 870	Re: Phono preamp valve kit? I doubt that your equalization is very accurate. You can't just stick a CR combination with a time constant of 75 us in the signal path : you have to take into account the output impedance of the EF86 and the input impedance and Miller capacitance of the following triode. And using negative feedback for the other two poles is even more complicated. You can find all the grisly details in Morgan Jones' books.