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PJL · 9th Jun 2019, 11:44 am

Seems to be jumping in at the deep end. Here is my thread on a valve phono stage and there are plenty of simpler designs in there https://www.vintage-radio.net/forum/...d.php?t=102751.

I found hiss to be a problem with a pentode (EF86) phono stage so why not start with a simple 2-stage triode design with feedback? You can then add constant current sources or whatever and see if there is any improvement.

A design feature of most phono stages is plenty of LF roll-off to remove the distortion caused by warps in the record. The commercial IC design had a roll off of -18dB/octave.

9th Jun 2019, 11:44 am	#17
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Valve preamp. Seems to be jumping in at the deep end. Here is my thread on a valve phono stage and there are plenty of simpler designs in there https://www.vintage-radio.net/forum/...d.php?t=102751. I found hiss to be a problem with a pentode (EF86) phono stage so why not start with a simple 2-stage triode design with feedback? You can then add constant current sources or whatever and see if there is any improvement. A design feature of most phono stages is plenty of LF roll-off to remove the distortion caused by warps in the record. The commercial IC design had a roll off of -18dB/octave.