I have a few ECC40 looking for something useful to do. Is there any phono schematic that is close enough to the ECC40 for me to try building it? (It's close to a E80CC or even a 6N1P) Or if any inspirational designers could suggest a circuit...... that would be great. Andy
Andy,
Talk to Thorsten. His passive EQ phono stage uses a 12AX7/ECC83 section in the 1st gain block and a 6922 section in the 2nd gain block. Given the near equality in mu between the 6922 and the ECC40, it MIGHT be possible to use the '40 in the 2nd gain block. The Rp of the '40 is a good deal higher than that of the 6922, which suggests possible drive problems. Think about buffering the ECC40 sections with ZVN0545A MOSFETs, as described in "MOSFET Follies".
BTW, a 7F7 instead of the 12AX7 would "be in character".
Talk to Thorsten. His passive EQ phono stage uses a 12AX7/ECC83 section in the 1st gain block and a 6922 section in the 2nd gain block. Given the near equality in mu between the 6922 and the ECC40, it MIGHT be possible to use the '40 in the 2nd gain block. The Rp of the '40 is a good deal higher than that of the 6922, which suggests possible drive problems. Think about buffering the ECC40 sections with ZVN0545A MOSFETs, as described in "MOSFET Follies".
BTW, a 7F7 instead of the 12AX7 would "be in character".
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