LR Phono with cathode feedback winding

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docali
Posts: 58
Joined: Thu Oct 16, 2008 7:16 am

LR Phono with cathode feedback winding

Post by docali »

Hello,

fo a log time I was thinking how to bias a potential LR phono amplifier. Steve proposed to use LED bias with a small portion of low frequency feedback. As proposed in the D3a line stage I tried to simulate the szenario with separate cathode feddback windings (CFB). LTSpice yielded goog results but I had to use the CFB of the second stage with inverted polarity and honestly I do not understand why - but it works.

Unfortunately I cannot find an option to attach the LTSpice file.
Attachments
RIAA_D3a_SB_CFB.asc
(4.95 KiB) Downloaded 724 times
d3a_TF.inc
(573 Bytes) Downloaded 789 times
docali
Posts: 58
Joined: Thu Oct 16, 2008 7:16 am

Post by docali »

Mmh, I think that this approach will not work. A transient simulation revealed a really terrible signal form. If tha CFB has the same polarity as the anode loading coil the signal looks fine.
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