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K&K Audio / Lundahl Transformers Welcome! Need support, you got it. Or share youe ideas and experiences. |
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In Reply to: RE: First stage phono preamp transformer output coupled posted by d888sp4@gmail.com on March 6, 2017 at 08:43:27:
It is difficult to make out the schematic values and the graph axis on the forum post. What operating point are you using for the E810F, 30mA? My experiments with 7788s have given me Rp=4K @ Ip = 12.5mA and Va = 155VDC. Of course, at higher currents, the Rp will be lower.. However, Amperex 7788s are, as a rule, too microphonic for phono use. I chose to use the 6J52P, which was quieter, albeit with an 18% higher Rp at 12.5mA. Although that circuit was a differential output stage using the LL1689/PP, the LL1692A/30mA (Lp = 54H @ 3.5:1) would be a better choice for your SE circuit. Perhaps the LL1971 just didn't have enough primary inductance.
Kevin Carter
K&K Audio
www.kandkaudio.com
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Follow Ups
- RE: First stage phono preamp transformer output coupled - KevinC 16:54:32 03/06/17 (3)
- RE: First stage phono preamp transformer output coupled - d888sp4@gmail.com 00:27:30 03/07/17 (2)
- RE: First stage phono preamp transformer output coupled - KevinC 17:34:19 03/08/17 (1)
- RE: First stage phono preamp transformer output coupled - d888sp4@gmail.com 23:57:32 03/08/17 (0)
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