Re: Valve Phono Preamp [message #68444 is a reply to message #68442] |
Sat, 02 July 2011 18:31 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to previous message](/forum/theme/AudioRoundTable/images/down.png) |
FL152
Messages: 29 Registered: April 2011
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Chancellor |
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Hm, I`d try half of that 113k value, say standard 56k. As you said, suprisingly, there are not too much RIAA deviation with some resistor values changes (tenths of dB, or 1 dB "over" 20 Hz in your case), but those deviations are in "wide" frequency spectrum and can be heard.
Quick calculation gives Rout~28k from SRPP (must be measured or at least calculated and/or simulated), and when we use about 56k for series resistor in parallel with 1 Meg, this gives:
R = (28+56)x1000 / (28+56+1000) = 77,5 k , about right.
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