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Old 4th April 2013, 09:43 PM   #111
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Please read several posts above, you will hardly get an answer:

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Old 4th April 2013, 10:36 PM   #112
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Default LP797 MC/MM

Thanks PMA. Sad to hear. Well, I viewed all previous posts came up with this:
"for switching the gain (MC/MM) in the second stage (where everything is already at 20-30mV)" he mentions a relay which I see on his schematic and it is not clear to me.

Oh well...if some patient person can spell it out for me, great. When I see Mr. Jung's phono pre using LT1115 in the data sheet for LT1115, switching in/out MM and MC makes total visual and electronic sense to me.

Again, any one else wants to take a shot, I would appreciate it.

Bruce
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Old 4th April 2013, 11:08 PM   #113
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Old 4th April 2013, 11:41 PM   #114
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Default LP797 simplicity

Thanks Jacco.

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Old 4th April 2013, 11:50 PM   #115
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No problem.

You could have figured yourself that the gain should differ 10x (20dB)

Afair, the value across the opamp is 1K.
say : R1 is the always-in gain setting resistor for MM.
And R2 for the switched one.

Gain MM : 1K/R1 + 1

1/R3 = 1/R1 + 1/R2
Gain MC : 1K/R3 + 1

(afair from Mr Colin's article, gain difference between the MM and MC setting is 19.93dB)
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