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Old 30th June 2010, 04:23 AM   #1
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Default cap coupled phono input?

Recently started using a old Linn LK-1 preamp - amongst a number of design features that are either interesting or bizarre -( your choice) both MC and MM inputs are capacitor coupled - why'd they configure it that way ?
Amongst other things - this would seem to make loading down MM carts by simply using the y-plug and parallel resistor technique ineffective ?
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Old 30th June 2010, 04:38 AM   #2
Salas is offline Salas  Greece
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They use BJT head amp probably and maybe there is significant input offset danger in their design (especially for production run, not lab matched and trimmed input section parameters) to create enough current through the carts. AC loading impedance remains unaffected.
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Old 30th June 2010, 05:09 PM   #3
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Default 47kOhm plus 47kOhm= 23.5 ?

If I understand this correctly (which implies I understand it at all -clearly not the case)- then adding 47kOhm via external Y-plug across the existing 47kOhm MM section will still yield 23.5 kOhm - the input coupling cap won't make any difference in this ?
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Old 30th June 2010, 05:38 PM   #4
Salas is offline Salas  Greece
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Will only remain 47K for DC and it will halve for AC. Music is AC. But I would do that inside, soldering the extra resistor on top of the original load resistor for quality reasons anyway. The distance's inductance for the resistor combo will make Y a poor & subjectively misleading choice.

P.S. Have a check it is 47k internally and not 100k, because I just saw a 1989 review that Stereophile's Atkinson had found 100k for MM, 220R for MC and 100k for line despite the published specs. He also confirms it is BJT input with an LM358 DC servo around a cascode dif head amp with tantalum(!) input caps most likely for MC, but thankfully polycarbonate for MM in your case.
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Old 23rd October 2013, 08:13 PM   #5
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Quote:
Originally Posted by Salas View Post
Have a check it is 47k internally and not 100k, because I just saw a 1989
review that Stereophile's Atkinson had found 100k for MM, 220R for MC and 100k
for line despite the published specs.
Vice versa, isn't it?
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