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Old 29th April 2005, 09:24 AM   #1
Franz G is offline Franz G  Switzerland
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Default NAD 541i CD Player: purpose of four resistors?

I got a service manual (thanks, Mario!) for the NAD 541i (requests please with subject "NAD 541i": franz.gysi@tiscalinet.ch).

I have a question, concerning four resistors: what is the purpose of the 220R resistors in the power supply part for the opamps?

Are this current limiters, for safety reason?

Do you think, they influence the sound (in a positive or negative sense)?

Kind regards
Franz
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Old 29th April 2005, 10:07 AM   #2
Franz G is offline Franz G  Switzerland
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Idea (I was thinking while taking a shower):

The resulting additional RC-filters (after the regulators), are responsible for a proper decoupling at audio frequencies between the two stages .

Could this be a logical explanation?

Franz
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Old 30th April 2005, 03:07 PM   #3
Franz G is offline Franz G  Switzerland
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Smile

I just remarked in the circuit above: the caps C372 and C374 are shown with wrong polarization

Plop...

Franz
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Old 30th April 2005, 04:10 PM   #4
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Default Re: NAD 541i CD Player: purpose of four resistors?

Quote:
Originally posted by Franz G


I have a question, concerning four resistors: what is the purpose of the 220R resistors in the power supply part for the opamps?

Hi

If you inspect with a scope , the power rails inside a CD player, you will find to much digital noise.
This RC filter , do the filtering of this high frequency rubbish ,specially because , at this high frequencies , the PSRR of the op-amps are poorer...

Regards

Jorge
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