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BUF03, BUF04 or BUF634 (and DC offsets)

Posted by avian (A) on April 24, 2003 at 06:47:54

G'day,
I've been searching the archives and unfortunetly cant find any solid answers to the below questions.

First I plan to make a simple preamp (like the old stereophile aunt corey greenberg "buffered passive preamp" article), with a stepped attenuator and buffer on the output. Ive been looking at the BUF03, BUF04, BUF634..

It seems most people have made the comment that the BUF634's are sonically the better of the lot, but what worries me is the biasing current and resulting DC offset (especially in wide bandwidth mode). Unless im reading the datasheet incorrectly, theres typically a 5uA biasing current in WB mode, if I use a 100k pot (or equivalent stepped attenutator), it'd result in 500mV DC offset which just seems too high. Am I missing something here?

So my basic question is this.. Which way should i go? Should I just settle for a BUF03 at the output of the preamp and be happy.. Or should I use a BUF634 and deal with the DC offset by perhaps using a cap or something? Which would sound better? Is there a way around the BUF634's DC offset that wont sonically degrade the preamp and isnt too hard to implement?

Thanks in advance!

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