Wiz wrote:Hey Terry
thanks for posting...
When I get the BOM I might pop back and get some eyes run over it...
I was wondering about resistors.... carbon comp, metal film. vishays etc..
It's really tricky recommending components where I don't know much about the rest of the signal chain.
Years ago I did repairs on an old Ampex 351 mic pre for a pro audio client. It had mainly old Allen Bradley carbon comp R's and a variety of C's. It had a lot of spurious noise which took a few goes to get rid of completely due to the random nature. I first replaced a bunch of CC resistors (with new carbon / metal film), asked the client 'does it still sound the same' - 'yep, still sounds great'. Did a second round of component changes, CC R's etc, client - "yep still sounds the same - great" In this case and his signal chain they didn't seem to make much difference. And this guy has got good ears. I figured this was a pretty colored pre (IP / OP traffos / tubes etc) so that seemed to dominate.
However later I was testing a DAC I had designed / built which had HQ film OP coupling cap, from memory a Relcap Tin/Polyprop. I swappedin a pair of esoteric Mundorf caps, same value and it made a big difference to my surprise.
So what I'm saying (in a long winded way) is it seems to vary a lot as to how much difference they make and it is not always predictable. So my advice is always don't throw too much money at esoteric components until you definitely find a spot where you can hear 'em.
WRT Redd 47 - it's a pretty simple direct circuit, I like it a lot. Components may well make a difference. I'm tempted to build a few myself.
What transformers did you use?
cheers