effect of parts quality on consistancy
2001-03-16 by GeorgeK
All, I'm just starting to build my first 300. Holy smoke, lots-o-parts! Now, I'm not picky, I just want a few things: I want to build it properly, :| I want it to work properly, I want it to perform consistency with future 300s, and I want more of them - oh, you already knew that. I see that, as in many other modules, there are different levels of precision components used throughout, and that the higher precision components are used at *critical* points in the circuit. I realize Paul knows exactly what quality components need to go where, no question. I also understand that there is a necessary compromise point between quality and affordability. (The difference between DIY and a business, er... hobby.) One good example of this is my latest oblivious trek: debugging a problem with the 410. Turns out I have a bad Vactrol - bummer. :( During this lesson, I also learned that resistors R53, R56 and R59 are used to set the idle current, and directly affect the freq1/2/3 pot settings for center frequency (Fc) accordingly. (These are 5% parts.) The 3 pots should *theoretically* operate the same, I believe. For my 410, however, the freq 2 and 3 settings for a given Fc are not the same. Actually, it's not a big difference, only about .5 on the scale. Just me bein anal. ;-) A resistor tolerance issue? In any case, I bet there will be other instances of parts just at the fringe of their tolerance ratings that may have minor unwanted side- effects and/or that affect the consistency across same-model modules. (This would of course affect patch reproducability.) And then there's that whole drift thing. So, this makes me wonder, would there be any advantage in using higher precision components across the board? Wouldn't the use of 1% metal film resistors and higher precision caps lead to more accurate module performance and/or consistency? Hey! I AM NOT questioning the performance/quality/consistency of MOTM modules, just wondering if a no-holds-barred approach in parts quality would actually make a difference. George -just bein anal- Kisslak