I'm stumped. I used some trimpots to bias a pair of low-volt tubes (12DW8s, cathode follower) and had some awesome sound, but when replacing with an equivalent resistor, the sound goes to crap (clipping and bassfarts at a much lower level than with the trimpots). As it's a low-volt headphone amp I'm not worried about the trimpots so I'll likely just leave them there, but I'm trying to figure out what makes it so much amazingly better.
All I can think is that it's not just a resistor, but a voltage divider, and that has something to do with it.
All I can think is that it's not just a resistor, but a voltage divider, and that has something to do with it.
It's possible that you measured the wrong part of the trim pot and hence installed the wrong value resistors. If you were using the trim pot in voltage divider mode then obviously replicate that with the fixed resistors. Replace a trim pot with exactly the same value resistors and the performance will be the same. If the performance suffers it's a measurement / installation issue, and nothing to do with "fixed vs variable resistance".
The difference in material won`t make any difference in level before clipping.
Possibly the viper point of contact in the pot doesnt like the current, and increase resistanse value when current runs through it. So if measuring the voltage drop across the pot and across the resistor you can find out.
Possibly the viper point of contact in the pot doesnt like the current, and increase resistanse value when current runs through it. So if measuring the voltage drop across the pot and across the resistor you can find out.
I think *you* like trimpots better.
Measure it, you won't find a single difference, assuming you have indeed chosen your resistors the same.
It's all in your head. So follow your head. Don't bother trying to explain it, because there is no explanation. Likewise, disregard any who try to explain it, because they're most likely way off the mark.
Tim
P.S. Ya know what... I'm going to add that to my signature.
Measure it, you won't find a single difference, assuming you have indeed chosen your resistors the same.
It's all in your head. So follow your head. Don't bother trying to explain it, because there is no explanation. Likewise, disregard any who try to explain it, because they're most likely way off the mark.
Tim
P.S. Ya know what... I'm going to add that to my signature.
I think it's gotta be that I measured it wrong or installed it wrong (which turned out to be right). Turning out to be a fun weekend if nothing else 😀
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