I routinely rotate the transformers in FW product to set the noise levels
at the lowest equal value. My F6 proto came out a bit over 0.1 mV
😎
Papa,
When you say rotate, do you mean swap one out for another or twist the torroid on it's mounting bolt for minimum hum?
When you say rotate, do you mean swap one out for another or twist the torroid on it's mounting bolt for minimum hum?
I believe that R1 is the feedback resistor from output ? If so I'd leave it at 100R as this would still get us close to the orig 15 db gain。if you would like the actual exact formula it's somewhere earlier on this thread - I can look for it.
I have been surprised a couple of times how much difference this can make. My builds tend to be in tighter quarters than what i have seen from the FW chassis.
I set both R13 and R14 at .025 ohms and spent a couple of days listening. I think the soundstage is both wider and deeper than with r13, R14 set to zero.I also appear to have more detail. Don't know if its me thinking I need to hear something different 😉 I am going to set R13 to .0125 , keeping R14 at .025and give a listen. Then I will reverse the two. In my system this resistance range is where I get the most stimulation to my ears. Resistors are 5W wirewounds
Best
Bob
Best
Bob
That did the trick. After rotating only about 15 degrees both channels are somewhere between 0.1 and 0.2mV RMS. (The Fluke meter indicates 0.1mV with its leads shorted).
wouldnt it be better to allow for the Toshiba jfets to be mounted either back to back, or side by side to allow thermal bonding either with grease/silver epoxy or one of EUVL's trick little heatsinks?
Face to face (flat to flat) allows them to be zip-tied together for thermal tracking.
Patrick's heatsinks have them side by side so a pair of J74 could be used instead of a J109, on the same pad. For good thermal tracking face to face would be the most logical in this project.
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