Hello Mark. Thank you for your feedback. The initial idea is to use the JFETs at Idss (or as close to as possible and select the groups for a close match. The JFETs that I have in hand have Idss grouping in the neighborhood between 5:4 and 6:4. The PBC may be populated in that ratio with some not populated to balance output offset voltage.
Thank you for pointing out the floating nodes. I have added the gate reference resistors.
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all roads are leading to Rome
Nah, scrape it, this one is a toll road, too expensive in terms of voltage: the double MOS current mirror is using up too much of it. Of course, it's originally designed as an HPA.
Thank you for the help. Here are the corrections. The input ref resistor can be non-populated if the builder wishes.
I will see how many of these can fit on a 100mm x 100mm PCB and build one. The resistor values can be played with to see what works.
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Swap the mirror FET's for BJT's (BC327/337-40) and use 100R & 50R emitter resistors.
I'd also move the feedback to the top end of R4.
45V is too high for the JFET's, you'll need to cascode them.
Thx for the hints.
I pick the UTHAiM on a whim, but I don't feel comfy with this topology: the original UTHAiM fed with +/- 24V starts clipping at about 16V peak, with all harmonics present.
Maybe I'll explore the F5 as a FE, or even something more buildable like the MP150/Goldmund FE, we'll see. No offence, but I don't like the BA3.
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Regarding rail voltages, found the following quote:
Radioactdave:
Nelson knows these IR parts inside and out. The operating voltage is always
matched to the the part having lowest possible gate capacitance for example,
same goes for operating temperature.
The Stasis SA3 has numerous avid fans, and it appears that one of the main differences was that it was strictly class A.
If we don't need the power of A/B, is it fairly simple to tweak the new FE it to be class A?
Or even better, a switch or two that would allow us to go back and forth?
If it's possible, add me to Zen Mod's "spoon-feed-me" list, and provide as many details as you have patience for...thanks!
If we don't need the power of A/B, is it fairly simple to tweak the new FE it to be class A?
Or even better, a switch or two that would allow us to go back and forth?
If it's possible, add me to Zen Mod's "spoon-feed-me" list, and provide as many details as you have patience for...thanks!
that's just matter of carefully chosen rails, resistor values in OS and how far you're going with bias trimpot crank
FE is pretty much not caring how much you gonna sweat OS stage
though - remember that I said I'm gonna be armchair Dodo Expert this time, Mighty Moi not going to build Stasis
FE is pretty much not caring how much you gonna sweat OS stage
though - remember that I said I'm gonna be armchair Dodo Expert this time, Mighty Moi not going to build Stasis
I am not going "over the top" with my build. 800VA toroid (2 x 30VAC secondaries) to give +/-40VDC rails, using LT4320 active rectifier, with approx 60,000 uF supply capacitance per rail per channel (240,000uF total). Using the 8 pair ZM OS pcb and Nelson's new FE pcb. 4u x 500mm deep pico chassis. Biased to around 45 to 50 deg C on top part of heatsink. Extras will include a mains soft start board and XRK's SSR solid state speaker pcb per channel. Plenty of room in that chassis for all those parts.