DEF Amp

Vgs: 6.35V @ Id: 1.305A
It seems a little too high for an ultra simple DEF. I begin to think that, for this types of devices, the Vgs of my three SIC is a rare exception.
The experiments with the DEF have gone a little further, but now they are stopped because I have to decide how to proceed for the PSU.
 
I have not read the entire thread but from what I have, it seems most of the efforts have been focused on speaker amps. What about a line level DEF? I recently came across a P channel mosfet that has a low enough threshold voltage to work well with a small jfet. The LP0701. Paired here with a J113, the couple bias up around 5.25ma. I don't think an output cap that large is necessary, I just oversized it to lower the noise floor in simulation to show the distortion. Even then, the only thing visible is the second harmonic.
 

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Here's another option. The BSP129 is a depletion mode mosfet, also with a very low threshold voltage. Replacing the J113, the pair autobiases around 9.5ma. The distortion profile is not as second harmonic dominant as with the J113. But the overall distortion is lower.
 

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A 2Sj201 with a 2.x Vgs would probably be a decent fit against a cascoded
LU1014, and might a 2SJ618.

But then I also count about 7 Ixsys depletion mode parts in TO-247's with a
depletion range of about -.7 V to -2.7V.

And we haven't begun to explore the SIT possibilities, including the Sony VFETs

Just getting caught up on 2 years absence and after reading 6 or 8 pages of this DEF thread, I believe the 2SJ115 might be a good candidate also for the P chan bottom device with a cascoded LU1014. It looks like it is from the same family as the 2SJ201. I have the Vgs range "O" which is -.8-1.6, darn close to the LU1014. I bought a tube of each 2SJ115/2SK415 many years ago for a couple of projects I was working on...so glad to still have some. :D

Am I on the right track? I'm going to try putting it in Spice as soon as I find all the models.

Thanks!
 

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