DEF Amp

[vdi_nenna]

What about the mosfet route- depletion mode mosfet?

https://www.mouser.com/datasheet/2/205/DS100261C(IXTH-T16N50D2)-1131746.pdf

 

[Zen Mod]

looking at Figure 4 - it'll work - Ugs around -2V

 

[vdi_nenna]

Nice! I LOVE the sound of Followers. Really want to hear this amp!

thanks!

 

[Dennis Hui]

Nice find Vince! Might be fun to get a couple to test.

Dennis

 

[indra1]

Can this jfet work?...

Hi Vince, I also find the UJN interesting. I try a follower topology sim with the help of a couple of pnps.

 

[Nelson Pass]

And this makes it difficult to match to a P-ch enhancement mode mosfet...

But you could easily use a conventional bias voltage network to get
what you need, attaching the P ch Gate to positive and so on.

 

[vdi_nenna]

The same approach that was applied to the IXYS Follower can be applied to a less than perfectly matched depletion mode N-ch jfet and P-ch enhancement mode mosfet? Only drawback is that it's not as simple and self-contained as the schematic in post #1?

 

[Zen Mod]

well, all iterations already covered ..... few latest schematics from indra being sort of new , if you like that approach

practically , all possible combinations of parts (regarding Ugs and polarity of same) are possible , one just need to choose path for fun

 

[claudio52]

Hi vdi_nenna, this is my last experiment with a DEF amp. I hope it help you. The thermal coefficients of the two FET and the resistor network stabilize the amplifier. The main harmonic until the clipping is the second(Vout=10.55Vrms).
The Vgs of the JFET can be a problem. See post #149.

 

[vdi_nenna]

Caludio52, thank you for sharing your work.

The UJN120K is at end of life. However, there are two suggested replacements on right side of the web page at Mouser Electronics. Can one of these be a suitable replacement?

UJN1208K UnitedSiC | Mouser

Thanks again,

Vince

 

[claudio52]

Mouser indicates the UJ3N120070K3S as a similar product. In an electric car it is probable. In audio????
Claudio

 

[indra1]

F5 topology, 2SK79 SIT DEF style at input, Lateral output

Good news guys, I found another one to spook you. Currently just a sim, a small SIT 2SK79 paired with a bjt DEF style performs well in the F5 topology with the lateral MOSFET at the output. H2 / H3 is predicted to be close to SIT3 with damping factor ~40.

 

[Zen Mod]

me likee

 

[MEPER]

The noise floor is very low...… -200 dB?
Is the simulation realistic?

 

[indra1]

So far Ltspice models I use predicts frequency response, H2 and H3 distortion pretty close to real circuit. I have not paid attention to noise, could be inaccurate.

 

[Tom V]

Completed DEF Amp

Anybody interested in a completed DEF amp? Asking for a friend.

-Tom-

 

[vdi_nenna]

When is the auction?

 

[Nelson Pass]

I have one ready to ship to management of BAF. He will figure out
how to turn it into BAF financing. Previously it was Ebay.

 

[Zen Mod]

it did good , on Ebay?

 

[Nelson Pass]

It did very well, going to a well known DIYer.